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Camera flips 180 degrees following the path
I am new to blender and I tried to animate a camera path following this tutorial:
https://www.youtube.com/watch?v=vasfFsxCsAE
The author creates a NurbsPath for camera to follow and an empty to specify the focal point. However, things don't go to plan for me. First, after inserting the path and making the camera follow it, I use Ctrl + A to apply location, rot and scale, as recommended at 6:33, but I get a "Objects have no data to transform" message. I don't know which effect it will have on the animation, but it doesn't seem good.
Also, during the animation the camera is often diagonal to the ground, I also tried to use Twisting->Z-up for the NurbsPath as suggested at 5:50, which doesn't have the effect I expected, the camera still stays diagonal. Then I tried to add "Limit rotation" constraint to the camera. Now it stays parallel to ground plane, but instead flips 180 half way through the path and then flips back.
Additionally, when I add an empty, move it to the point I want and do Ctrl + A to apply the location as suggested at 7:07 my empty actually moves to a different location, which doesn't happen in the video. So it looks like something is wrong with my coordinate system.
Could anyone help me to resolve these issues?
The file is here, I got the model from blendswap.com, it is made by aXel.

I think I have reproduced part of your problem, but could you upload your file here ? http://blend-exchange.giantcowfilms.com/ ? Also can you try to add a vertex in the nurbs path, just to check if the camera flipping problem is still there after that ?

Ok, I edited the question to add the file.

thanks @cegaton, it works. But I am stuck on a curious behavior.. will add a question about that.

thanks @cegaton, works for me too! I think it wouldn't happen if it was interpolating in quaternions and not in Euler angles.

Noidea, @cegaton, FYI I have added this question http://blender.stackexchange.com/questions/58812/damped-track-is-this-behavior-expected

@cegaton you should make your comment an answer, if you don't, I will probably community wiki it for you.

https://docs.blender.org/manual/en/dev/modeling/curves/introduction.html Have you read this? I would also check the math in it also play around with your aperture

Nice car, that's my favourite one... so applying scale of the curve doesn't helps.
That was just a guess, I already thought that my idea wont work....
So well, your curve flows like that: sometimes the curve is over the handles and sometimes under them. On the place were the cam switches, the curve is at two places over the handles (so like Adrian Monk would Say it's not perfectly symmetric...) I checked with the fishbones the directions of your curve, but it looked okay...
Sometimes I'm a bit confusing, sorry for that!

can you edit this? I'm having a hard time understand the last part of your answer. Remember when writing an answer you should not only be thinking about the OP but everyone that will see this.

Be aware that this is purely a question and answer site, it doesn't work like a forum. Answers are only used to give a full answer to the question asked, not to discuss it. It sounds to me like you are talking about things you tried with the file when you downloaded it?

Yes, I also rewrote my post to make it better to understand... I should go to bed now ... :-D

Remove the constraints currently on the camera and use a "Track to" constraint instead, as shown below:

The camera is initially tilted because the curve is a slope. The
"Damped track constraint" doesn't rectify this because it only performs the minimum necessary rotations to have the object face the target. The flip occurs because of limitations with the actual "Limit rotation" constraint; it only works from -180° to 180°, anything outside of that range results in flipping.


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Lamp visible in solid shading, but not in rendered mode
so I'm new to blender. I was following this tutorial and found out I might have done something wrong. In object mode -> solid, I can see my lamp and the effect it has. In object mode -> rendered it's just dark and no sign of a lamp nor light.The strenght of the lamp is high enough.
Can someone help me out and tell me what I might have done wrong?

Add a screenshot to your question

@Crantisz done :)

@Lisa first, that one on the right is not "solid mode" but "rendered mode", then, you wrote two times "solid mode"  above...  then , why did you set "background" as surface, instead of "emission"?

@m.ardito oh crap, sorry! I meant render mode!
I have no idea why, but this just solved my problem. Thanks so much!

Strength 18 for cycles spot lamp is to low. Try to increase this value up to 1000 or more

This didn't work, I don't even have that faint light/light grey area like in the top picture..

This setup is pointing in the right direction, but probably @Lisa just mistakenly set a wrong "surface" type.

@m.ardito this was the problem indeed, thank you!

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


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Blender Saves game as .blend when exporting as runtime,
I made a simple game when I was bored, blender just saves it as a .blend file when I try to save it as a standalone game. I have the add-on and everything, but it just saves it as a .blend file. I saw one website that said I should copy certain files from the blender directory but I can't find that either. Does anyone know where I can find that directory, or does it work differently for linux, and if so, how do I save it as a standalone game?
I'm running Blender 2.78c with Ubuntu 16.04.
EDIT:
I saw this post Linux, Save As Game Engine Runtime not working and one of the answers says that I should check if the player path was filled in, and it is. I got curious and searched for the file, and couldn't find it. Could this be why the blender saves it as a .blend file?

Have you supplied the addon with the path to the blenderplayer binary?

Also are you sure you are using File > Export instead of File > Save? The directory for the files is the place you installed blender to.

You're probably exporting it wrong. Make sure you have the save as runtime addon enabled (User preferences>Addons>Game Engine). Without this you can't export as a game runtime, meaning people can't play it, like the issue you described.

Once that's done, make sure you are viewing the FIRST SCREEN you want the player to see. Splash screen, main menu, level 1, etc. When exporting, the scene you are currently viewing will be the first thing players see. Also make sure you have selected "Blender Game" under render engine options. Then you're good to export it.
NOTE: I'm on Windows, but should be the same with Linux, part from the .exe obviously.

Hope this helps.

Thanks! It worked. I didn't know I was suppose to enable game engine publishing.

Glad it helped you! Please consider marking my answer as the solution.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


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Blender Global undo is very slow on complex scenes
When I'm working with complex scenes (a few million polygons with +- some subdivision), say you're making a weapon highpoly model, the Blender's Global Undo becomes extremely slow.
Even with simple changes in the object mode, moving something and undoing, applying a modifier and undoing it or anything like that Blender freezes for 5 - 10 seconds and then responds again.
This is making working on such scenes really difficult. And it isn't my specs, I've got an i7 6700, 24 gigs of memory etc.
Are there any options, maybe addons or something to help avoid this issue?
Thanks! :)

Maybe restricting the view plane to show only the part of your object you're working on, plus reducing the number of undo steps in Preferences. Not sure if that will help, haven't tested, just ideas. Also, lighten up the viewport settings in general, for example by making sure AO is off, and that kind of thing. You could also use the Mask Modifier to hide regions of your object, and hide separate objects altogether.

My understanding is that Blender has to recalculate the dependency graph on every global undo, and this makes things slow. There isn't really a good way around it.

@Mentalist Viewport settings wouldn't give any effect, it's not related to graphics or actual preview.

@MikePan Thanks for the explanation though that's kinda sad...

The undo buffer works by actually saving the entire blend file in memory, and loading it to undo. If you have such big, complex files, that'll take a while.
A possible way to speed things up would be to enable Simplify (scene properties panel) to restrict the subdivision level, and to write parts of the scene to different blend files and link them into the scene (rather than having all data in one blend file).

Awesome idea, I'll try that out thanks! :)

@Aras if it helps, please accept this answer as the answer.

A linked scene can still slow the undo operation.

I would try to divide the object into several parts and make the object I am working on visible in a layer. This would make the computer more relaxed
Divide and conquer.

please only post in english.

That wouldn't help. As I said undoing even simple operations with any object like a cube or plane causes a short freeze. But thanks! It could help if the freeeze would be because of mesh density.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Subtract the weights of one vertex group from another
I have an issue with a rig (this is my first time rigging) where it requires the subtraction of the weights of many different Vertex Groups from the head (root) vertex group to make the rig function properly.
Here is an image showing what I wish to accomplish:

The result image is an inversion of the middle image. Do keep in mind that inversion will not cut it, since I have to remove more things from the head (root) vertex group other than just the jaw itself.
Using the remove button in the vertex group tab gives me this result

This is not satisfactory, as it removes the vertices from the vertex group, but does not subtract the weight values from it.
Google has not turned up anything so far.
Normalizing solves nothing as it still causes deformation when moving parts with Children i.e. opening and closing the jaw deforms the lower lip bones.
Removing the influence of the head (root) bone will also cause irregular behavior as well since Blender treats all weights which aren't zero as one regardless of the weight assigned due to the vertices needing a weight of one.

related: Select overlapping vertices from vertex groups

I don't think there is a command to do what you need. Maybe there is an addon but making a python script for it wouldn't be too hard. Have you tried the conventional way, ie. painting the weights making use of the possibility to hide faces and pose the bones while painting?

You can use a Vertex Weight Mix modifier.
Say you have Vertex Group A :

And B :

In order to subtract B from A, add a Vertex Weight Mix set to Subtract and to effect only group A.
Result when viewing the A Group after adding the modifier :

The data transfer function may help you.

You will have to set your two objects as they overlap. Then use the "data" button in the "Data transfer" section.
Then choose "vertex groups" as shown here
And then go to the operator options (bottom part of the first image here).

You can then choose de source : probably your group name.
Then the destination : "by name" for the same group name.
And the operator ("mix mode") :

You also have an "invert" function here in weight paint mode :


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Transparent Texture doesnt come up correctly in texture shading. A glitch?
I have 2 questions:

I am using a texture with a transparent alpha channel. It renders alright, but it displays in the 3D Viewport's texture shading mode all wrong, as you can see below. Is this a glitch or did I do something wrong?

Is there any way I can make the grey area outside the texture a different shader? Everytime I put a UVmap there, thinking nothing would appear on the model, the texture still appears! Is it obligatory to fit everything in that little square?

Any help will be appreciated! Thanks!

As for "..make the grey area outside the texture image empty of texture" I think you mean to avoid tiling image texture which uses UV coordinates; for answer see  http://blender.stackexchange.com/questions/1258/cycles-option-to-turn-off-texture-tiling. Texture shading mode can be inaccurate with textures with alpha channel, it's better to check it once rendered. Please ask one question per post, thanks.

Starting your question with, "I have two questions" is a bad idea. If you have two questions, ask two separate questions.


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Is there a way to export a rigged model with animation with IK from Blender to C4D?
I'm used to modeling and animating in Blender, but I need to render my scene in Cinema4D. I tried Collada and .fbx export, but only my controller keeps its animation; once the model and the rig are imported in Cinema4D.
I don't know if it's possible, or if I'm missing something, but is there a way to export a rigged model with animation with IK from Blender to Cinema4D ?
Thx in advance !

See this: http://blender.stackexchange.com/questions/28452/export-constraints-and-inverse-kinematics. Your best option is to bake the animation into a .mdd file.

Thx. Actually, one option I thought, was to find a way to apply the bone-driven animation to all the object of my scene, in order that they each have their own individual keyframes. Doing that isn't possible ?


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Animating a Cell Fracture Explosion
I am doing a Minecraft animation, and I am going to use cell fracture for an explosion. I had a character throw some TNT, I created the cell fracture on an alternate mesh, and I swapped the whole and cell fractured as it explodes. I animated the Rigid Body Physics before the explosion, and I turned it off after. I did the margin thing, but it doesn't move at all. It's active, and it won't respond to keyframes (normal). I set it to a location on frame 33 and to another on frame 34. When I go back to frame 33, it's still at location the frame 34 location. Essentially, it only responds during the whole thing to the most recent location keyframe. I did set the physics to all the pieces. Please help.
Before (both object and fractured are there)

After (May look like something's happening, but it just stops). Before that, it looks like that TNT is just chilling there and not responding to keyframes.


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Help baking procedural textures
So I tried baking some textures for my character and then exported the FBX to unreal.
Some textures dont have the shinyness or extra flavour in the texture.
Am bit of a noob when it comes to baking.
Please help!

Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.

From this link:

From this link you can see my model with textures:https://blender.stackexchange.com/questions/253652/mesh-is-white-when-exporting-to-fbx-cannot-get-original-textures

When i bakle a procedural texture and import the fbx to unreal the texture is not as good/same. please help.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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The environment texture and material output - Principled BDSF nodes are connected but do not show up in object view. Blender 2.9
I think my Blender is broken because I've tried everything I could source from the internet and spent hours just exploring blender.
I have 2 problems but I'll start with the environment texture. In the shade editor, I connected the Environment Texture (I uploaded a jpg image) to the Background and to the World Output. I also tried connecting the Environment Texture just to the World Output. I checked the box for "USE NODES" and in the World Properties it says the nodes are connected and yet my jpg isn't displayed. It is still the viewport display color. In the viewport drop down I made sure that WOLRD is selected. I even connected the nodes in the Shading tab, still nothing. (photos below)
The other problem I have is similar but it's for the material output. In the shade editor, I connected the Principled BDSF to the material output, checked the nodes are connected properly and nothing is working. The only way I can change my material is by disconnecting the nodes and using the Material Properties in the editors panel (there are only 3... metallic, specular, roughness).
I've googled, read forums, restarted my computer, and nothing has worked. Am I missing something or should I throw my computer away?

hello, could you please pack your images (File > External Data > Pack All Into .blend) and share your file? upload and share the link it will give you in the URL field: https://pasteall.org/blend/

For the world settings: Looking at your screenshot I can see your 3D Viewport Shading set to Solid in the top picture and Material Preview in the bottom pic. None of those views shows the background image (by default). If you want to see it there, you have to either use Rendered view or change the Shading options to Scene World in Material Preview. In Solid view it will only display a color.

For the material: if the second screenshot is supposed to show the object's material, then you have to set the Shader Editor mode to Object, yours is set to World. In this case you can only edit the world material, not the object's material.

In the upper screenshot, you are in solid mode - you won't see materials in that mode. In the lower screenshot, your are in Material preview, here you won't see any World material by default.
But as Gordon mentioned, you can see the world material by checking "Scene world" here:

Press the right button here for rendered view:
then you will see both: material for objects and your world material.

You can see the World material in Material Preview, if you set the Shading option to Scene World.

Thank you, i updated my answer


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AMD RX550 (4GB) GPU - OpenCL not available in Cycles Rendering Compute
I recently purchased a new GPU, and AMD RX550 (4GB), but in Blender OpenCL does not appear as a choice.  Would this have to do with the fact that AMDGPU-PRO drivers include AMD's OpenCL?  I don't think xserv is running with the public OpenCL - How do I test that?

Specs:
Processor: AMD FX on a Gigabyte 970A MB with 16 GB of Ram (GPU not integrated)
GPU: AMD XFX Radeon RX550 (Polaris 12)
OS: Ubuntu 16.04
Blender: 2.78c
Initially I installed version 2.76b (2.76.b+dfsg0-3build1) from the Ubuntu Software Center.  I would see similar to the above screenshot only I would also see "CPU" as a choice.
The bummer is that I haven't seen or been able to utilize my GPU for rendering.
After reading a bunch of threads on this problem, I thought maybe it was my setup not working in that version (some had success with installing a direct package from the Blender.org website).
So, I downloaded and unpacked 2.78c from the website.  When I ran blender it looks like the above screenshot. When it renders, it renders using the CPU (obviously as default), because I can see with my System Monitor the CPUs being pegged.
I'm still bummed though, because I can't use my GPU to render.  Any ideas on how to get my system and blender to communicate? (that's my hypothesis...)
I (re-)downloaded and installed the latest drivers from AMD: AMDGPU-PRO  Everything appears to have installed correctly - AMDGPU-PRO, OpenCL, etc...
However after install, I still have no choices
Also, lspci | grep VGA returns Advanced Micro Devices, Inc. [AMD/ATI] Device 699f (rev c7) - the name is a bit different, but it should be available, yes??
Any ideas on next steps?
Thanks for any help!
--Dave

I don't use Linux or AMD cards, but it sounds like an OS issue to me.  Just for kicks, you could try the 2.79 beta.  It's suppose to have improved OpenCL support, but I doubt that's what's preventing Blender from recognizing the card.
https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.79

Also, FWIW, I have used an FX-8320 CPU with a Radeon HD 6870 (yes, the ancient generation) and I was able to GPU render on Windows 7 on Blender 2.77.

@bertmoog thanks for your ideas.  I really think it has to do with the way that blender is reading my system configuration.  I've loaded blender on my work computer (W7) and I've been able to choose the correct GPU no problem.  It's Linux & Blender conflicts.

I know this isn't the answer you're looking for (it's not one I'm happy with either), but, at the moment—even two months after you first asked…
You either need a different video card or a different OS.
OpenCL support is currently broken in the official AMD drivers for the RX 550 specifically {1}. This is still true as of the 17.30-465504 AMDGPU-PRO drivers and Ubuntu 16.04.3 (which they finally support).
While the card supports OpenCL natively and works in Windows, it is unclear when fully working (i.e. including OpenCL) Linux drivers will be released.
A comment on the AMD Community boards suggests that there is a working internal build that has been tested against the RX 550 as of August 11th, 2017. When this will be publicly released is unclear as of now. In addition to the evidence I've linked to supporting this conclusion, I've personally confirmed that the issue is specific to the RX 550 by dropping an RX 580 into a Ubuntu 16.04.3 system with identical drivers without any issue: the RX 580 shows up and works fine with OpenCL, the RX 550 continues to not be seen as an OpenCL device.
I've also personally tried the oibaf open source drivers, but have not been able to get OpenCL working on the RX 550 with them. This weekend I will give that another try using Ubuntu Zesty instead of the 16.04 LTS, now that I have an RX 580 to help act as a control comparison case.
I would suggest posting in the above linked thread or contacting AMD directly, referencing the linked comment, and asking for the internal build that is working for OpenCL on the RX 550. Otherwise the only available options seem to be either waiting for them to be released publicly, getting a different graphics card, or not using Linux with the RX 550 for now.
{1}: Supporting evidence (in addition to the thread linked in the second paragraph):

https://community.amd.com/thread/217469
https://github.com/ethereum-mining/ethminer/issues/88
https://community.amd.com/message/2804598

Allegedly the fix: https://cgit.freedesktop.org/mesa/mesa/commit/?id=69e6eab6533ff48f72223cd21ef640242c52598b

It's 3 years later and google bought me here, My RX 550 does not have the OpenCL option, I have amdgpu-pro-20.30-110958 installed and the current Blender, so has it still not been fixed?

Today I found a solution in installing drivers for this video card here https://forum.ubuntu-it.org/viewtopic.php?t=639965
I ran the installation with options (previously - removed the driver):
sudo ./amdgpu-pro-install -y --opencl=pal,legacy --headless

OS: Ubuntu 20.04
Blender: 2.83.10
Radeon™ Software for Linux® Driver for Ubuntu 20.04.1: 20.45 (Download driver)
GPU: AMD Radeon RX550
CPU: AMD FX-6100

I'll add that after a reboot, I was unable to start a user session ...
I had to go through the following steps to restore the system:

upgrade the system kernel to 5.10.6-051006-generic
kernel module amdgpu set to autoload in file /etc/modules-load.d/modules.conf
(just added the module name amdgpu)
also deleted amdgpu from the black list - moved the file to a temporary folder mv /etc/modprobe.d/blacklist-amdgpu.conf ~/downloads/
executed the command update-initramfs -u
after that the work was restored.

install linux-image-5.4.0-54-generic only
see here for more information
upd:
New driver 21.10
with linux-image-5.8.18-050818-generic works now too


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How to render with alpha-channel defined by object form?
I need a transparent hole in a specific part of my render defined by object. For example, I have a cube. How to make an alpha-channel on the place of a cube?

There may be a simpler way to do this, but since no one's answered yet, here's a way:
Put the cube on a separate render layer from the scene:

Set transparency under Render properties:

The Scene layer image should be used for the output image.  The Cube layer's alpha is inverted and used as the output image alpha.

Composite image:

If you don't want the shadow, just exclude the cube's layer from the scene:

Composite without shadow:

EDIT:
If you want to use this with an environment map as the background:
Make the cube Diffuse and perfectly (1.0) white:

Uncheck Transparent:

Use the Diffuse Color render pass:

Invert the Diffuse Color pass and use it as the composite alpha:

The holdout node can be used to cut an object from the scene.

The Holdout shader node is used to create a “hole” in the image with zero alpha transparency, which is useful for compositing

Note that the holdout only cuts through objects in the scene, you need to render with transparency and composite the scene onto the environment pass if you want the background.
You can also set the object pass index and use the ID Mask Node to mask it out in the compositor. The material index is the same thing applied to the material instead of the whole object.


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Mouse click released immediately on drag; can't drag nodes
I've recently switched to Linux Mint from Windows. Everything in Blender is running fine, except for the fact that I can't seem to hold down 'mouse drag' operations.
I click, hold down the mouse button - yet as soon as I move the mouse, the button is showing as released by Blender. I've installed the Screencast Keys add-on to demonstrate this. When checking the console, I get a weird warning related to keycodes.

Bad keycode lookup. Keysym 0x0 Status: XLookupNone
'' 0x7f9503135200 0x7f9533585b40

Here is a GIF to demonstrate the problem:
Value sliders in the UI seem to work, but nodes and their connections can't be dragged - making it pretty difficult to work.
EDIT:
To clarify, I'm using XFCE as the window manager

When I try to move nodes like this, it sometimes releases on its own too, which is pretty annoying. Just click on the node and press G to move it. It never let me down. ;)

Yeah, I know about the translate hotkey; but this has been failing continuously, and it also won't allow me to drag node connections - which is a major hassle having to rely on the hotkeys.

This sounds like an OS settings problem. If not, though, report it on developer.blender.org

@ZargulTheWizard If it is an OS settings problem, then it only affects Blender. Programs like Krita and Openshot can perform drag operations without a problem. It seems to only affect the node system.

That is weird. This may be a bug, or potentially just a user preferences problem. Try resetting the preferences, and if the problem persists, go to developer.blender.org to report a bug.


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How to indent a cone, like a rocket engine nozzle
I'd like to indent a cone on a RCS port I am making for Kerbal Space Program, I have the model mostly but do not have the RCS nozzles indented, they are just a cone. Here is a picture if that helps:
Reference:

Scene currently:

It helps to add more detail such as a reference image of what it is you are modeling so people that want to help can guide you the right direction.

Ok, I want it to look like this: http://www.space-propulsion.com/launcher-propulsion/rocket-engines/images/hm-7-nozzle.jpg

Try deleting the bottom face of the cone, if that's what you're trying to accomplish.

hit the bottom face. press e to extrude s to reduce size then limit the axis, probably shift-z or z to scale only in 2 dimensions. type 0.9. this creates a ridge. press e to extrude again, g to manipulate position and shift the bottom of the cone upwards. (z direction) then scale down until it falls inside the outer cone.


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How do you transfer Weights?
I have good weights for my upper arm on the left side, as shown, but how can I apply those weights to the upper arm on the right side. I already tried transfer weights and chose destination as the upper arm right, but it didn't work. Please help

Did you try mirroring weights ? Transfer weights works for vertex groups of different objects, not only one.

Related - http://blender.stackexchange.com/questions/9390/how-can-i-mirror-weight-painting

I think what you're looking for is mirroring weights, not transfering them.
First, just for the sake of having a clean file, delete the Armature modifiers you're not using. Second, to mirror weights you need two things: that the bones are correctly named, telling Blender which are right bones and which are left bones (see Naming Convention here*), and that you have an active mirror modifier or the X Mirror option turned on in Options, in the T menu while painting weights. If you didn't have the bones named correctly when you created the Armature modifier and created the vertex groups then you need to either rename them manually in the Data menu or delete them and create the Armature modifier again, recreating the vertex groups.
So, explained in other words:

Name your bones correctly BEFORE creating the Armature modifier (which creates the vertex groups with the same names).
Have your model with an active Mirror modifier or turn on X Mirror in T menu in Options tab without the Mirror modifier.
Paint.

*Extract from Blender's Naming Convention documentation linked above:

If you have a bone that has a copy on the other side (a pair), like an arm, give them one of the following separators:
  Left/right separators can be either the second position (L_calfbone) or last-but-one (calfbone.R)
If there is a lower or upper case L, R, left or right, Blender handles the counter part correctly. See below for a list of valid separators. Pick one and stick to it as close as possible when rigging, it will pay off. (...)

The workflow for your goal requires you do a few extra steps:

Delete half of your model(assuming there's no asymmetries you want to preserve).
Put a new mirror modifier on it.  Make sure its above the armature modifier in the modifier stack.
Weight paint onto the remaining half of the model.
Once your done weight-painting, apply the mirror modifier.


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Enabling import/export .FBX addon
I have User Preferences --> Addons --> Import-Export: Autodesk FBX Format checked, but .FBX does not show up in  File --> Import.
Is there something else I need to do to enable this?
Thank you.

Did you click "Save User Preferences"?  If so, it should be under File --> Import --> FBX (.fbx)

Thank you for the responses.
I have done:
File --> User Preferences --> Save User Settings
Should that be sufficient or is there something else I need to do?

@DrMark Strange. That add-on is normally automatically included and enabled in Blender. Is it possible that you accidentally disabled it because it was already enabled?

Just to make sure I enabled everything (for some reason 'Nodes Efficiency Tools' wouldn't enable) and I restarted Blender.
I still see 'Autodesk FBX (.fbx)' on under 'export' but not under 'import'.
I didn't see any Autodesk entries under 'import' - lots of import types
but not that one.
FYI: I'm running Blender 2.67b under Windows 7 Enterprise.

The fix was to upgrade to version 3.77. The DBX addons worked fine after that.


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How to display patterns on an LED cube?
I'm trying to render a test for a large scale LED cube, and it would be cool to light it up virtually.  I can't think of a way to add textures other than on the surface of the LEDs themselves (i.e. all of them being one colour, as opposed to some being the default plastic shaders and others being emissions).  Currently, all balls are set to a procedural transparent plastic texture. What I want is for some balls to illuminate entirely and others to be off, like an LED cube, but in a definitive shape, like a lotus or wave.  Rendered in cycles.
This is the cube for testing:

This would be an example of a shader effect that shows pixel for pixel an accurate image like this lotus:

Are you trying to use an image texture, a procedural texture? What is your current shader tree now?Cycles or EEVEE? Please [edit] your question and share enough information so that other users will understand your goals and current progress. Thanks

Done.  Please see edits.

Read https://blender.stackexchange.com/questions/39508/how-to-give-an-image-or-video-a-tv-screen-effect "color" LEDs are small pixels of RGB emitters.

But if you want to use a single LED as a color pixel, just use the same emission material for all of the LEDs and usa an image texture that uses an empty as coordinates, like in the link above.

@susu thanks for the link...I tried that and it was very cool but it basically projected a 2D image on the balls.  So I wouldn't have been able to see depth or be able to move the camera around and see the image in perspective.  However, I was able to simply use a boolean modifier on the icosphere (see my answer) set to intersect and that kind of worked.

So pretty simple solution actually...I basically used an object (in this case icosphere) inside the cube and gave it an emission shader and used the boolean modifier set to intersect with the cube.  Not perfect, but did the job somewhat reasonably.


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Quick Explode Modifier in Blender Internal Does Not Affect All Objects
I'm not sure if this problem is common, but I was working with the Quick Explode modifier, and in the pre-rendered scene it worked alright, even when I pressed rendered view, but after I actually rendered it, the exploded object remained visible.

Pre rendered (everything is ok).

Post rendered (2 of the exploded Islands to the left are still there).

Could you upload a .blend file?

With quick explode, under the modifier settings ensure that dead is not ticked on.

Otherwise, the particles will not disappear after their lifetime. Under default settings, this is the only reason that I know of that the particles should remain. If your animation is shorter than 50 frames however, which is the default, then go to the particle tab and change the lifetime of the objects particle system as needed.


text:
Understanding Fluid dynamics - ridiculously large tmp folder
Recently, I've received access to a high-performance PC; I wanted to check on its capability with Blender's fluid dynamics. First, I set simple system of fluid domain, fluid inflow, etc., with Final Resolution: 200, time from 0.000 to 4.000, and 1000 frames of animation. Blender told me, that it will get 770 Mb of space. After this, I made a script to run by the CLI through SSH:
import bpy
bpy.ops.fluid.bake()
bpy.ops.render.render(animation=True)

Then I ran a command:
nohup ./blender -b ../u3.blend --python script.py &

After 48 hours of computing, I received this from my tmp folder:
179G    /tmp/blender_lFkZps/

Animation looked great, though - below I present single frame:

Now for the questions.

Why the /tmp/blender_*** took so much space?
Why, even if fluid simulation had only 4 seconds - which gives 4*24=96 frames - it lasts for all 1000 frames? Does it mean that if I would change setting to 2000 frames it would be 2x slower?

Cache size
Fluid cashes are BIG. Blender must store the entire mesh (which is considerably dense at higher resolutions) for every frame.
If your fluid mesh comes out to an average of say 500K verts, well, you've seen for yourself what happens when you need to store 1000 versions of a mesh of that density.
 It only gets worse if you want to store additional data such as velocity vectors.
Instead of putting all of it in /tmp you probably want to configure this to go somewhere else by setting the path in Properties > Physics > Fluid:

Simulation time
The way blender's current fluid simulator works with time is rather confusing.
Based on my tests, it seems the fluid simulation always goes from frame 0 to the scene end frame (set in the timeline or in Properties > Render > Dimensions > Frame Range)
The start and end time settings in the fluid panel influence the speed of the simulation. If you want the fluid to move in "real time", you'll have to manually calculate how long the range from frame 0 to the scene end frame is in seconds, at the desired framerate (you can change the scene framerate in Properties > Render > Dimensions).
For 251 frames (counting from 0) at 24 frames/second, that works out to 251/24 ≅ 10.46. So, set the start time to 0 and the end time to 10.46.
Setting the start time to something other than 0 simulates up to that point, but discards prior frames and sets the fluid frame at that time to the scene frame 0. In other words, with a start time of 1 the simulation will appear to "start" one second in, but in order to do this the previous second must still be simulated behind the scenes.
All of this is made even sillier by the fact that you can also adjust the speed of the simulation much more easily with the fluid speed factor, just below the start and end time settings.

This is admittedly a spectacularly messy example of one of the darker sides of Blender's UI. The good news is that the current (ancient) fluid simulator is being replaced in one of the upcoming GSoC 2016 projects (hopefully the UI will be going too).


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How to join multiple separate faces into one mesh
I imported a model into Blender and all faces are separate. Nothing is connected together except the three vertices of each triangle. Is there any way to join all of the triangular faces at once in a logical manner? This is the model with one face separate for demonstration purposes.

Select all, ctrl-V -> remove doubles. On the left there is a panel where you can adjust threshold for merging.

Use A once or twice while in edit mode to select all faces (will be outlined in orange, then key W and click on Remove Doubles from the menu that appears.


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Increase Intensity of Vertex Group
I am trying to create some low poly mountains.

My issue concerns the pine trees, which I have added to make my lake look bigger. I have used the Properties panel > Particles tab > Vertex Groups dropdown > Length: setting to control the length of the trees (Hair particles), for added depth.
My Weight Painting for the Length: setting:

I like the transition, but I'm wondering if it's possible to increase the intensity (i.e. lesser values become less, greater values become greater) to increase the contrast of the sizes between the trees in the foreground and background.

Is that using several PS can be a solution?

@lemon Fair point. That would work. If no one can come up with a way to increase the intensity, I'll do that. Thanks!

If you go into weight paint mode with vertex select mask selected...

...and selected all your vertices, you can use the smooth button which works both ways.

Interesting idea, but this does not answer my question. This averages/increases the weight. I'm hoping for something that makes the high's higher and the low's lower. And perhaps not just to 1.0 and 0.0 weights, but to like 5 and -4, for example. Stark contrast!

"No weight will ever be set to values above 1.0 or below 0.0 regardless of the settings." Blender Manual. I understood that you wanted more contrast which is possible.


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How to delete vertices that are not part of a face using python
I want to delete vertices that are not part of a face (as for example the selected ones in the image) using python.
What I tried so far is:

switch to face select mode
select all faces
switch to vertex select mode
invert selection
delete vertices

This method is very unstable though, blender crashes every other time.

This code will do literally the same thing as you suggest.  It operates on the active object.  Change the line that starts object = to the object you want, if you don't want to use the active object.
import bpy
import bmesh

object = bpy.context.active_object

if object.mode == 'OBJECT':
    bm = bmesh.new()
    bm.from_mesh(object.data)
else:
    bm = bmesh.from_edit_mesh(object.data)

bm.verts.ensure_lookup_table()
bm.faces.ensure_lookup_table()

for face in bm.faces:
    face.select_set(True)

for vert in bm.verts:
    vert.select_set(not vert.select)

for vert in bm.verts:
    if vert.select:
        bm.verts.remove(vert)

if object.mode == 'OBJECT':
    bm.to_mesh(object.data)
    bm.free()
else:
    bmesh.update_edit_mesh(object.data)

There are other ways to do this; but this is the simplest to follow.  For example, the two loops through bm.verts can be combined to one loop, by noting that all of the verts you want to delete are deselected after you've selected all the faces.  So those two loops become simply
for vert in bm.verts:
    if not vert.select:
        bm.verts.remove(vert)

Thank you so much! Took me a bit to implement it in my code but now it works!


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Copy object 'ai-is' (without animation / transforms / etc)
I have an object that's been animated, shape keyed, transformed, etc over the course of 800 frames. Now I want to make a copy of it. But I don't want to copy all of the shape keys, keyframes or anything else. I don't care about that stuff anymore. I don't want it attached in any way. It did its job, now we're moving on to something else.
I just want to make a copy of the object (every vertex, edge and face) as it's sitting there, in that position, in the layout editor on frame 801 as a fresh, clean, unlinked, etc. object.
Can this be done?

Depending on whether "as is" means with or without the deformations due to the animation (armature, parents, shapekeys), the actions to perform are as follows:
Taking the default cube as an example, with deformations from an armature and a shapekey:

With animation deformation

Select mesh object, ⇧ ShiftD to duplicate,  RMB to keep it in the same position.
 RMB > convert to mesh (with is the same as going in the modifier tab and applying every modifier one by one and also applies all shape keys "as is" into the final mesh).
⎇ Altp > Clear parents keep Transformation.
⎈ Ctrla > apply all transforms

Without animation deformation

Select mesh object, ⇧ ShiftD to duplicate,  RMB to keep it in the same position.
In modifiers tab, delete Armature Modifier
In Mesh data tab > Shape Keys panel, use the popover menu to delete all shapekets:

⎇ Altp > Clear parents keep Transformation.
⎈ Ctrla > apply all transforms

add any object you like, add this geometry nodetree:

of course, for "cube" you have to choose your object with your shape keys.
Then apply the GN modifier.
Done.


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CUDA Error in Cycles on a Mac
I keep getting a CUDA error when I try to render cycles with GPU Compute selected. In this answer (the site won't allow me to respond there) https://blender.stackexchange.com/a/18408/20471, @BlendingJake says that SSS on the GPU eats up so much memory that it is recommended to have more than 1 GB of memory on for your GPU. I'm having the same problem as the OP in that string; however, I have 2 GB of RAM on my GPU. Why do I still get this error?  My specs are below:
1.System: OSX 10.11.3
2.Blender version: 2.76
3.Processor: 2.3 GHz Intel Core i7
4.Memory: 16 GB 1600 MHz DDR3
5.Graphics: NVIDIA GeForce GT 750M 2048 MB
6.CUDA Driver Version: 7.5.25

Depending on the size of your scene overall, it's quite likely that 2GB isn't even enough.

Also depends if you're using your card for video display as well as rendering, this leaves less resources for Blender.

I have the same issue on a Mac Pro 5,1 using an Nvidia 980GTX with 4gb of ram. It'll CUDA error on a simple scene sometimes.
• What I can find help is to shut all other apps down reopen Blender and try again.
• Reboot, only open blender and try again
• I use a 4k monitor, sometimes, halving the resolution can make it work.
I think it's a known error, that I really hope it's something that's addressed in the future.
Is this only mac users or do windows / linux users suffer the same problem? I might make a bootcamp or linux partition if there's no issues there.

Thanks, @cshelswell. When I only have Blender open, I am able to render a moderately complex shot. But a shot that is probably twice as complex results in the same error.  I guess I know what my limitations are. I don't know if this is a Mac problem or not. Please post if you find that the bootcamp or linux partition solves it.


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How do I make these facial tattoos without messing up the topology using nodes in cycles?
I made the black tattoos on the model on the left by sliding vertices and coloring the faces. Of course this messed up the topology of the face (which I would like to animate). I've been trying to use texture painting to achieve the same look of the model on the left on the model on the right without sliding the vertices and messing up my topology. I can't figure out how to do this. I've come close, but I'm sure there is some concept concerning texture painting that I don't understand that keeps me from getting the result I want. How do I make these black tattoos without messing up the topology using nodes in cycles?

I finally figured it out with the help of someone at Blender Discord. I used texture painting and the node setup below. The key is the RGB to BW node. This allowed me to paint two separate materials onto one quad face. I appreciate your help, @JtheNinja.

The RGB to BW node shouldn't be necessary, Cycles should apply one internally automatically when you attach a color (yellow socket) to a float input (gray socket). It's just a legacy feature leftover from before that was available. If you've found a situation in the current version where it's necessary, you may want to report it as a bug.

So, @JtheNinja, I could just delete the RGB to BW node and attach the Color from the Image Texture node to the Fac input of the Mix Shader and get the same result?

Correct. Early versions of Cycles this wouldn't have worked, and that's what the RGB to BW node was created for. Modern-day Cycles essentially just adds it for you internally. The node is only still around to avoid breaking old scene files that use it. (AFAIK, anyway)

If you want to do this with Blender texture painting, use the stencil brush mode:
https://www.youtube.com/watch?v=gacSqM7kHGg
Stencil will allow you to "spray through" a 2D image to project it's patterns onto the mesh.
To back up to a more general sense, the way I'd approach this is to build the tattoos marks on a 2D sheet using your drawing/image editing tool of choice (Illustrator, GIMP, Photoshop, whatever). Then you can either use a projection tool (like Blender's stencil paint or the projection brush in Substance Painter) to spray the appropriate symbols into place. Symmetry can help you keep them even on each side. Alternately, you can lay the symbols into place in a 2D editor, but this requires a UV sheet free of distortion and with seams out of the way (such as the back of the head).
Doing this via a texture will also allow you to use a lower resolution face mesh, as you might find the one in your file tricky to weight paint and set up shape keys for.

Thanks for the info, @JtheNinja. But the tutorial you linked to does not use nodes and is in BI - not cycles.  The render engine probably doesn't matter, but I can't figure out how to use my node setup as the paint in texture paint mode. Can you tell me how to do that?

Yep, in the end you're just attaching a texture to your shader, so the only difference is the UI while you're painting. This video has a good explanation of how to do it in Cycles: https://youtu.be/LcCQKuWPhXk Short text version: the image node you have highlighted in the node graph is the one that gets painted into. Don't forget to manually save it!

In the second video, he is painting with colors from the texture paint toolbar - not with the nodes in his node editor (or maybe I'm missing something). I want to paint with my nodes - not the diffuse colors in the toolbar. I'm sure there's some idea that I'm missing here. I appreciate any more advise you (@JtheNinja or anyone else) might be able to offer.

Not sure what you mean by "paint with nodes" You don't paint patterns with nodes, that's not what they're for. Do you want to paint specific sockets in your node graph? Then you'd create the appropriate image textures and paint them individually.

I would like to use the Red_skin_102 material node group that I created to paint the red part of his face and the Black Tattoo material node group to paint the black part of his face. Does that count as painting patterns? Thanks for your help, @JtheNinja.

If I'm understanding you correctly, you want to get your nodes for both the red and black materials into a single material, attach them to a mix shader, then add a texture to the mix shader "factor". You can then paint that texture as a mask for where the black material would be, and where the red material would be.

I don't think I am describing what I want to do clearly. I tried your last suggestion, and it didn't do what I wanted. My problem boils down to this question: Is it possible to apply two separate materials to one quad face of a mesh? E.g., If I have a red material and a separate black material, is there any way to paint both of those materials onto one quad face? If I can do this, my original problem will be solved. If I find out that I cannot do this, then at least I will know not to pursue this solution anymore. Thanks again, @JtheNinja.


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Why can I pose my rigify model in Weight Paint mode, but not in Pose mode?
I have used rigify to add a rig to my model. However, I can't pose the model in Pose mode. I have checked the model in Weight Paint mode, and everything seems to be painted correctly. I can even manipulate the rig and pose the model in Weight Paint mode. But when I go back to pose mode, only the rig moves and the model does not. I have linked the .blend file.

The issue seems to be the boolean modifier, which cuts your mesh with the nail mesh. when you disable the visibility of that modifier, the armature deforms the mesh as normal. I'm not 100% sure why this happens, if it is an issue due to laggy update because the boolean takes too long, or if the boolean (more likely) messes up your vertex groups, and thus the weights. It's also interesting that weight paint ignores the boolean apparently.

That fixed the problem, aliasguru.

@Fletch thank you for providing feedback!


text:
Creating Trees and Grass for unity ? How to add alpha layer to Vertex Colors?
Ive been working for quite some time in small scene for unity, the scene is in a forest so there is plenty of trees and grass Im creating in Blender.. Im using the same technique in both cases, baking a high detail mesh into low poly planes and using these planes to populate the tree branches or making bushes of grass.
Everything is perfect, but Unity uses Alpha Vertex values to figure out how much those planes will swing with the wind, but Blender apparently doesnt have this feature!! So my tree branches planes and grass swing as a full object, I cant make the bottom vertex fixed because Unity considers they all have the same alpha value.
How can I work around this problem? Ive been looking in the internet for sometime and cant find a solution.
Thanks

If you use one of the recent nightly builds of blender
you can use the Blender Vertex Color Master Addon to get access to alpha channel.
From my quick experiments, the FBX exporter supports vertex colors. They show up in Unity. I couldn't text the animation because you didn't mention what shader you were using.

But the texture is not the problem, it is the verticies.
Unity uses the vertecies values to tell how much effect the Unity wind will have on those. It uses the Alpha value on each vertex to make this calculation.
So the problem is not the texture but the imput the mesh vertecies carry, and apparently Blender has no tool to allow us to edit the alpha value on the vertex

sorry, I mis-read. there is a 'bake to vertex color' option. I'll see if I can get that set up. Should be a similar process of baking the gradient to the vertices.

@Togu  I updated answer based on what you were asking. I think...


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Is it possible to execute an add-on when choosing 'New' to open the default file?
I am interested in creating a script that would prompt the user to either set up or starting working in a set of project folders when blender starts up.  Thanks
more details...
I was hoping to do this as a modal pop-up prompting the user whether they would like to create a new project file.  If yes, then present them with a dialog window that would allow them to either accept a set of defaults that they can create/save or alter for specific use in any given project.  For instance, a VFX project would likely need a place for media files but would probably not need a folder for a rig(s).
Perhaps this will be a moot point with the work going on in asset management now.

Can you give some more details? executing Python code on 'new file' is possible but it seems you want to initiate some kind of interaction with the user (some menu?), and Im not sure if this can work or not without more details.

Like a popup, that let's the user select from a list of templates (startup blends)? Or shall the script create asset blends for every new blend the user create?

You can capture the event like:
import bpy
from bpy.app.handlers import persistent

@persistent
def new_file_handler(scene):
    if not bpy.data.filepath:
        print("New file!")

bpy.app.handlers.load_post.append(new_file_handler)

In order to run a popup dialog, a little hack is required to delay the operator invocation (because there's no valid context for a dialog at the time of the load_post callback):
bl_info = {
    "name": "New file prompt",
    "author": "CoDEmanX",
    "version": (1, 0),
    "blender": (2, 69, 0),
    "location": "File > New",
    "description": "Open a popup dialog after a new blend is created",
    "warning": "",
    "wiki_url": "",
    "tracker_url": "",
    "category": "System"}

import bpy
from bpy.app.handlers import persistent

class SimpleOperator(bpy.types.Operator):
    """Tooltip"""
    bl_idname = "object.simple_operator"
    bl_label = "Simple Object Operator"
    bl_options = {'REGISTER', 'UNDO'} #?

    prop = bpy.props.StringProperty(name="Material", maxlen=63)
    mats = bpy.props.CollectionProperty(type=bpy.types.PropertyGroup)

    @classmethod
    def poll(cls, context):
        return not context.blend_data.filepath

    def execute(self, context):
        print(self.prop)
        return {'FINISHED'}

    def draw(self, context):
        layout = self.layout
        layout.prop_search(self, "prop", self, "mats", icon='MATERIAL')

    def invoke(self, context, event):
        self.mats.clear()
        for i in range(1, 7):
            self.mats.add().name = "Material %i" % i
        return context.window_manager.invoke_props_dialog(self)

@persistent
def scene_update_handler(scene):
    bpy.app.handlers.scene_update_pre.remove(scene_update_handler)
    bpy.ops.object.simple_operator('INVOKE_DEFAULT')

@persistent
def new_file_handler(scene):
    if not bpy.data.filepath:
        print("New file!")
        bpy.app.handlers.scene_update_pre.append(scene_update_handler)

def register():
    bpy.utils.register_class(SimpleOperator)
    bpy.app.handlers.load_post.append(new_file_handler)

def unregister():
    bpy.utils.unregister_class(SimpleOperator)
    bpy.app.handlers.load_post.remove(new_file_handler)

if __name__ == "__main__":
    register()

You may want to remove
bl_options = {'REGISTER', 'UNDO'}

so it doesn't appear in the Redo panel afterwards.
It also shows the dialog on Blender startup (needs to be installed as addon and enabled by default). This may not work with older versions, which did not trigger load events for the startup.blend. Note that the dialog may overlay the splashscreen, but there's no real problem with that.

Nice code :) Happy me :)


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How to make a camera follow a specific particle
I have been tasked with having a camera follow a specific piece of paper as it moves through an office environment. The paper is one of many that are flowing along and the shot is from the view of this one piece of paper. I know I can hand animate it, but I was wondering if there is a way to track the camera to a particle and see from it's POV (so to speak).  I would like to attach to the particle and look from it as if the camera were riding on the paper.

Do you want the camera to track the particle (look at it)? Or look from the particle (attach to it)?

I opted to manually animate the camera and keep a single particle object (piece of paper) in the field of view. Thanks

Have one piece of paper not a particle.  This item is special and follows a path. Use the follow path constraint.
You might consider baking a one particle  .. particle system.  Total 2 particle systems.
The camera can follow the path as well thus following the paper as well.
The other pieces of paper remain as particles.


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How to transfer uvs from static mesh to the same rigged and animated mesh
The problem is quite simple, I have a static character, which is not rigged, this one is fully unwrapped and textured.
Next to it, I have as well, the same mesh, this time rigged and animated, but uvs aren't done yet.
So what I would like to simply do, is to apply uvs from my static mesh to the one animated, as they are the same, that should work whitout any problem. (Although I mostly use this only on statics meshes usually, first time I try with an animated mesh and that doesn't work).
Anyway, I use CTRL+L (the join uvs function in fact). When I open the uvs of my animated mesh, they look good, well unwrapped, but on my model, the texture seems totaly messed up, not applied correctly.
Does anyone know the answer of that question ? The best solution ?

EDIT:
Another test with CTRL + L => OBJECT DATA, this time the mesh has the texture applied well, but gets deformed.
EDIT2: I just would like to mention also this. To be sure it doesn't come from these manipulations. In fact, at first, I received the animated mesh, but the uvs were not done, so what I did, is I applied the armature of this animated mesh, which was mirrored, to get a static mesh. From that mesh, I started to create the uvs. But, I deleted the half of the mesh, to work on my uvs, and then, once the uvs were done, I applied again a mirror modifier, this way I could save some uvs space (as you can seen on the screengrab below).. Do you think the fact I can't copy my uvs to the animated mesh could come from these manipulations I had done previously !?

Area both attached to the same texture image on the Image Editor?

Not sure to understand what you mean, could you explain it further ?

I see the image to the left of both screenshots, they are different. Both objects may have the same UV map now, but the destination object is still attached to a texture image related to its previous UV map. That's why it looks messed up.

Regarding your 2nd edit: deleting vertices or applying some modifier will change the object's vertex order. That's why the UV transfer gives the wrong result.

thanks for your help, but after some hours looking for a solution, It seems, It's now working corretly. It seems I've found a way to fix it.
The way I've just done it:
1) I deleted the half of the animated and rigged character (I left the skeleton, I just deleted the faces once again).
2)I deleted as well the half of the static mesh which has overlapped uvs (as a mirror had been applied just after I had done the uvs on the hald of the mesh, uvs were still good).
3) I copied the uvs from my static mesh, to the destination object (the animated character) => CTRL+L -> transfer uvs LAYOUT, and magic, it works !!!
I don't fully understand why this way it works, but maybe It's related to the fact my uvs were at first overlapped...
I hope I was enough clear... Thanks once again for the time you put to fix my prob :) !

Select the object you want to copy UV map to, then the source object. Execute Ctrl-L > Transfer UV Layouts. If you're using an older version of Blender, it's in UV Maps property group's dropdown button. This will work flawlessly only if both are exactly the same, no vertices/edges added or removed.

You still need to edit the destination object's texture to use the right UV map, afterwards.
Edit: In your case, it seems like both character meshes are attached to different image files. Two identical objects can have identical UV maps, material and texture, but look different in the viewport because they're attached to different image files:

To fix this, make sure the image file being displayed on Image Editor is the same, when both objects are edited. This doesn't affect how they're rendered, though.

That's exactly what I do ! As you can see on the screenshot above, the uv map seems to be well laid, and fits perfectly the texture, however, It's not the case in the viewport, the textures apprears like if the uvs were messed up. That's exactly the same mesh ! Except the fact one is rigged and animated. Another thing, instead of transfer UV LAYOUT, I've tried to use CTRL+L => OBJECT DATA, this time, the texture is well applied on the animated mesh, but... It deforms my characters... I've just edited my first post to add a screenshot with that problem.

@Azuk: When you enter Edit mode for the destination object, and all faces are selected, make sure the image file shown in the Image Editor is the same as when you enter Edit mode for the source object.

That's aswell the case...

@Azuk: I think you'd better just copy the UV maps, for this purpose. Copying object data also transfers the Vertex Groups, making it deformed by the other object's armature (if it also has an Armature modifier).

Your answer helped me. I needed to UV unwrap from the pose position, but stubborn Edit Mode would only unwrap from the rest position. Duplicating the object and applying the Armature Modifier produced a mesh I could unwrap from and then transfer the layout back to the original. Thank you!


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Rigging & animating a rolled chart?
I am working on an animation in which character opens a chart. The Chart will be rolled like that :

I want to rig this kind of a rolled chart & want an opening animation after that chart will look like this:

I have no idea how to do that only simple short answer will be helpful... (is it possible to do that in blender or not?). Only Short answer will be helpful.

Yes, it's possible.

But how to do that? Any Help will be appreciated.

Yes that's what I need. It meets my question & thanks for help.


text:
What should be the mesh count when I submit a model?
I have been planning to upload a 3D model lately. What is the actual definition of
polygon numbers as I don't know what subdivision level is taken as the standard for my submission. The 3D website didn't state which subdivision level of my model
should be taken as the standard for polygon counting. Any help is appreciated.

It could be a bit opinion-based, but - 1) consider triangles or quads only, in the count: if your model has n-gons (5+ vertices) those should be retopologized/converted to tri/quad polygons only - 2) It also depends on the model inherent complexity, and the target usage: interactive (games) models that should be animated (characters) are better designed with the least (or suitable) amount of (good) geometry, static models (for stills) that should be the main subject are better designed with the more detail possible, and perfect topology is somewhat less important (except texturing easiness).

How many “polygons” does my model have? apart from that we have no way of knowing how many you should have in your model.

Polygon: a plane figure with at least three straight sides and angles, and typically five or more.
The faces you see in blender are actually Polygons.
First of all you take account apply all modifier that are in .blend file.The site on which you're uploading the model usually show the guide "how to do that?".
Delete all unnecessary objects (like: camera,lights etc.).Secondly select your final model after applying all modifiers

You will see whole information about the Faces, Vertices, Edges count. No. of Faces will be the polygon count. There's no restriction on subdivision level what you used in blender that will be just okay!

This is not correct. The Face count is not the polygon count. See this answer here.


text:
Precision of Z-coordinate
Setup (reworked):
Camera position:   (0, -6, 6);
Camera angles:     (45, 0, 0) (zyx rotation sequence);
Camera resolution: X=64 [px]; Y=64[px];
Sensor sizes:      32 [mm] x 32 [mm];
  => px_per_mm:    2 [px/mm];
Focal length:      35 [mm];
Clipping:          Start = 2 [m]; End = 16 [m];

Object:            Plane orthogonal to z-axis located at z=0.
[EDIT] Used 'Blender Render' not 'Blender Cycles'.
The depth map is determined by an easy-to-compute formula, namely:
 depth(x, y) = fy * sqrt(2) * L / (fy - (y - cy))                       (1)

Where:
   L  = 6 [m] (height of the camera)
   fy = focal length * px_per_mm = 70 [px]
   cy = y-coordinate of the principal located in the middle of the screen,
        i.e. at 32 [px]

Then:
 depth(x, y) = 593.969696 / (70 - (y - 32))                             (2)

Saving the rendered image into an OpenEXR file 'plane.exr' allows to access the
depth- coordinate and compare it to the theoretical solution in (2). Save the
script below into 'extract_this.py':
import OpenEXR, Imath
import numpy
import sys

pt     = Imath.PixelType(Imath.PixelType.FLOAT)
handle = OpenEXR.InputFile("plane.exr")

dw             = handle.header()['dataWindow']
x_size, y_size = (dw.max.x - dw.min.x + 1, dw.max.y - dw.min.y + 1)
array          = numpy.fromstring(handle.channel('Z', pt), dtype=numpy.float32)
array.shape    = (y_size, x_size)
it             = numpy.nditer(array, flags=["multi_index"])

while not it.finished:
    depth = float(it[0])
    if depth < 10000:
        y, x = it.multi_index
        print x, y_size - y, depth
    it.iternext()

The call it with:
> python extract_this.py > tmp.txt

will deliver the a data file with x and y in columns 1 and 2. The depth is
stored in column 3. This can be displayed with gnuplot:
 > depth(y) = 593.969696 / (70 - (y - 32))
 > splot "tmp.txt" u 1:2:($3 - depth($2-0.5))

and delivers a picture as shown below. A '0.5' is subtracted to account for the
fact that blender seems to deliver the depth at the pixel's center. As can be
seen, there is a line where the z-coordinate is simply off the track. What can
be done about that?

Are you talking about the z-depth image data from a render? Does this answer help explain the image data variations? I also believe blender calculates z-depth from a single camera location, so each pixel is a different depth due to the angle change. Have you also considered floating point innacuracies?

My knowledge is not sufficient in order to link between the answer you mentioned and my question. Floating point inaccuracies may not account for errors in the range of 1%. The z-coordinate seems to be roughly quantified at some point in time and then brought back into float values. Of course the depth changes, and I provide the formula based on the camera intrinsics.

There are no columns in your graph. What are you referring to with "fhe first column" etc?

@Dr.Sybren; thanks, 'column' refers to columns in the data file "tmp.txt" which contained the extracted data from the EXR file. I edited the text.

Added wiki link to q, wondering whether this link would also shed some light.

The graph still has no legend, so I still have no idea what I'm looking at...

@dr Sybren: The legen says "u 2:($3 -depth($2))" and the text explains what column 2 and column 3 is.

Sure, but the lines have hard to distinguish stipple patterns, and there is no indication which line is which.

Those are not lines, those are dots. It is unclear to me why the errors appear on discrete graphs.

@Frank-ReneSchäfer maybe you are plotting non pixel values that are shifting the graph?

@Denis you are not serious, are you?

You have a plane, so it's 2 triangles. The line where the errors occur, have you checked if it's on the edge between the 2 triangles?

Just an hypothesis, if the errors match the diagonal of the plane: maybe with floating point errors, the rays pass through the plane (on the edge), and then with sampling (I don't know if the z pass has several samples, for anti-aliasing, need to check somewhere) it mixes the good value with the 'inf' value, producing the errors.

I think I found the problem.
Look at the diagonal in the picture, I just output the z pass, and get the high frequencies with substracting a blurry pass. Then the power node just reveals the error for the eye.

The effect is only with Blender internal, and not with cycles. There is an error along the edge which is the diagonal of the plane.
Now I'm not sure why it does this, but I think it's probably something like as said above:
"Just an hypothesis, if the errors match the diagonal of the plane: maybe with floating point errors, the rays pass through the plane (on the edge), and then with sampling (I don't know if the z pass has several samples, for anti-aliasing, need to check somewhere) it mixes the good value with the 'inf' value, producing the errors."
Maybe the devs are aware of the problem, I don't know.
[EDIT]
In addition here is the same pass with cycles:

The z error is not here, AND the z seems to be correctly computed. I mean by this that with blender internal z is the distance between the geometry and the plane which crosses the camera, but in cycles z seems to be the distance between the geometry and the point from which the ray is casted (so on the sensor).
So here with cycles Z depends on Y and X, not only Y.
Also the white borders you see on both images are due to the blur combine with the power node, it's a normal effect.

The line disappears if anti-aliasing is turned off (BI)

Nice, thank you. It's strange because I would say anti-aliasing could solve this issue, not create it...

Maybe anti aliasing is applied per triangle and using z depth (AA between the triangle and a surface behind)... just an hypothesis.

In my case, turning off anti-aliasing did not make the error disappear

The error dots seem to appear on discrete lines. The lines have the shape of the 'depth(y)' where 'y' is the y-pixel coordinate. Thus, I assume that the error comes from a 'y + delta-y' in the determination of the coordinate for which the z-coordinate is computed.

Sorry, I'm not sure to understand what you say... Especially the second sentence. Could you elaborate please? (maybe I blocked by the english, sorry for that :-)).
Also if you have problem with BI, can you use cycles instead? If you need the orthgonality of the z-pass, maybe try with an orthogonal camera in cycles.

Naively I thought it wasn't important because the devs are not focused anymore on Blender Internal, but you're right it is the most important thing to do. So I just followed your advice and reported the problem.

After some experimenting with different engines, I came to the conclusion that the BlenderCycles rendering engine is by far the best solution. In our experiments it is precise down to the micro-meter range. Such a precision was not possible with the traditional BlenderRender rendering engine.
However, it needs to be mentioned that the Cycles engine delivers the length of the sight ray, rather than the orthogonal distance of the point. A detailed solution, how to get the z-coordinate is provided in Question about Cycle's Z-Coordinate.


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Odd behaviour origin to 3d cursor
I'd simply like to set the origin of some meshes to the 3D cursor which is centered using SHIFT + CTRL + ALT + C.
For some reasons that doesn't work anymore with some of objects the character I'm working on. (With the shoes It still works).
The version of Blender I'm using is still 2.69.

EDIT 1 : Here is the file with the issue (I've installed the last version of Blender in the meantime as well and the problem is still there).
https://drive.google.com/open?id=0B9BrCn1hOwOWdk44STRyV3l3dzA
Note that at the moment the only solution I've found is to import the model in a new scene with the append function of blender.

No, nothing yet.

Try applying scale before positioning origin. Also are there any constraints / modifiers on mesh ? Are objects parented ?

@Azuk could you provide a .blend file to be able to help you?

This is most likely caused by any deformation hapenning on your mesh, like rigs, armatures, deformation modifiers, shape keys etc. You mesh is deformed and moving the center creates unexpected behavior. Try temporarily disabling all deformation before proceeding

In the pivot point Median point from 3D cursor

@Tak I've just edited the description and put a link to the file with the issue. In the meantime I've fixed it by creating a new scene and then I used the append function by going through File > Append... It's a workaround. That's probably a bug unless someone finds an explaination.

This is somehow caused by Rigid Body World... If you apply Scale and Visual Transform with Ctrl+A menu and then delete Rigid Body World, the object will be more predictable. However I'm not aware of Rigid Body well enough. I don't think it's a bug though - it's likely that object takes into account presence of physics and changes its location when changed origin point.

@MrZak Rigid body World ? I'm not sure I follow you. However I tried to apply all transformations with CTRL+ A (scale, location, rotation), but oddly when I do that, the mesh moves, it rotates as well. What I don't get is I haven't used any rig, shape keys, bones that could cause that behaviour if I understand well the comments I've read... It's just a simple mesh. Unless I've missed something.

The object will obviously rotate and/or shift if you apply rotation and location while Rigid Body physics still affect it. As I wrote apply Visual Transform and Scale, then delete Rigid Body World.. Here are these steps shown. Once I set origin to geometry it worked well.

Your comment should be the answer as It is the solution to my problem. Thanks, I now understand what was wrong.

I've downloaded your file and I copied the mesh you're having trouble with to a brand new blend file and Origin to 3D Cursor is working just fine! In your original file, it's acting really weird and I don't know why...

Update: Removing Rigid Body physics also seems to solve the problem. I don't know about physics so I can't help you there but it does seem like the problem is related to that!

It could be some possibilities to cause the problem. I did the job as Mr Zak and also clear all keyframe of that object, and the problem sloved. I haven't found what exactly make the issue, but I do need clear keyframes also.

I am not sure, I have never seen that shortcut used before, However, You can move the origin down to the location you want it in object mode, tab into edit mode, and move your object back up to its original location, this should produce the same result.


text:
Which is better extrusion or assembly for creating blueprints?
When creating a a model of something that will be assembled, in particular furniture blueprints, which is a better approach?
To do many extrusions of the object or the create the pieces separately and join them in parent child relationships?

I don't think this will have a definite answer. There is no 'better' way. It all depends what you are modeling or what the model will be used for etc.. Both have their pros and cons. You will tend to find assembly is used more often as it makes the model easier to manage. A blend of both might work equally as well also.

Also note that if you model pieces as separate objects, you can join them together as one object with J

Voted to close, I think we can't really give a good answer to your question... There are reasons you might do either and it depends on the project you work on, you can also join or split out objects as you work.

I would create the pieces separately and then join them later. Here are some reasons why:

It allows you to preserve separation of concerns. This in itself has many benefits; for example, you could have different team members working on different parts.
It allows you to easily animate assembly instructions by simply moving the objects.
Logically, it makes more sense: the pieces are physically separate; in the real world, they are separate objects, so they should be in Blender as well.
You can join the pieces together at any time by selecting them and pressing CtrlJ or 3D View → Tool Shelf (T) → Join, and you can separate them again with Separate (P) → By Loose Parts while in edit mode.


text:
Other possible expressions like #frame
I have learned a few minutes ago that you can type # into a numbutton to create a driver. So far the only value I know is frame. While this works nicely, it's still a bit limiting. What are the other possibilities I can input to create a driver on the fly which is a great feature btw?

frame is currently the only updated value in the driver namespace. The rest are functions, available for use in scripted expression driver through bpy.app.driver_namespace.
Several modules are already pre-imported to the driver namespace, like builtins, bpy, math, and mathutils.noise. So, other than frame, and unlike manually-registered functions, functions from these modules are available to scripted expression by default.

Can we get more examples? #noise.random() is an option. I suspect other noise types might work if they return a float number value instead of a vector (x, y, z) value. docs.blender.org/api/current/mathutils.noise.html


text:
Where are influence and mapping settings of a texture saved?
I just did the following:
  I created one material and one texture. I applied this texture to 5 slots and, which is nice, can assign different settings to each instance of the texture (influence, mapping etc).
  Does that mean texture slots are a data block? It can't be in either the texture or the material, since I only have one of each. How is that organized internally?

You're right if you switch the Properties View to Datablocks you can examine the datastructure.
You find the per slot settings (Texture Layers) under /Materials/MaterialName/Textures /TextureName.
Each texture slot has its own settings.

How the different settings influence the resulting material is controled by the influence sliders of the checked properties and the Blend Mode setting.


text:
Equivalent of the old beauty button for subdivide?
I'd like to subdivide a mesh, but only cut the long edges of the quads. So, with all faces selected, I want to halve the quads instead of quartering them
Beauty and short were settings for the subdivide tool. They did that wonderfully. Seems the functionality has been replaced or removed.
Look under options and you know what I mean.
To illustrate it further:

The top mesh is the base, the middle mesh is the result of an ordinary subdivide and the lower mesh has only it's long edges cut. Imagine thousands of long faces that need more topology.
Why don't I want to do it manually? Becaus or cases like this one:

What's today's way of doing that?

Could you add some screenshots or something to illustrate what you mean by "but only cut the long edges of the quads"? Also, back then when? In which previous version was this available?

Actually the beauty and short button were common knowledge and there for 10 years. dunno why that question deserves a downvote

maybe you could link to some old wiki pages? (BTW, it wasn't me..)

If I understand your question, you basically want Loopcut, but for many face loops at once?

I don't think you need such a thing now that Ngons are supported. You can, however, triangulate with a beauty option (if that helps). Or use one of the new tools like vertex connect, not sure what you actually wanna do without a screenshot.

@CoDEmanX I think the OP wants to take something like this and turn it into this without individually loopcutting each face loop. Subdivide gives this

I want to turn every selected face, let's assume they are all quads into two faces so that the long edges get subdivided, but not the short edges. Boy, you guys make me feel old. I admit that I'm a Blender Dino of sorts though.

I added an example image to make it more clear.

I guess I could script a specilized operator to divide quads into halves, but first tell me if you still need it, or if any of the suggested methods worked.

You can select an Edge Ring (sort of the opposite of an Edge Loop) with Ctrl+Alt+Right Click and subdivide that.

Also remember there's Subdivide Smooth as well, which is nice for interpolating the curvature of the model (though it cannot do this on a flat 2D surface like this example).
Unfortunately it won't really help in that Icosphere case though.

i did not know that. Great tip!

The trick in this case is using edge select mode.
Select one set of the long edges you want subdivided.

Use Select similar length to get all the same length edges you want subdivided.

Subdivide. Adjust the operator properties to get multiple cuts.

By only selecting the long edges when subdividing your cutting the long edges only, so you don't subdivide the short edges that gives you the 'extra' unwanted divisions between existing edges.

That works if they have the same length, but beauty took the longer edges relative to the four edges of each individual quad

I have a non-related question, how do you make the "operator properties" floating panel to appear, where you adjust the subdivide options?¿

@invicente - Press F6 - it's also the same as what is available at the bottom of the toolbar - press T

Found this post because I also miss the 'beauty' feature. You end up with useless subdivisions when subdividing short edges too. My solution is to subdivide and then remove doubles with an appropriate merge distance.


text:
Import & Render all GLBs inside a folder
Ive been working on this issue for a while and cant seem to get it quite right.
I have a batch render script that works for rendering each model individually inside a collection.
The problem is when I import 100+ items into blender they don't seem to load in, in order.
Using Blender Python, How can I:

Import 1.glb
render 1.jpeg
Delete/hide 1.glb in blender
Import 2.glb
etc.

so that each jpeg file rendered lines up with the glb file name in the folder.
Any help would be greatly appreciated!

I actually built a script for this a while ago:
https://github.com/torrinworx/Blend_My_NFTs/blob/main/src/Model_Generators/Model_Generator.py
It was made for a different purpose, importing/exporting randomized 3D models, but the core functionality of what you are looking for is there. With some slight modifications you can have this up and running:
The approach
The script needs to import the files, turn on the render cameras, render and export an image, select, then delete the files (now scene objects) you imported. All of that is looped through the directory you are storing the .glb files in, for each .glb file.
Code
import bpy
import os

path_to_glb_folder = "/Users/Path/To/Folder" # If you are using Windows use r"\Users\Path\To\Folder"
path_to_jpeg_folder = "/Users/Path/To/Folder"

def deleteAllObjects():
    """
    Deletes all objects in the current scene
    """
    deleteListObjects = ['MESH', 'CURVE', 'SURFACE', 'META', 'FONT', 'HAIR', 'POINTCLOUD', 'VOLUME', 'GPENCIL',
                         'ARMATURE', 'LATTICE', 'EMPTY', 'LIGHT', 'LIGHT_PROBE', 'CAMERA', 'SPEAKER']

    # Select all objects in the scene to be deleted:

    for o in bpy.context.scene.objects:
        for i in deleteListObjects:
            if o.type == i:
                o.select_set(False)
            else:
                o.select_set(True)
    bpy.ops.object.delete() # Deletes all selected objects in the scene

deleteAllObjects()

glb_dirList = os.listdir(path_to_glb_folder)

removeList = [".gitignore", ".DS_Store"] # If you have . files in your directory
glb_dirList = [x for x in glb_dirList if (x not in removeList)]

for i in glb_dirList:
    bpy.ops.import_scene.gltf(filepath=os.path.join()) # Import .glb file to scene

    bpy.context.scene.render.filepath = path_to_jpeg_folder # Set save path for images
    bpy.context.scene.render.image_settings.file_format = "JPEG" # Set image file format
    bpy.ops.render.render(write_still=True) # Tell Blender to render an image

    deleteAllObjects()

Is there a script to do this for all .gltf files in a folder?


text:
After defining a new bone chain the Rig is not generated (no error displayed)
Good morning everyone, I am new to the forum so if you have any advice/comments on how I wrote the post I will be more than happy to receive them.
I'll try to explain the situation: using Blender (v 2.9) I've built a 3D model of a character and now I'd like to try to move it to make simple animations (running, jumping etc.). To do this I have seen that it is necessary to define an "armor" and then generate a "rig" in order to make it easier and faster to pose the character.
I was able to understand how to set a basic armor (only the human body) and generate the rig of this, but my model is more complex, below I attach photos:

[![Lateral View][3]][3]

NOTE: I am not an expert of the Blender environment.
To understand how to use the "rig" function using already defined chains I followed the video tutorial shown at the following link:
https://www.youtube.com/watch?v=tZFnrvsZ-ds&ab_channel=CGDive
The problem I have now is to define a chain of bones for the upper and lower arms that allows the generation of a working rig exactly like that of normal arms.
I try to explain better: if you look at the image below you will see the armor that I built following the tutorial at the link above and the rig generated. And this is correct.

Now I generate a new chain of bones (by pressing shift+a) and extrude the bones I need. That done, I apply keep-offset to bind the newly generated bone chain to the rest of the armor:

At this point, going to "Object Mode" and clicking on Generate Rig, only the basic rig is generated, but not the one for the chain I built and I don't understand why (image follows):

I've tried to use the chain of bones related to the spine, or to modify the one of a leg, but without results.
Conclusions:

Can you help me understand how I get a working rig for the other 4 arms as well (with the same movement properties of the normal arms) ?
Also, if I want to move the reticle that I have made on the back of my character, in the sense that it also moves as a result of the movement of the 4 arms how could I do?

Thanks in advance of your help and support.

Rigify is modular and comes with predefined metarigs (that's what you called "armor"). These metarigs are templates for humans (basic & detailed), birds, cats, dogs, etc. They are used to align the bones to the mesh. Have you done this you can generate the final rig. If you want to have 4 more arms you need to extend the human meta rig with Rig Types bones (building blocks). Adding a simple bone chain doesn't work. Todor (CGDive) has a complete series about customized Rigify rigs: https://www.youtube.com/watch?v=-JSFcSxsaTs&list=PLdcL5aF8ZcJv68SSdwxip33M7snakl6Dx

You followed the tutorial for the two "normal" arms, right? Why don't you repeat the process for the additional arms? Just add two more arms "samples" align them to the mesh and symmetrize them.


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How to add an object with texture inside another object?
I am trying to make an eye. I made the iris in Photoshop and now I am trying to add it to a UV Sphere. I would like to make a realistic eye but maybe I am not in the correct way. Any thoughts? This is my work so far:

what do you mean by adding object to another object ?

The first thing you need is to model a proper eye. Like so:

The outer part is 0.1cm away from the inner in this case.

The outer part needs to be refractive (or even just transparent) and it will also need specular as it will catch the high spec of the eye.
Depending on the render budget you have you can add SSS to the inner part. I did in this case but the difference here is subtle. In this case i'm aiming cartoon semirealistic eye but the principles are pretty much the same for any eye.
You now have to UV unwrap the inner part. Easy, divide the eye in two parts on its XZ plane center and Unwrap.

Now you can add the diffuse texture to the inner part of the eye, but note that for a proper eye render you will need more than just a diffuse shader.
Personally I add a specular map only to the iris using an high IOR and roughness value, a bump (or displacement if needed) map aswell.
Here is the final graph of my setup:

and a little GIF preview:

Consider including a .blend file so that the user does not have to build all this.

Thanks a lot @Akelian. It is so wonderful. When you say "You now have to UV unwrap the inner part. Easy, divide the eye in two parts on its XZ plane center and Unwrap." What do you mean?  Sorry I don't have enough knowledge. Thank you.

@Akelian. For sure I will follow your stepts but I want to  compare with iris makes in photoshop so I'll make the eye but how can I add the iris? Thank you again.

i'll update the answer in the hour ;)

@Meri I have updated the post.

There are many ways to accomplish this. One approach would be to select your UV Sphere (Eyeball), Tab into Edit Mode, and select a ring of vertices

From here, press Shift + S and choose Cursor to Selected from the drop down menu. Then Tab into Object Mode and select your iris object. Press Shift + S and select Selection to Cursor from the drop down menu. NOTE: the origin of your iris object needs to be in the middle of it's geometry. If it’s not, select the iris object in Object Mode and choose the Set Origin drop down menu in the tool bar (Pressing T with your cursor in the 3D Viewport will toggle the tool bar on and off) and choose Origin to Geometry from the drop down menu.

Then in Object Mode, you can select the iris object and while holding down Shift key select the UV Sphere and press Ctrl+J to join the meshes or in “Object Mode” you can select the iris object and while holding down Shift select the UV Sphere and press Ctrl+P to parent the iris object to the UV Sphere.

Idle Chit-chat
If you are going for realism, I would suggest switching to Cycles Render (much faster, newer, better, AND built for photorealism). So, this tutorial is for Cycles. This will be the final result:

Materials
I will use a sphere to represent the eye (smooth shading), and the following eye texture from Google (full size linked) in my demonstration.

With the sphere selected, go to the Materials tab in the Properties panel. + New a material to the sphere. Go into the Node editor, and use the setup shown.

Now, go to the sphere in the 3D Viewport. Tab into edit mode, Numpad 1 to front view, and Numpad 5 to orthographic view. Enter Face Select Mode. Select these faces:

Press U and select Project from View (Bounds). Split the screen into a 3D Viewport and a UV Image Editor by dragging the marks in the top-right corner to the left. Make sure you are still in edit mode. Open the image of the eye through the toolbar at the bottom of the UV Image Editor. The orange should already be aligned over the eye.
Final Notes
I added the nodes at the bottom to create red veins in the eye. It's more realistic.
Here is the finished .blend file:

Thanks Shady, but that will not provide realistic result. You have to reproduce the way a real eye is made. I'm preparing a proper answer.

There is a place where it should have 3 buttons: a dropdown, a + New, and an open. Also, if this helped, consider accepting.

Thanks @Shady but I think you didn't finish. Now the eye is unwrap. Please can you go on? Because I want to make the pupil part. Thanks a lot for your time.

if I can help. I saw this tutorial https://vimeo.com/2830890 but I can't follow because I don't see anything and also the man doesn't talk much.

I did finish. If u did the node setup, everything should be good.

Ok, thanks. Do you know how to do it?

Just copy it or download the .blend file.

Try to avoid explicit tutorials. The idea is for this answer to be helpful to as many people as possible. I think the human eye is common enough that this will still be useful to a lot of people, but try to be generic.

Cycles is not faster than Internal

Perhaps consider accepting?


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Do not repeat the texture on Collada export?
I am trying to apply a UV mapped texture to an object and export it in the Collada format. The result is not what I designed in Blender. Here's the simplest procedure that shows what I did.

Start with the blank file and add a cube mesh.
Select texture viewport shading.
Unwrap the cube mesh (Smart UV Project).

In UV/Image Editor, open random image.
Position and scale islands so that the image is only on one side of the cube (that's how I want it).

The texture is now repeated on all sides of the cube in the viewport.

From this point on, I have three choices.
Don't assign any material

Export to Collada.
Cube is grey when viewed in MeshLab. No material, no texture, nothing. And that's fine.

Assign the material

Assign a new material to the cube (it did not have a material before).

Without changing any material properties, export to Collada. Or do make changes, the result is the same.
Cube is black with texture applied and repeated.

Why is there any texture on the cube when the material doesn't have any textures by itself?
Assign the material and the texture

Assign new material to the cube.
Add new texture, set it as image, load the same image as texture as when doing UV mapping.
Image Mapping > Extension, set to Clip.
Mapping > Coordinates, set to UV.
Mapping > Map, set to UVMap (only choice available).

Observe that none of the changes made make any difference in viewport (in render, however, they do).
Export to Collada.
Cube is black with texture applied and repeated (same as before).

Collada model represents what is viewed in the viewport, and none of the changes made in material/texture after making UV mapping get reflected on the exported model. How to get them exported?
Notes

Using Blender 2.69 with Blender Render.
When exporting to Collada:

Include UV Textures is checked.
Include Material Textures is checked.

As far as I know Collada (and most other export formats for that matter) concern themselves mostly with exporting geometry, UV's and some times animations and constraints, not materials or textures.
Materials are very tied to the rendering system they belong to and can't generally be easily exported between applications apart from some basic properties.
Whatever changes you make to your material and/or texture settings are not at all guarantied to be correctly exported, and will most often get lost, many of them are (as you already stated) not even supported as in the viewport as rendered preview (like the clipping setting).
Now I do not know Collada export very well, nor do I know MeshLab software, but if you want your texture to show up in one face alone I'd advise either to use a different material for that face, or to unrwap your mesh accordingly, having in mind that by default all textures will tile infinitely.
That probably means setting the UVs for the faces that should have no texture to 0,0 like for example scaling them down to one corner of the UV editor.
For any other more complex material properties it's probably better to do it in meshlab or whatever final destination application you will be using.
Also see .fbx export why there are no materials or textures?

If you read the Collada specification you will find that is uses a very complex way of doing materials. Basically materials and textures are treated separately.
"...Why is there any texture on the cube when the material doesn't have any textures by itself?..:" - Because any texture can be proyected onto any surface with Collada's sampler objects. When you applied the material, the texture was already set to wrap around your cube. Remember that the material is nothing but a set of properties for shading, and it may or may not include textures in them, but it's not mandatory as you can see.
"...How to get them exported?..." - I'm not sure I understood what you are trying to do. if you want the texture on just one face, unwrap that face only. If you still need to unwrap the whole thing, scale it to 0.25 or so, then offset it (those transforms will be ported to Collada).
So you need that your UV's keep the original 1:1 size, just adjust the texture, not the UV's. Remember that Collada is an exchange format, but it's not magical. You have to adjust your workflow to it.


text:
Why is the preview animation on my cloth simulation slow?
I have been trying to get the cape on my figure to work right, but the preview animation plays at about .12 fps.  This is my first attempt at cloth simulation.
Also, the cape starts to go through the shoulders at the end of the simulation.
Is there a setting that I am missing with either of these problems?
Hardware information:
Processor Name: Intel Core i7;
  Processor Speed:  2.3 GHz;
  Number of Processors: 1;
  Total Number of Cores:    4;
  L2 Cache (per Core):  256 KB;
  L3 Cache: 6 MB;
  Memory:   16 GB
You can get my blend file here:

I think this answers your play back speed issue.

Thanks, David. But I don't see how that answers my playback speed issue.  The OP of your linked question was getting 5 fps; I am only getting .12 fps. Also, the OP was asking about render animation speed.  I'm asking about simple preview playback in the 3D View Editor.  I'm pretty new to Blender, so I may be missing something.

It's all about complexity, the more data in a scene the more work there is to do scan through it during physics simulations as well as drawing it all to screen and the lower the frame rate during playback.
Your biggest culprit is the helmet, with the mirror and subsurf modifier it ends up with 1.4 million vertices. Also a subsurf level of 4 is rather high, unless your right up close you will not tell the difference between level 4 and 2 in the final render, even up close the difference is small.
If I remove the subsurf modifier from the helmet I see the frame rate jump to about 15 fps. With the subsurf level at 3 I see 5 fps and at 2 I see 9 fps.
By removing the collision from the helmet I also see 15fps with the subsurf at level 3.
If you are planning an animation then you might want to create a low poly mesh that sits close to the surface of the shoulders, parent it to the helmet so they move together, disable render visibility and use that for the cloth collision. For a still image just wait for the simulation to play through and do a render.

Thanks, sambler.  That information really helps me out here.  I appreciate it.