text:
Array modifier offset problem
I'm having a problem with the relative offset the array modifier creates for the added objects.
When I add the modifier, the relative offset is set to 1.0 in one direction and 0.0 in the other two. To me, this means that the object is being duplicated in only one direction. However, the new object appears to the upper right of the original, as if it had been moved by equal amounts in x- and y-direction. There is no displacement in z-direction.
When I enter a value into the upper box of the relative offset (x I assume?) and enter the same but negative value in the second box (y?), the object appears moved in x-direction only.
In another blender file I received from a friend the Array modifier on a very similar object behaves normally, moving the copies in only one direction.
Does anybody have an idea how to fix this problem?

After some more investigation, I think this is because the bounding box of the object is not parallel to the world axes, so the local axes which it is moved along are off. Can someone confirm that? The object was created by joining several smaller ones but from the moment of joining onwards the bounding box is at about a 45 degree angle.

The Array modifier offset can differ if object has rotation unapplied, i.e. it was rotated in Object mode (Ctrl+A > Rotation to apply).


text:
Material showing on wrong faces
I'm following this tutorial and I have applied a material to the body mesh and when I apply the material to the faces to the side of the mesh, I can see the top/bottom material is showing on the top and bottom parts of the side faces.
This is the rendered view:

https://i.sstatic.net/J9YUL.png
and this is the wireframe showing the selected faces which the side material is applied to:

https://i.sstatic.net/mD2XI.png
I'm not sure why this is happening, can anyone advise?
Thanks

As there are some modifiers on the object, could it be that there is Subsurf?

Yes there is a subsurf modifier active on the mesh.

Not sure if its the best way to go but I applied the modifier and then dissolved all the unecessary horizontal edges on the body sides and reapplied the material. Looks fine now http://imgur.com/EQrVrG3.png . Thanks for the suggestion.

The white line is trim geometry (its part of the tutorial steps)

source: Stack Exchange

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

sort: votes


text:
Dynamic Reaction Control System Animation
I'm attempting to create a node tree using the Animation Nodes addon to have automatically scaling "Reaction Control System" plumes on any arbitrary mesh.
Essentially, I am hoping to create a single "RCS Plume" object (in my test case, a simple cone), which is then instanced via the object instancer node to occur once per face, with its local z axis facing along the normal of each face. After that, I run the object list of each "plume" through a loop that is supposed to scale each plume depending on the acceleration (currently only rotational, to make things simpler in my test cases), using ClockMender's My-AN-Nodes Object Speed & Acceleration node.
However, I've only been able to get all the plumes to scale the same amounts simultaneously, or to not scale at all. Is this something that's possible with Animation Nodes and Blender?
My attempts so far are:
The uppermost nodes, creating the instances of the cones.

The nodes being used to calculate the scale when provided the value of one axis on the current, previous, and previous previous frames.

The loop itself, and where I suspect the issue lies.

Specifically, I'm unsure as to why all three object transform inputs are providing the exact same value from their rotation output, given that each should be giving a different frame. (The "Use Current Transforms" option on the two using offsets is unchecked). If instead of giving the loop a object list of each plume, I instead give it the single object that the plumes are being created on, the rotation values are different, as expected. However, this results in the same scaling occurring to each plume regardless of position, as mentioned above.
Finally, a view of my test setup:

The cube is the object that the cones are being created on, and the selected objects are the cones, currently stuck at a local z scale of 0.
My desired result would consist of each cone only scaling when it is tangent (this may be the incorrect term, apologies) to some component of the rotation, and not on the half of the object that is in the direction of motion. Additionally, the scaling would be in proportion to the acceleration, up to cap. Effectively, I would like it to appear as if the cones "firing" are the cause of the rotation, and eventually translation.

Edit 2018-03-11 13:59 EDT:
To better explain the effect I'm looking for I've created a small animation manually doing what I'm hoping to do automatically. In the dynamic version I would want a cone to scale to "slow down" the cube on the appropriate/opposite side, rather than it stopping itself.

Edit2 2018-03-13 00:28 EDT:
I've come up with a partial solution, which doesn't fulfill all of my initial requirements, but does come fairly close, and most importantly, looks decent. For reference to anyone looking to implement a RCS animation in blender with animation nodes in the future, who are looking for a (potentially useful) starting point, I've uploaded the file to Blend-Exchange:  (Look at NodeTree.001, I forgot to rename it before uploading)
This solution seems computationally heavy, in addition to not being completely physically accurate. It requires each object being instanced to become an RCS plume to have fcurves for translation and rotation. This is accomplished via Animation Nodes' Set Keyframes node, inside a loop.
The RCS effect only fires appropriately for rotation, but if translating and rotating, it will take the translation into account. This can be removed by removing the translational acceleration frame in the nodegroup.
The key to getting only one side to fire, instead of the opposite firing at the same time, was to multiply the scales for each plume by the normals of each face of the base mesh. I've absolutely no idea why this seems to mostly work.
Again, this is not physically accurate, and doesn't take relative position on the base object into account, but hopefully may be useful to someone in the future.

What version of AN are you using? Why do you think the problem isn't in your custom acceleration node? It seems it is returning zeros and thus causes the problem? It is a good idea to enable the $x$ and $y$ scales as well because they may be initially zero.

@OmarAhmad I'm using animation nodes 2.0 (the version posted on July 15, 2017 on JacquesLucke's github). You're correct in that the custom acceleration node is returning zeros, but the reason that it's doing that is because the input it's being fed is the same for each of the frame inputs as far as I can tell. I'm not sure why that's happening as I've set the Object Transform Input nodes to have the appropriate offsets, and when provided a single object, rather than an object list, I do get differing values from the 3 Object Transform Input nodes. Could this potentially be some sort of bug?

I am not sure, but frame definition in the Object Transforms Input was removed in the latest version, so I can't test it. How is the animation of your objects defined? Blender animation? if so, I recommend using Evaluate FCurve Node to compute such properties.

@OmarAhmad Unfortunately, the animation of the cone objects is dependent on the translation and rotation of the cube object, so the cones have no fcurves of their own. Using the fcurve of the cube object results in uniform scaling, in a similar way as to mentioned in the main question as well.

But isn't this exactly hat you are trying to do? that is, compute the acceleration data from the rotation data of the cube?

@OmarAhmad To my understanding, if I want to have a realistic looking RCS effect I would need to grab the acceleration data from each cone, rather than the cube, as grabbing the acceleration data from the cube results in all the cones scaling equally, which would realistically result in zero net movement of the cube. I've edited the main question with a link to an animation example of the effect I'm looking for, which will hopefully clarify things a bit better than what I can type?

I see what you are trying to do now. The original question was rather about why something isn't working than about how a DRC system can be achieved. I will research this and hopefully write an answer.

@OmarAhmad Thank you very much, I appreciate it!

I have tried to solve this as much as I can, but I failed to do so at the moment. If the magnitude of the thrusters $\vec{F}{i}$ are $\alpha{i}$ (which we want to compute) then they have to satisfy this relation:
$$
\begin{bmatrix}
\vec{A}_x \ \vec{A}_y \ \vec{A}_z
\end{bmatrix} =
\begin{bmatrix}
\vec{F_1}_x & \vec{F_2}_x & \cdots &\vec{F_n}_x\
\vec{F_1}_y & \vec{F_2}_y & \cdots &\vec{F_n}_y\
\vec{F_1}z & \vec{F_2}z & \cdots &\vec{F_n}z
\end{bmatrix}
\begin{bmatrix}
\alpha{1} \ \alpha{2} \ \vdots \ \alpha{n}
\end{bmatrix}
$$
Where $\vec{A}$ is the acceleration.

There, however, may be, infinite amounts of solutions and so the system above is not sufficient. However, we are limited to a principle of moments that is equal to the angular acceleration. This is the part I am not sure about. How do we relate them? What is the angular acceleration. As for computing the acceleration, it can be computed using a 1D laplacian of the Fcurve.

@OmarAhmad Ah, no worries, I appreciate the help regardless, and if I manage to figure something out I will update the main question or post an answer if I solve it. Thank you for the assistance and suggestions!

I believe that I've solved the issue. The solution isn't 100% physically correct, but it appears reasonably close with a few caveats:

Use Animation Nodes 2.1, no My-AN-Nodes required (this could probably be redone on 2.0)
You must also instantiate empties on each location you want a plume, then use the animation nodes Set Keyframes node set to record rotational keyframes for every frame, running entirely through your animation at least once to get that data. (This can be temperamental on Ctrl+Zs, sometimes requiring one to re-keyframe them again)
The object/cage you want to have RCS plumes must be reasonably symmetrical for the effect to look good, and be able to have some portion of it (usually all the sections below its center of rotation) covered by an invisible mesh, which determines which half of the object should have the RCS plumes fire in the opposite direction.
You must be willing to run a small bit of python code to calculate the acceleration.
You may need to tweak the values in Map Range node, depending on the speed and scale of your animation.
At this point, this node tree only handles rotational acceleration, not translational acceleration, though it is possible it could be adapted.
I am not a mathematician, and may be using any number of these nodes incorrect or only accidentally correct ways.

To start with, you'll want to create 4 objects, an object to be the RCS "plume" (I'd recommend a cone), an empty to calculate individual acceleration on, a "cage" to place the RCS on, and finally, another "cage" to mark which parts of the mesh are the "bottom" half.
Once you've positioned the second cage appropriately, parent it to the RCS cage (or whatever you've parented the RCS cage to). Next, animate the RCS cage in whatever pattern you want. Keep in mind that if you change the animation at all at a later time you'll need to re-keyframe the empties!
At this point, you're ready to create the NodeTree.

Start with the generic support nodes, including the script node to calculate acceleration. The python script is as follows:
# Mostly borrowed from https://github.com/Clockmender/My-AN-Nodes/blob/master/speed_acc.py

fps = bpy.context.scene.render.fps

dec_n = DecimalPlaces

if Minus0 == 0 and Minus1 == 0 and Minus2 == 0:
    spd_u = 0
    acc_u = 0
    acc_g = 0
else:
    spd_c = abs(Minus0 - Minus1) * fps
    spd_o = abs(Minus1 - Minus2) * fps
    acc_u = round((spd_c - spd_o) * fps,dec_n)
    spd_u = round(spd_c,dec_n)
    acc_g = round(acc_u / 9.81,dec_n)

Next, create the loop that'll calculate X, Y, and Z rotational acceleration based on the empties' keyframes.

Make sure that the the frame offsets are set on the Evaluate FCurve nodes!
Initialize all the objects and empties.

Note that the "Copy Full Object" option for the object instancer for the RCS Cone is likely only necessary if you've fiddled with the object's settings, such as their Cycles Settings.
Next, we grab the BVH tree of the Bottom Cage and check what RCS Cone objects are inside of it.

We feed this into the List Boolean subprogram we created earlier, as the Boolean Switch node is not vectorized that I can tell. This list of either -1 or 1 gets fed into a Combine Vector node, though I suspect a Vector from Value node would work as well, which is then sent into a scale Compose Matrix, which then feeds into the overall scale calculation.

I don't fully understand why the Vector Math Cross operation (of the polygon normals of the RCS Cage, and the acceleration vectors) works in keeping the scaling on "one side" of the mesh, but it does. Next that list of vectors is fed into another support subprogram that uses the Transform Vector node on each pair of vectors and matrices. Next, we separate the vector, add its components, and multiply them by 100 (to get less fractional numbers). The Map Range node determines how far each plume can scale, based on the input (set the input min to 0, and input max to whatever seems a reasonable value based on a viewer node), and the output (set the output min to 0, and the output max to however long you want the maximum length of the plumes to be). Finally, combine that value into a vector and feed it into a Object Transforms Output node with only the Z axis selected, also being fed the list of RCS Cone/Plume objects.
This next part is more cosmetic and QoL than necessity, but it will keep plume objects with a Z scale of 0 from being visible (which can cause z-fighting).

Additionally, the Keep Layer subprogram will make sure that your plumes stay on whatever layer you've selected in the subprogram's body.
For people who'd prefer to have an existent blend file to work with, here's a link:

As mentioned above, you'll need Animation Nodes 2.1
If you've made it this far, congratulations! Here's a 4 second video of the nodetree in action. (The spaceship is not included in the above blend file)

I ran out of links in the main answer, due to low reputation, so here's the link to the whole node tree, too zoomed out to be read, but helpful for seeing how the different bits in frames connect.

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

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


text:
Changing UV seams, no change in Cycles?
I'm new, and I'm texturing my first model following the very popular series on YouTube by BlenderGuru. The texture looks really nice, the only issue is that there's ugly seams where I don't want them, and as far as I know, that's from UV unwrapping. I have gone back and changed where seams were, and it's represented on the UV/Image editor, but when I go into cycles to look at it with the texture, the seam is still there. Am I misunderstanding how this all works?

enter image description here

The circled part is where there are no seams in the UV, but then in cycles it shows the seam. There WAS a seam there before I removed it.

I select all and then hit U, > Unwrap. In the UV Image editor I see the new "setup" of the unwrap. But when I go into cycles, I still see ugly seams where I had them to begin with. Is there an "update UV" button somewhere?

I updated the main post with pictures of my problem.

Could you add a screen shot of your material node set up into your question as well? Here's a couple of things to try: In Object Mode select the anvil and press CTRL+"A" and select "Scale". Then Un Wrap again. In the UV editor select your texture image as the background for the UV Map.

Added a picture of the nodes. The scale thing didn't work unfortunately and I don't know how to set a background image in the UV editor.

It looks like you maybe missing a seam(s) in the area you drew a circle around. Maybe revisit His tutorial around 16:30 where he explains that part of the anvil.

The point is that any change to the seams does nothing... I even cleared all seams and went to cycles and it is all messed up. I figured it out though, I think I would need to redo the seams on the original mesh and then rebake the normals.
Removing that bottom node, which is loading the normal map I made, fixes the ugly seams because I think it is now using the correct UV map. I have a vague idea but still confused.

There isn't any reason to mark seams and unwrap highpoly model, only lowpoly requires that. Normal map can be one of multiple reasons for that seam; seam from image texture can be as well (not necessarily, it's all theoretically). UV map updates after unwrapping (pressing U) unless uv map is pinned (which isn't from your screenshot). Though island on the bottom right in UV map seems off to me with quite a bit of stretching, maybe check it with image in the viewport and add more seams

It may help if you uploaded you .blend using http://blend-exchange.giantcowfilms.com/ and pasting the resulting link into your original question. Also, the Seams you mark on your mesh are telling Blender where to "Unfold" your mesh into the UV Map not where to "Split" it.

I'm definitely still wrapping my head around UV unwrapping. I've solved my issue as stated above, but somehow along the way I messed up the normal map? It's completely off center now. I had dents along the edge of the anvil and now they're on top of it.

Ok when I tried the "scale" option above, I think it caused the normals to be offset because i hadn't done that "Scale" thing before, so i just had to redo the baking of normals. Now everything is working nicely and I know to scale things.


text:
Blender freezes when adding a material
I have recently installed the Pbr shader. I have created a material for a landscape mesh. Later I created a rock. I tried to add a material to the rock but the screen freezes. Blender doesn't work, and the mouse doesn't move.
Now every time I open up Blender and try to add materials to anything the same thing happens, the screen freezes. I'm using cycles.

Using all caps is considered rude. What do you mean by "recently installed the PBR shader"?

sorry, I didnt wanted to sound rude. With pbr shader I reffer to an aditional shader that´s free. I download it from http://remingtongraphics.net/?s=pbr

Blender 2.79a now has a built-in PBR shader called Principled shader. Try using that instead.

this problem dosnt allow me to open up the section of materials, I dont think I can change the shader. :/ Anyway, thanks ! :D

When opening the file try do it via Ctrl+O and unchecking Load UI option in the settings on the left, this will revert to startup file settings when opening. You can temporarily create another startup where Node Editor isn't present.. Then once opened remove all materials from the file, https://blender.stackexchange.com/questions/7160/can-i-delete-all-materials-of-all-objects-in-a-scene-quickly. From your description seems that you saved PBR materials you downloaded into startup file as well

Mr Zak and Mike Pan solutions actually worked, Thanks :))))) Is there anyway I can thank your help? I mean, are there stars or something? Thanks for helping :)))


text:
why my uv maps are deforming
Note that this uv was way worse earlier. Seamingly smooth perfect squares warp and mangle unless i make more cuts than it seems like it should need.
Ok so i have props for my first ever scene for a game. Its a pretty basic set of platforms,  hand rails, and endposts, corner post and what not. I had no issues 3d modeling it. Ive been modeling for over a year now.  But im just starting to look at using my models so im learning UVs. But I cant seem to just get nice clean geometry.  Every thing blows out of proportion strangely.
there are no triangles in this model except for 4 at the bottom face to kill the n-gons. And its really just been beveled and inset to make this shape. and 1 side has been left flat. Most of the problems ive had i would use orthographic and project from veiw. But these wrap around the egde. How do i get clean square uvs from this. Im mostly worried about the top. But the sides also uv'ed to different sizes? There identical. how?
The pictures below are
So after several hours this is the cleanest result i could come up with. everything is some kinda warped, there are identical geometry that have different sizes on the uv map. And the cone for the top is slightly warped and i worked pretty hard on it. Because it was originally mangled.
i added 2 different attempts i would rather attempt 1 work .but i could settle for 2. stretching is ok in the small insets.
notes: i have already
- applied rotation and scale
- removed duplicates
- thought about applying and very heavy deform modifier.
enter image description here

https://www.take-a-screenshot.org/

Sorry ray. It was super late last night and i can get better shots this afternoon.

You aren't expected to wait until the afternoon as you shouldn't do shots altogether, take screenshots instead and include whole editor windows, not cropping only part where UVs are

shot in the dark; did you apply the size to your object?

merge duplicate vertices?

Yes actually. I tried all of the typical fixes. I just got home from work. Give me a sec and ill get proper shots.

Also Mr Zak. No aggro. But i have a full time job and mouths to feed. The afternoon bearly exsit so please bear with me. Its all i have is mabey an hour or 2 ever other day. I pretty much have 2 jobs and one works 50 hours a week. Im new here so please go easy on me

@Sphinix We're just teasing. Don't worry, the Blender community is pretty cool. I hope you can slowly optimise your workload though. But that's a topic for chat, not comments.

no problem. not harm ment. ive been given the welcome tease in several places


text:
Geometry Node Extrude Mesh, How to Apply a Material to Random Groups of Extruded Side Faces of a Cube
first time poster and Blender novice here. I am trying to use Geometry Nodes in Blender 3.1.2 to extrude subdivided faces of a cube at random to make something like a Borg Cube. Then, still using geo nodes, I want to apply a glowing/emissive material to randomly chosen "little cubes"  on all 4 of their sides (If they are not chosen by the random number generator then I do not want that extrusion to have any glowing faces. This way it makes it look like some of the small cubes can glow on their sides while others cannot glow at all.)
A quick example image of what I have so far:

The problem with that image above is that I am simply scattering glowing faces randomly across the sides of the extrusions. They aren't grouped up in any way. I would really like to group them up based on randomly chose top faces but I am having a hard time mapping the effect.
For further clarity if my goal doesn't make sense yet:

Here is my node tree so far:

Am I going in the right direction trying to use Transfer Attribute to map the 'Side' output of the Extrude Mesh node to a randomized index of the cube's faces?
Is there something wrong with my Index node? Multiplying by it seems to dristribute the emissive material all over, including on my top faces. What nodes should I be using to do this kind of material mapping (if it's possible at all). It seems like I'm just barely missing something and could not find any info on the web after hours of searching and trying all day. I would be so relieved to get some guidance and thoughts.
Lastly, for what it's worth, here is my original node tree set up, with very similar output results as my current:

Result:

The way I did:
First I separated the extruded faces from the top faces, then, for every four indexes, i got a different ID for the Random Value node that outputs a boolean to the Set Material node, which has the side faces geometry as input. In the end, I joined the top geometry with the sides.

Edit:
No Separate Geometry method:

Edit 2: Capture Attribute

This method is better because it's not dependent on the face index order, so you can modify the mesh but still know what faces are from the same group.
Here's the result when triangulating the faces before setting the material with the older methods:

The new method still works when doing this:

Note: The Floor node is not needed since the ID integer input will convert the value to the closest smaller integer. The node is there just for easy logic understanding.

Can verify this method works! Thanks so much! :)

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


text:
Texture Paint Strange Behaviour
I have just finished sculpting a character..
Will start texture painting it..
I have done this several times without any problems, but for this character the texture paint shows up on totally different spots than where I paint. I can't seem to figure out the problem. Has any of you encountered similar problems and found a cause?
In attachment Blend file and colourmap..
https://jumpshare.com/v/0iLa4sG3XPqRhm72OMXw (Blend File Link)
https://jumpshare.com/v/l18DphvIDGy2VVW7kmih (Colourmap, click on 3 dots to download)..
Map is not painted yet, but included it to be complete..

The problem is that you have two UV maps for your model and have the wrong one selected for painting.
The first, "female_1_female_base.017DiffuseUVlayer" is the one one you want to have selected in the list and have its little camera icon enabled. The UV map with the enabled Camera icon is the UV map that will be used for rendering AND painting.

The second,"UV Map" is just a mess and it would be probably best to delete it from the list.

Damn, thanks a lot!


text:
Texture Painting a HDRI Background
I would like to texture paint a HDRI background for my projects.. The idea is to texture paint an image and then use it as an environment texture in the Shader for my World Object. I would like to be able to texture paint my own sky domes..
There is one Youtube video on this topic, but it's very unclear on how exactly to achieve this result..
https://www.youtube.com/watch?v=S8gsDJs8xWA
And a Twitter Message on this topic..
https://twitter.com/mathiaszamecki/status/1418230264942243843?lang=en
I would like to know if I can realise this in Blender..
If so, how exactly?
If not, what program do I use for this?
Thank you guys!

He paints a landscape on a sphere, at the end the image can be used as HDRI.
To do it, create a sphere (it will already be unwrapped by default), scale it a lot, like 60 times, give it a material with an Image Texture (the image needs to be 2:1, for example 2048 x 1024), paint the horizon on it:

Then flip the normals, switch to Perspective mode, put your point of view in the middle of the sphere, and paint again, this time you'll paint all the details (or just some of them, it may be more convenient to paint later in the Image Editor):

Once finished, open the Image Editor and paint all the parts that have been left unpainted, you can even rework your image, add details, etc:

Now you can use the same image as Environment Texture in the World material:

Thanks moonboots!! :-)


text:
Objects behind glass shader appear black
Why is this Iris not showing? It worked previously, before I started working on the fur and particle system today and other parts of the model (a monkey model) and at the end I realised that the Iris disappeared. I haven't touched the eyeball, but now the iris doesn't show. I suspect that it has to do with the UVs, but everything is in place, I didn't tweak anything, it should work. I'm attaching a stripped down .blend (only the eyeball) and a screenshot. Can someone have a look into the file, and try to make the iris show?
I should also note, that when I open the previous file, it shows. But when I append that eyeball to the new file, it doesn't show.


text:
Why does this baked Ambient Occlusion have a dark patch on one of the faces?
I'm baking Ambient Occlusion for a game asset. It worked on the cable part (see image and blend file). But now on the camera, on its side it makes a weird split on one face, half of the face is shaded, the other not, also other faces of the camera are not shaded. But the front of the camera is shaded. What am I doing wrong here, how to get proper AO for this camera object and fix the erroneous face?

It looks like there are two overlapping surfaces here... don't you think ?

Nope, there is only one face.

I put more geometry on the camera and then it was ok. Just divide the mesh (Ctrl + R in vertical and horizontal direction) and it should work.

Ok, I figured it out, it has to do with the mirror modifier. Had to turn it off temporarily (for view and render), and then everything bakes good. Then turn it back on.


text:
Unable to separate by loose parts
I am unable to separate all the loose parts of an object which I combined from several objects.
After combining all the objects, I removed doubles.
Now I want to separate the parts again to do some additional editing.
I used the following steps to try to separate the parts

selected the object
tabbed into edit mode
clicked p
clicked on "By loose Parts"
tabbed back into object mode
unselected everything with A
clicked on part I wanted to edit and noticed two other parts  were still connected.

I repeated the process of separating by loose parts, but they will not separate.
How can I disconnect the two side panels?

I have highlighted the faces/vertices, I think might be causing the problem.  When the file is opened they should be visible.  At this stage all the components of the arm assembly are joined.  When separated by loose parts the two side panels stay joined to the main arm.
Is it possible the problem occurs because I extruded the highlighted parts through the two side panels without cutting a hole in them first?
Thank you in advance for any suggestions you may have to help me solve this issue.

hard to say, could you please share your file? https://blend-exchange.giantcowfilms.com/

Removing doubles quite likely joined two parts. Consider copying the default cube, (no transforms)  and joining.   Separate by loose parts will return two cubes.  Removing doubles will merge the two into one.

batFinger, thanks for the feedback.  I thought that might have happened, but was hoping if intersecting vertices were removed they could be separated.  At this point it may be easier to just recreat the objects unless some other option is posted here.

Well it's been about a week and with no real help here, I tinkered and finally came up with a solution.  Deleting the connecting vertices between the side panels and the arm.  There were two cylinders I had extruded from the arm through the side panels, which caused the problem.

You can test yourself by using the sample file I uploaded here at moonboots  request

tab into object mode
select object
tab into edit mode
select all faces
click P and select "by loose parts"
tab back to object mode
deselect all
select long arm and notice side panels are still connected
tab into edit mode
using faces select mode, press Alt and LMB to select all faces of first cylinder in the center of the arm.
press Shift-Alt-LMB and select all center faces of 2nd cylinder
press delete button and select vertices
tab into object mode and deselect all
verify side panels have been separated from arm by selecting each item

I now just had a few missing faces that needed to be filled in, but I preserved the location and size of all the pieces so they would fit in the model.  Also I was able to finish the editing I needed to do, to prepare my model for 3D printing.  You can verify how the assembly fits into the total model by clicking on the eye icon next to "frame" in the outliner.


text:
When can you no longer switch from Evee to Cycles render
It is a lot easier to work in Evee, but I'm trying to learn layers and collections.
Some actions are not compatible in both Evee and Cycles.
I see in some online tutorials the author will say we now have to switch to cycles because of this next action is not compatible
I would like to know what actions prevent you from changing rendering engines?  Specifically when can you no longer switch to Cycles from Evee.

This question is far too broad to be reasonably answered in it's current state, but rather than flagging it closed, perhaps the following information is useful.  Please take the time to edit your question accordingly.
You will likely have more problems going from Cycles to Eevee rather than the other way round.  If you are having a more specific problem switching to Cycles then you need to specify this in your question.
Please note that both renderers have additional settings in the material properties panel, sometimes these need to be enabled under the render settings panel before taking effect.
There's a great article about Eevee limitations on CG Cookie.
I defer to the vast knowledge-base that is the blender documentation on Eevee limitations:

Eevee Limitations
Eevee’s goal is to be an interactive render engine. Some features may
  not be there yet or may be impossible to implement into Eevee’s
  architecture without compromising performance.
Here is a rather exhaustive list of all the limitations you can expect
  while working with Eevee. Cameras

Only perspective and orthographic projections are currently supported.

Lights

Shadows are not supported on light instances (instance objects, group instancing).
Only 128 active lights can be supported by Eevee in a scene.
Only 8 Shadowed sun lights can be supported at the same time.
As of now, lights can only have one color and do not support light node trees.

Light Probes

Eevee only supports up to 128 active Reflection Cubemaps.
Eevee only supports up to 64 active Irradiance Volumes.
Eevee only supports up to 16 active Reflection Planes inside the view frustum.

Indirect Lighting

Volumetrics don’t receive light from Irradiance Volumes but do receive world’s diffuse lighting.
Eevee does not support “specular to diffuse” light bounces nor “specular to specular” light bounces.
All specular lighting is turned off during baking.

Shadows

Shadows are not supported on light instances (instance objects, group instancing).
Only 128 active lights can be supported by Eevee in a scene.
Only 8 Shadowed sun lights can be supported at the same time.

Volumetrics

Only single scattering is supported.
Volumetrics are rendered only for the camera “rays”. They don’t appear in reflections/refractions and probes.
Volumetrics don’t receive light from Irradiance Volumes but does receive world’s diffuse lighting.
Volumetric shadowing does only work on other volumetrics. They won’t cast shadows on solid objects in the scene.
Volumetric shadowing does only work for volumes inside the view frustum.
Volumetric lighting does not respect the lights shapes. They are treated as point lights.

Screen Space Effects
Eevee is not a ray tracing engine and cannot do ray-triangle
  intersection. Instead of this, Eevee uses the depth buffer as an
  approximated scene representation. This reduces the complexity of
  scene scale effects and enables a higher performance. However, only
  what is in inside the view can be considered when computing these
  effects. Also, since it only uses one layer of depth, only the
  front-most pixel distance is known.
These limitations creates a few problems:

The screen space effects disappear when reaching the screen border. This can be partially fixed by using the overscan feature.
Screen space effects lack deep information (or the thickness of objects). This is why most effects have a thickness parameter to
  control how to consider potential intersected pixels.
Blended surfaces are not considered by these effects. They are not part of the depth prepass and do not appear in the depth buffer.

Ambient Occlusion

Objects are treated as infinitely thick, producing overshadowing if the Distance is really large.

Screen Space Reflections

Only one glossy BSDF can emit screen space reflections.
The evaluated BSDF is currently arbitrarily chosen.
Screen Space Reflections will reflect transparent objects and objects using Screen Space Refraction but without accurate positioning
  due to the one layer depth buffer.

Screen Space Refraction

Only one refraction event is correctly modeled.
Only opaque and alpha hashed materials can be refracted.

Subsurface Scattering

Only one BSSRDF can produce screen space subsurface scattering.
The evaluated BSSRDF is currently arbitrarily chosen.
A maximum of 254 different surfaces can use subsurface scattering.
Only scaling is adjustable per pixel. Individual RGB radii are adjustable in the socket default value.
Input radiance from each surfaces are not isolated during the blurring, leading to light leaking from surface to surface.

Materials
Refractions
Refraction is faked by sampling the same reflection probe used by the Glossy BSDFs, but using the refracted view direction instead of
  the reflected view direction. Only the first refraction event is
  modeled correctly. An approximation of the second refraction event can
  be used for relatively thin objects using Refraction Depth. Using
  Screen Space refraction will refract what is visible inside the view,
  and use the nearest probe if there is no hit.
Screen Space Reflections and Ambient Occlusion are not compatible with Screen Space Refraction; they will be disabled on the surfaces
  that use it. Surfaces that use Screen Space Refraction will not appear
  in Screen Space Reflections at the right place. Surfaces that use
  Screen Space Refraction will not cast Ambient Occlusion onto other
  surfaces. Bump Mapping
As of now, bump mapping is supported using OpenGL derivatives which are the same for each block of 2x2 pixels. This means the bump
  output value will appear pixelated. It is recommended to use normal
  mapping instead.
Tip
If you absolutely need to render using Bump nodes, render at twice the target resolution and downscale the final output. Volume Objects
  Object volume shaders will affect the whole bounding box of the object. The shape of the volume must be adjusted using procedural
  texturing inside the shader.
Shader Nodes
All BSDF’s are using approximations to achieve realtime performance so there will always be small differences between Cycles and Eevee.
  Some utility nodes are not yet compatible with Eevee (e.g. Sky Texture node).
See also
For a full list of unsupported nodes see Nodes Support. Memory
  Management
In Eevee, GPU Memory management is done by the GPU driver. In theory,
  only the needed textures and meshes (now referred as “the resources”)
  for a single draw call (i.e. one object) needs to fit into the GPU
  memory.
So if the scene is really heavy, the driver will swap things in and
  out to make sure all objects are rendered correctly.
In practice, using too much GPU memory can make the GPU driver crash,
  freeze, or kill the application. So be careful of what you ask.
There is no standard way of estimating if the resources will fit into
  the GPU memory and/or if the GPU will render them successfully. CPU
  Rendering
Being a rasterization engine, Eevee only uses the power of the GPU to
  render. There is no plan to support CPU (software) rendering as it
  would be very inefficient. CPU power is still needed to handle high
  scene complexity as the geometry must be prepared by the CPU before
  rendering each frame. Multiple GPU Support
There is currently no support for multiple GPU systems. Headless
  Rendering
There is currently no support for using Eevee on headless systems
  (i.e. without a Display Manager).

Ad endum
There are a couple of other Eevee gotchas that you should be aware of that aren't listed here, perhaps beyond the scope here, but relate to shader nodes.

Eevee doesn't truly support displacement.
Particle Info node is Cycles only.
Other nodes may be specific (always read the docs for the node)

Exactly what I was looking for.

Glad I could help.  I've added an ad endum for some things that recently caught me out and left me scratching my brain.


text:
Unpainted object
I'm painting letters with a series of key frames.  As the brush nears the top the painting stops.
I've tried changing the size of the brush, the paint source from volume to volume + proximity. but it seems to run out of paint at a specific frame.  What is the explanation for what is happening?

The problem was in the Canvas setting, where I had to change the last frame which is 250 by default and my final frame was 350. Did not see that because I was key framing the brush


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What nodes to use for enhancing an image texture imported as a plane
I have created a mesh plane with two image texture nodes. I want to improve the quality/color of the "A Logo Text" image so I can make it stand out from the 2nd image texture.
I've to go through some node tutorials and tried to plug in various nodes, but I'm at a total loss.
What nodes can I use to enhance the "A Logo Text" image? and where would I plug it in?
The "A Logo Text" is a .png image with an alpha channel for the background as shown here.
My version of Blender is 2.82.7

Here is some of the progress I made following moonboots suggestions

"enhance" is a bit too vague, try the Color nodes, like for example RGB Curves if you want to control the general RGB intensities

Thanks. You gave me an idea and direction to go in. I see they have a hue, saturation and contrast nodes, I can insert between the image texture node and the add node. This make the text pop out, what I meant by enhancing

I think you need to put a Diffuse (or Principled BSDF) after the Math node

I was trying not to be too verbose in my original question. I am making a video title effect following the tutorial of tutor 4u seen in this link where he creates an animated scroll in blender https://www.youtube.com/watch?v=Aes92iyzFWA  Following that example, I created the scroll and some text overlay in my video editor as seen in this link https://drive.google.com/open?id=1xW9HqTfLzeznSWPlDfkm63mNTA_eZPga  What I really want now is to make the text scroll out as if it is written on the paper itself. So I need two texture images but I want the text to stand out as shown in my clip

I tried the principal shader as suggested but my adjustments on the different setting did not produce a satisfactory result.  I will edit my original entry where I can add another picture of what I have accomplished based on your suggestions

maybe you need to use an Emission shader instead of a Diffuse, it will make the letters lightening...

Why do you suggest after the math node. I really only want the text to stand out. The background is supposed to look like old paper

I've been working in the Shader tab, maybe I should be working in the compositor tab, but that leaves even more confused on where to start.

it depends on what you mean by "stand out", for example if you need a glow effect in Cycles, you'll need to use the compositor, if you need the letters to be bright, use an Emission instead of a Diffuse, mix with the background (page texture) in a Mix Shader with the alpha plugged into the alpha socket of the Mix Shader, etc...

Let us continue this discussion in chat.

Your text image needs to be a PNG with a 0% alpha background (transparent background). Then use this nodes setup: plug the 2 Image Texture nodes into 2 Diffuse nodes, mix them into a Mix Shader, use the text alpha as the factor of the Mix Shader:

Bless your patience with these questions :).

Thanks Jachym!!


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Add>Object Menu disabled?
Whenever I created an object (<2.83) a properties menu would appear allowing me to change whatever about the object (ie. vertex count on a circle/cylinder, cube size, etc), but now (2.90>) the menu does still appear but it just doesn't work.
Could the update have caused this? It's a vanilla install plus I already checked the Preferences menus for anything that could be affecting it but no luck
I greatly appreciate the help!


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Operator addons with multiple texture inputs in Python
I'm fairly new to Python in Blender and working on an add-on to allow users to input their textures without accessing the node editor. I take reference from some of the codings within this website and create an add-on with one file input but still getting struck on how to do multiple ones(e.g. diffuse, rough, normal).

Here is my original script for one file input:
import bpy
from bpy.props import StringProperty, PointerProperty

class MaterialRoughnessPanel(bpy.types.Panel):

    bl_label = "Texture Input"
    bl_idname = "MATERIAL_PT_PANEL"
    bl_space_type = "VIEW_3D"
    bl_region_type = "UI"
    bl_category = "Material Parameter"

    def draw(self, context):
        layout = self.layout
        ob = bpy.context.active_object
        ma =ob.active_material
        row=layout.row()
        row.prop(ma.slot_setting, "rough")

def updateRough(self, context):

    mat = self.id_data
    node = mat.node_tree.nodes
    nodes = [k for k in node
            if isinstance(k,  bpy.types.ShaderNodeTexImage)]

    for k in nodes:
        k.image = bpy.data.images.load(self.rough)
        return k

class roughSet(bpy.types.PropertyGroup):

    rough: StringProperty(
            name="ROUGH",
            subtype='FILE_PATH',
            update = updateRough)

def register():
    bpy.utils.register_class(MaterialRoughnessPanel)
    bpy.utils.register_class(roughSet)
    bpy.types.Material.slot_setting=PointerProperty(type=roughSet)

def unregister():
    bpy.utils.register_class(MaterialRoughnessPanel)
    bpy.utils.register_class(roughSet)
    del bpy.types.Material.slot_setting

if __name__ == "__main__":
    register()

I try to do multiple inputs by telling Blender to access the maps with if...else condition. The script can execute but it seems that Blender is confused about the condition and texture input is not working as usual.
Here is the excerpt of the script:
def updateMat(self, context):

    mat = self.id_data
    node = mat.node_tree.nodes
    prxy = bpy.types.ShaderNodeBsdfPrincipled
    img = bpy.types.ShaderNodeTextImage
    imgdif = bpy.types.ShaderNoteTextImage
    if mat.node_tree.links.new(img.outputs[0], prxy.inputs[5]):
        spec = img

        nodes = [k for k in node
                if isinstance(k, spec)]

        for k in nodes:
            k.image = bpy.data.images.load(self.rough)
            return k
    elif mat.node_tree.links.new(img.outputs[0], prxy.inputs[0]):
        dif = imgdif

        secNode = [s for s in node
                if isinstance(k, dif)]

        for s in secNode:
            s.image = bpy.data.images.load(self.diffuse)
            return s

class materialSet(bpy.types.PropertyGroup):

    rough: StringProperty(
            name="SPEC",
            subtype='FILE_PATH',
            update = updateMat)
    diffuse: StringProperty(name="DIFFUSE",
            subtype='FILE_PATH',
            update = updateMat)

I figured it out. I'd tried to think too much and the solution can be very simple. As nodes variable is already a list, I can simply tell the system which map belong to diffuse etc.
Instead of
 if mat.node_tree.links.new(img.outputs[0], prxy.inputs[5]):
        spec = img

        nodes = [k for k in node
                if isinstance(k, spec)]

        for k in nodes:
            k.image = bpy.data.images.load(self.rough)
            return k
    elif mat.node_tree.links.new(img.outputs[0], prxy.inputs[0]):
        dif = imgdif

        secNode = [s for s in node
                if isinstance(k, dif)]

        for s in secNode:
            s.image = bpy.data.images.load(self.diffuse)
            return s

I have done something like:
mat = self.id_data
node = mat.node_tree.nodes
img = bpy.types.ShaderNodeTexImage
nodes = [k for k in node
         if isinstance(k,img)]
nodes[0].image = bpy.data.images.load(self.rough)
nodes[1].image =bpy.data.images.load(self.spec)


text:
Animating with Action Sets and Action Constraints
I have a rigged robot. I want to animate it so, that when I rotate or move the bone above the head, named EarMover, the EarRingL and EarBallL will move to the side. I set up an action for this movement. The EarRingL and EarBallL move to the side and back over 40 frames. Now I need to attach the action constraint to the EarRingL and EarBallL bones so that when I rotate (or move) the EarMover bone, the Action will get played.
This is what I don't know, how to set up this action constraint so that one triggers the other?
I'm attaching a screengrab and the blend file. It's educational material for me, based on a freely available tutorial, so it is open-source. You may reuse it freely.

Here are some finished constraints.
Below Bone.Left has an action constraint.

Below Bone.Right has an action constraint.

In both cases above

[Bone.Control] of the armature is the target bone.
X location is used.
The action name [Armature.C006Action]
All settings are the same because we used one armature and this is intended to be a simple example.

In pose mode keyframes were inserted on Bone.left and Bone.Right on frames 1 and 20.  Inserting keyframes created actions with a name we can use in the action constraint panel.  When Bone control is moved in the X direction here is the result.

The action name came from the DopeSheet/Action Editor Window

In the image above the action name was created. Saved to the Abstract Vault by clicking the letter F next to the name.  The action name is remembered for the constraints.  The action is removed from the armature. Repeat. The action is removed from the armature. If you leave it by mistake the action will dominate the [action constraint] and the flexibility you want will not function.

I understand now. It has to do with Target Range, Action Range and From Target fields. I had 'zero' values there. Now I set it up and it works. As I understand, the Target Range determines how far (in BU) I have to move (or rotate) the controller bone, to play the action, right?

Yes, and its time to rely on your experimentation.

Ok, will do :-)


text:
How to fix this bone? Piston example
I followed a tutorial and created this simplified model and rig. It's a piston (blue), rod (green) and flywheel (red) example with 2 armatures consisting both of 2 bones. It works almost. Problem is with the connection-joint between the piston (blue) and the rod (green). It doesn't keep the same rotation axis or the same location (I'm not sure which one), when I rotate the flywheel the axes are off. I need the piston and rod, to connect well, to have the same rotation axis. (Along global X). Note that it probably has to do with the BHelfer2 bone (AHelfer armature), it needs to stay at a certain Z and X position, but move only on the Y, I don't know how to achieve that. How to fix this?

link to tutorial?

See also https://blender.stackexchange.com/a/263852/125879

It would be really nice if you could post the link to the original Tutorial, as this is a quite common rigging problem with multiple solutions, and it would be interesting to see the approach with two armatures in action.
I found a different solution which deals with one single armature only, and gives you a physically correct motion. See this blend file here:

The trick is to use one bone as the master controller, and a second one mirroring the master controller's orientation. By using that, a simple IK chain can be spawned inbetween, and that serves as the master for the rod. See this screenshot:

Arm.Top is the master, which shall be rotated by the animator. Arm.Bottom receives a Transformation constraint like this:

So whenever Arm.Top rotates by a certain number of degrees, Arm.Bottom rotates the same amount, but the other direction. Arm.Bottom needs to be rotated by 180 degrees in Edit Mode already for this to work, and the Axis have to be oriented sideways by pressing Ctrl + N, using Global +X direction as the target.
Arm.IK.Target and Arm.Base.Parent are helper bones, they have Inherit Rotation set to off to avoid axis fliping issues. They are simply childs of Arm.Top and Arm.Bottom.
The IK Chain has to be modelled in a way so top and bottom arm have equal length. Arm.Base is a child of the main bone, and receives a Copy Location constraint like this:

For Arm.IK I've added an IK constraint obviously:

The targets of both of these are always the helper bones. Finally, the Piston bone, also a child of the main bone, is added and receives another Copy Location Constraint. Rod and Piston are now parented to the respective bones, the flywheel is parented to Arm.Top, and the grey part to the main bone.
In the blend file, you can play the simple animation which I've added to see the stuff in motion.

I suggest you to align your bones at the "X" axis.
This can be done manually by aligning the bones using the pose mode, or by removing the constraints for a while and aligning them in edit mode. When you finish alignment you  can put back the contraints.


text:
A rectangular-parallelepiped of light in a volume shader
(related to this and this) Well, I'm not yet (but not so far) ready for cylinders but still trying to learn!
Now let's play with rectangular-parallelepipeds and do the same thing : A shape of light inside the same bigger shape with a volume scatter. :)
The goal is to do this with 1 object, only playing with math and vector nodes connected to an emission and a volume scatter nodes in a single shader.

Thanks to Chebhou's setups (see question for links) I found something that fits my question. here is the node setup:
But I wanted to know how to make the light inside from all sides...
here is the node setup

The important things to note are the placement of the object's origin (all rotations applied) and the value node controling the space between volume scatter and light, normalized. 0.2 means 20% up/down (Z), 20% left/right (Y) and 20% front/back (X). The last multiply node just adds strength to the light.

you did it ! I'm waiting for an answer that my help to make this effect in any object

@Chebhou That's exactly what I was about to ask :) My answer is good but looks like a workaround. I'll try to use objects geometry or something like that. BTW thanks a lot, the study of your setups allowed me to learn more in a day than in a year :)


text:
Can a curve object modifier created geometry be used as boolean factor
This question is related to this question.
Let me use an exemple to illustrate what I mean.
We've created a text object (made of curves). It can't be used in a boolean modifier as it won't appear in the list of usable objects in the modifier because it's a curve object.

But if we add a remesh modifier on the text, geometry is created from the shape.

The object could be used as boolean if we convert it to mesh. The remesh can't be applied on curve object.
My question is : Can we dynamicaly use the remesh modifier created geometry as real geometry or make the boolean modifier consider the text modified object as a real mesh?
The idea behind this is to be able to change the text (or any curve 3D shape) without having to make it a real mesh.
(don't hesitate to edit my poor english to make it understandable :) )

so lets get this straight, you're not wanting to use {Alt}+{C} > convert to mesh?

I don't! I want to be able to change the text AND use it as boolean.

As you have guessed blender doesn't let you use a curve object for boolean operations. While the remesh modifier technically turns the result into a mesh, it is still a curve based object.
I think your best option is to duplicate the text ⇧ ShiftD, then ⎇ AltC to convert the duplicate to a mesh and use it for the boolean. As you leave the original text object you can delete the mesh text, alter the text and repeat.

This is Cegaton's answer on the linked question, but I want some magic trick!!! :)

You could make an addon/script to do all steps in one go.

Do you think it's possible to make a script to use the curve object as a fake mesh using the modifier created geometry?

An addon wouldn't make blender accept the curve object for the boolean, it could convert the text and hide the original, then set the the modifier, just simplifying the process to one command.


text:
Motion Blur Render Time
I am rendering a pretty simple animation using Cycles. I render with my GPU, not CPU, and it's pretty nice. I have, however, encountered a problem.
If I turn on Motion Blur, frame takes half of forever to render and crashes my GPU.
If I turn off Motion Blur render is really quick. Is there a way to make it render faster? I would prefer not to use compositor to add the motion blur.

Sorry but there's no way to make motion blur rendering in cycles any faster for now. how blender developers made motion blur 10x faster
As you can see in the article that they have already improved and sped up motion blur rendering by a lot. Compositing is your only choice left if you want it fast.

I realize this post is a few years old, but this is one of the first things that comes up on Google when you search for this issue and perhaps my experience will help some passersby.
I recently ran into a situation where I was animating a plesiosaur in Cycles at about 16 samples with motion blur turned on. It was taking between 2 and 10 minutes per frame (depending on how dramatic the frame-to-frame movement was).
On the very last frame, the estimate suddenly jumped up to 7 hours, with no discernible reason as to why. However, upon further inspection, it suddenly became clear that I had made a frame AFTER the last frame... wherein the plesiosaur was in an extremely different position. In other words, the motion was no longer continuous, so Blender was calculating overtime to try and figure out how to render such an insane motion blur.
Bottom line, if anyone does run into this issue, try to make sure none of your objects suddenly have an extremely dramatic frame-to-frame movement, because that can slow things down to a snail's crawl when motion blur is turned on. The more continuous your motion, the better. Hope this helps any passersby! Peace and God bless!


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Blender object sensor doesn't exist
When spawning an object into a game, I check its hit objects from my master python script, accessing the object spawned in.
For some reason, the "Collision" sensor does not exist in the object, although I can put any controller into the object and that is accessible.
Heavily simplified code to explain what's going on:
c = bge.logic.getCurrentController()
o = c.owner
s = o.scene

sph = s.objects["Sphere"]

col = sph.sensors["Collision"]
# doesn't work

a = sph.controllers["And"]
# works for some reason

col = a.sensors["Collision"]
# also doesn't work

The code worked a few days ago, but has mysteriously stopped working and I am at a loss as to what's going on. Any ideas would be greatly appreciated.
When looking at the object, it may have controllers, but the actuators and sensors both return an empty list.
Edit: I had disabled collision on the object, please do not make the same mistake as me.

Instead of adding Solved in title please write an answer to your question and in some details outline how did you solve it. You can mark the answer as accepted then

So, apparently I need to add an answer to mark it as solved.
Basically, if your object doesn't have collision enabled in physics, it cannot use the collision sensor. Sounds pretty obvious, but it's easy to forget about it.


text:
Matching physics properties for multiple objects
I have about a thousand cubes in my scene that all require the same physics settings. Is there a way to do this without having to change each mesh separately?
I wish I had added the physics first then duplicated but still it would be helpful if there was a way to add settings to multiple meshes at once.

Select all the objects you want to apply the physics to, then click on the object that already has the correct settings whilst holding down Shift.
Then navigate to the physics tab and click Copy from Active.

No problem. Be sure to mark the thread as answered so it doesn't stay in unanswered unnecessarily.

I have no options to mark as answered only option is add comment


text:
Why has everything only one colour in my final render?
i am new to blender and this amazing 3D community .I was working on a fun project but the fun project become a headed I don't know how .I got wrecking ball , cubes and a base but problem is everything showing same colour in final render .in render mode everything is fine even in camera also but I don't know whey final render is showing only one colour.here are some images of my fun project(which turn into headed .)

this one was rendered mode.this is what I want .

this is what I am getting blender is not even reading emission .
P.S -  this was just a fun project so i did not took much care of textures and lighting as I planned to keep it myself.
hope I gave enough details .

Welcome to Blender.SE. Could you show your Render Layers tab instead of the Scene tab? What happens if you enable Render layer options in the 3D viewport?

Attach your file here http://blend-exchange.giantcowfilms.com/?ref=be-community-add-2

@Carlo  thanks i just checked my render layer tab and found something strange .There was a material assign to render tab which was creating all trouble .I removed it and boom! it got fixed .

Please put the answer into an actual answer, instead of rewriting the question title.


text:
Blender Necklace Neck Rotation Deformation in Rigid Part
I am creating some props for a character I made.. I made a peace necklace that is moving with the rig and fully weighted to the neck bone.. So only one bone carries weights..
The strap moves correctly, the sign is deforming like on the picture.. The hippie iron part should be round & is deforming a bit from circle into an oval.. Anything I can do to prevent the sign from deforming?
Thanks!

without seeing any settings you made - we can just guess around. So pls provide blend file so we can check it out. thx.

Give it uniform weights and it won't deform.  To give it uniform weights, select all verts in it, actively select one vertex, and hit the "copy" button on toolbar/item/vertex weights.

My approach was too simple.. :-).. The 'right' way to do it apparently is through simulation.. Don't know if the complexity is worth it for me yet.. Youtube: https://www.youtube.com/watch?v=CjVhS0TyyX8

Thank you for your answers..
Nathan, I used solution as you suggested. But there was only one vertex bone group with weights, which is on the neck. So this was not the issue..
Chris, next time I will provide a Blend File..
Issue was in surface deform modifier I used.. This caused the necklace to deform other than bone deformation..


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Light Reflection Problem in Eevee
I have rendered a scene both in Eevee and Cycles.. Render in Eevee is really bad and not showing any reflections of the lighting..
Settings in Eevee:

Render Properties Screen Space Reflections on.. Refraction checked.. Base Settings..
Material Settings Screen Space Refraction on..

Is there a way to get Eevee Reflections to approximate the Cycles Reflections so I don't need to go for the longer rendering time when rendering animations?

Cycles Result

Eevee Result

See my answer here: https://blender.stackexchange.com/questions/190642/how-do-i-get-proper-reflections-eevee

Stupid question: screen space reflections and refractions are for glossy reflections on surfaces, mirrors and glass. But what I see in your screenshot looks like a fire illuminating the scene, is this correct? Of course surfaces get illuminated by reflecting light, but therefore light has to hit these surfaces. In Eevee, all kinds of material-based lights like emissive meshes, fire materials etc. don't generate light.


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Blender 3.1.0 Repeatedly Rendering Previously Rendered Image
I am trying to render a scene in cycles. I have updated the scene a couple of times already. However, when I try to render an image, it displays the old scene.
I even tried changing the render to EEVEE. But, the issue still persists.
How can I fix it?

have you add an image into the Video Sequencer? In that case in the Output panel > Post Processing, disable Sequencer

No. I have not used the video sequencer at all. I have already disabled sequencer but even that didn't fix the issue.

maybe you have selected a wrong camera, or keyframed it?

I just modeled the object, added the materials and lighting. I even deleted the camera and added back and there was no keyframes on the timeline. I just uninstalled the latest version and installed the LTS version to check if there was a bug in the newer one.

in the Scene panel make sure that you've selected the good camera, if it's still not the problem please share your file: https://pasteall.org/blend/

I did that. Even installing the LTS version did not fix the issue. Ok I will send the file to you.

This is the link: link

it seems to work: https://zupimages.net/up/22/16/uf54.jpg ... there's a plane but it's just that you haven't disabled it for render in the Outliner

thank you so much! It was a huge help. Thank you!!

There's an object called Plane that is disabled for preview but still enabled for render, disable it as well:

Thank you so much for your time and effort. You have fixed my issue. Thank you!


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Blender layout - Geometry nodes
I'm currently trying to figure out how someone has laid out their blender; how would I make my geometry nodes look like the picture below(If they're even geometry nodes..)? - I'm new to blender.
the person
image

Is your question how to display the 3D viewport and the node editor side by side?

Yes Exactly that! I've been having some trouble figuring out that.

They're not geometry nodes.  You can tell from the upper left corner that he's in the Shader editor in that window.  But if you want Geometry nodes you can modify the standard layout to look like this fairly easily:

Move the mouse over the border between the 3D viewport and the Outliner until the cursor turns into a two headed arrow.

Right click and select "Vertical Split"

A thin line appears.  Move it somewhere in the 3D viewport and left click.

Now you have two windows side by side both with the 3d viewport.  go to the top menu of the one on the right and click the left most icon.  Select "Geometry Node Editor" from the popupu menu:

You may want to look at the manual's User Interface Introduction for more details.

Ah I see now! Thank you it worked. By any chance, do you know how I could get the "principled BDSF" to appear? I can't seem to find it. -- Edit: Grammar

Principled BDSF is a shader node, not a geometry node.  Switch to Shader Editor if you want that.  (IT's the next entry down in the list)

Oh my god, thank you so much! I've spent the past hour trying to figure out why I couldn't do any of this. Turns out I'm in the wrong area.. Once again, thank you so much for your help :D

@aserient you're very welcome.  You may want to read the introduction in the manual, or even do the first part of an introductory YouTube tutorial to learn about things like this.

Will do! Have a good day/night!


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Motion Blur not working for newly imported SVGs
I returned to an older project because client needed a revision. Originally I had 2 imported SVG files of some typogaphy and those blur fine, but when I returned a month later and needed to update the copy the new SVG won't blur in the render but the original SVGs still do (w same animation). Help??

I figure it out, I forgot to "convert to mesh" hopefully this helps someone!

Motion blur should work with curves as well. Perhaps you can investigate further and check what the actual root cause was?


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model-file is too big
I´m realatively new to Blender. I am currently modelling a bigger model and working on the highpoly version of it. My problem is, that the blender-file is getting really big (~2GB). And I also dont want to loose detail, like cracks and so on.
Is there a way to shrink the file without loosing any deatil?

Are you running short on disk space? Shrinking file size on its own will gain you nothing other than saving storage space. You can artificially make a file smaller by compressing it, but that wont necessarily guarantee better performance, nor faster renders. What exact issues are you experiencing? What does your file contain? How did you model it? Without details it will be hard to help

Turn on blend file compression in the preferences, save and load> compress file


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modling tube for 3d printing
I'm trying to create a coupling in blender, that I can export to cura slicer program.
My problem is the slicer program fills in the center of my tube as if it is a wall.
I have tried creating it from a cylinder and just a plain circle/circles (inside and outside walls).
I exported both .obj and .stl files with the same result.
I'm uploading my file here once I post my question.

I thought you clicked "edit" to attach a .blend file.  Not sure how to do it.

While there may be ways to correct non-manifold vertices in blender, the only real correction to this problem appears to be in the slicer program preparing the g-code for the printer instead of blender.
These settings corrected the problem for me (I use cura 3.6 as my slicer).

Set infill to 0%
Set top and bottom layer to 0
increase the wall line count (thickness) from 2 to 5

These settings created a perfect print for me.

Check your 3D printer settings and limitations for how much empty space you are permitted between structures, sometimes you will have to model in support beams in hollow areas and you will have to remove them once printed. You could print a mold and use latex and resin or print and glue together two halves.

Thanks that is more of a slicer fix. I wanted to model it in blender.  Easier ways to fix in slicer set infill to 0 set top and bottom layer to 0.  Then set wall layer to 5


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Can't figure out why one of my assets is shiny?

Hello, I'm new to modelling and have been making a few small tiles to snap together in unity. As you can see, Tile A has sides of the same color, with no strange lighting going on. Tile B's sides, however, appear to have different lighting. I've looked around and cant figure out how to make tile B look like tile A. Both of these files use the exact same options; B is a copy of A which I reconfigured into a bend.

set the shading to flat.

The easiest way while you are in Object Mode is to switch to flat shading in the Tools panel. Alternatively you can add an Edge Split Modifier in the Properties Editor.


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Extracting a text string info (character's indices) to use it as a material mask
I think an image can say more than words sometimes... :)

The idea is to use a different color from the color ramp for each character in the string.
It's related to this question

so you need the index of the currently rendered character not just the char index

i guess you're right :)

The color of each character is determined by the material index on the text object. Therefore, to have each character use a different color from the color ramp requires a material for each color.
The steps involved:

A material for each color in the color ramp node.
The text object must have all the materials applied to it.
The characters must reference the index of the materials.

This script takes the colors from a color ramp node, makes new materials and then assign each character a material.
import bpy

txt = 'Text' # The name of text object and text curve.
materials = bpy.data.objects[txt].data.materials
i = 0

# This material holds the color ramp node, change 'material name' to the name of your material.
rampMat = 'material name'
colorRamp = bpy.data.materials[rampMat].node_tree.nodes['ColorRamp'].color_ramp.elements

# Convert colors from the ramp to materials and add them to the text object.
for element in colorRamp:
    color = element.color
    material = bpy.data.materials.new('color')
    material.diffuse_color = color[0], color[1], color[2]
    materials.append(material)

# Loop through the characters setting their indexes.
for character_format in bpy.data.curves[txt].body_format:
    character_format.material_index = i % len(materials)
    i += 1

because it looks awesome

@Chebhou it was a little tongue in cheek, I just wrote the script to do exactly that.

This looks like what i wanted, with some awsomeness, thanks!!  I'll check this tomorrow. If you want to animate this, you can answer this question too :)

easy to use, simple. That's really cool!


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Origin rotates but object does not
Baffling problem that is a follow up to unresolved problem (Object created by joining several objects doesn't rotate uniformly consistently). This object is created by joining 3 objects..large gear, shaft and small gear. Its rotation is constrained to object in scene that's hidden along with other objects. When I play scene it rotates correctly until I change direction of target object, Then the large gear appears to stop rotating while its origin (denoted by axis and widget) and the shaft and small gear resume rotating.  Here's youtube vid https://www.youtube.com/watch?v=NfXAFHCkRxE&feature=youtu.be
My Blend:
Any ideas?

If you rotate something at the right speed it will appear to be stationary even though it is moving.  Try moving the key frame a little.

Object is keyframed to rotate at same constant pace in both directions..it is NOT moving

As already said by @Xtremity in the comments, it is rotating but you don't notice it. Your big gear has 30 teeths, so every 12 degrees (360 / 30) one teeth. Before the short stop, you rotate by +6 degrees every frame, so half a teeth of the big wheel. After the pause however, you rotate by 12 degrees, exactly one teeth, per frame, so you just don't see it rotating.
By the way, you're not rotating in the opposite direction after the stop, it just looks like it.
Rotation in frame 209:

Rotation in frames 210 to 230:

Rotation in frame 231:

You can clearly see, that before frame 210 it rotates by 6 degrees, after frame 230 by 12 degrees.

Really? So why is the rotation of the larger gear in either direction noticeable when rotated frame by frame from 190-210 and clearly not from 230-250?

Because from 190-210 it only rotates half a teeth per frame, from 230-250 a full teeth per frame. You can't see the difference since all teeth look exactly the same, so you don't notice, that after one frame, every teeth rotated to the exact position of the next teeth.

Just go in edit-mode, grab one teeth and move it outwards a bit, then play the animation again, you'll see it's actually rotating.

(sigh) that doesn't help...i need it to LOOK like it's moving during frames 230-250, just like in frames 190-210..is there any reason why it would not look like it's moving when the rotation rate is the same.

Because the rotation rate is not the same!

Ah, I get it now  tkausl.  I just changed the rotation keyframes from 190-210 to match the rate of 230-250 and sure enough it appears NOT to rotate.  So I just need to find a rotation rate that works.  Thanks, ur a genius!

Per tkausl answer, I revised scene to rotate object at same rate by changing keyframe to rotate 6d/frame in opposite direction so rotation is visible.  Also duplicated problem..gear meshes appear almost static when tooth count=frame count producing rotation of one tooth per frame..I'll avoid this now on.


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Object created by joining several objects doesn't rotate uniformly consistently
Aloha.
I'm experiencing a similar problem I had with a prior posting Joined spin dupli objects don't rotate together with another object I created by joining 3 objects that doesn't rotate uniformly consistently.
I tried clearing and applying rotation of individual objects and joined objects to no avail.
I have screen cast of defective object as well as object by itself in blend file if you need to see them
Any ideas?  Thanks.

I uploaded clip of defective object in scene.  Notice the large gear stops rotating as shaft and smaller gear continue.
https://youtu.be/obdnMVLQpiQ

I'm sorry but its not very clear what you are trying to do. How are you joining your objects? they seem like two separate objects, not one. Could you upload a blender file?

Exactly the problem!  It's 3 objects--small gear, shaft, and large gear--joined using join button under tools so its supposed to be one object. I uploaded .blend file if it helps.   Thanks

I just replaced this defective object in the .blend file with a similar object from another .blend file that works fine in its animation scene...and low and behold it does NOT work just like the original object...the large gear does not rotate when the shaft and smaller gear does..gotta be some defect in the scene...really bizarre

Now you have to join them together with Ctrl + J

Your problem is with the precision of your model, you should improve your modeling skills and take care of your mesh.
You model needs some serious clean up, there are quite a few misplaced vertex, inverted normals, non manifold faces, overlapping geometry, etc.
There is also one unused Copy Rotation constraint, probably a leftover from when there were several objects
Now to the problem at hand, what you are seeing is probably an optical illusion, your model seems to be rotating at different speeds because the center is not accurately placed relative to the geometry, making the center part "wobble" in relation to the rotation center.

Now your geometry is really uneven and you should probably model it cleanly from scratch, but if you don't want to, just enter edit mode, select the central vertex, move the cursor to selected, exit edit mode and align objects center to the cursor position.

Do this for all objects, although they are all slightly skewed and wont easily be totally perfectly aligned

whoa, Duarte, thank you for the detailed tutorial.  I'm still learing Blender, but for what I need precision clean up is not a priority.  But I know it's not an optical illusion.  I just tried a similar joined object from another file and same thing--it rotates like a single object for most of the scene then separates so small gear and shaft rotate while larger gear is totally stopped. So by process of eliimination it has to be something with the scene animation.

[SOLVED] It is an optical illusion.  I happened to keyframe a rotation rate that moved the teeth of the large gear one tooth per frame so it looked like it wasn't moving. I changed the rotation rate by trying different keyframes and it now appears to rotate.  Thanks, Stack Exchange, ie tkausl!
Origin rotates but object does not


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How to properly riggify character`s face
I"m trying to riggify my character's face after successfully riggifying the whole body, but it seems that it doesn't work out for me. Can I have some kind of guidance what to do.
In short, I've been trying this method with a tutorial of a guy on YouTube (It's called "Facial Rigging With Bendy Bones")and nothing happened.

it's because of the Stretch To constraints, what are the bones they are supposed to stretch to?

sORRY i DIDNT UNDERSTAND

you've give a Stretch To constraint to your eyes bones, what is it for? where are there targets? Also, could you please be more specific, what doesn't work in your rigging?

Like,I use this plugin called "Control Bones" and it just gives me out the errors when I try using them

@ViktorOlivye you should edit your question and add the error message, what you have done, in which mode is active, etc. It's hard to help you and further readers with so few informations.


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Using Dynamic Paint To Spawn Particles Through Vertex Groups
What is causing the particle system to not follow the density group? Use modifier stack is enabled, both objects are well subdivided and the canvas object is an unmodified plane.

The emission is not keyframeable, one of the many shortcomings of the particle systems they promised to fix since 2015. Depending on what you want to achieve there are workarounds, I don't want to post any answers, though, because I would probably get downvoted. They are kind of hacky.

appricate the answer nonetheless, what I'm trying to accomplish is basically this https://youtu.be/OkAaLd0FdK0?t=3 but using dynamic paint, got all of it to work except for the sparks, and placing those manually is not really an option

Geo Nodes ...https://www.youtube.com/watch?v=ABftdilHiBw  or
https://www.youtube.com/watch?v=Sv8B9KxGhW8

https://blender.stackexchange.com/a/308540/2214

Unfortunately it's much more complicated than it should be. I can elaborate once you tell me if that's an option for you.
A possible workaround: Create a particle system sparks that is emitting continously. Place the PS where the laser hits the surface. If you want to randomize the bursts of the sparks some more, you can randomly turn on and off the visibility in render. Note that this might look weird if your spark lifetime is more than a couple of frames.
You could refine that a lot more using animation nodes, by grabbing the position of live particles and placing a custom object where they are relative to the point where the laser hits the surface. This way you have more control when turning them on and off.
Or you could try baking the sparks using physical objects and rigidbody physics. Bake 10 or so, parent them to an object that follows the laser, use animation nodes to only show 3 or 4 at a time and evaluate their f-curves, depending on the current frame and their "birth time".

I came across the same problem. Seems the Particle System does not update the emission distribution relative to the Modifier Stack. God knows when the Blender people will get around fixing/implementing this. Quite the bummer...


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Images as planes are not appearing in final render but in viewport are visible
I imported images as panes to create mist effect using PNG images. These are not appearing in the final render but are appearing in the viewport in render mode.

Link to the image
https://drive.google.com/file/d/11sllNa-BkFEZ-Od-tiV9eCP2c2h0CWh-/view?usp=sharing

have you checked the render visibility in the Outliner?

Yes @moonboots, all are visible. I realised I might have dragged and dropped them in the viewport. These are appearing as Empty in the layer panels. Is there a way to convert them to image planes? Thank you! :)

so they are not Images as Planes but Reference or Background images, you need to reimport as Images as Planes, or create a plane and give it the image

Awesome, here's a link to a similar question. There's an add-on to convert reference images to planes. Thank you for the help @moonbots  :D https://blender.stackexchange.com/questions/161610/how-can-i-convert-empty-images-so-that-they-would-show-in-the-render

@Sherry1221 for future reference, any future new information, please add to the body of your question as an [edit]. Many users choose not to read the comments, and the comments are also not searchable and thus not useful for future visitors looking for an answer to their questions. Thanks :)

When you drag an image into the viewport, or use Add > Image > Reference, or Add > Image > Background, those images will have no real geometry (they are just an empty with an image associated to it), and as such they are not renderable. They are just reference.
Use Add > Image > Images as Planes (or File > Import > Images as planes) to have an object that has 4 vertices and a face with the image used as a texture on the material.


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Blender Time Remapping "Bug"?
I have a plane with an animated gradient. I had to use time remapping because the animation is quite long and complex. When I Render it out with cycles it skips part of the gradient animation and it begins to stutter.
Instead of a movement every frame in which the gradient progresses, which in the viewport works fine, it goes Frame with movement, 3 frames without movement, frame with movement and so on.
When I switch to EEVEE everything works as it should. Unfortunately EEVEE in this case is only an option for preview.

Hi and welcome :) Please add as an [edit] some images of the scene, render settings, materials, etc Gifs are also helpful if they show the problem clearly. Thanks :)

Hi thanks for the reply an the advice for future posts. Fortunatley I found a workarroung. It seems as if some texture properties don't work well when using time remapping. So instead of animating the gradient I animated the position which worked great.


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Splitting A Game Texture Into Quadrants In The Node Editor?
This game texture has four different tint masks in the alpha layer:

Is there any way to access them one by one in the node editor? I could edit the textures manually but a node solution would be easier in the long run

I've tried this node setup below:

I'm not sure why this attempt doesn't work but it somehow delivers the same tint mask except mirrored (mirrored mesh/UV) on outputs 1+2 and 3+4 respectively. So this is effectively only returning 2 out of the 4 masks and I don't understand why.
If I only use one output of the above group node, one of the tint masks is correctly applied to only half the mesh.

How is placed the UV map here?

I took a whack at this the other day and came up short, I'm gonna try again tonight, I think.


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How to improve geometry by merging these ngon faces?
I have a model with a frame and a pattern, made after applying the Boolean modifier. The resulting mesh has unconnected faces. How should I "pull" those faces together into a plane? Merge by distance doesn't work because they are not close enough.

Enable snapping to vertices:

And auto-merdge:

Now you can snap vertex to vertex, and they will be merged


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Python bpy 2.8 render directly to matrix/array
I'm new to working with both Blender and bpy, and I'm trying to render directly into Python. Best case, I could render directly from bpy 2.82 into a byte stream or numpy matrix.
I've been trying to follow the instructions here https://ammous88.wordpress.com/2015/01/16/blender-access-render-results-pixels-directly-from-python-2/, using bpy.data.images["Viewer Node"].pixels, but it's returning something of size 262,144 which doesn't make any sense. The link was written for Blender version 2.7, so I assume the API changed somehow between the two.
I have bpy.context.scene.render.resolution_x and bpy.context.scene.render.resolution_y set to 320 and 480 respectively, so I would assume there would be 320x480x4=614,400 total pixels.
Is there any way to do what I'm trying to do in Blender version 2.82?
Here's the code from the link above:
import bpy
import numpy as np

# switch on nodes
bpy.context.scene.use_nodes = True
tree = bpy.context.scene.node_tree
links = tree.links

# clear default nodes
for n in tree.nodes:
    tree.nodes.remove(n)

# create input render layer node
rl = tree.nodes.new('CompositorNodeRLayers')
rl.location = 185,285

# create output node
v = tree.nodes.new('CompositorNodeViewer')
v.location = 750,210
v.use_alpha = False

# Links
links.new(rl.outputs[0], v.inputs[0])  # link Image output to Viewer input

# render
bpy.ops.render.render()

# get viewer pixels
pixels = bpy.data.images['Viewer Node'].pixels
print(len(pixels)) # size is always width * height * 4 (rgba)

# copy buffer to numpy array for faster manipulation
arr = np.array(pixels[:])
```

You may need to check your render resolution setting to be at 100%.

check out answers to this question, especially https://blender.stackexchange.com/a/3054/111042

262,144 = 2562564. 256 is the default size of the viewer node image

https://blender.stackexchange.com/questions/195289/compositor-viewer-node-output-never-updates-when-rendering-via-python-script?rq=1

render_res = bpy.data.images["Render Result"].pixels returns None actually


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How do I remove the Blender FLIP Fluids addon demo watermark?
I have recently purchased the FLIP Fluids addon however the demo watermark still remains in my scene. However I have deleted the demo and updated to the version I have purchased. Is there a way to remove the demo watermark from my scene?

Hi :). It'd be best to contact the addon developers directly.

As a commercial addon they have a customer support, why not ask them?

Make sure you've followed the addon installation instructions exactly

I did not think about contacting them directly. I'll get right on that. Also I have been reading the instructions but I don't know what could have caused this.

The demo watermark of the FLIP Fluids addon is baked directly into the geometry of the simulation meshes. After installing the full version, you will need to re-bake the simulation.

Thank you... I was insanely worried that would be the case. I think I messaged you directly on the Blender Market. Thanks for getting back to me. Well here goes another bake of 101 frames at Resolution 600. Oh well, anyways thank you so much for answering my question!

Oof, your poor computer


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Blender Rigid Bodies don't touch
I am trying to make a 0 gravity scene, I'm trying to make a spaceship (which as a passive rigid body) drift into a small collection of asteroids. The problem I am facing now is the Asteroids don't interact with the mesh, even after changing the settings from convex hull to mesh (which did solve a completely different issue that was causing the asteroids to randomly fly in a direction when the objects are very far apart) Regardless there is this tiny gap between the two objects that I cannot seem to get rid of. It's almost like the rigid body of the starship as become desynced from the rest of the mesh, which if I could somehow make it visible and edit the rigidbody myself I would. What I currently need is just something that can get rid of that tiny gap. Also if it is relevant: Editing the margin doesn't seem to have any effect no matter what number I make it, high, low, or 0.

After some trial and error the solution was the asteroids had a lot of unapplied ,modifiers on them so the mesh that Blender saw was not what I was seeing. After Applying the modifiers the asteroids now behave properly.


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Where is "Film" setting to allow rendering transparent background?
I have been working with blender 2.79 and trying to render a two dimensional video with a transparent background. When I look up examples they all seem to use a tool called "film". I can't find this anywhere can someone help me. Am I missing a setting?

if I got what you mean, you have to use cycles render engine, then it's n the render properties

You have to be in cycles render, then look to the render propreties tab


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Batch Generate Previews Not Working
Even for the default cube, when I go to File -> Data Previews -> Batch Generate Previews, it seems that it's doing something.
Then I save the file but when I try to append the cube to another project I get no Image preview!
Does anyone know what I'm doing wrong or what I'm missing? I'm running blender 2.78c.

You might be using it wrong, I think you misunderstood how it is supposed to work.
Generate Data previews is not meant to be used for a currently open file, you are supposed to use it on any saved file in your harddrive, not being worked on at the moment.
If you batch generate previews for an open file, Blender will work to generate them then save them to the file. However when you save the open file Blender will write to disk the version it had previously loaded into memory, prior to thumbnail generation, thus not yet containing the generated previews.
It wil then overwrite the the preview file with non generated version, thus effectively erasing the work done.

You are right, I tried generating previews from a different file and it worked like a charm :) Thanks a lot!!


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any way to remove doubles in uv editor across different uv islands?
I was exporting uv-mapped model back and forth and at some point it should have messed up my uv map. It is aligned properly with all vertexes where they should be, but every face became a separate island.
it looks ok when you don`t touch it:

but when I use pack islands, this happens:

is there any way to restore a proper uv map?
P.S.
some islands are mirrored and placed directly above each other
Edit: the file itself

Not quite sure, so I won't put this as an answer, but you can select the face on your mesh. This will also select the island on your UV map. That way you can simply drag it to where you want it. Btw, what's wrong with your 1st UV map? it's fully textureable...?

@Mr Zak, that merges all selected vertices into one. which would simply destroy the uv map altogether

@FreemoX,it is indeed texturable but i need proper islands for zbrush.
it's normal map baking relies on islands and this uv map creates an unusable bake.
Also I'm afraid even if i manage to deal with it in zbrush it will mess up something else later.

i meant that "weld" would merge all selected vertices into one. Remove doubles on the other hand only works within one island. in my case every face became an island of its own

@Mr Zak, afaik remove doubles in 3d viewport will merge the vertices but not their uv representations. In my model the actual vertices are connected but in the uv layout all faces are separated. When i use remove doubles in uv view, the selected vertices are merged into one single vertex. when i use remove doubles in 3d view nothing happens (as there are no double vertices).

I uploaded the file to the question. Thanks for the link. Though i had to delete one of the images because of reputation restrictions

Trying to reproduce the problem i was able to track down who messed up the uv in the first place. It was zBrush's UV Master. When I copied uv's from another .obj with same topology it shattered uv islands, strangely leaving some of them intact. To make sure you don't find yourself with same problem check the UV's every time after copying. Trying this several times lead to same effect so it`s not just random error.

Honestly I don't really have idea how to ccorrect that quickly other than reunwrapping. If selecting one vertex on the mesh it appears that vertex is presented in several UV islands. Weld or Remove doubles won't remove "double" vertices here as they aren't double. Some of the isllands are stacked on top of each other..Thanks for the info about UV Master, this can help at least to show when did this appear and now I know even more how powerful is it.

just to clarify: this uv is not generated by uv master. It's blender unwrap with custom seams and heavily adjusted by hand. ZBrush does not handle low poly unwrapping very well (at least not for me).

After some experiments i was able to find a way to properly transfer uv from blender to ZBrush, though its overcomplicated to say the least: 1) export from blender to fbx. 2) import fbx to zbrush as a new tool 3) export this tool from zbrush as .Goz 4) go to your tool, select lowest subdiv level and freeze subdivisions 5) import .Goz over your tool 5) copy uv in uv-master 6) unfreeze subdivision 7) paste uv from uv-master.

In this case the uv is copied and pasted over the same mesh and works fine. The problem seems to be caused by copying uv from another mesh and having same topology does not guarantee it will work as expected.

Also be carefull with .obj format. It works fine if your uv does not have small details. But if it does .obj can mess them up because of low prevision vertex positions. (in my example it messed up fingernails uv)


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I'm not sure how to fix this scaling issue
I'm pretty much brand spanking new on blender and I was following a tutorial on mirror modifiers when I realized my cube was not scaling as it should.
As you can see here, I was scaling out the inner faces on all six sides after I subdivided the cube twice. Problem is on alternating corners such as the top left and bottom right, it's making this kind of corner as if it doesn't want to move like it should or how it did in the tutorial. I looked up the tutorial several times to see if he had changed a setting and I hadn't seen a thing different between what I did and what he did. Below is a link to the tutorial in case this helps because I'm thoroughly stumped.
Edit: Adding a few other pics to show the problem a bit better.

So that backward L shape on the upper left is not supposed to be like that at all. It's supposed to look like this instead according to the tutorial.

The reason is so that I can grab that vertices in the last picture and pull it in to make it a low poly sphere, but for some reason on the 4 corners it keeps alternating between that weird backwards L and the shape it's supposed to make.
Below is a link to the tutorial in case this helps.
https://www.youtube.com/watch?v=3LwQO_tWTAQ

It looks like you are doing it right...

I edited the post to show the corners a bit better and show the problem I'm having.

There shouldn't be any problems achieving that but in your case you have 0-area faces around those faces you're supposed to scale, probably it will help if you select all and press W > remove doubles or you can start from scratch. Aside from that I'd like to add that shape - scaling faces out and corner vertices in - can be created in 1 step by selecting all and pressing Shift+Alt+S to activate To Sphere tool.

Thank you so much for that awesome tip. I'm never forgetting that shortcut for the rest of my life. You have no idea how bad it had hindered me since last night when I started this. Thank you again.

There shouldn't be any problems achieving that but in your case you have 0-area faces around those faces you're supposed to scale, probably it will help if you select all and press W > Remove doubles or you can start from scratch.
Aside from that I'd like to add that shape - scaling faces out and corner vertices in - can be created in 1 step by selecting all and pressing Shift+Alt+S to activate To Sphere tool.

Although not always necessary, and I'm sure @MrZak doesn't mind, generally the etiquette would be to ask the user (in this case MrZak) to post their comment as an answer themselves to allow them the chance to earn any reputation that might be earned from this answer being upvoted or accepted, as opposed to you answering with their comment. See this question for more information: https://blender.meta.stackexchange.com/questions/436/what-to-do-with-questions-which-have-been-answered-in-comments

I sincerely apologize! I'm pretty new to the site and have used it few times honestly. Thank you for that. I'll bear that in mind next time. Thank you again and apologies.