text:
change walk mode keys configuration
I can't find the entries in User Preferences (input tab) to change the keys for navigating in 3D view, using walk navigation mode.
Currently it's bind to WASD keys, and since I have an AZERTY keyboard, it would be nicer to have ZQSD mapping to move the view.
Is it hard coded into Blender's source code ? Or do I miss the entries in User preferences ?

Nevermind, I finally found the entries in User preferences.
Into 'Input' tab, then into 3D view > View3D Walk Modal, all keys bindings are listed here.
Oddly, we can not find it using the search tool at the top...


text:
Quick Smoke Causing Grainy Renders
I was messing around a bit with Blender 2.79, and what i found was when i was doing smoke simulations, the renders turned out really grainy with a lot of noise (kind of like scattered pixels around the smoke) in the simulation its self. I never really came across this problem till now, maybe there's something that I'm missing? I attached an image below, I hope you know what I'm talking about. :)

Thanks

Okay, so i found the problem i had if anyone interested... it had to do with my lighting. i guess for smoke simulations you cant use planes with a emmision node property. i had to use actual lamps or sun lights to avoid noise, but i still cant get it around my head how that works.
Thanks.

Lamps are generally much more efficient that using emission meshes, resulting in the need for much fewer samples to render the noise out of the scene. See https://blender.stackexchange.com/a/89665/29586 for a comparison - the same would be true for rendering a volume (smoke).

Thanks for the comment! you're right, once I dug a bit deeper emission meshes are really only at their full potential on scene lighting. Thanks!

source: Stack Exchange

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

sort: votes


text:
weird artifacts with procedural texture
In blender cycles I tryed to create a brushed aluminum texture using a node setup with a voronoi texture and a mapping node but when it was rendered I noticed there was a weird ripple artifact when using this node setup
here is a more zoomed in look at the artifact

here is the node setup

here is the blend

Please add the .blend

The weird ripple seems to be apparent in both though?

yeah the second image was just to show it zoomed in more to make the artifact more visible

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


text:
Rollercoaster Problem: Bones following Curve
I'm trying to make a train mesh follow a curve path. The Curve modifier does this admirably, unfortunately I need to export the animation to a game engine so a modifier just won't do.
I tried adding bones to the mesh but it turns out making those follow a curve is not trivial. I copied the workflow outlined here by adding a second "helper" curve, making that one follow the path with the Curve modifier and putting a Spline IK constraint on the tail bone targeting the helper curve.
This works perfectly as long as my path is flat. Unfortunately, even the tiniest hill causes my train to flip over and do a full 360 (in direction of travel) around the track in one specific location, and I can't figure out why.

I tried all sorts of settings on both curves. Handles are aligned, twisting is set to Z-Up on both curves, and I added multiple Limit Rotation constraints to the bones. Nothing helps. It's interesting to note that when I set the helper curve to extrude, I can see that it stays perfectly upright when following the path:

So it's only the bones rotating, presumably because of the Spline IK constraint.
Please help, I'm going bald pulling my hair out over this. Any solution that keeps the wagons upright in this setup is welcome, though I'm also open to alternate suggestions on how to get them to follow the curve in the first place. I've uploaded the .blend file so you can take a better look at what I'm doing:

Please use https://blend-exchange.giantcowfilms.com/b/4741/ for blend file hosting.

I managed to find a solution, but it's a bit of a hack. Most notably, the process involves baking the animation, so it needs to be redone every time you want to change the layout of the curve.

select every bone in the chain and make sure "Inherit Rotation" is turned OFF
keyframe your "helper" IK curve to whatever you want the train to do (I wanted mine to go full circle around the curve)
Add a cube or empty somewhere high up in the scene (doesn't matter what it is)
make a copy of the armature/mesh in case we want to go back
bake action (visual keying and clear constraints)
select every bone and add a locked track constraint to each one, targeting the cube or empty or whatever you added in step 3. Fiddle with the settings until it makes your train stay upright.
bake again and export for use in Unity or other game engine.

Simple, right? Repeat steps 5-7 every time you change the curve or otherwise modify the setup. I'd much prefer adding the locked track constraints without baking in step 5 to avoid this, but I simply cannot get that to work, the Spline IK constraint overrides my Y axis rotation. So this will have to do. If anyone has a better way to do this I'd be very much interested.

Answer for other users with updated versions of Blender*
Go into edit mode and select a point on the curve. You can view the "rotation" of this point by bringing up the 'N' panel(simply hit the 'n' key). In this panel, there should be an option called 'Tilt', under the transform menu in 'Control Point'.
https://i.sstatic.net/sSauC.jpg

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


text:
Armature Single Bone: Extruded Child Bone not Follow Parent
I follow a tutorial for the creation of armature.
Steps:

Add single bone ("main bone").
Go to Edit mode.
Extrude from tip ("tip bone").
Extrude from root ("root bone").
Go to Pose mode. Move "main bone."

When I move "main bone," the "tip bone" follows the main bone. The "root bone" stays in place and does not follow the "main bone."
In Scene Collection pane, there is information that indicates that the "tip bone" is parented to the "main bone." This information indicates that the "root bone" is not parented to the "main bone."
I parent "root bone" to "main bone" so it follows "main bone."
The tutorial I follow indicates that I don't have to do this, manually.
Is there a way to extrude bones from the first single bone in scene so that extruded bones are automatically children of the "main bone," so they follows the "main bone" as expected?
Summary:
Bones extruded from "tip" of bone follows bone in pose mode.
Bones extruded from "root" of bone does not follow bone in pose mode.

This is how it is supposed to work, if you extrude bone Tip from the tail of bone Main, bone Tup will automatically be a child, if you extrude bone Root from the head of bone Main, bone Root won't be a child, you need to parent it afterwards

As @moonboots said, this is how it is supposed to work. Since you followed a tutorial, is it working differently there?

This is how it is supposed to work, if you extrude bone Tip from the tail of bone Main, bone Tip will automatically be a child, if you extrude bone Root from the head of bone Main, bone Root won't be a child, you need to parent it afterwards


text:
Rigged Character - Knees Bend Outwards

Technically, the rig works as intended.
The knees behave in unexpected ways.
I adjusted the rig several different ways.
The knee behavior remains.

Rigify sometimes does this when you change the hips and knees of the metarig to some bowlegged config.
To prevent this from happening and to force the generated rig to bend at the local x axis of the bone, you can select the bone in the metarig in pose mode, go to the "Bone" tab and open the "Rigify Type" submenu.
There change the "Rotation Axis" from "automatic" to "X manual".
After re-generating the rig, the leg should bend around the bones X axis.

⭐⭐⭐⭐⭐ The recommended solution is applied. The "knees" of rigged model behave as expected.


text:
How to set color of the Viewport Background?
Here is my view:

I want to make the floor less dark so my wireframe objects are not the same color as it.
I tried setting the background color on the world, but that has no affect.
I searched the Internet, but that only told me how to change the color of the grid lines
and none of the other preferences seemed to do what I want.
Anyone know how to do this?
In his answer to this question, Abraham Reinhardt showed me his Viewport Shading menu, but mine looks like this and does not have the same settings as his:

In a comment, Blunder suggesting setting the world background and strength.  I tried that and it did nothing.  Here is the menu I am editing:

Abraham Reinhardt also suggested changing the Viewport Display color, but that did not change anything either.  Here is a pic:

hello, what floor are you talking about? also, maybe share your file so that we can try

There’s no such floor in blender. The dark gray background you are seeing is the world background. I don’t know what setting you tried to change, but that color should change in viewport render (which is the viewport mode you are in) when you adjust the world shader color.

In the World settings you have set a bright color which is visible in the Rendered viewport shading mode (key Z). That's correct. But you have set the Strength to 0 which results in darkness. Set World Properties > Surface > Strength to 1. (I only wonder why it's not pure black in your screenshot)

@moonboots -- I believe Neil is talking about a color in the "Preferences >> Themes >> 3d Viewport" ... somewhere...

@Blunder I set the I am in the rendered viewport.  I set the strength to 1 and the color to red, but the view did not change.  I can't figure out how to add an image to this comment so I will edit my original post to show the menu I edited.

See below, you need to enable Scene World in your Viewport Shading panel.

You are using a rendered viewport, with Scene World disabled.
I include an example where I enabled Scene World, that then uses the World color/nodes:

And then in World Properties -- with Use Nodes enabled -- I changed the background color:

Of course, as the world color may be reflected off of the other objects' materials, it will affect their color also.  But some variant of white shouldn't mess you up too much!

Yes it's a workable way in Rendered mode with Scene World checked. He still said it didn't work maybe he want that unchecked? I'm not sure. But I find another way inspired by your answer. Since comment cannot post image I'll edit my answer.

When I check the Scene World checkbox, it changes the color of everything in my scene.  That is not what I want.  I only want to change the color of the floor itself.

@Neil -- it doesn't actually change the material colors on your other objects, but rather is like blending colors, as if you changed/colored your room lighting.   If you want a dark background (object), your only choice is to create a object (e.g., plane mesh) "behind" your other objects, and use a material with your color of choice.

@james_t I think you are right.  I will have to design my own workaround.  Blender won't give me what I want to do.

There's a way to change background color that can be seen and only in Solid mode. Switch "Theme" to "Viewport" and change the color below.

Inspired by james_t's answer. There another way to do it in Rendered mode with Scene World unchecked. Go to World Properties and change the Viewport Display - Color.

The needle in the haystack was found !

My interface is different than yours, I could not figure out how to add an image to this comment so I edited my original post to add it.

It's because mine is using Solid mode and can only be used in Solid mode whereas yours is in Rendered mode. I'm sorry that this solution does have its limitation.

@AbrahamReinhardt I see what you are saying, I did not realize the drop down box was relevant in all the modes.  Unfortunately, Solid mode makes all my objects gray and translucent.  That is a bigger problem.
Also, I tried going to World Properties and setting the Viewport Display color and it did not change anything either.  I will add a picture to my original post.


text:
Target text to viewer (Not camera)
Is it possible to target text objects to the viewer (In viewport mode)?
I know I can target text to a camera, but I am finding it convenient to move the viewport around my object and use the Viewport Render function. But, when I do that, the text does not follow and I have to change its orientation manually.

I don't think so but if you enable the Lock Camera to View option the camera view will work  as a viewer

@moonboots That is not perfect but will work for me.  Thanks!


text:
Intersection of Particles in a Hair Particle System
I have another question :D
So, currently I am planning to create a short film in Blender for my intermediate project at uni.
I am trying a few things out right now to tackle probable future problems already since my project is not green lit by prof. yet.
I have a few very low poly buildings and want to create a city line for a background shot later.
I use a Particle system with children. The problem I have is that all the buildings intersect and overlap. Looking for a solution, youtube and blendernation were not helpful at all unfortunately.
Do you have any idea how to solve this?
My result

What I am aiming for

Btw. if you have any tips or ideas how I could achieve my aim better and nicer and with more fidelity, I would highly appreciate it.
EDIT:
I solved my problem with Blue Noise Addon from Github!

Anyone? No, idea? :(

I'm not sure there's a way to avoid particle overlapping (except maybe with the help of this tuto?), but you can:

Create several buildings, texture them. Put them into a collection called Buildings:

Create a plane (let's call it Generator) and give it a Particle System > Hair, activate the Advanced option,  choose the collection you've created as particle, give it an Emission > Number of 20:

In the Modifier panel > Particle Settings, click on Convert. It will generate instances, reorganize them so that they don't overlap, select all, make the objects single users and join them with J to create an object:

Come back to your Generator plane, generate a new combination, vary the Emission > Seed and the Render > Use Count settings so that it differs from the previous combination. Do the same as before in order to create a second object. Do it again several times, put all these objects in a collection called Master.

Create a new plane, subdivide it for example 10 times, give it a Particle > Hair, activate the Advanced option, choose Master as its particle, give it an Emission > Number as high as you have faces on this plane. In Emission > Source, deactivate Random Order, choose Particles/Face = 1.

Hey thanks for the Idea, that would work but the buildings look to unique in position because they were joined before. Useful for other things though, I will save that! Thank you!
I solved my problem with "blue noise" addon from Github!

oh ok, great then! Maybe give an answer with this solution so that people know how to fix the problem

edited the post :D


text:
Cycles - rendered viewport really slow in Blender 2.8
So since months I am experiencing that cycles is getting slower and slower for me
in Blender 2.8 and I thought with the release coming it might become better.
However when I have a very simple scene and use cycles to have preview it takes several seconds just to update small position adjustments i make to a sun lamp for example.
I do not know if I am having a setting wrong so it would be really nice if someone could help me.
I use a GTX 1070 as GPU and have enabled it.
Tile size is 240x256 (autotile)
viewport tile: I tried 64, 128, 256, 512.
CPU is i7 6700K and 16GB DDR4 2800Mhz.

I'm not sure how simple your simple scene is. Cycles isn't really meant for real-time rendering/preview, that's what Eevee is for. Although Cycles needs time to render the samples in preview I haven't experiences it becoming slower over the course of the development. It does become slower with growing scene complexity.

Well, yes you are right that it is not meant for a real time rendering / preview, however it was always able to show me complex scenes  in 2.79 and i could adjust lights etc.
As for the scene, My profile picture is the scene ^^, really just 3 lowpoly buildings and really no difficult materials.

That should work fine. Can't give you a definitive answer, but I can suggest the following: The first thing I would check is that your GPU is selected as CUDA device in Preferences > System > Cycles Render Devices > CUDA to rule out that it uses integrated graphics. Then I'd update the graphics driver: https://www.nvidia.de/Download/index.aspx?lang=en

"takes several seconds just to update small position adjustments" Small or big, adjustments require recalculating and re-uploading the scene, there are no optimizations here as far as I know, so regardless of how small the change is it will re-render everything

Hi, thanks for the replys guys!
Yes the GPU is set as cuda and it is using the 1070.
Sorry i dont know how to quote,
Before it was not like that. I could handle heavy glass shaders, the engine
started of course to render unless i moved something so it had to start again but now it takes several seconds maybe up to 25 seconds till it even starts doing that. Before it was immediate. I think I should capture what I mean and upload it right? Maybe it would be easier to understand what I mean.

10-15* seconds not 25.

try to run blender from command line with --factory-startup option
for example: "c:\blender\blender.exe --factory-startup"

Try to use combined GPU AND CPU for rendering. Using square tiles will increase render speed (any square numbers "X²" for better performance). You can find some sites to help you minimizing the render time.


text:
Help with rendering a google sketchup file, on blender?
I have inserted a google sketchup file, when i clicked render this happened. It is not rendering, and is turning up pixelated like this, and unclear.
blend-exchange.giantcowfilms.com

Share the "proper" texture.

Please share the file with https://blend-exchange.giantcowfilms.com/ and put the link in your question by editing it


text:
Rigid body motor constraint reversing when crossing the 90 degree angle on the Z axis
I'm experiencing some strange behaviour on a rigid body simulation. First I'll explain my situation a little bit.
There is half a cube and a cylinder, both with an active rigid body. The cylinder is attached to the cube with a hinge rigid body constraint so it can rotate like a wheel. The cylinder also has motor constraint attached to another small cube (passive rigid body).
With this setup I would expect that the wheel keeps spinning in the same angular direction but it doesn't. In the animation below you can see that the angular rotation of the motor reverses when crossing the Y axis on the world axes.
http://s27.postimg.org/4jha0ugkh/mechani_small.gif
Any idea how I can overcome this problem? I just want the wheel to be spinning in one direction while dragging the cube along with it.
UPDATE
Bithur's solution works like a charm:
http://s10.postimg.org/6jhof0buv/mechani_02.gif
Here is the file:

Changing the Object 2 to geo_body in the motor parameters seems to solve the problem

@wout glad to help, and thanks for the fixed animation :)

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


text:
How to add a "select path" input in a UI addon script?
I have to allow users of my addon to select a path via the directory browser window of blender.
The path is already set in an external ".conf" file, but I need it to be customizable via blender GUI, to avoid users to edit the config file manually.
I tried many things, (note that I'm a novice with the blender API), for example :
#(...)
bpy.ops.buttons.directory_browse()
# or
col = layout.column()
col.operator("file.directory")
# or
col.operator("buttons.directory_browse")
# or
col.prop(path, 'choose a folder')
#(...)

But nothing works. And can't find a way to do this after a day of seeking.
What I want to achieve is something like this :

Note that the input could be pre-filled with the config file's default value.
Thanks by advance.

I'm completely new to all this.
I wanted to know if theres a way of storing a path enter by the user in the select path box into a variable PATHVar in order to use it later.. bpy.ops.export_scene.fbx( filepath=PATHVar + name + ".fbx") I know that I should be using the solution mentioned by Polosson but conf_path would simply batch export to the blender directory and not a custom one.
I only ask here because it seems not to be much information around addon development really. Thanks in advance :)

Well, I finally found a solution:
First, I had to define a custom property in the register() function:
def register():
    bpy.utils.register_module(__name__)
    bpy.types.Scene.conf_path = bpy.props.StringProperty \
      (
      name = "Root Path",
      default = "",
      description = "Define the root path of the project",
      subtype = 'DIR_PATH'
      )

def unregister():
    bpy.utils.unregister_module(__name__)
    del bpy.types.Scene.conf_path

Then in the draw() method of the panel class, I had to call the property this way:
def draw(self, context):
    layout = self.layout
    col = layout.column()
    col.prop(context.scene, 'conf_path')

And... it worked!
Now, I wanted to display the default value (which is stored in a separate ".conf" file), in the "file input" when Blender starts (or the add-on is enabled).
To do so, I just had to call a function which get this value, and put it in the "default" parameter of the property definition:
def register():
    default_path = get_path_from_config_file()
    bpy.utils.register_module(__name__)
    bpy.types.Scene.conf_path = bpy.props.StringProperty \
      (
      name = "Root Path",
      default = default_path,
      description = "Define the root path of the project",
      subtype = 'DIR_PATH'
      )

And that's it!

Use the layout.template_image command:

template_image(data, property, image_user, compact=False)

Item(s). User interface for selecting images and their source paths
Parameters:

data (AnyType, (never None)) – Data from which to take property
property (string) – Identifier of property in data
compact (boolean, (optional)) – Use more compact layout

Here's a link to the relevant documentation for bpy.types.UILayout.

Well, I tried this too, but can't get it to work. Anyway, in my script the path won't be used for images. However, I think I finally found a solution, so I'll answer my own question. Thanks !


text:
Is there a way to acces external .blend file's data with python script?
I'm writing an addon to parse a directory (and its sub-dirs) to write an XML file which describe the tree-structure of the assets contained in that directory.
At the moment, my standalone script works pretty well.
The fact is, I need to add some info to the XML, like the dependencies (linked libraries) of each .blend file the script found.
I found a way to do this (outside blender), with the module "pyblenderfile" : http://code.google.com/p/pyblenderfile/
The principle of this module is to open a .blend and get all its data. But it's pretty long and often buggy on large .blend files. Especially since it's included in a for ... loop!
So I wonder if there is a utility function or method into Blender API, to access other .blend files data (without having to wm.open() them) ?

There's no data API for the .blend file format.
However, it sounds like you're trying to make a tool similar to Blender-Aid (code is here). Perhaps that's better place to start.
Note that blendfile.py from Blender-Aid can be used as a standalone blend file reader.

Note that I've updated blendfile.py for use in BlenderAssetManager,  https://developer.blender.org/diffusion/BAM/browse/master/bam/blend/blendfile.py

Yes, you can load in blend file data without opening the blend file using the library API.
Though this is intended for linking in data, you can use it to get data-blocks from a blend file. However it may not be a solution for you since you can only list the data-block names.
Optionally you could link the data, then remove it if you wanted to find out more about the data-blocks.
Note, I realize that blendfile.py may prove a better solution regarding the use case described in the question, but adding this answer for completeness, others who read this question may find the library method useful.

Thanks @ideasman42, the blendfile.py script did the job pretty well (I had a little issue with "string length" while reading blocks, but I found a workaround and everything works perfect)

@Polosson, I noticed string length needed changes too, would be good to get these updated committed back to the original repo.

well, I made a very small modif in the blendfile.py... Just increased the range (line 122), up to 1250. It prevent the use of FindBlendFileBlocksWithCode(), then block.Get() to raise the list index out of range exception, but it return some strange strings, like link1.blendnk1.blend, instead of link1.blend. So my workaround was to split the string to only get the first :.blend string! Not very neat but it works. :D

I've since made an updated blendfile.py, with quite a few changes/optimizations - linked in the answer.


text:
How to follow a path by curve points rather than length?
I am trying to visualise some physics simulations in Blender. The simulation result is a path that an object travels over time. I am importing the collection of points as a curve into Blender using a python script. I then use a "follow path" constraint on the object and set the curve as the target.
So far so good. However, the motion of the object is not as I expected. Blender seems to interpolate the motion along the distance of the path. The spatial co-ordinates are correct, but the time doesn't match.
For example, assume that the points are (in 2D for simplicity):

(0,0)  (1,1)  (4,4)

And I want to run the animation for 20 frames. I expect the object to be at (1,1) on frame #10.
However, what Blender does is, it takes the length of the total path and then interpolates. Since the last point (4,4) is much farther away, on frame #10 the object is not at (1,1) but somewhere between (1,1) and (4,4).
My workaround was to write a script instead of using the "follow path" constraint. The script inserts keyframes at each position in the simulation at the corresponding frame numbers. In the example above, key frames will be inserted at frames 0, 10 and 20.
The script is hacky and slow. My question is, can this be done in a better way?  I suspect this will be very useful to many people who try to visualise data.

Could you please post your script?

@OcasoProtal You can follow the link to the gist. Thanks for looking.

Ahh, sorry, I didn't see the link.

One issue with that script is that the object would not follow the path, but rather go in straight lines from control point to control point.

Manual solution
You could achieve this manually.  Start by giving the object a Follow Path constraint and setting the target to be your curve.
In this example, we have 3 control points (of a Bezier curve) and 20 frames.
Go to frame 1, and keyframe Evaluation Time to 0.  Also make sure to set Frames to 20. (these settings are found in the Object Data tab of the curve).

Now, go to frame 10 and slide the Evaluation Time until it appears that the object is at the same location as your second control point and keyframe it.  (being in Edit Mode allows you to see the control points)

Finally, repeat the above process to ensure that object will be at the third control point at frame 20.
Python Solution
If you have too many control points to go through by hand, then scripting this would be possible too.
The script could start off by calculating the lengths of each segment of curve.  You'd have to numerically integrate the formula for the cubic Bezier curve (numerical integration because it can't be solved analytically).  If you could successfully install SciPy into Blender, you could use their integration functions, otherwise you could write your own script using Gaussian quadrature or any other numerical integration algorithm).
Once you have the lengths, the user could input a list whose n-th entry specifies at what frame the object should reach the n-th control point.  Set the Frames property of Path Animation to the last frame in the list.  For each entry in list, set the Evaluation Time to be the sum of lengths of segments up to that control point divded by the total length multiplied by the last frame.

Thanks for the thorough answer. In my case, it was fine to have straight line interpolation between the points.


text:
Viewport pivot point changed from scene objects to around viewport camera origin
I am starting to learn using blender, and at some point I managed to do something to the 3D view camera.
Usually the camera orbits around an object, but now the rotation seems to happen (atleast very close to) around the "camera's origin". Neither the input setting in "User Preferences", the pivot point selection nor Ctrl-Alt-Shift-C (as suggested on some forum) do anything to the issue.

Try Shift+C and Numpad . (period)

Related: http://blender.stackexchange.com/q/696/599

@gandalf3 Both move the camera, but neither of those fixes the pivot. I think the issue is not the "pivot", but that the camera is in a wrong mode of some sorts

By "camera", do you mean the viewport view or the scene camera object?

It sounds like you centered the view on the camera.
Here are some ways to set the view center:

ShiftB or 3D view header > View > Zoom Border (Note that this will also zoom to fit the view to the defined border)
Select an object/vert/face/spline etc. and press Numpad . (period) to center the view to the selection.
Press ShiftC to center the view to the world origin (default). Note this will also center the 3D cursor.

If none of these work, then it sounds like you have Locked the view pivot to the camera object (ShiftNumpad .). See if there is any object  selected in the Lock to object option in 3D view > Properties region (N) > View > Lock to object:

You can remove this lock by clicking the X next to the object name, or pressing AltNumpad ..

CtrlShiftAltC is a shortcut for snapping object origins. (it does not affect the view)

"View -> Lock to object" did the trick. I had somehow specified a (scene) camera there.

Helpful tip here, even though it's already been answered: You can also press Shift + Num . to lock it, and Alt + Num . to unlock.


text:
Cycles emission behavior for colors at high strengths
I have one object in my scene that I want to make really emissive and purple.
When I input the color purple (#8800FF) and crank up the emission strength to 100, the object turns pink and nearby surroundings turn pink.
When I input the color red (#FF0000), the object and its nearby surroundings remain red.

I realize this is due to RGB math, but regardless, I haven't found a way to fix it.  I'm basically looking for a purple lamp to have the same emission behavior as a red lamp.

Possibly related: http://blender.stackexchange.com/questions/46825/render-with-a-wider-dynamic-range-in-cycles-to-produce-photorealistic-looking-im

Red lamp behaviour is impossible in the real world. every color should have at least SOME color from the oher two channels to behave realistically. That said, there is no way that i know of to do what you are trying to do besides maybe clamping or compositing?

@SebastiánMestre This is false.

@troy_s Lasers are the exception but they aren't a very common light source

@SebastiánMestre This has nothing to do with lasers. 709 red produces a chromaticity that exists out in nature. It just happens to be the colour of the primary light in question. If it is inside the spectral locus, it is a proper colour that can be seen by a standard observer, and the reason that your suggestion is in fact false.

@troy_s sorry but what is 709 red? I was just saying that most materials have light from all over the visible spectrum in their emission spectrum even if they are primairly emitting light that corresponds to the

@SebastiánMestre RGB displays are not spectral, nor are RGB renderers. They are tristimulus, meaning they work on three lights. 709 (more specifically REC.709) red is the colour of the red light in the display you are (likely) looking at and the colour of the red in the OP's post. While it is possible that to make 709 red using a mix of wavelengths outside of a renderer or display, in this scenario, it is a single light.

Not possibly related @JTheNinja, absolutely related.
The answer is that your colour values are rendered in the scene referred domain. This means that whatever view transform you are using will end up having a "maximum" scene referred value. So what is happening with purple?
In the case of the red, we expect it to actually "blow out", or turn white. This is due to the emergent and learned aesthetic of photography. It however, remains a perfectly saturated 709 (Longer term ITU-R Recommendation BT.709) light red.
In the case of the purple, we are relying on a mixture of the 709 flashlights to mix to the colour. In this case, a purple clearly needs some 709 blue, but also possibly a bit of 709 green. What is critical to understand is that the colour of the purple is a byproduct of the ratios between the flashlights. Those ratios must always remain identical to "hold" the colour we see.
As a result, as the 709 flashlight for red exceed the display referred transform, the other values continue to ascend. The scene referred to display referred transform however, has ceased being able to maintain that ever critical ratio as the lower values crush towards the maximum ceiling. When the ratios skew, the resultant colour skews. In this case, given that we cannot express "more 709 blue", we lose the ratio, and the 709 red continues to crawl up and give you the more fuchsia colour.
So what is a more ideal solution? Ideally, what would happen is that the colour maintains a straight line between the original colour and the Illuminant white point. Why is this more ideal than what you are seeing? Because it allows you in grading to go back and pull in those desaturated values as you creatively need, maintaining the original colour if done correctly. It also "looks more normal" in that as a colour ascends up our virtual camera's dynamic range, it indeed "blows out" according to what our mental models expect. This has a tremendous impact on the aesthetic of renders. So it is win-win[1].
In the case of an ignorant tone map / sRGB transform however, the values have a fixed scene referred value (a dismal and pathetic scene referred value of 1.0 in the case of the sRGB EOTF), and the original colour, or chromaticity in colour nerd terms, is skewed wildly.
If any of this interests you, go take Filmic Blender for a whirl, as it seeks to solve this very issue.
[1] This is in fact a key difference between the hacky cameras such as RED and Ursa, and the more high-end industrial cameras such as the Sony F55/65 and the Arri Alexa. In the case of the formers, they skew their colorimetry precisely as you are seeing in your demo. In the case of the latter, there is a careful hardware transform that attempts to gracefully desaturate higher values such that the chromaticities hold, albeit desaturated.

I don't exactly understand the technical terms, but Filmic Blender did give me some intruiging results.  You try and see if you can submit the changes to Blender.

@kizlink There is much room for improvement with Filmic, but it does address your issue specifically. The key thing to focus on is that ratios of light define the colour and that when faced with rendering ceilings (maximum values in the scene referred domain) you have to deal with how those ratios compress against the ceiling. If you don't compress them, you end up with the rather whacky colour results you discovered.


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Blender 2.79b not using full AMD GPU (RX550)
I think I may have solved the problem. GPU Usage is still really low but buffering is much better after creating a proxy for the video stipe.
I am having an issue rendering & skimming through video on my machine. I have a 7th gen i5, 8GB ram, SSD & an AMD Rx550 GPU.
The problem is that when I try to render video it is really slow. Skimming through the timeline is also slow (around 18 fps @ 1080p).
When I look at the GPU usage in wattsman it is literally at idle. Sometimes it goes up to like 300+ mhz which is still nothing.
What I have already done
- I have gone into settings and enabled OpenCL computing and set the RX550 as the device.
- Changed ram to use 4000.
- Changed from blender render to Cycles Render (this improved performance a bit but still the GPU doesn't seem to be used.
- Changed
I am out of ideas on what the problem is. I would appreciate any help you guys can offer.
Thank you in advance!

Yeah, I've noticed it lags a lot but I have figured out how to make it work for my needs by watching a few tutorials on youtube. It definitely is not very user-friendly. Thank you for the recommendations, I'll definitely have to check out those other video editors and see which one works best.

I have a Ryzen 7 and a GTX1060  and VSE is still causing me a crippling depression. It isn't your RX550. Apparently a solution is to use multiple blender calls to render a frame, for now.


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Asset Library Not Importing Image Sequence
I use an image sequence node in order to change character expressions for the robot. I wanted to use the Asset library to import the character on over. But when importing it over using the asset library the image sequence becomes broken. Is there any way to preserve the images in an image sequence node when importing from an asset library?
I had to unlink the image sequence in order to have the image sequence working again.

In which way does it break?


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Problem with UV mesh
I seem to be having trouble with one of my UV meshes. For some reason, a number of vertices/faces have decided to detach themselves and, not only are there too many, but I can't re-attach them. The simplest thing to do is to unwrap the mesh again, but now I can't get it to align properly. The save I've attached is with the broken vertices... Any ideas what I could do? Thanks.

If you have multiple vertices sharing the same location, you can select all and press W -> Remove Doubles

I don't think you can avoid re unwrapping.
The reason why you have the separate UV island in the head unwrap is because that is the way the UV seams are marked   at the top of the head.

To make the head a single UV island clear the unwanted seams and mark a new one along the top of the head as in the screenshot below. Then UV unwrap again.
You will have to experiment a little to have the exact seams to get the correct unwrap island shape and then scale to match (align to) what you had before.

Just a note : usually the ears of a head will need UV seams so that they will be separate islands when unwrapped.

No, that's not the issue I'm having; that's intentional. When you load the save up, you'll see some of the faces/vertices of the UV map in the centre of the map. They've somehow become detached. However, if I unwrap again, I can't get the UV of the head/face to match up. No matter how much I resize it.

You're going to have to weld the vertices back in to place. There aren't that many, but if you're trying preserve your existing UVs, I don't think there's another way. I would turn on the Sync UV and Mesh Selection button and select a vertex. The vertex that it should be welded to will also highlight. Turn off the Sync button, move the vertex that is out of place over to the one that is in place and weld them together. That will work for the verts on the edges of the rips, and then it looks like you will have one or two loops in between the ripped edges that you will have to use your best guess at placing.
Edit: It looks like several vertices are mapped to a single point. You'll need to spread those out so you can see each vertex individually. You could possibly create new UVs for those to make your job a little easier.
Turn on slection Sync, select the bad faces in the UV editor and unwrap in the 3d View. This will give you something cleaner to start with.

What you are talking about is that you selected a face or mesh part and it came of with extra vertices, so accordingly when you select one of them the others get selected too, right?
This can happen when you are in face select mode and UV sync selection is on. To fix this you have to unwrap again with seams marked but this time turn on Live Unwrap, unselect the UV sync selection, select the ones you don't want rearranged in the editor and press P for pinning. This way it will keep those pinned vertices the way they are when unwrapping.


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Shape Keys - opening the mouth
Any advice on the best way of opening the mouth using Proportional Editing or rotating the bottom jaw from the pivot point/3D cursor? It's the latter I'm trying to achieve. Sadly, the jaw always looks a bit too wooden, like a ventriloquist dummy's.

Thanks

Please show your work  with Blender screen captures. Yes there is an attached Blend file. Still it clarifies your question to readers to include screen captures in this question and all future questions.  Probably the reader above could make the observation and corrections you need without opening your file, if you choose a meaninful screen capture.

I'm sorry if I sounded rude. If you included the armature and the original weights in your file, it would be easier to demonstrate some weights which can open the mouth with only the jaw bone.

Updated the original post with an image. I'm aware I could use armature instead, and I do have some set up, but I'm practising with Shape Keys at the moment. Plus, I had to delete some stuff for that save file as it was over 30Mb

Bones/Joints are much better suited for movement which rotates around a pivot point, namely the eyelids and the jaw. Both will interpolate strangely if their not pivoting the base of the movement (where the bone would sit in reality). Shapekeys will only switch between states and are best suited for the eyebrows, mouthcorners and and other movements which rely more on muscle contractions instead of mechanical relations (like bones).

Can't seem to get Weight Paints to work with my jaw bone anyway, which is weird because I swear I did at one point. I keep trying to parent the head to the jaw bone and applying Automatic Weight Paints, but nothing happens. If I paint the jaw in red manually, manipulating the bone doesn't do anything

From my comment

Bones/Joints are much better suited for movement which rotates around a pivot point, namely the eyelids and the jaw.
  The Jaw will interpolate strangely between open and closed if it is just shifting between a shapekey. A bone would ensure a rotation similiar to the real world jaw bone.
  Shapekeys are best suited for the eyebrows, mouthcorners and and other movements which rely more on muscle contractions instead of mechanical relations.

Edit: To understand the images illustrating this post, you must note, that I have used a custom weight paint range. Every vertex weight above 0.000001 looks similiar to the standard weight settings. However, a weight of 0.0 is set to white. I did this to be able to tell the difference between a very small weight (e.g. 0.00001) and actually no weights, which is not possible with the standard mapping of blue.

Weight Painting the Jaw

Make sure all of your head geometry is associated with the head bone.
Add the jaw bone, make sure that

there is a vertex group named exactly like the jaw bone
the jaw bone has deform enabled
the jaw bone is part of the armature used by the the mesh (via the armature modifier)
your geometry is not unnecessarily dense (it seemed you have applied the subsurf modifier, this makes the process very difficult. I would unsubsurf the model 1 step with the decimate modifier.)
in weight paint mode, Auto-Normalize is checked

Lock all groups except for the head and jaw vertex group.
Roughly paint the jaw to the jaw bone.

Now open the jaw with the bone and make sure the complete jaw is fully assigned to the jaw bone.

Now choose the the mix brush and paint weights of approximately 0.5 on the corners of the mouth. Choose other quantized weight for other areas if needed. Roughly block out the correct shape. You can raise the mouth corners by adding weights to the head vertex group and you can lower them, by adding weights to the jaw group.

Using the blur brush smooth the area. Then use the add brush with a very fine Strength to shift single vertices untill the desired shape is reached.

Image shows the head's weight group.

Thanlks for this. I'll give it another go. Looks like the reason why I couldn't get it working before was because I'd forgotten to set the bones to Deform. Also, what exactly does Auto Normalise do?
Thanks

The manual explains it well: "Auto Normalize_ Ensures that all deforming vertex groups add up to one while painting. When this option is turned off, then all weights of a vertex can have any value between 0.0 and 1.0." In this case, we want weights to be removed from the head when we add them to the jaw.

Not having much luck with this; I find weight painting to be tedious, finicky and time consuming. :-\

May go back to using Shape Keys; I was finding those easier to use. I suspect the book I’m following suggests to use them for the mouth as well

I can't, for the life of me, get this nailed. :( No matter what brush I use, I can't seem to match how you've done it. I keep trying to paint over the vertices and nothing happens. I can't seem to get passed this ventriloquist dummy look. I've updated the first post with an updated image showing what I currently have.

Is there no way I can unsubsurf whilst having Shape Keys? I really don't want to have to delete them...

@Dusty That may be slightly difficult. If you have searched the forum and not found any similiar question, this would be a good new question.

But it sound strange that you're not able to paint other weights. Let's resolve this in chat.

I did find this though... https://blenderartists.org/t/subsurf-applying-in-objecs-with-shape-keys-to-use-in-bge/573439


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Why is proportional editing only effecting one side of my mesh?
I'm currently working on facial expressions and using Shape Keys and I've just run into this weird problem...

Whenever I manipulate one side using Proportional Editing, the other side won't follow or match, no matter the size of the fall-off. It's like the other side just stays where it is. I'm not sure what's happened. There are no modifiers active or waiting to be applied, such as the Mirror.

I can't figure out what's wrong. Any ideas?

Please upload your .blend via https://blend-exchange.giantcowfilms.com

Edited the original post

You probably have to disable the X Mirror option in the Tools Options panel

Yeah, I tried that. Everything else has been great using X Mirror to manipulate both sides, so I could do with doing the same here, but it just isn't working properly

I've downloaded your file and I don't have any problem if I disable the X Mirror and enable the Proportional Editing option, so it's weird

So if you disable X Mirror and use Proportional Editing, are you still able to adjust both sides at the same time, or are you doing one side at a time?

The X Mirror option will work as long as Blender finds a symmetric vertex, if  you switch off the X Mirror, move a vertex on a side, you break the symmetry for each vertex you've moved (including the ones that have been moved with the Proportional Editing). What exactly is you goal? Why don't you disable X Mirror?

I've had to whilst working on the mouth, but I'm trying to do facial expressions with Shape Keys. At the moment I'm trying to do an angry mouth position.

Why are you using the X Mirror? Also, it's more convenient to use bones, but it depends on your final purpose

So when changing the expression of the mouth etc., it does it on both sides...? I have the Vertex Groups and Shape Keys set up so I can assign one side of the expressions to its own Vertex Group - Left or Right. I'm following a book and an online guide, which use Shape Keys for the expressions. I'm finding these more convenient than bones, but I think those will be used too following the book.

if you keep the X Mirror it will symmetrize all the changes you make, but if you make a-symmetrical expression, you won't be able to use the X Mirror on these vertices


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Link collection from external .blend in 2.8 via python
I tried to recreate the File->Link...->somefile.blend->Collection->Collection linking mechanism in Blender 2.8 (Release canditate) in a script.
Unfortunatley my linking code does not behave like when I link via the GUI.
GUI:
-> I get an EMPTY that I can move/rotate/scale /duplicate etc. (orange collection Icon without a "link symbol"). A linked collection inside of it. Perfect! This is what I want.
SCRIPT:
-> I get a collection that is linked that I cant move etc. This behaviour seems not really usefull to me. I want to at least do the basic opperations on a "referenced"/linked object like move/rotate/scale.
I tried to place the linked collection in an EMPTY but the GUI does not allow that.
My script so far:
    context = bpy.context
    scenes = []
    mainCollection = bpy.data.collections['Collection']
    with bpy.data.libraries.load(blendFile) as (data_from, data_to):
        for name in data_from.scenes:
            scenes.append({'name': name})
        action = bpy.ops.wm.link
        action(directory=blendFile + "/Scene/", files=scenes)
        scenes = bpy.data.scenes[-len(scenes):]
    for scene in scenes:
        print(scene.name)
        for coll in scene.collection.children:
            print(coll.name)
            context.scene.collection.children.link(coll)

Any ideas how to place the linked collection inside an EMPTY via script to move it?
collection.parent = empty

A collection does not have a "parent" attribute.
Thanks in advance!

Thanks for your initial self-answer! It got me on the right track.
I think this way is even easier:
import bpy

master_collection = bpy.context.scene.collection

blendFile = 'path/to/file.blend'

with bpy.data.libraries.load(blendFile) as (data_from, data_to):
    data_to.collections = data_from.collections

for new_coll in data_to.collections:
    instance = bpy.data.objects.new(new_coll.name, None)
    instance.instance_type = 'COLLECTION'
    instance.instance_collection = new_coll
    master_collection.objects.link(instance)

I actually solved it myself:
    import bpy

    blendFile = "path/to/file.blend"

    context = bpy.context
    scenes = []
    mainCollection = bpy.data.collections['Collection']
    with bpy.data.libraries.load(blendFile) as (data_from, data_to):
        for name in data_from.scenes:
            scenes.append({'name': name})
        action = bpy.ops.wm.link
        action(directory=blendFile + "/Scene/", files=scenes)
        scenes = bpy.data.scenes[-len(scenes):]
    for scene in scenes:
        for coll in scene.collection.children:
            instance = bpy.data.objects.new('Instance', None)
            instance.instance_type = 'COLLECTION'
            instance.instance_collection = coll
            mainCollection.objects.link(instance)
        bpy.data.scenes.remove(scene)

This behaves now like the link from GUI.
The magic happens here:
instance = bpy.data.objects.new('Instance', None)
instance.instance_type = 'COLLECTION'
instance.instance_collection = coll
mainCollection.objects.link(instance)

Maybe this is usefull for someone else. :)


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How to export your Ocean Modifier Mesh and Animation to Unity? | Blender v2.80.72
/*Edited: For Blender 2.7 Users I found a detailed articel with pictures. */
I want to build an VR-Scene in Unity with a little Island and and ocean around.

For the ocean I am quite happy with the ocean modifier and made already an looping animation with the water.
animation Gif
But I simply cannot find a solution to export the mesh + animations to Unity. I keyframed the time and scale and found the problem, that these can't update when I apply the modifier. To my understanding blender needs to apply the modifier when exporting, so I can even get the shape of Ocean.
[
I tried and failed with this explanation.
Could somebody please give me an more beginner friendly explanation?
Here is my blendfile:
google drive link

https://blender.stackexchange.com/questions/1186/ocean-modifier-and-foam-data-export https://blender.stackexchange.com/questions/72279/export-ocean-modifier-animation-to-game-engine https://blender.stackexchange.com/questions/53464/trying-to-export-ocean-modifier-animation-as-collada-file

https://drive.google.com/open?id=1KFXwSZOEZkUK1K4hLUY0APrCdHQQexrJ

@DuarteFarrajotaRamos yeah, none of them solve my question, where the third one doesn't even really has an answer.

@FFeller okay! Seems like you applied the modifiers and baked the Animation to the frames! That's exactly what I want. So how did you do it?

First you have to apply the scale with ctrl+a on the ocean (this will mess up the scale, but you can adjust it after the procedure). Then select the ocean and export it to mdd. Then apply the modifiers. After all, just select the ocean again and import the mdd. Then the keyframes will appear, you dont have to use any other modifier. May be you will have two extra frames before the first and after the last frame, which are a little dislocated, but you can easily delete them.

@FFeller for future readers I want to mention, that you have to enable under  edit -> preference -> add ons ->  Import-Export: NewTek MDD format to even see the option when clicking export.

@FFeller furthermore I just get an error when I try to export. Am I doing something wrong or is it just the 2.8 beta?

Picture of the Error

I used the official Blender 2.8 release and it works fine.
What to do:

Select your 'Ocean Object' and press ctrl + a to apply the scale.
With your object selected click file -> export -> Lightwave Point Cache (.mdd)
Save the mdd file.
Apply your ocean modifier
With the object selected click import and import your mdd file again.

The whole process takes only seconds now.

You need to have the NewTek MDD format addon enabled to this this option in the export menu.


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Black Shadows issue on Cycles Engine

Blender File: https://blend-exchange.com/b/xNR6Mv94
I'm having an issue and it's taking me weeks to solve. When I created a group of leaves from a transparent image and went to viewport shading to preview it, These black shadows appeared around them. I had the same issue earlier with a different transparent object but I solved it by putting on alpha clip and alpha blend. I attempted the same thing here but it didn't work.

I googled my problem and one of the solutions was to put the Transparency in Render Properties --> Light Paths to 32 but the black shadows are still there. It seems like this issue only applies to the Cycles Render Engine as when I apply the Eevee Engine, the black shadows are gone.

Does anyone have any idea what's happening and is there a way to fix this on the Cycles Engine?

You could have edited your original question and put your file. The weird thing is that it seems to work fine at least for me: https://zupimages.net/up/22/44/sre6.jpg

I apologize for the repost. I'm new at blender.stackexchange. I don't understand what's happening to my leaf, I looked through every nook and cranny and I still can't find the problem. Maybe it's my computer? @moonboots Was there anything that solved the issue for you?

i didn't change anything to your file, but maybe someone will understand


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My Bevel Modifier isn't applying correctly
I'm having a problem where when I apply my Bevel Modifier, this extra bevel appears in the middle of the mesh. The mesh is mirrored which would explain the extra bevel. The only problem is that prior to applying it, the bevel didn't appear, giving me the illusion that there was no problem. And I added clipping when mirroring the mesh so there isn't a noticeable gap (I doubled check).
Here's a gif that best explains my situation.

Here's the Blender File

Is there a solution to this problem?

You have internal faces across the edge of the mirror. Go into Edit mode then Shift-Z for X-ray mode.

Select and delete the faces with X > delete Only Faces and you can then apply the bevel without problem.

Your mirror modifier merges the vertices at the mirror plane. The bevel modifier being after the mirror, it only sees coplanar faces there, so nothing happens.
But when you apply the bevel modifier, it applies it to the base mesh, ignoring the mirror. And there the geometry is different, hence the result is different.


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Fancy Dispersion / Diamond material looks sadly underwhelming and dull in render
I am working on a high heel shoe model (See picture below) that has two straps with each around 600 tiny diamond shaped crystals on it. I am using a high quality shader, that has yielded good results in other situations, however, I don't get it shine in my scene. The diamonds are multipied on a mesh through a particle system.
I fiddled around with the scene scale, different lighting setups (point/spot lights, HDRIs, etc), ramping up the light paths (global illumination) didn't resolve and is also not a great solutions, since it's going to explode the render times. Rendering in cycles.
Grateful for any pointers! Thank you!
ps. blender file:

I don't think without actual file and desired result, people here can help ... it is definitely about light condition (lamp, reflections, environment) ... also there ca be some issue with shader it self that works better with some internal setup in different scale than in your case ... so probably better share file via https://blend-exchange.com

maybe add strong lights and also some effects like bloom in Eevee or glare/blur in the Compositor?

added a scene file:

Cycles
Your diamonds look quite different in your image than what I got from your shared file ...
Cycles (12 samples)

Since the final effect remains on all materials and environment you could keep also leather materials to see how it affects result - reflection from material behind could be important.
So for a tests I added leather simple color and will follow your given file ...
Cycles (1024 samples)

"Black" looking diamonds in render are artefacts generated by overlapping particles. Your upper emitter object has 295 vertices, but your particle system is set to emit 683 diamonds. If you match particles with number of vertices, than issue is gone.

Now you are facing to another issue - leather visible at a centre of each diamond, because the tip of diamond penetrates into the leather. So you would have to avoid that in some way ... here I just set Shrinkwrap > Offset -0.001

Since for cycles it could take a lot of time to calculate clean render with all the refractions (or what ever ...), consider to use ...
Eevee
Eevee (with Bloom) - your studio environment

Eevee (with Bloom) - blender's studio.exr

Eevee (with Bloom) - blender's courtyard.exr

Footnotes:

I don't know how about diamonds, but what I saw with bijou - crystals are placed into a glossy silver holder or galvanised by silver material on back sides to create like a mirror surface ... so they appear very shiny even gluwed at dark surface.
In Outliner editor you have some object disabled for Viewport but still enabled for rendering ... so just be sure it is set as you really want to be.

thanks @vklidu highly appreciated. i removed the all other materials to decrease the file size. it was too big before. i know eeve does a quick and fairly ok job, but the cycles renderer seems to give a more accuracy. still there are a lot of gemstones that stay dark and don't catch any light. here's a reference images: https://www.ebay.com/itm/175332111226
also, my eeve result doesn't look like yours in the render. is there anything else that you did to the scene? cheers!

Also your reference is a full of black diamonds (blacks in my first image can be just I used 1ě samples :) ... your image looks flat, yes, are you sure World was set to your studio (Lightbox) texture? Looks more like greenish reflection of blender's forest.exr ... eve I think I add only Bloom (I will edit the A with setup ... I have also one more thing in mind to extend my answer (I'm not sure it make a difference :)

If you would need my blend I can share ... just let me know :)

Sorry, for the slow response. I've been away over the weekend. Thank you, you are amazing. I was suspecting that it has to do with the tips of the diamonds penetrating the leather material. If you don't mind, please share the file with me. Thanks again!

Temp link https://we.tl/t-DYZjiThHyU Good luck with your project :)


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Driver bone not working
For some odd reason I can't get my driver bone to work. I've followed tutorials, but whenever I move the bone on the Z axis (local) to control whether my eye opens or closes, it doesn't do anything. :-/

you can upload the .blend here https://blend-exchange.giantcowfilms.com/ I never seen any tutorials but I want to give it a shot

I've updated the original post

Its really too much for me, srry. Im going to have my existential crisis now.

Your driver was working with local X movements, while moving a bone along its longitude is local Y axis. I changed the driver formula to "scripted expression" and multiplied the variable (named default "var", but you can change it) by - 10 for having consistency between bone and eyelid movement.

I can't seem to get that working; it also says ERROR: Python auto-execution disabled. :-\

Okay, got the error message fixed, but I still can't seem to get that working. The Graph Editor really confuses me...

Didi you try to copy my two corrections? If yes you could upload your new file...

Actually, it does work. I was locking the other axis via the N properties bar. I would like for the changes to only work with the Z axis, but it appears it needs the Y axis for some odd reason. Is there anyway to fix that? Also, how can I adjust the speed at which the Shape Key animates via the Graph Editor?

Nothing odd (or, pehaps nothing completely odd): simply local coordinates are calculated related to the object (in this case the bone) and the bone has its y axis aligned with world's Z axis, so if you  move the bone along the world's Z axis, in fact you are moving the bone along its (local) Y axis. This is the difference between local and world coordinates, very useful because if the head is rotated the world coordinates will be twisted, but the local Y remains exactly local Y.

If you vary the angle of the line in the graph editor (select a point and use G for grabbing it) you will vary the speed of the movements (eventually you can also invert it). I prefer to use multiplications in the variable formula, but it's the same effect.


text:
X Mirror and copying weight paints
I'm a bit confused with the X Mirror option and how you're supposed to copy weight paints from one side to the other. Is X Mirror supposed to work by painting the opposite side automatically as you paint the other? Or am I misunderstanding how it works. Either way, it doesn't appear to do much for me. Failing that, how am I supposed to copy my weight paints from one side to the other?

Thanks

The only problem is that your model is rotated 90 degrees on the Z axis, also the scale is not 1.0 but the skeleton scale is 1.0, which might make it not work properly. It worked perfectly for me after I applied all the transforms (Rotation, Location, Scale), as a plus I did a symmetrize because the model is not perfectly symmetrical and finally I checked for any unwelded vertex.
Hope that helps.

x-mirror in weight paint mode is meant to mirror your actions between mirrored groups.
Let's say you have group four your right and left arm. If you paint the weights in the left arm group, x mirror will do its job on the right arm group.
In order to paint in symmetry inside a single group, you need the purposely named symmetry tool :

Oh, I'm so confused... I have Vertex Groups for my two shoulders, the (character's) left shoulder has had its weight paint adjusted, the X Mirror is enabled, but it doesn't replicate it on the right shoulder. Also, I'm not getting an option for Symmetry.

Are you in weight paint mode?

Yeah, I am. ...

provide your .blend file then.

Uploaded it to the original post. I asked the same question before and someone tried it and it worked for them, so whether I'm just completely misunderstanding how it works, I don't know...
At the moment I'm trying to copy the currently selected weight paint to the opposite shoulder.

watch closer my screenshot, you will notice that I am in the tools tab, while you are in the options tab. For the x mirror to work, try to enable "Multi-Paint" in your brush settings.

Yep, that's exactly what I've been doing. I don't have a few of those options you do - Accumulate, Front Faces Only, Falloff, Symmetry etc. - so I don't get it. :-\

show a fullscreen shot

https://imgur.com/a/7brvLrH

Oh, shoe. Maybe those tools are only available through blender's daily builds... you can download that here :
https://builder.blender.org/download/
Be aware, it's less stable than a usual release. Maybe just download the zip version and put that on the side, don't overwrite your stable installation.

Oh, okay. I'll probably just wait for the newest stable release with EVEE. Thing is, a book I've been following uses an old version of Blender - 2.78b - and the author suggests to use X Mirror. Even the names of the bones are set up correctly - Shoulder.L and Shoulder.R.

Just enable multi-paint for that, i'm sure it's in 2.79

Yep, did that. Nada. I painted on one side and it doesn't get copied to the other side. I did read a little something though - that if one side isn't symmetrical, it won't do it. I don't know why it wouldn' t be though - I duplicated the right side and mirrored it on the X axis.

Curious, it works for me. Maybe try enabling topology mirror in the options tab ?

Aha, that seems to have done it. :D Thank you.

As far as I can understand, X-Mirror does NOT work retroactively!  You have to have it active before doing any weight painting.


text:
Problems with Render Layers
I seem to have nothing but problems with compositing and Render Layers. :-\ Every tutorial I’ve followed so far on Blender Guru, I’ve been unable to replicate the process whether in 2.79 or 2.80.
As part of a tutorial, I’ve added some lights in their own Collection, added another Render Layer and called it (Spot) Lights, disabled all the Collections I don’t want, unchecked the eye for everything I don’t want, and the other Layer has everything else in the scene enabled with the eye on. Rendering out my first scene/RenderLayer proceeds to render out the next RenderLayer containing the lights. However, for some weird reason, it renders out some of my other lights in the scene, along with the background and the floor.
If I continue to follow the tutorial and set up the nodes the same, the end result is almost there, but my main building/object becomes semi-transparent.

How could I fix this? How can I prevent the second Layer from including those objects when they're not even enabled in that layer?

It is kind of hard to follow and understand your question. Could you add your .blend by uploading it to https://blend-exchange.giantcowfilms.com/, edit the question and paste the link into it? That way it is easier to figure out whats wrong

Save file added.

One thing - disabling Eye icon in Outliner Editor hides object from viewport not from Rendering, for that you have to enable Render (Camera) icon in filtering.
Disableing these objects from rendering will affect both Layers. To fix it you have to place them into separate Collection (I called it "Scene"). Like that you can disable it for one layer and keep in others by switching checkbox of collection.

Second thing - To add additional Lights with Glare in compositor I would use rather enable Film > Transparency and in compositor use Alpha socket as input. Alpha because even you disable whole Scene collection you still use world light that will affect compositing. Like that you can also save one Mix node from tree to get same result.


text:
Problem flipping/duplicating keyframes
I seem to be having issues with flipping and duplicating some keyframes. I've tried using Ctrl + C, Shift + Ctrl + V and duplicating keyframes in the Dope Sheet, but I can't get copied frames to work properly. I've already keyframed the motion of the left and right legs/feet, but whenever I try and duplicate what I've done for later in the timeline, such as the left leg, it gets stretched out of proportion. :-\ I'm not quite sure what I'm doing wrong or what I should be adjusting instead.

Any suggestions?

At least make sure that your armature is symmetrized. As you can see it is not. So in Edit mode select the left (or right) part and Symmetrize. Also, you'll have to correct the Pole Angle of some bones like the forearm, fingers...

Thanks for the suggestion. I'll play around with it after both sides are now symmetrical. I can't say changing the pole angle has helped though. Putting the right one to 90 degrees just twists the arm around the wrong way.

Yes it depends on which side you've symmetrized, find the right pole angle  ;)

Okay, I think I've got it. I take it it's just a case of repositioning the arm/hand for it to untwirl and be in the correct direction...?

once you've symmetrized you often (always?) need to twist some of your IK bones so that they are correctly oriented, but it was not your problem, I think it has too see with a bad symmetry, I'm not sure though, you need to test.

The finger positions still get messed up if I copy the right hand's armature position over to the left.

yes because you also use some IKs for your fingers, so you also need to correct their own pole angles

yeah, I've done that as well. I've even reset the position, rotation and scale of every bone, but the fingers are still completely twisted out of proportion. I've added a screenshot to the first post.
EDIT: Turning off the influence for each finger IK fixes them, but is it wise to do that...?

well, I don't know, it's the choice you've made, I personally prefer to use other techniques for the hand  ;)


text:
Node settings to composite my character within real footage through camera tracking
I'm following a book on character creation in Blender and I'm currently trying to composite my character within real footage through camera tracking. I'm at a part where I'm trying to set up the character and its shadows in a separate Render Layer and adjust them through Nodes. However, in the book, the two Render Layers have a transparent image showing. They're not showing for me. Also, adjusting things like the RGB curves has no effect. Have I set this up right? Or have I missed something?

Thanks

Nope, I don't have a transparent object. The object appears in the footage fine. It's the Render Layer image that should be showing something and it's blank.

Okay, so I think the issue was, was that I needed to do a test render, and then transparent images appeared. However, the one for the character's shadows don't. I've still yet to add the rest of the nodes from the book, but I'm pretty sure the shadows should be appearing within the image.

For those more serious about compositing into footage, I’d recommend Paul Chamber’s excellent series http://www.paulchambers3d.com/blog/2017/8/22/adventures-in-scene-referred-space-part-one as well as Sebastian König’s post which tackles similar issues http://blendfx.com/working-with-blender-and-the-arri-alexa/.

I’ve set up all the nodes now from the book, but the shadows won’t show. I’ve rendered the scene with F12, but only the character shows. I have the character on one Render Layer and the plane he walks on on another. I’m working in Cycles, by the way.


text:
how does one install "audioanalyse0.1.1" module in blender?
hello im doing a little project I try to analyse sound from a mic. in the bge. I whant to use numpy pyaudio and audioanalyse. the first two are pretty simple. I have some difficulties trieing to install audio analyse. Does someone kniw how to install it and what version of python to use?
cheers, tim

I'm not sure if it's the right place to ask about this. Anyway, a link to this "audioanalyse" module would be great, at least for us to understand what exactly it is.

Assuming you mean Audio Analysis v1.1.0 this script was developed for Blender 2.43 (around 2007) and is unlikely to work with the latest releases.
Meanwhile there was an addon Import_Movement_From_Audio_File which could be a better starting point. Unfortunatly it seems that it has been removed from the current distribution (the documentation refers to 2.64.9).
You could get an older Blender version from here.


text:
Cannot Select Linked When Sync Selection Is Enabled
So, I'm currently developing a game with unity for which I created a bird, rigged it, and created several actions for it. I then unwrapped and textured it.
But now all the actions aren't working anymore! And whenever I try to rotate/move a bone all i get is the error message: "Cannot select linked when sync selection is enabled".
I think it might be related to the UV editor, but i have no clue what I should do there.
I hope anyone can help!

Can you share the blend file?

That's nothing about UV in this case. That's because you were trying to tweak pose in Rest position. Just remember to simply switch to Pose Position to continue tweaking. :)
Location:
Properties Editor > Object Data Tab > Skeleton > Pose position

BTW, there are indeed two such messages, located in:

source/blender/editors/transform/transform_conversions.c
source/blender/editors/uvedit/uvedit_ops.c

True, it's a strange message for bone transform system, which seems hard to make sense, probably needs to be improved.

Edit:
In the latest build, this puzzling message has been fixed as "Cannot change Pose when 'Rest Position' is enabled". So it is not an issue any more.


text:
how to create UIList with auto-aligned three columns?
I want to create nice-looking auto-adjusting UIList with three columns of data inside. Some of the values in columns are different in length. They are: float value, unit (usually 2-3 chars) and name of the corresponding object (could be longer, but nvm).
Here is the sample code:
First, I have a collection object defined like this:
class Area(bpy.types.PropertyGroup):
    id = IntProperty()
    area = FloatProperty(default=0.0, description='Area measured')
    atxt = StringProperty(default='0.0',description='Area converted to text and formatted')
    unit = StringProperty(default='',description='Unit item choosen from UnitTypes')
    name = StringProperty(default='',description='Object name which area is calculated')

Then I have a draw_item function, which is defined like this:
class AreaItemList(UIList):
    def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
        if self.layout_type in {'DEFAULT', 'COMPACT'}:
#           line = ('%-12s %4s %-s' % (item.atxt,item.unit,item.name))
#           layout.label(text = line)

            layout.prop(item,"atxt",emboss=False,text='')
            layout.prop(item,"unit",emboss=False,text='')
            layout.prop(item,"name",emboss=False,text='')
        elif self.layout_type in {'GRID'}:
            pass

Please note the commented section: it does work, but looks ugly, and there is no align in columns because of variable char length. So, the question is:
- how to make aligned columns in UIList?
It could be either by using layout.split (but it's hard to predict the split ratio, and there are three columns, and by the way - the documentation is pretty poor about this layout function), or either by using monospaced font and string formatting. How to do this? Any ideas?
Look of the list for the code from the comment:
http://storage3.static.itmages.com/i/16/0423/h_1461384717_4797711_d3f6576ba9.jpeg

By default when you place multiple items on the same row blender will give each item an equal portion of the row eg. three items get 33% of the row each. Due to the fluid nature of blender's layout, we can't specify an exact size of each column, they will get resized as the user resizes the layout.
You can use UILayout.split() to alter the percentage of a row that an item uses. To expand on my earlier answer to include an example of splitting three columns you can get the following result.

Note that the split works on the allocated space, the first split turns a row into two columns, the first column gets the percentage size of 60%, the remaining items then use the remaining 40%. I have then used split again so that the second column gets 30% of the available space - that is 30% of the remaining width after the first split not the entire row.
def draw(self, context):
    measure_size = 0.6
    unit_size = 0.3
    box = self.layout.box()
    col = box.column()

    row = col.split(percentage=measure_size)
    row.label(text='9.3000168000e+03')
    row = row.split(percentage=unit_size)
    row.label(text='in')
    row.label(text='Cube')

    row = col.split(percentage=measure_size)
    row.label(text='7.176e+00')
    row = row.split(percentage=unit_size)
    row.label(text='yd')
    row.label(text='Cube')

Thank you for that answer. I think I have to stick with that method, although I wonder if there will be possible to format all columns in a way they could adjust themselves when I put something significantly longer into any column. In the other words, is this possible to mimic the behavior of for example html table, which adjusts it's content automatically? Here if I define constant split as .6, it will remain as such and then I have no way to adjust column lenghts in any way to fit their content. Do you think it's possible?

Blender adds vertical scrollbars to long lists but not horizontal scrollbars to wide lists. Users can also zoom the properties area and alter DPI to make everything larger/smaller. That is the dynamic nature of the blender UI. If the user resizes their properties to an inch wide then they won't see long items, it won't matter if you have it set to 60% or 300 pixels. You could calculate the width based on text length instead of using a fixed size.

I understand this behavior and I love it. However in this case I would like to put 'denser' data into small region than it would be in default. So is there any way to decrease the space created between columns with split? Even in your example in the picture there is a significant space between columns, which for small panel size is a waste and causes text labels to hide behind dots (...). I would like to keep those columns but without such wide margins in them.

I don't think we can alter the padding around each item.


text:
World appearing black
For some reason, whenever I do a test render with Shift + Z, all I get is my character and the world is black. In the World properties, I have a Sky Texture with a strength of four, but it still shows as black. The only thing it effects is my character. Also, I'm wondering if this is related to why I can't get my character's shadows to render/show on a separate Render Layer...? I do have some Nodes set up, but deleting all of those hasn't fixed the issue, so I'm not sure if they're to blame.
Any advice?

in the Render settings is Film/Transparent checked?

Ahh, yes, of course. I totally forgot about that. Thank you. :D

I don't really see the point in creating a new thread because, to me, it's the same issue. My compositing is pretty much finished, but when I go to render, the video footage isn't being rendered out. My character does, but everything else is a black screen. I've attached an image of my node setup.

I have a Viewer node set up, though it's at the end of the tree. I also have an Alpha Over node in there and I tried setting Environment on with both layers. I'm still getting a black screen though.

I can't get the Viewer node to work either. I get what it's supposed to do, but connecting it to each node isn't doing anything from what I can see. I'm not seeing any changes anywhere.

I had this same issue with Blender 2.8
This worked for me :-
under View Layer tab, select Filter drop down and make sure that the Environment Checkbox is checked
Hope this helps


text:
How can I fix this finger rig?
I'm really stuck and confused as to what's wrong with my hand/finger rig. In my reference model I'm trying to copy, the green controller bone for the little finger moves the finger and is connected to the red hand deform bone. I can't seem to get it to work though. In an earlier save, my green control bone is connected to the green hand deform bone and it works. Either one I try, it doesn't work now.
Also, if I set up the IK constraint like the reference model, and put the pole angle at 90 degrees and have the influence at 1, the finger twists upwards, whereas in the model I'm copying, it isn't like that.

Anyone? :( Otherwise I may have to try deleting every hand and finger bone and start again, which I don't fancy doing. And even then the problem may still persist.

I can't open your file (tried 2.79 and 2.8)

Odd. Downloaded and tried it and it opens fine for me. I'll try re-uploading it.

As an aside: I've noticed there's a strange green line pointing to the origin in the centre and I'm not sure how to get rid of it.

Is the save working for anyone?


text:
Armature not staying in place
For some reason I'm not getting, the armature for the arms aren't staying in place when I move the root bone. I've added weights though, and they have vertex groups, so I'm not sure what's wrong. They just seem to 'fold' whenever I move the whole character.

could you please share your file? Why should the arm bones stay in place if you move the root? Maybe you meant something else?

Sorry, I have worded it wrong. Basically the armature doesn't move with the arms; they fall out. I've added a save to the original post.

I think that you first need to make some armature corrections :

Rotate your IK controller in Edit mode to make it more easy to handle.
Deactivate its Deform option as it is not supposed to influence the mesh.
Unparent it, it is not supposed to be child of the hand, it is supposed to be parented with offset to the root bone.
Select the hand and make it the child of the controller.
You may also need to move the Pole Target, and also deactivate Deform.

Now when you select the mesh in Weight Paint mode, you can see that the chest bone influences the arms while it is not supposed to, so use the brush to correct that.

As far as I'm aware, I've followed your steps, but it's still doing the same thing. :-\


text:
Thickness of mesh important for successful deforms?
I’m currently having problems with deforming my mesh with the arms of my armature. I was wondering if the thickness/length of the mesh can contribute to a successful deformation with weight paints? My character only has simple cylindrical arms, with the tip being the hand. They’re not exactly long/thick with an elbow either. Will this contribute to my current struggles?
Thanks

hard to say without screenshots or without the file itself...

Please clarify this question by showing your work.  The question as currently written is vague.

Updated original post. The arms of my character are small and the way they deform is weird.


text:
A part of model broken whilst posing
Is there any way I could fix this issue easily? I discovered a part of my model was broken whilst I've been posing it. I reset the pose to default and fixed the object, but it still goes a bit deformed once it's back in its pose.

Improvement:

First, the mesh of your belt is not closed, you should delete some vertices and use W > LoopTools > Bridge. Also, it's not parented to the good bones. You should join it to the rest of the body ctrlJ, select your belt in Edit mode, remove from any group in the Properties panel > Data > Vertex Groups and Remove From All Groups function, then in Weight Paint you assign it to the bones that you want i.e. same bones as this part of the body) with the Limit Selection to Visible option disabled (on the horizontal menu bar) so that it paint the vertices you can't see.

I've closed the gap and joined it with the torso. Adding Weight Paints has helped a bit, but it's still a bit wonky. I've added another pic to the original post.

I've tested and it works, so you must have skipped a step, I've edited my answer, you need to remove from any group: in Edit mode select your belt and in the Properties panel > Data > Vertex Groups and Remove From All Groups function, then in Weight Paint you assign it to the bones that you want with the Limit Selection to Visible option disabled (on the horizontal menu bar)

Thank you. That's fixed the issue nicely. :D Also, that Remove from All Groups option is useful. I didn't know it was there.


text:
how to flatten out the middle part of landscape
I made a landscape using ANT landscape add-on. Here's what I have:
What I want to do is to flatten out the middle part, to render sth like a valley. Specifically, the area that I circled below:
How do I go about doing this? (btw I don't necessarily have to use ANT landscape).
EDIT:
If I use S+Z+0, I get this:
where vertices are not at z=0, instead just levels the vertices I've selected. How can I set vertices to 0?
EDIT2: I tried setting the z values to 0 for the selected vertices. As yo can see they are stretched equally but are not at z=0. In fact, the top right panel seems to set the 'median' of the vertices, not individual vertices... How do I set them to 0 using to transform tool?

Sculpting would be the second option. You could go into "sculpt mode" and use the "smooth" brush on that area.

@moonboots I'm sorry but I'm new to blender and I tried S+Z+0 in edit mode but it didn't place vertex at 0. How exactly do I set vertex z location to 0?

sorry I meant select a vertex on the centre of the area that you want to make flat, enable the proportional editing option (play with the mouse wheel to increase or decrease the influence zone), then S+Z+ drag the cursor to flatten

is there a way i can set them to 0?

Make sure you are using the pivot point you intended before you scale. But after they are all flat (and before you change the selection mode--this works correctly only for Cursor pivot in this context if you are using proportional editting), press the N key to bring up the Info panel and change the Z coordinate value to "0".

Select the vertices you want to be leveled, set 3D cursor to world origin, change pivot point to 3D cursor, S+Z+0. Don't forget to reset pivot point, or other things could go wrong. Hope this helps :)

I second this but will add that if you want a smooth falloff, use soft-selection or vertex/weight painting. You can also set the pivot to Median instead of Cursor, scale to zero, and translate all the points to the desired plane.

How do I change the pivot point to 3d cursor? I'm using blender 2.8. Is it in layout mode?

S+Z+0, and then setting the median to 0 worked.

@MoneyBall It's in the top middle of the viewport.


text:
How to loop an animation in Animation Nodes?
I would like to loop an animation such that the final frame becomes the same as the initial frame. For instance, I would like to loop the following animation:

If repeat time rate of 45 frame, animation change direction each 45 frame. I change to 450 frame because my animation is total 450 frame. But repeat time does not work well.

Welcome to StackExchange! Do you want to loop the noise falloff?

Yes, It's Noise Falloff. I want to make seamless when animation change from end frame to first frame. it's like endless loop animation.

You can use the Ping Pong option of the Repeat Time node as follows.

I really appreciate. I could make complete node. Thank you so much!

@ACE Glad I could help. Please accept the answer if it answers your question.


text:
How can I set the number of samples per View Layer?
In 2.79 I used to create several Render Layers in order to optimize rendering time. I sometimes use a sphere with an emission shader to simulate the sky. It doesn't require many samples to be rendered accurately. So having a sky rendered with a minimal number of samples and the rest with bigger samples numbers was quite efficient. And as compositing is powerful in blender; all was kind of easy.
In 2.80 I can group objects in collections make several "View Layers" and use "Holdout" to achieve the same thing for compositing. But I cannot find any individual View Layers setting for samples. I have one setting and it seems to be global.
In other words I'm looking for a "per View Layer Sample setting". What I would like to achieve is to render my "sky View Layer" at 8 samples (as an example) and the other View Layers at 640 samples.
I can't find anything on the matter to my despair.
Edit:
The suggestion to use >Scene>ViewLayerXXX>Override>Sample doesn't seems to work. I tried different values than the global one (=23 samples) for each ViewLayer and it end up rendering with the global setting. Both on Linux and Windows10 version (x64 portable packages)

This may suggest that >Scene>Render>Sampling>Layer Samples=Use isn't related to ViewLayer, though it could be appropriate considering the 2.79 -> 2.80 context.

The render settings are shared for view layers in a scene. You can create another scene with different settings though. Not sure if that's helpful for what you had in mind.

Well... If i have to create several scenes to get it working like i want; it's kind of defeating the purpose of collections and ViewLayers in my opinion. I'll try that to see if it creates a mess or not.

I just spotted the edit saying that this didn't work in 2.80 and have re-tested with my current Blender version (2.91.2) and this seems to be working as described - ie, I created two View Layers - one with Override Samples set to 5 and the other set to 5000. This seems to have correctly used the overridden number of samples for each layer. If you're still having problems at the most recent Blender version then it would be worth raising as a bug if you can't explain it any other way.

The setting is still there - but it is in a different location. You now need to look to the Override panel where you'll find the Material override as well as the Samples override.


text:
Add object constraint to a number of selected objects
I have a large number of objects, and I wish to add a Track to constraint to each object.  When I select the group of them and then add the constraint, it is added to only the active object, of course.  How can I add the constraint to all selected objects?

Do you want these to have a target?

Yes, I want them all to have the same target.  Basically, I want them all to have the same constraint.

With the objects selected, add the desired constraint to the active object.
From the 3D View header menu choose Object > Constraints > Copy Constraints to Selected Objects.

All the objects will now have the same constraint.
This method doesn't require an add-on to work.

That is exactly what I was looking for!  I can't believe I never noticed this menu before.  I also see it has a Clear Object Constraints command, which I now know is a thing!

This does not appear to work in newer versions of Blender.

@VRM I've just checked in the 2.79 release candidate and it still works.

I was using a different branch when testing, my bad

This answer doesn`t work unfortunately, tested in Blender 3.0.

@Joehot200 Works the same as it always has for me (Blender 3.1).

You could also just loop through the selected objects and apply the contraint to each one.
The line with objs.target is an example of how to set the target object. In this example, I assume that all the selected objects will have an Empty as the target.
import bpy
context = bpy.context

for x in bpy.context.selected_objects:
    objs = x.constraints.new(type='TRACK_TO')
    objs.target = context.scene.objects.get("Empty")

I like this answer because it gives me more flexibility than my discovered answer, but it's also a lot more complex than just using an add-on.

@Jason it is very simple to use actually, just drop it into the text editor and run it as you need it. If need be, you can also put it into a small addon and map a shortcut to it. Also, based on your comment on the question, if you want to add a new object with the same constraint and target, just select it and run the script again.

I'm comfortable using Python to manipulate Blender, but this seems like a task that someone might want to do who was a relative newcomer to Blender.  For newcomers, Python can be intimidating.  For complicated tasks that are relatively uncommon, I think a Python solution is fine, but for a task that is simple or common, I would rather there be a UI solution.

That being said, your solution did show me how to create a new constraint using Python, which is something that I was having trouble with.

Happy to report that this solution STILL works as of Blender 2.83. Thanks!

I discovered how to do this using an add-on.

Enable the "Copy Attributes Menu" addon
Use Ctrl+C to activate the menu
Choose "Copy Selected Constraints"

This doesn't let you modify the constraints, though, or remove them.

This addon has restored the old inbuilt functionality of pre 2.5 versions. Very useful in my opinion.


text:
Is it possible to change the width of edges in edit mode?
I'm a math teacher.  I like to use Blender to demonstrate some ideas when we talk about geometry in 3 dimensions, so I display it on our projector and the class will work together to edit some basic shapes.  I've changed the size of vertices so they are bigger and easier to see, but I haven't found a way to increase the size of edges.  Is there an option to do this?

Has far as I know this isn't currently configurable. maybe in the upcoming viewport refactor

Unfortunately, you cannot. You can edit vertex and face dot size but not edge thickness.

I defer to the other answer for the (easy?) workaround.

I think I understand your question.
Don't use wireframe mode. Instead, use solid mode and use the wireframe modifier. Here is a quick recording using the mathematical object hexagonalmonkeyprismoidalsphere:

The wireframe modifier is a nice idea, but I want to still be able to see the solid geometry.  I was really just hoping to be able to change how edges appear so they're easier to see on a projected screen.

@Jason You can uncheck the "Replace Original" button, and then you can change the material index of the wireframe

Only one downside I see here is that it will only work with objects which have faces.... I use wireframe meshes also for similar things and often I need to have edges only...

You can change the width of the lines in the interface tab of the Blender preferences.
This will also increase the thickness of the lines in the interface, but perhaps this will suit your needs.

Although if in edit mode and your creating a whatever.... Yes the vertices can be made to thick.  but, the edges cannot.  There is a way to help though.  Go to user preferences and increase the scale of the display.  look under interface, then display.  Increasing the scale, or zoom make it appear that the edges are thicker.  in reality its the same size but, when its scaled to sale 105 or more the edges are a lot thicker looking. and easier to see and it really doesn't effect the work area field of view.


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Smoke Render Problem
I don’t have time to add an image to show what I mean, so I’ll have to do that later, but I’m having an issue rendering out an animation of smoke in Cycles. Every time I do it, I’ll set the necessary frame that smoke is visible during the animation, hit the Animation render button, and the smoke looks barely visible. It’s thin. Whispy. Transparent. I’m not sure what to do. I’ve checked a few tutorials, but they all seem to be for a single frame render rather than an animation. I set up the smoke using the Quick Smoke effect, so it has an emitter and domain etc. I even tried adding a plane behind it and gave it an emission material, but the same thing happens. What am I doing wrong?
Save file
Thanks.

If you haven’t, try baking the smoke simulation first. A blend file would be helpful.

Hi. Please make the the title of your question specific to the problem you are having, not just the general topic.

@BigfootBlondy: I forgot to mention that I've tried baking my simulations. But I'll upload a save.

Every time I try a simple Quick Smoke in a new file and use the OpenGL animation render, it renders out the simulation one frame at a time just fine. However, in my model, it doesn't. It just renders out a single frame instead of a sequence.

Thanks for the .blend file @DustyShinigami it really helped me answer the question.
To create a more dense smoke sim, you need to select the domain, then go to the node editor. There should be a Multiply node, ramp up the adjustable value. I set mine to 50 and got some good smoke. I also upped the Anistrop to 0.2.
I also recommend expanding the domain up and out as the simulation is hitting the sides and makes it look fake.
As for the waterfall, I recommend using a fluid sim if that is what you are trying to make. It is there for a reason, use it :D.
Rendering in open GL should work fine. It may be something to do with your save location so double check it. Also, make sure you have run through every frame first.
Your project looks good BTW. :P
Good luck with your project and I hope I helped,
BFB

Thanks for the suggestion and the feedback. I’ll look into the node editor and play around with those settings. :) I did originally have the domain’s top expand outwards in order for the top of the smoke to expand and have a sort of ‘plume’ look to it. However, for some reason I don’t get, even after baking it, it would randomly stop doing that when I went back to check on it and just do what it does now. I also did look at adding a fluid simulation for the waterfall, but haven’t quite mastered that yet. The project was for a college assignment and it needed to look cartoony. :)

Also, what do you mean exactly by making sure to run through every frame first? Thanks.

Okay, in all honesty, adjusting the multiply value just made the smoke look like ash or black dust. Also, I definitely prefer the OpenGL render! It's so much faster and everything looks like my finished result. :D It seems to work fine on my PC, but it didn't appear to work on my laptop. Odd.