text:
Blender for optical modeling II
My question is similar to this question: Can blender be used for simple optical modeling? .
I apologize for asking a similar question but I don't have enough reputation to comment on the original question.
Like in the original question I would like to view a scene through a modeled lens.
What I want to archive in the end is "real" out-of-focus blur (I am aware that one can play with the blur-nodes of the build-in blender cam, but I want to see the blur as generated by my specific lens)
As suggested by Liss' answer to the original question, I set up my scene using Luxrender as renderer as follows: (the answer contained guidelines, the specific details are my guesses of how to exactly set it up)

created a simple lens (intersecting two smooth UV-Spheres, luxrender material glass or glass2 with IOR=1.41)
created a translucent plane (alpha 0.01) to act as film
set blendercam to orthogonal and placed behind film
as a test-object to be viewed through the lens I set a cube with a checkerboard pattern (to detect blurry lines when out of focus)

However when rendering the cube (or film) at distances to the lens where the cube should clearly be out-of-focus I still get a pretty sharp image.
From what I had understood Luxrender is very physically accurate so that tracing rays through a lens should result in blur.
Is this correct? And if so, what am I missing to achieve the blur?

Did you find a solution to this?

Blender Cycles is decent at rendering some optical effects.
This is an example of Total-Internal-Refraction simulation. This is done by placing a light source close to one end of some tubes set to a +IOR.

Source File for Fiber Optics
This is an example of (heart) shaped bokeh by placing a cutout in front of the Blender camera. (There is no lens simulation)

Source File for Shaped Bokeh

My first approach would be to attempt to match the camera in blender.  If your camera is part of the presets in blender I would try that first.  If you need more accuracy have a look at this.  It's a bit old so I'm not sure it will work still but worth a look.
If that approach doesn't work/isn't accurate enough I think you are missing out some parts that are vital in a physical camera that cause DOF (Depth of Field).  Understand why DOF occurs in physical cameras in order to emulate it in blender, read this/google how camera lenses and apertures work.  The main thing you are missing is the aperture.
There is a chance that the way LuxRender works won't cause this type of blur but I would have thought, as you do, that it should.

A.vector, thank you for your answer. However, I'm interested in the actual optical effects of my lens, not only in the perspective (your first link is about matching perspective to real world cameras and "it does not give Blender a complete optical lens simulation" ). Also, while aperture does influence the DOF, a larger aperture results in a shallower DOF --> no aperture ~= very large aperture -> objects at closer distances to focal plane are blurred. So a missing aperture can't be it.

@129 Good point, fair enough.


text:
Problem moving selected UV islands with Python
I've read all questions and answers about moving UV island here. The most relevant are these:

How to move selected UV Island?
Python - move UV for selected items

But they do not solve my problem, my code is just not working. What is wrong with my code?
for area in bpy.context.screen.areas:
    if area.type == 'IMAGE_EDITOR':
        bpy.ops.transform.translate(value=(125, 0, 0), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)
    else:
        area.type = 'VIEW_3D'

This is the result:

The other areas changed to VIEW_3D, but the IMAGE_EDITOR area did not make the translate. The translate is still happening to the object in VIEW_3D.

I think it as to do with the position of the mouse, try running the script with it on top of the UV Image editor

I'm not programming at Blender's Text Editor - I'm programming python with gedit. When I run the script, it creates a new Blender file with my commands. Because of this, doesn't matter my mouse position - also because I can't control this. Maybe what could be done is to leave all areas and keep open just "Image Editor" area. Do you know how I could do this?

I've change my code, and use one "meta-code" - inside my code, I've opened an "Text Editor" area, and include another python file. At least, this is my code:
text = bpy.data.texts.load("translate.py")

for area in bpy.context.screen.areas:
    if area.type == 'IMAGE_EDITOR':
        area.type = 'TEXT_EDITOR'
        area.spaces[0].text = text

        ctx = bpy.context.copy()
        ctx['edit_text'] = text
        ctx['area'] = area
        ctx['region'] = area.regions[-1]

        bpy.ops.text.run_script(ctx)
        break

for area in bpy.context.screen.areas:
    if area.type == 'TEXT_EDITOR':
        area.type = 'VIEW_3D'

And, my translate.py code:
import bpy

area = bpy.context.area.type
bpy.context.area.type = 'IMAGE_EDITOR'
bpy.ops.transform.translate(value=(-0.449219, 0.425781, 0), constraint_axis=(False, False, False), constraint_orientation='GLOBAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=1)
bpy.context.area.type = area

Thanks everybody :)

source: Stack Exchange

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

sort: votes


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UVs applied in viewport, but not in render
I noticed that one of the UVs on my model does not appear the same in the viewport as it does in the final render. The appearance in the viewport is correct, and matches what is shown in the UV editor, but the render is different. This applies to both Cycles and Eevee. The issue is only with one object for some reason. Note: there is only one UV per object.
UPDATE: I gave the objects proper names as opposed to their placeholder names, which were formatted like: HairRemeshedVersion.00X, and now the UVs are fixed? I have no clue why that worked, but it did.
The vertical lines correspond to the vertical direction on the UVs
Viewport (correct)

Render (broken)

Here are some things that I have tried which did NOT solve the problem:

Applying transforms
re-unwrapping
Deleting unused UV maps (there were none)
using the texture coordinate node instead of the UV map node
Deleting the UV map and then re-adding it

In order to give the character's hair fine details, I use a shader which requires a UV map to give the direction of the hair strands, so it is very important that these UVs work!

Check for a hidden object in the outliner

@Allen Simpson I Checked for hidden objects, and didn't find anything, but I did notice the hair objects still had my temporary names, such as HairRemeshedVersion.001, and when I changed them to something more appropriate, the problem was gone! I have no clue how that worked, but it did!

That is strange, maybe somebody else knows something

If you found solution please create regular Answer for your Question so others can learn from that. If you still want to know more please attach blend with problematic part of mesh with texture packed. Thank you

How the issue was resolved:
I was able to fix the issue by giving each hair object a new name. The previous objects were named "RemeshedHair.00X" with "X" being incremented every time I created a new object. After changing the names to "Hair front/Hair side/Hair back" the UVs were able to be applied properly.
My hypothesis on the cause of the issue:
I no longer have a copy of the .blend that contains the issue, so I can't say for certain what happened, but I can guess. It might be possible that this issue was just some bug in the way that blender handles it's internal data structures. It might be the case that the UV map was somehow unlinked from it's object in the portion of the structure where rendering data is stored, and renaming the object caused an update to that portion of the structure, resolving the issue.

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


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How do I make edges tube-shaped?
I have a large block. I want the edges of this block to have a cylindrical mesh centered around them, spanning the entire length of the edge. I want to be able to choose the circumference of the cylinder. I want it to follow the edges like with the curves in the first 5 minutes of this video. If this is possible, how do I do it? If possible, link a video because i am not very good with technical terms.

Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues.

i doubt if the video is really necessary to understand my issue but the problem is i don't have any image of what i want.

the step by step seems to be what i want but right now it is way too thicc, it looks more like a pancake then what you showed, how to i thinn it out?

never mind ctrl a worked

I think this method may work:
Step 1: Press delete and select "Only faces"

Step 2: Add a skin modifier

Make sure to select "Smooth shading"

Step 3: add a subdivision modifier

Step 4: enter edit mode with "X-Ray" enabled

Step 5: Press CTRL + A to adjust the radius

Step 6, and all the ones after are optional, but they can give your object a more defined shape.
Step 6: Subdivide your edges in edit mode

Step 7: Select only the newly created vertices

Finally, press CTRL + SHIFT + B to bevel the vertices. Adjust untill you get a result you like

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


text:
Why won't Blender select all visible faces?
I'm trying to select just the faces the camera can currently see to do some specialized uv mapping for them.
If I leave "Limit Selection To Visible" off, I can select all visible faces - but also all non-visible faces.
When I click this on, though, it doesn't seem to select all visible faces - just some of them.  Please see screenshots, one showing me using border select to select the faces, and one zoomed in a moment later showing what was actually selected.
What am I doing wrong? Is there some sort of tolerance config parameter somewhere?
EDIT
Per @Vince's comment, I should clarify what I think I'm doing.  In the first screen shot, I took a camera, right clicked on it, went into camera perspective via ctrl-num0, put a mesh in edit mode, Select > Deselected All, pressed B to start border select, made sure Face select was on and "Limit Selection To Visible" was on, and you can see me dragging from top left down to bottom right over the mesh.  I expect that every face visible in this view should be selected.  HOWEVER, immediately afterward, when I zoom in (second screen shot, all I did was scroll the middle mouse button), you can see that not all the triangles were selected.  There's a patchwork of white areas, which are the selected triangles from that operation, but all of the dark areas are faces that were facing the camera but weren't (for some reason) selected.  I expect that all of these should be selected (ie white).
Furthermore, if I try this exact same thing again zoomed in, more things that weren't selected become selected; and if I start over but further zoomed out, even fewer faces end up selected in the end.
And yes, this is a straight flat noob question about selection.
Please excuse the funky texturing (blue/green), which has nothing to do with the question.

It's quite unclear what you're problem is, could you explain "It doesn't seem to select all visible faces"? Limit selection to visible doesn't ever actually select anything, it just limits what you can select with [B], [c] or RMB.

I've attempted to clarify; if this still isn't good enough please let me know so I can try again.  To respond directly, I meant "with [B]" it doesn't seem to select all visible faces.

if you hit [ctrl] + [+] it will select all faces adjacent to currently selected faces, it's not the best for your situation, but all those tris that didn't get selected in the first place should get hit up immediately.

I assume that would also wrap around to the backfaces too though, right?  Better than no answer, but certainly sub ideal.

The face has to be able to be seen directly. I imagine it is likely using a backfacing functionality of some sort, so protruding parts on the front of the mesh will have parts that do not get selected. The same for any major details that seriously change the mesh shape. Also, what effect are  you trying to achieve? There may be an easier solution.

The issue is likely due to the way blender draws faces. Since some faces are likely too small to be drawn properly by OpenGL, all of the faces you "see" aren't selected since some of them aren't drawn at all. The only suggestion I can think of is to retopologize this mesh and then do your selection.

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


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How to have a real-time feedback in a menu/panel/pie?
In the code below, I'm invoking a custom property that redefines itself every 1 second inside of a pie menu, but in the pie, nothing is in real time, it's "stuck in time", is there a way to make it real time?
import bpy
import datetime
from bpy.types import Menu

#delete me after the first run
def every_sec():
    #bpy.context.area.tag_redraw() #didnt work
    #bpy.context.scene.update() #didnt work
    bpy.context.scene["GGG"]=str(datetime.datetime.now())[-15:-7]
    return 1
bpy.app.timers.register(every_sec)
#delete me after the first run

class Pie_menu(Menu):
    bl_label = "Some Pie Menu"

    def draw(self, context):
        layout = self.layout
        pie = layout.menu_pie()
        ups = context.tool_settings.unified_paint_settings
        sculpt = context.tool_settings.sculpt

        col = pie.column(align=True)
        col.prop(ups, "size", text="Radius", slider=False)
        col.operator("mesh.primitive_plane_add", text="Plane", icon="BLENDER")
        col.label(text=bpy.context.scene["GGG"])#THIS IS SUPPOSED TO BE REAL TIME

def register():
    bpy.utils.register_class(Pie_menu)
def unregister():
    bpy.utils.unregister_class(Pie_menu)
if __name__ == "__main__":
    register()
    bpy.ops.wm.call_menu_pie(name="Pie_menu")

and bpy.context.area.tag_redraw()and'bpy.context.scene.update()didn't work either, but i did'nt know this line of code, thanks for letting me know (sorry i deleted your comment by mistake)

I delete my self after finding out it is useless since the context is not the one we want.


text:
Why do the controls for materials look different?
The first image, the material properties shows in one way.

On the second image, the material properties, is displayed in a different way

Why is it different?
could you tell me why this happens to me? thank you, regards

You are using two different render engines, in the first image you are using cycles, in the second blender internal.

more info:
Which engine in Blender should i start with?
How is Cycles different from Blender Internal?

Hi, thanks for your information, exactly it looked like this for having the engine in internal, greetings.


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Can I change texture of a mesh with the command line?
I know it is possible to render a 3D model with blender's command line interface, but is it possible to also change the texture?

If you write a script in Python to change the texture, you can execute that from the command line with blender -b <file> -P <script>

@ScottMilner that means it is also possible to add a mesh to a coordinate of a scene with blender CLI

Yes. Anything you can do without GUI input in Python can be done with the command line.

As far as giving input to the script goes, (i.e. to select a texture), you can give arguments to sys.argv with blender -b <file> -P <script> -- arg1 arg2 argn.


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Array modifier changing second array modifier
I'm trying to array an object in two directions, like this:

But when I try to have both at the same time, the first array influences the other and the objects will not touch anymore:

So how can I make both modifiers independent of each other?

Hum... A question about Modifiers that doesn't show the modifier stack

Use Object offset in Array settings. Pick different objects (empties) for different offsets. Modifiers won't be independant on each other on one object

It would be helpful if you included your modifier-settings in the screenshot. It is difficult to locate the error without that information.
Anyway I created a setup like you want with two array modifiers.
You can see the settings in this screenshot.


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Diffuse render pass looks different from original texture
I have tried to follow these instructions on how to get a diffuse render pass of a brick texture that exactly replicates the original colors of the texture. But even with all the settings in place I get a render pass that looks slightly off from the original texture as you can see here:

I was wondering if there is some other setting that I've missed? I'm using blender 2.8. If you're interested, here is the blend file too. All help is appreciated!

Why not bake it? It's definitely a color management related thing, my guess is that left image is in sRGB and right in Linear color modes.


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Material not rendering right despite texture being correctly unwrapped?
That was a long title, but my problem is simple. I have some objects with a brick material which looks different when you look at it on "solid" mode with display set to "textured" (left) compared to "material preview" mode (right):

The part that looks stretched out is a different material than the normal brick material which I applied to th rest of the faces. Why is it causing this effect?


text:
How to backup Blender startup file?
I recently changed my computer. So I opened the blender, and I have so many custom parts that I want to transfer the startup backup file to a new computer.
I don't know the location of the startup file, but I couldn't find it.
So, how can I bring the startup file at new computer

what kind of startup file?

You can just save that file

The easiest way is to start a new scene and then save it as a file.  Copy that file to the new computer. When you're ready open that file on the new computer and then use the file menu to "Save Startup file".


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How can I normalize UV unwrap in blender?

This picture is the UV unwrap in Maya.
Using a function called "normalize",
I spread the cylinder uv into a square shape.
I think there's a way in Blender, too.
Can you tell me how to do it?
here is my blender unwrap

Open a UV editor.  Select all verts in it.  Look on the UV menu for the UV editor, for a toggleable option called "constrain to image bounds."  Now hit s to scale, drag your mouse, and see what happens.  It won't go out of the 0,1 range for the UV editor.  Mouse click to confirm.

Or you use Cylinder Projection for unwrapping and select the option Scale to Bounds (if the UVs are not already scaled to bounds).

...and the Pivot Point should be set to 2D Cursor if the UV map is like shown in the screenshot, or else hitting S won't scale anything since the map already hits the bounds on the left and right. This way you can only scale smaller.


text:
A question about UV wrap
Hi there:) I came from Maya to blender, but I'm asking because don't know.
This 'Mark Seam' was used to spread the doughnut-shaped mesh into a rectangular shape. How can I change it to a square?

After adding a new seam, you need to re-unwrap the mesh to see the new UV map

You can use the Follow Active Quads unwrap mode: Select one quad to make it active then select all and Unwrap > Follow Active Quads, you'll have a square UV (that is cut along the seams if you've created some):


text:
Questions about "Import Image as Plane "
I brought the .mp4 and .avi video files on the plane.
It played and stopped as long as it is set.
Is there a way to repeat this indefinitely?(maybe loop?)

in materials properties tab, Alpha opion then you can click on cyclic button


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How to clear "Face sets"?
I want to clear this at all. But unlike Mask, it is indelible.

In the Face Sets menu, go to Face Set from Visible. As long as everything is visible, this should clear the existing face sets.

This turns everything in one single Face Set which is not shown colored:

seems it doesn't work in some situation

@snoobdogg Could you be more specific in what "some situation" is? Because on the one hand this solution was posted three and a half years ago, so maybe something has changed, but on the other hand I just tried in the latest version and it worked. So I probably need more information to reproduce your issue.

In that case, if Face Set from Visible doesn't work, the work around I've found is to go to Edit Mode then, selected everything then Face Set From Edit Mode Selection then Face Set from Visible. it's seams to unblock the situation


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Can I Adjust Thickness of bone "Stick"
I'm going to animating and I thought "Stick" was perfect, so I chose this one.
But it's just a little thick, so it's too confusing with the mesh.
Can I adjust the thickness of this?

Maybe consider B-Bone instead of Stick, then you can adjust the size. Go to Edit Mode and with the bone(s) selected, hit Ctrl+Alt+S to scale the thickness. Instead of dragging the mouse you can also enter a small value like 0.01 to scale it down, hit Enter to set the scale.

After all, B-bone is more convenient than stick when customized. So I'll go with B-bone. Thank you.


text:
Rigid body simulation explodes instead of collapsing
I want a part of a dinosaur to collapse so that the bones fall to the ground and bounce a few times. I have enabled a rigid body simulation for each bone. The problem is that the bones seem to bounce off each other and get thrown away. But they should just fall down from gravity. Thanks for your help!
Blend File

Select all the bones,

Bounciness 0,

Sensitivity/Margin to 0.

Object/Rigid Body/Copy from Active.


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Why is bpy.ops.ptcache.bake is not executing bake to external cache when bake_all() working?
I'm trying to bake externally a single cache smoke domain, with multiple/other domains in the same scene file which I don't want to cache, but when I run the below it simply returns {'FINISHED'} as a result without executing the external bake to disk.
Am I needing to specify another element or flag in the modifier's attributes before I execute it?
I'm close to getting a solution to this and can see all the attribs but it's tricky getting a clear guideline as to what's making this refuse to bake to an external cache location.
import bpy

def cacheThisSmokeSim(smokeCacheName):
    for scene in bpy.data.scenes:
        for object in scene.objects:
            for modifier in object.modifiers:
                if modifier.type =='SMOKE':
                    if object.name == smokeCacheName:
                        override = {'blend_data': bpy.data,'scene': scene, 'active_object': object.name,'point_cache': modifier.domain_settings.point_cache}
                        #bpy.ops.ptcache.bake_all(override)
                        print ("CACHE THIS*:",smokeCacheName,"\n")
                        result =  bpy.ops.ptcache.bake(override,bake=True)
                        print ("END OF CACHE")
                    else:
                        print ("BUT NOT THIS:",object.name)
    return result

cacheResult = cacheThisSmokeSim('SMOKEDOMAIN')

Please also note that I'm able to bake everything well enough but for big scenes when you want to simply adjust one cache this would be super helpful without having to execute:
bpy.ops.ptcache.bake_all(override)

which works perfectly.

make sure use_disk_cache is enabled or enable it before baking the cache :
object.modifiers['Smoke'].domain_settings.point_cache.use_disk_cache = True

Yeap, this is on in all cases but it seems to either not cache if believes that the baked flag is True at the current frame and doesn't check around it.
Would love to know which attrib it is that definitively tells it to write out from scratch. Trying to ascertain if it's some combination of out_of_date_cache attrib etc
Trying to remove_all and remove of bakes ahead of it seems to have some success.
I'm testing some of this (above for example) within Blender desktop session so that may behave differently from the cmdline -P method.

Execution on commandline is reliably baking the domain when I remove_bake but even though I'm picking out the domain with the above it's baking both.

Another thing, and I think this has been explained when the ptcache systems were added to Blender, was that there was no means to bake only one cache at a time.
Next issue is to tell the following Blender scene that the commandline generated bake to disk data is up to date and usable.

@JamieMurray are you now able to bake the cache to disk , and the problem is in baking individual object cache ?

it is. Exploring how to cache one of the two smoke domains using command line executed script and how to go about rendering the frames of the newly updated sim caches using the same scene file that generated the updated cache/bake also via command line.

Would seem that there's a couple of things that prevent this from being able to happen:

The ability to bake out one cache from commandline is tricky, possibly down to my lack of knowledge as to how to address a single cache to be baked. Will explore this further and educate myself more and then post a solution/forum post about it.

Looks like there's some form of customised file header information being baked into the files and somehow Blender, when you re-open it and try to re-link it back up to the commandline generated cache, ignores the different cache files you've just generated.


text:
My object's grey colour has disappeared
Ok so I'm new with blender, as I was working on my project the object disappeared. The grey colour of the object disappeared. I can still see it just not the grey colour. Think I must have clicked or pushed something because Ctrl+Z doesn't work.

Ok so problem solved..vieportshading - Solid.

You've probably set your viewport shading to 'Wireframe'. Either select, say, 'Solid' from the 'Viewport Shading' rollout menu in the bar  at the bottom of the 3D View region - (just to the right of the Edit Mode/Object Mode etc. rollout) or hit 'Z' if your shortcut is the default.

Just push Z in wireframe, which is where you are. ShiftZ from while in the rendering view will put you back in solid viewpoert


text:
Parts of my model are a different color to the rest
I have a Problem with my first Blender model. As you can see in the images, the color of the legs are different to the rest of the model:

I haven't applied any modifiers besides the Subdivision Surface and Mirror.
Can anybody tell why it looks like that and how I can change it to the normal solid look?

The normal of your mesh are pointing in the wrong direction, in this case inwards instead of outwards. The easiest, most clean way to fix this is by going into Edit mode, then Shading/UV Tab and click on Recalculate normals with all the mesh selected.

okay i already got it  by extruding the mesh it with e (like duplicating).
notice that you should mark all faces, if you have the same problem.
llink to discription: Why are some faces in my mesh darker?


text:
Property's update function not called
I made a new panel in the N bar that contains a boolean property for which I put an update function, but after adding a debug line at the top of this function I can tell it's never called when I click my checkbox.
It's the first time I'm doing this so I don't know if I'm doing it right but for me so it seems, everything else is working fine...
To avoid more explanations, here is the structure of the key parts of my code:
import bpy

class MyPanel(bpy.types.Panel):
    bl_label = "My Panel"
    bl_idname = "OBJECT_PT_my_panel"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'

    def draw(self, context):
        my_props = context.scene.my_props
        self.layout.prop(my_props, 'my_bool')

def my_func(self, context):
    # some stuff that's never done
    print("Running update function")

class MyProperties(bpy.types.PropertyGroup):
    my_bool = bpy.props.BoolProperty(update=my_func)

def register():
    bpy.utils.register_class(MyProperties)
    bpy.types.Scene.my_props = bpy.props.PointerProperty(type=MyProperties)
    bpy.utils.register_class(MyPanel)

if __name__ == "__main__":
    register()

It works for me.

I added a few extra lines of code so it can be easily copied and pasted without needing any changes for it to run (otherwise everyone who wanted to test it would have to add these extra pieces).

Thank you Ray, and yes actually my function is called, I just discovered I had to open system console to see it, I thought it would appear in the info area... So I'll do some more debugging for now, because I've got another problem with a modal that sometimes keeps running when I deactivate my addon and I can't access it anymore ><

Ok so I'm trying to call the invoke and cancel methods of an operator inside this update function, but, I tried with op.invoke(), I got AttributeError: Calling operator "[its_name].invoke" error, could not be found , then I tried with op() with a lot of sh*t to get it to work, I got TypeError: 'BPyOpsSubMod' object is not callable . I don't understand how I'm supposed to do it, and I tried different solutions I found on this site (there aren't too many)... But maybe I should create a new topic.

Actually it's called (and doesn't work), but to see my debug messages I had to do Window -> Toggle System Console... Sorry I'm new to this ^^'

Agree, sounds like you need to create a new question.

Why did you tell me "This does not provide an answer to the question"? It does, or there isn't any answer.


text:
Recursive search for selected vertices
i am working on a tool and need to get selection islands in the mesh. I want to keep only the biggest connected vertex selection in the mesh.

I wrote a function that recursively searches a bmesh for connected and selected vertices:
bm = bmesh.new()
bm.from_mesh(obj.data)

_verts = [v for v in bm.verts if v.select]
_edges = [e for e in bm.edges if e.select]

islands = [] # all selection islands

#iterate all selected verts in mesh
for v in _verts.copy():
    #check if that vert is already registered
    if not any([v in i for i in islands]):
        #new selection island
        _island = []

        def get_selected_connected_verts(v):
            '''
            recursive search vertices for connected and selected vertices
            @v : bmesh vertex
            '''
            #iterate all edges linked to the vertex
            for e in v.link_edges:
                #is edge selected
                if e in _edges:
                    #get adjacent vert
                    v_other = e.other_vert(v)
                    #register vert to island
                    if v_other not in _island:
                        _island.append(v_other)
                        #search again
                        get_selected_connected_verts(v_other)
        get_selected_connted_verts(v)
        #register island
        islands.append(_island)

This works great for most meshes. Sadly with higher vertex counts python returns the following error:
RecursionError: maximum recursion depth exceeded while calling a Python object

When i try to increase the recursion limit, the following error appears:
Error   : EXCEPTION_STACK_OVERFLOW
The terminal process terminated with exit code: 3221225725

Theoretically i know that i should be able to make the recursive function iterative... I am just not able to..
 Also, if there is a totally different way to do this, please tell me!
I kindly ask for support of more talented programmers.
Thanks a lot!

Related: an iterative approach for counting loose parts https://blender.stackexchange.com/questions/75332/how-to-find-the-number-of-loose-parts-with-blenders-python-api/75384#75384

thanks for the quick reply. This definetly set me on the right track ;)

Some code from this answer. But adapted for bmesh and the selection aspects of this question.
The principle is to start from selected vertices, and:

Make a dictionary of possible links to other vertices
Iterate available vertices and for each follow all possible remaining paths

The code with comments:
import bpy
import bmesh

def make_vert_paths( verts ):
    #Init a set for each vertex
    result = {v : set() for v in verts}
    #Loop over vertices to store connected other vertices
    for v in verts:
        for e in v.link_edges:
            other = e.other_vert( v )
            if other.select:
                result[v].add(other)
    return result

def make_island( starting_vert, paths ):
    #Initialize the island
    island = [starting_vert]
    #Initialize the current vertices to explore
    current = [starting_vert]

    follow = True
    while follow:
        #Get connected vertices that are still in the paths
        eligible = set( [v for v in current if v in paths] )
        if len( eligible ) == 0:
            follow = False #Stops if no more
        else:
            #Get the corresponding links
            next = [paths[i] for i in eligible]
            #Remove the previous from the paths
            for key in eligible:
                island.append( key )
                paths.pop( key )
            #Get the new links as new inputs
            current = set( [vert for sub in next for vert in sub] )

    return island

def make_islands( bm_verts ):
    paths = make_vert_paths( bm_verts )
    result = []
    found = True
    while found:
        try:
            #Get one input as long there is one
            vert = next( iter( paths.keys() ) )
            #Deplete the paths dictionary following this starting vertex
            result.append( make_island( vert, paths ) )
        except:
            found = False
    return result

obj = bpy.context.object

bm = bmesh.new()
bm.from_mesh(obj.data)
bm.verts.ensure_lookup_table()

bm_verts = [v for v in bm.verts if v.select]

islands = make_islands( bm_verts )

print( len(islands) )
#print( islands )


text:
Animating robots and vehicles--What are the pros and cons of adding rigging and bones, vs. using separate objects and manipulating those?
When animating something like a robot or a vehicle that has clear mechanical hinges or wheels, should one use typical rigging and bone animation methods, or just make the animated regions separate objects to manipulate over multiple keyframes?
For example, I'm making a fictionalized/lower-poly space shuttle in Blender. The wing flaps, rudder, and wheels will be animated. I have made all the parts that I want to animate (like the landing gear and the wing flaps) as separate objects from the main body.
Should I keep these as separate objects and simply rotate them over the desired keyframes? Or should I attach them to the main object, add rigging (with 100% weight to the animated parts and 0% to the main body) and animate the bones over the desired keyframes?
Same thing for robots. Should a (low poly) Iron Giant type robot be animated by manipulating separate objects, or by traditional rigging? What about a simpler wheeled robot?
My goal is to import it into Unity, if that changes anything.

This is opinion based as it is written, the site rules discourage this because it tends to start fights between people who have a favorite method.  You can avoid this by re-wording the question to ask what are some of the pros and cons to using either method.

For instance, many separate objects will have a GPU driver penalty because many draw calls have to be made for every model.  On the other hand, using rigs/weight maps can bloat the vertex shader and cause inefficiency there instead.  Separate draw calls for every part of the model does however allow you to use different textures for every part which allows for much higher overall resolution without using huge textures which can stall the pipeline. Of course having only one object with only a couple textures is much easier to manage. There are likely many things that people can add to this list

@MarkClintDion Thanks for the info. I reworded the question. Basically, will modelling with or without separate objects give more versatility to the animation (particularly after exporting from blender into another application)? As far as the GPU penalty you mentioned, how severe would it be if I had, say, 6 objects, with one having 900 polys and the other five having less than 20?

Even a 4th gen ipod touch could handle that with no issue.  The thing about performance issues like this is that it's very sensitive to the specific video card being used.  About 10 years ago, an ATI programmers document was recommending that VBO's(model data) should be about 1800 vertices.  I think that's still good advice if you want to target mobile devices.  I've read that some modern high-end games running on modern desktop GPU's go as high as 8000-9000 vert's per model now.  There is no rule to fit all the possible situations, it's just something to keep in mind and test often.

You could armature bones to control the subobjects instead of doing it manually, as a third option.


text:
How to Save Particle Combing Data to a Normal Map Image File in UV Space?
How can I extract the data created by a particle combing operation (on hair particles, for instance) to file (even if some Python code is required) in a 3-component RGB normal image map to UV space (when the unwrapping has already been done for the geometry), and then (that's a second question, I guess) feed it back to the particle system without having to recomb again?

I do not have an answer for you, although I can provide you with a few nuggets of info that will come in handy.
Here is some python code that shows you how to dump the coordinates of the root and tip of the hairs:
import bpy

def dump_particles(ps):
    for p in ps.particles:
        print(p.location)
        #print(p.fuv)
        print(p.hair_keys[-1].co_local)
        print("_")

dump_particles(bpy.context.active_object.particle_systems[0])

The major stumbling block is that the barycentric coordinate of the hair is NOT exposed via the python API.  (see also How do I comb hair in python?)
This makes calculating the position of the hair in UV coordinates much harder (although you could probably reverse-engineer it from the location if you are willing to do a lot of analytic geometry).
Even once you do figure out where the hair is in UV space, you'll need to choose how to interpolate to compute the values for the image you want to use as a normal map.  (Maybe compute the dual of a voronoi diagram and use barycentric coordinates again).

I'm checking this before the end of the week. I was thinking of voronoi too. Having the same problem in Houdini, BTW. Prefer to solve it in  Blender, but VEX+COP might be easier than reverse engineering Blender's object model. Also, are you from this world? I was sort of prepared to give up on this thing! :D

I am from this world, but I have ventured deep into realms nobody else cares about and come back bearing grumpiness.  It's an occupational hazard.

Ah. I find it hard to believe. :D I don't know many people that are into writing AVC/HEVC NALs handlers from scratch just for fun. Anyways, I might have found a way to save 32-bit float OpenEXR normal maps from the comb tool in Houdini. I will be investigating this solution this week and see if what I learn is back-portable to Blender.


text:
In Blender 2.8 +, how do I limit the (animation / multi-frame) render to only one pass (e.g. only z-pass or only Mist pass)?
Related, not properly answered: How to render only a mist pass
Related, talks about using compositor: Render Passes separately
I have the rendering engine set to Eevee here:

I have only the "Mist" pass selected and everything else (including the "Combined" pass) in View Layer Properties:

Yet, when I'm trying to output the animation like so

, the "combined" pass is rendered anyway:

I need just the Mist pass to be saved, like I can see in the Image Editor after the render when I choose the "Mist" pass from the dropdown:

I'm looking for a simple solution with the EEVEE engine, without compositor if possible, because I am doing this programmatically, via Blender compiled as a Python module.
Alternatively, if you can think of a simple way to do this programmatically via the compositor, this would also work for me.
This used to be possible with the Blender internal rendering engine before 2.8, so, if there is no way to do this with Eevee, I would consider this a regression.
Aside: In the meantime, I'll try to compile some older version of Blender as a Python module, e.g. 2.78 (2.79 has build errors that are fixed in some later commit before 2.80) and see if I can get that to work.

I figured out a simple way to do use the compositor programmatically to isolate the mist pass in the renderers (Inspired by this answer).
import bpy

# (perhaps) more code here

# perhaps defined in some function or method
node_tree = bpy.context.scene.node_tree
render_layers_node = node_tree.nodes.get("Render Layers")
composite_node = node_tree.nodes.get("Composite")
links = node_tree.links
links.clear()
links.new(render_layers_node.outputs["Mist"], composite_node.inputs["Image"])

# (perhaps) more code here

bops.render.render(animation=True)
```


text:
Bevel modifier causes shading issue
I was using a Boolean modifier with a cube as a cutter for a cylinder. When The bevel modifier causes a shading problem coming from the beveled corners. I've already tried adding loopcuts to isolate the area, but it didn't help.

If you want to keep the modifier, create this edge loop and it will prevent the bad shape:

Or apply the modifier and create this topology:


text:
Why does the median z value seem wrong?
I have a circle. I checked every single vertex's z value individually, and they're all 0.0:

But when I select all the vertices, the median for the z value is not 0:

Why isn't it showing as zero? This has been very frustrating for me. I kept trying to set the value on a larger mesh to 0 (using s -> z -> 0) to no avail. But it didn't work. So I cut down the mesh to just this small portion and I saw this problem still.
Here's the file in case you're interested:
https://www.dropbox.com/s/jqi3eljppr8gcvv/uneven.blend?dl=0
This brings up a side issue I've been having using blender. I do an action (like s -> z -> 0) and it brings up a little window in the bottom left:

Is it still waiting for my input? What's it doing there? I can make it go away by deselecting vertices or something. Sometimes, like when I do a bevel, its purpose is obvious, and I change values in there and it affects the geometry. But most of the time it sits there and I need to do something funky to make it go away.
Thanks for any help with either problem!

https://blender.stackexchange.com/questions/3168/digits-of-precision-of-vertices-coordinates

Hm -- using @Henning's blend file, I get exact float 0.0 if I execute this in a Blender scripting window:
>>> np.median([(bpy.context.object.matrix_world @ v.co).z for v in bpy.context.object.data.vertices])
and yet I also see -0.000458 mm as the displayed value. I think this may be related to the way Blender modifies the Transform median to reflect Scene Units; if I switch Length to "Adaptive", I get -0 m, without any small non-zero part. Setting Unit System to None gives 0.000061, though, which surprises me a bit.

The side issue can be gotten rid of by clicking anywhere on your screen. It's a part of Blender.
It's used to set how you want your scaling, moving, rotating, added object, etc.
For example: You add in a UV sphere but you don't want a lot of segments so you change the amount of segments it has using it.

There might be another vertex hidden on the underside of your object.


text:
Can't Paint in Texture Paint
I have tried all the fixes I could find with no luck. Can someone take a peak at my blender file and help me figure out why I can't paint in Texture Paint?
https://drive.google.com/file/d/10qybvIDgkR-VLeLwaWkIyVdXHQZHrfAR/view?usp=sharing

Do blend-exchange.com instead.

Hello and welcome, please add more details for your question. Like: did you create a new texture, paint settings, object, material settings and so on. the more, the better to help you

In your active brush a completely black texture is enabled, so that every stroke has 0 effect. Just disable the texture in brush options.

Thank you, it worked for my problem!


text:
Blender 2.9 Not Displaying DDS textures in viewport
I've heard something about Blender not rendering DDS textures in the viewport somewhat. It does seem to be true. Is there not a fix to this?

Hello, could you rephrase your question so someone who is not familiar with the subject could try to help you out ?

I'm having a similar issue with .DDS files on a project and apparently all you have to do is convert them to .png. Should be as simple as just renaming the suffix from .dds to .png (but make sure you do this with backup files!)
Can Blender open .DDS files?

Renaming the extension will not convert the file. In fact it may lead to applications being unable to open them because of the incorrect file extension doesn't match the mime type. To convert you have to open it with an application that can read the format correctly and save-as as a new format.

Kind of rude and hasty downvote, did you look at the other thread I linked to at all? I suggested specifically to use back up copies of images... and that comment has been upvoted 5 times. Dont shoot the messenger thanks.

"did you look at the other thread I linked to at all?" Yes, the answer there suggest converting the dds texture to another format, not just changing the extension. That would be the equivalent of pasting a sticker saying Orange Juice over your glass of water and saying you are now drinking orange juice


text:
My mesh looks awry
It can be a basic question.
I made random shape to explain my situation.
This object is basically box shaped and a round shaped hole is connected.

And these kind of shadows in both sides makes me frustrated sometimes...
Weird shadow and gloss are on same simple surface without any doubles.
The mesh is just as itself, welded as one.
Please take a look and tell me what's the problem.
And I'm new to topologies too, so I welcome advices for making good flows on mesh.

please attach your blend file.  You might have bad geometry, such as extra faces or doubled vertices, or you may just need to enable auto-smooth in object data properties. But it's hard to tell without looking at the actual blend file.

There is a blend file attached, that's how I made my answer.

The reason for this is that your object is shaded smooth, and it's smoothed around the sharp edges. Usually Autosmooth avoids this, but in your case it's not working because under Object Data Properties > Geometry Data you have stored custom data. To make Autosmooth work again, click on the button Clear Custom Split Normals Data.

Thank you! It totally fixed my mesh.

@user123730 Maybe you would consider to mark this answer as accepted so that other users can see there is a solution to this question. Read here: What should I do when someone answers my question?

I just voted up but my reputation is only 11 because I just signed up. However they said my feedback is recorded.

You don't need more reputation to accept an answer. Just click on the grey tickmark under the vote number.

Oh, I found the tick mark! Thanks again.


text:
Background in the 3D view appears black instead of transparent
When in the rendered shading view the background is normally transparent, but all of a sudden it turned black. I don't know if I accidentally pushed a button, and I don't know how to turn in back to transparent.
The Transparent Film option is checked in the render properties panel.
What did I miss?

Odd.. Is it possible you could upload a .blend which demonstrates this?

@gandalf3 how do I upoad a blendfile?

Upload it to some hosting service (e.g. pasteall or blendexchange) and put the link here.

You appear to have a background image which is being displayed under the viewport render. If you disable it in 3D view > Properties region (N) > Background Images, the transparent background is visible once more:

In case this happens while looking at the Render Result, check your channels of the image to draw.

the question was about the 3D view, not looking at the render result.


text:
smoke+fire simulation fine in viewport but jittery in render
Here's my blend file. The camera shake is intended.
Here's what it looks like in the viewport:

(source: gfycat.com)
When I render, however, even after the camera shakes, the fire clearly jitters a little bit:
http://zippy.gfycat.com/WeepyAnchoredJanenschia.gif

I fixed the problem by disabling "Smoke Adaptive Domain" in the Physics tab in the Properties panel, while selecting the domain:

For whatever reason, this caused the domain to shake around a little bit, causing the jittering. I'm still not sure why it doesn't jitter in the viewport but does in the final render.

Works fine when I Bake the simulation before rendering. I did observe the same jittering when I did not bake first, and let blender calculate the smoke on the fly.
It's aways recommended to bake simulations before rendering, precisely for the purpose of preventing glitches like this.
Also note that it's also recommended to render to an image sequence first, then render that to a video.


text:
Correct way to render crepuscular rays in cycles?
While trying to use the new cycles volumetric rending features to create crepuscular rays (with the intention of updating my answer here), I have found this to be a little trickier than I anticipated.

When I create a basic setup with a spot lamp (sun lamps don't seem to work, not sure if that is a result of their one directional nature or what..) and a world material like this:

Which gives me this (500 samples):

The problems with this that make me think that I'm missing something (aside from the rendertime and noise, which I understand to be a part of using bleeding edge new features) are:

The background shader/sky texture isn't visible at all (volume is too dense?)
The lamp needed to be set to 50000 strength (this is of course dependent on the distance from the camera, but the kinds of strengths required to get some nice defined rays will blow everything out if volumes are disabled)

I can't seem to get a straight render (no compositing tricks) to look anything remotely like the pretty image in the release notes:

(source: blender.org)

Is this just how it works?
Or is there some trick I have missed (not counting compositing/renderlayer tricks)?

This is really a tricky one.
First off, world surface shader and sun lamps dont work for world volume shading for now (as stated in the manual). Also, if you use object volumes the camera can not be inside the volume. But you can make a cube bubble around the camera and parent it to the camera. E.g use a "Boolean Modifier" with the bubble (intersect) to cut it off. Of course this only works when your bubble sticks out of the volume but you can extrude it in any direction that doesnt point forward anyway.

Here is an example of the node setup for a volume:
volume scatter shader and volume absorbtion shader as input to an add shader. Thats it.

For the sun lamp use simple emission with strength of e.g. 9 to get deeper shading for the rays. Also helpful is to set the sampling size for the shadow to 0 to get crisp lines. Background can be set to a Sky Texture.
To keep render settings simple volume scattering events can be set to 0. For the Volume Sampling it might be necessary to tweak the Max Steps (e.g. 2048) and Step Size (e.g. 0.04).

This is what it would look like:

To get more crepuscular rays (like in the image you provided) you could add some shadow shapes between the sun and the volume (acting as clouds). Of course this example looks horrible but you get the idea.


text:
How to move collection without moving the instances?
I want to move the collection without affecting all the instances since I would have to rearrange the scene. Is there a way to do this?

https://blender.stackexchange.com/a/164070/86891 ?

Thanks, but that‘s not quite it. The question in the link is about the origins but I want to move the main collection without moving the instances.

You can move the origin collection, then change its origin, this will reset instances to their starting position


text:
how to change the pivot point of an animated object?
I want to animate a cube that moves from right to left, falling from one side to the next, and so on. But to animate the cube, the pivot point must change. Because the cube falls first over edge A, then over edge B, then over edge C and so on. To change the pivot point, I tried to set the origin always to another edge. But that doesn't work because then the origin changes permanently. I would always have to move the origin to where I need it to make the animation work. How would you solve this? Thanks for your help!

On youtube there is some very good videos of how to approach this issue. The first one is using geometry nodes to animate the cube, and the second approach is using empty objects to set new pivot points. Geometry nodes video: https://www.youtube.com/watch?v=qXx7yZbX76w Empty objects pivot points Video: https://www.youtube.com/watch?v=R1_6l9vxyKs

To add to Mr Bill's answer, you can parent your cube to an empty, and parent this empty to another one, and so on. Here the cube is parented to empty 1, and empty 1 is parented to empty 2:

Now you can animate empty 2, then animate empty 1. Don't forget to keyframe empty 1 just before its own rotation so that the cube correctly sticks to the the right position. Here is what it gives:

In a more complicated case, the best would be to change the parent of the object, for that purpose you can use the Dynamic Parent addon.

Add an empty. Place it where you want the pivot. Parent the cube to it. Rotate the empty and the cube will follow. You can then move the cube relative to the empty to change the rotation position b

Thank you, mr bill! how to move the cube relative to the empty? I just know how to move the children.


text:
Purchased object wont work in quick liquid simulation
I bought a brick on blendermarket and want to melt it with a simulation (quick effects/quick liquid). But for some reason, it does not work with this object. I have tested two other objects (a cube and a sphere) in the domain. For them, it works, but the brick does nothing. Thanks for your help.
Blend File

Please don't upload blend files to sites that require registration to download. Use https://pasteall.org/blend/ and put a link to it in your question.

it doesnt, it's wetransfer, its free and no registration is required!

Ok. But I'm not agreeing to their terms of service without reading them by which time I've lost interest!

You're a free man, John. You can do whatever you're interested in.

Phew! :^) Actually I've seen other blend files posted on that site which haven't required me to agree the T & Cs so I'm not sure why yours did. Anyhow you have yor answer now.

fluid objects must be manifold meshes, else it won't work.
Your brick is non-manifold:

You can check "is planar"

to make it work.

Auf dich ist einfach verlass! Danke!

Sehr gerne!!!!!!


text:
Can I remesh an object including all modifiers?
I appied different modifiers to a text (curve + subdivision). The text is curved now but I want to shift and rotate some of the letters a little bit. This is not possible at the moment because the curve modifier is still there. I want to make a new mesh of the text as is and then finetune some of the single letters. Just like in photoshop where you can merge down all effect to a new layer and keep working from there. thank you!

Yes you can.  I would make a copy of what I had now before I started, but you can apply the curve modifier and then edit the resulting mesh.

thank you! how would you apply the modifier? object/transform/ mesh from curve?

If I understand how you did things, yes.


text:
wrong material showing - faces show different material altough they use the same material slot
I have an object with an image texture. somehow one of the faces is brighter than the other ones although every face uses the same image texture and the same material slot. it drives me crazy. can someone please help me figure out whats wrong?

Hi Christoph...schöner Name :D ....please provide blend file so we can check it out.

Maybe you have a flipped normal? Try selecting the whole mesh in edit mode, then select Mesh > Normals > Recalculate Outside from the menu at the top of the 3D viewport.

Hello Chris and Chris, here is the Blend file! Thank you in advance!
@Christopher Bennett I binged the procedural Texture vid you recommended. It was awesome! I wished the guy had a "level 2" video :)
https://we.tl/t-PitIWb1iMi


text:
Different HDRI Resolutions for Viewport and Render
I want to use the 1k version of my hdri for the viewport and the 8k for the render. I know how to set up the hdri for the render, but how can I use the 1k version for the viewport? Thank you!

You can only do this in Material Preview mode.  It won't work in any of the other three Viewport Shading modes.

Set Viewport Shading to  Material Preview.
Left click the ↓ next to the Viewport Shading mode selector in the header.  This will bring up the Viewport Shading menu:

Left click the gear icon.  This will bring up your preferences, with Lights Selected.
Under HDRIs you can add the 1k version of the HDI as a custom world.
Your HDRI will show up in the list of HDRIs you get when you left click the world sphere in the Viewport Shading Menu
Left click to select it.
Make sure that Scene World is not selected.


text:
Is it possible to gradually increase/decrease values using arrow keys?
When I'm changing the values in Blender (for instance in the nodes) I find it kind of inconvenient to type in the new values or using the slider. Especially, if it's about subtle adjustments. The slider is often lagging if the preview is heavy. In Adobe Programs you can change the values gradually by using the arrow keys. But it doesn't seem to work for Blender. Is there another way to do that? Thank you!

You can hold the mouse over the slider, hold down Ctrl key and scroll the mouse wheel. This will change the value incrementally.


text:
How do i delete faces and keep faces next to deleted faces smooth?
Basically I am trying to delete faces from a place and doing so either by selecting deleting faces only or disolve faces makes the faces around the now deleted faces unsmooth and jagged.
Is there a way i can delete current faces, but keep faces around the deleted faces smooth?
This is the gif of the problem i have

You may try adding the extra loopcuts at the edge. Select the whole mesh with A and get rid of tris with Alt+J. Add two loopcuts (Ctrl+R) and place them very close to the edge. Then triangulate the mesh with Ctrl+T.

Result:

If you don't want to add extra geometry as above just check the Autosmooth checkbox in a Mesh Data header.

So, what does triangulation do to the mesh in this case?

its just because your Mesh was Triangulated but in general you should use Quads with the Subdivision Modifier


text:
My object displays wireframe in 3d view. How to make it solid?

I just want to make every object solid and don't care if there is the anser to the question or not.

Could you tell a bit more about how the "non solid" object has been made? What have you tried so far? Could you also ceck the title? I'm not sure about what is it saying.

There are two ways to solve it I guess:

You're in the Wireframe display mode and need to cange it to Solid.

You've Maximum Draw Type set to Wire and need to change it to Textured and uncheck Wire and Draw All Edges boxes (if present).


text:
How to turn my honeycomb pattern into the sphere?
I'm new to bender and followed some tutorials. After following this one I'm trying to make the pattern I have into a ball. I can make the pattern follow a path, so it's probably not that hard to make it follow a sphere. However I'm stuck and I don't know if it's possible. Hope somebody can help. Thanks in advance.

This video is half an hour long and doesn't explain what you are trying to do, so you need to add images of what you are doing and what exactly is the problem. Also, it can be deleted later on and then the question will be meaningless.

@KMFrits I think I understand waht you mean but no, it's not as simple as a curve modifier! If you can use a texture, you could probably search some other question like http://blender.stackexchange.com/search?q=sphere+map. If you really need a spherical honeycomb mesh, it's more difficult, probably... It could be constructed by a python script, perhaps?

The nearest shape I can think of is an ICO sphere... but it has 5 and 6 sided faces... see this (3dsmax) video for reference https://youtu.be/9AOUTy2BlAk?t=34

You can deform a sphere from plane by using 2 curves, 180 degree one and 360 degree one. The hard part is trying to make it contiguous or without seams. This approach would make the shape infinitely stretched near the polar areas. You can't build a sphere out of regular hexagons because that would constitute a flat shape (6*60 = 360 degrees). That's why soccer balls have the pentagons. Can you elaborate on what you're trying to make?

Thanks a bunch, I can go on from here! I'm trying to create an image, that makes it seem like a honeycomb planet. I've used some tips from you guys and got what I needed for this graphic.

You may achieve it beveling the Ico Sphere (Percent mode) and inseting the faces.

Add an Ico Sphere and subdivide it (in my case I've made 3 subdivisions).

Select the whole mesh in Edit Mode with A and press Ctrl+B to bevel it. Use the Mouse Scroll to reduce segments to 1. Press M twice to enable the Percent mode and scale hexagons to lay as close to each other as possible. Next remove doubles with W-->Remove Doubles. Increase the Merge Distance value if needed.
NOTE: You can achieve similar effect using the Bevel Modifier, but geometry may be more dense then.

Now add a Subsurf Modifier with some subdivisions and smooth the object in the Tool Shelf's (T) Edit panel. With the whole mesh selected press I twice to inset individual faces, then scale the faces inwards to create the holes.

Finally with the whole mesh selected (A) press Shift+E to crease the edges. Play with the Mean Crease value in the Transform panel of Properties Shelf (N) to adjust its strenght as you like.

FINAL NOTE: The model has pentagons as @kheetor warned about, but they're not much noticable.

Just found a related answer: http://blender.stackexchange.com/questions/3212/how-can-i-create-a-hollow-sphere-with-regularly-spaced-holes Maybe helpful for you.

Really like Paul's solution, but just to give another option. With the understanding that a perfect honeycomb sphere is theoretically impossible, and just going for a look here. This option does require the Tissue Add-on.

Create a hexagon from a 6 sided circle and give it some thickness.
Add a cube and sub-divide it smooth.
Select the hexagon, then the 'smooth' cube and Tessalate
Choose Quad and adjust scale if you    like..

You can always adjust the original mesh and update the generated.

Note: Do this is Top view for predictable results.
Just for reference, these were the settings...

Update: Tried the same procedure again but this time with a different connector...


text:
Straighten the series of vertices in UV editor
I've got a bottle modeled and I want to put a Nuka-Cola label on it. I took where I want to put it, marked the seam, and unwrapped it. It looks like this:

I want to straighten the UV so that it matches the angle of the Label, is there any way I can do this? I understand it will be a bit distorted, but i'll deal with that afterwards.
Here's my project files (Not using Blend-Exchange because you need the images aswell)

Related: http://blender.stackexchange.com/questions/41132/how-do-i-straighten-uv-maps

What about using Mesh -> UV Unwrap -> Cylinder ? (You need to be in front + ortho : 5 + 1 )

If you don't want to straighten your UV islands (How do I straighten UV maps?), cause in your case it might be very time consuming you might repeat the steps I've shown in the .gif below.
In Edit Mode select all faces (A), press U-->Lightmap Pack-->OK. Now select one of the face to make it active, then again press U-->Follow Active Quads-->OK. Your UV island is straight now. Adjust it using G, R and S to fit the image. If your mapped image is upside down just scale it negative 1 (S,Y,-1).


text:
More effective way to subdivide the cone?
Was wondering what is the most effective/fast way to subdivide the cone to make the subsurf modifier work properly?

I assume using a beveled edge on the base is not an option? One thing that comes to mind is making a cone from a cylinder, then you can add loop cuts easily. Once you are done you can remove doubles/merge the top vertices to remove the extras.

There are many ways to do it I guess. Here's mine:
After adding a cone set it's base fill type to triangle fan. Select the lower edge and press Ctrl+B to bevel it and scroll the mouse to add two additional edges. Change the mode to Percent (press M tree times) and place the edges very near to each other. Next select the very upper edge and place it on top of the cone pressing G twice. Add a subsurf modifier.

Finally dissolve the edge at the bottom (X-->Dissolve Edges) and add the edge loop (Ctrl+R) to replace it.

Thanks!, handy to know, I was wondering that for a while and I should probably look up some more tutorials. which leads to another ( Kinda off topic ) question: What software do you use for recording and splitting your gifs? Blender?

For .gifs recording, please check out this topic: http://meta.blender.stackexchange.com/questions/963/what-is-the-process-for-creating-gifs-for-questions-and-answers

Cone radius2 0.001!
Loop Cut.
Merge top vertices.

fantastic way to resolve the issue :)


text:
Wave modifier doesn't work on my cylinder
I'm still trying to get used to using Blender, but I'm having trouble animating a cylinder the way I want. I want to get the cylinder to move in a wave motion, like this:
So I figured I should use the wave modifier tool because you can make sinusoidal type motions with it, but when I try to use it, it only really animates the circles at the ends of the cylinder.

I thought maybe I needed to subdivide along the surface of the cylinder to allow it to move in an up and down motion like I'm looking for, but that didn't seem to help. Any ideas?

Did you rotate the cylinder in object mode so it's horizontal? Try applying the rotation Ctrl+A > Rotation.

To make it work properly you have to apply transformations to the object and divide the mesh to make the Wave Modifier work.

First apply the Rotation and Scale (Ctrl+A-->Rotation&Scale) to the cylinder.

Then divide it using the loop cuts in Edit Mode. Press Ctrl+R and increase the cuts number using the Mouse Scroll.

Important thing here is to place the origin point in the desired position, since the wave movement starts from where it is. Select the desired edge loop in Edit Mode, then press Shift+S-->Cursor to Selected.

With the cursor placed press Shift+Ctrl+Alt+C in Object Mode to move the origin point there. Then add a Wave Modifier and play with its settings.

Paul, what you showed at the top is pretty much exactly what I'm looking for, but moving the origin to the end of the cylinder did not seem to change anything the wave modifier does. Do I need to change anything in the wave modifier itself?


text:
Why am I missing nodes in the 'Add node' menu?
I have the problem that my blender hasn't updated correctly and is stuck on version 2.78 while it says that it has version 2.79, the issue is that I'm missing nodes like image textures and diffuse BSDF and the whole shaders option in the 'Add node' menu.

What exactly do you mean by "nodes un-updated"? What specifically is wrong?

The 41000hz is unrelated and regular behavior, could you explain the issue better, what is wrong with your nodes? Have you tried clearing user data and preferences between installs? Try the standalone zipped install instead. Current version is 2.79 not 1.79

What does this have to do with updating blender to make you think your blender version is 'stuck'? Nodes should be largely the same in both versions.


text:
Display DPI in image properties
Is there a way to display an image DPI in the properties of the Shader Editor?

For context, I was trying to find a way to automate this in the Group node (or other option). But can't. So I'll leave this as a manual input. For a smoother pipeline, I want to display all information within the Sidebar.

If I'm not mistaken only printers will use the information on a screen and in a texture, 1px is 1px, regardless of DPI.

This for accurate print, fabric design, etc placement on garments. All 3D fashion application (such as Clo3D) use this.

I think those other softwares use it so the end consumer doesn't have to worry about it. Just my guess: It will rescale the texture based on the DPI so it matches printing behaviour. This is not necessary in Blender, if you want to use it, just read the DPI from the file and multiply the size by: (72 / YourDPI) 72 is the standard for screens, as far as I know.

The primary purpose of the Node Group is to handle the scaling.
It would be great if I could display the DPI of an image. Instead of the user going back and for between apps and folders. Not all design have the same DPI. We work 150, 300, 600 and on rare occasions 1200dpi.

But how "big" a texture is is solely defined by the UVs, it has nothing to do with DPI. If you want the DPI displayed, I suggest using python to read the header of the image file.

That is true. But we are using DPI to have correct real world proportions and repeat the texture. Our workflow (to export an object to Blender) is to setup the UV with a real life scale 1 meter. This also places some object outside the UV box. Within Blender, since the UV is constant to 1 meter. I can scale the texture to re-world scale. This is done with the images DPI.                         Hope I need sense.

In this case I would read the dpi from the image file directly (header) and multiply the uvs by that factor. Or - change the DPI so it is converted to 72.


text:
Principled BSDF subsurface scattering values for skin material
I had some difficulty finding information about the usage of the Subsurface Scattering parameters in the Principled BSDF node for a skin material, so here are some questions I have that are still unanswered despite my efforts regarding the parameters:

Is the Subsurface parameter value always at 1.0 for a skin material? If not, does it need to be mapped with a texture?
Would the Subsurface Radius parameter be constant across the face of a real person? If not, how can I map this value with a texture given it accepts a Vector input?
Is the Subsurface Color intended to have a subdermal map as its input?
Is there a document that lists parts of the skin and common SSS values for them?

I'm working with a cartoonized character and I think introducing more realism to its skin can give me better results, but accuracy isn't a priority.

Is the Subsurface parameter value always at 1.0 for a skin material? If not, does it need to be mapped with a texture?

Some parts of the skin have more SSS than others, therefore a texture helps... and rarely a skin gets 100% SSS. So a value of 1 is unrealistic.

Would the Subsurface Radius parameter be constant across the face of a real person? If not, how can I map this value with a texture given it accepts a Vector input?

Also another non-constant value. Depending on the density and depth of the skin, if there's bone or flesh under it, etc; this value can change. Here you can play in conjunction with the SSS color, as this parameter is only there to help SSS color to get higher radius. Note that Cycles simply multiplies both Radius and Color. If your SSS has a maximal radius less than 1, you can just use the SSS color. Vector texturing is possible in formats like EXR or HDR (and since in this case, the radius is allways positive, you can use also PNGs or any +16bpp format)

Is the Subsurface Color intended to have a subdermal map as its input?

Same thing as the above.

Is there a document that lists parts of the skin and common SSS values for them?

There are plenty of artists who shared their common values... But this is not rocket science, and there's always plenty of room for artistic interpretation.

Great answer, helped a lot :). I believe Subsurface = 1 isn't unrealistic in 2.82. The slider only multiplies radius values, so if they're correct (eg. scaled to milimeters for skin), Subsurface = 1 gives correct results. Comparing different engines seems to support this. Am I missing something? Thanks :).

@JachymMichal, having a material with SSS=1, even if the radius' scale is correct, is still unrealistic. All subsurfaced materials have a bit of diffuse in it (i.e skin, much more than wax), and SSS=1 simply removes the diffuse component completly.

Okay, thank you for answering. Have a great day :).

Okay,I can tell that you're a little confused and I was too when I first used the Principled BSDF shader. I'll clear up the controversy so you can better understand it.

The answer is no. Nothing in this world is completely translucent. Human skin typically has a susbsurface value between 0.1 and 0.2.
If you're asking if the color is consistently red,then yes. If you're asking if its brightness is consitent,then no. The Subsurface Radius is lighter or darker depending on how thick or thin the tissue is. The most noticeable examples of thin tissue include the lips,the ears and the inside of the nostrils.
The Subsurface Color socket is actually the color for SSS shading. It can be used any way you want it,but if you want to create realistic skin,I would definitely recommend using a subdermal map just to be safe.
As of right now,there isn't one. As Rey said,it's open to interpretation.

I hope this helps you. :)


text:
My blender 2.77 wont start
on startup my blender version 2.77 crashes, have any off you been through this and know a solution? I have already tried re-installing it but its no use.
Thanks

do you have correct version for your os ?

you mean like 32 bit or 64? yes i have the right version

did you try to compile blender from the source ?

yes i did, it didnt work

i can't understand .... you have this problem with normal install file of blender, or compiling source code ?

Source, I'll email some blender people and see if they. Can do anything.

There's not nearly enough information to be able to help you. Don't bother blender people until you have something conclusive to bother them about. What are your system specs, what operating system? This may be caused by bad graphics card or bad drivers. What GPU so you have?

Do you have another version of Python installed on your system?
My version of Blender 2.75 would not start in Win10, complaining about unhandled exception 0xc0000409.
I re-uninstalled Blender 2.75, re-installed the MS Visual Studio redistributable (msvcr120.dll), went through the usual windows service troubleshooting steps starting from a clean boot.  All no help.  I finally ran the Program Compatibility troubleshooter on blender.exe, the diagnostics log in %appdata%/temp said "python incompatible".
So I deleted the PYTHONPATH environment variable.  Voila! Now Blender starts fine.

try deleting everything in %appdata%\Blender Foundation\Blender before installing
open explorer, copy/paste this : "%appdata%\Blender Foundation\Blender" in the adress bar

Delete everything you'll find in this folder

No, it did not work


text:
How to preserve the main dimension when adding space between elements
I’ll ask simple, then explain why I need it. Here’s the idea –
There are 2 squares and rectangles next to them (image below).
The height is 1.795 and their combined width is 5.795. If we add spacing between each element the dimensions for the height and width will be preserved (image below).

Also, the space between the squares is the same length as the space between each rectangle. Now, the snapping tool works well for preserving the main dimensions (shown in orange), but how can I make the spacing the same length between each element? Yeah, I can bevel them, but the squares are supposed to be identical as well as the rectangles.
I need this for creating kitchen cabinets where the main dimensions are already defined. This is sort of a practice where I’ll get serious later on and make some money. There’s no overlapping edges in real life and I believe this is an essential feature for architectural visualization, such as: Desks, Cabinets, Objects next to\on top of each other etc. Is there a way to make this in blender? Any workaround will be appreciated :).

I'm having a hard time understanding how this differs from your other question http://blender.stackexchange.com/questions/27055/how-to-preserve-measurements-when-manipulating-an-object

I can honestly say that the other question is not about making the spaces equal (vertically and horizontally). I understand that they look too similar and I'll update it (the image was not supposed to include drawers, sorry about that)

let's start from your exemple with those objects (i'll call them Base):

1st, we create objects (i'll say Spacers), they don't need to have geometry but giving them a shape make them visible and selectable. The important thing here is their origin, it has to be in the middle of the space between the objects we want to control.

The horizontal Spacers on the right have to be rotated 90° on the Y axis in Object mode, because we'll use their local X axis.

Now select 1 of the Spacers RMB and the Base object touching it (in this order) Shift+RMB and enter Edit mode Tab. Select the face touching the Spacer, hit Spacebar to search for Hook to selected object, click it with LMB. Now your face is hooked to the spacer object. Get out of Edit mode Tab. You can move the spacer to check if the face is following as it should.

Repeat the same operations on every Spacers and their  adjacent faces. There are 3 Base objects that needs to be hooked to the same spacer.

Now select the second Spacer, go in constraints tab and add a Copy Scale constraint. The Target has to be the 1st Spacer, the controller. Remove Y and Z axis, choose local space from in 2 Space menus. For this spacer, we'll use an Influence of 0.5. This is important because the concerned Base object will be affected by 2 spacers but the left Base object is affected by only 1, so the scale has to be 1/2.

This one needs an Influence of 1.

The selected Spacers have an influence of 0.5, the others have 1.

Now you can select the Controler Spacer and scale it on it's local X axis with S->X->X and all object should be modified to use the same space between them!

Here is the .blend file

That's sort of what I need because the cabinets are not identical when scaled, as well as the drawers and that is a problem. Thanks for the Blend file, I learned something :)

If it does I will :). Here's the problem - http://www.pasteall.org/pic/85270
Maybe they scale equally and I'm doing something wrong, but I need them to be equal.

i see, i'll think about that

That's exactly what I was looking for (the second file)! Can you briefly explain what you did, 'cause this is a sort of new to me. Thanks :)

@cegaton That's what i want too, but i have to think about how i'll do that, not easy to explain, even harder to do it in english...

@cegaton rework the answer with explainations and simplified the setup by removing empties.


text:
Automatic baking followed by a render for animation
I'm looking forward on making an animated movie of 2 hours and the challenge are these "Animated Maps (Normal map, Specular map)" - https://www.youtube.com/watch?v=mc7ADD4b8_0. I want the animations in the movie to be quite accurate which means that the maps would change on the model on pretty much every frame depending on how each model is animated. Is there a way for the maps to be baked, then assigned on the model and then render the scene and all of that to be done automatically for every frame by the program by clicking "Render" only once (it pretty much seems like everybody's dream though)?
The maps would be baked on the lower poly model who's rig is a duplicate of the other that is assigned on the higher poly one.

Not sure if this would actually be faster or slower than rendering with the high-poly model..

gandalf3@ The idea is not to click bake and then put the maps on each frame and the render speed doesn't matter since I'm not going to be around the computer. is there a way to do it?

Well, yes, I imagine this could be done fairly easily with python. But I'm not convinced that the total render time would benefit from using normal maps if you are re-baking them every frame. It might be better to use the high poly model, which will give you a slightly higher-poly result. (no low-poly edge artifacts)

gandalf3@ What you're saying is, the render time will take faster with the high poly models than what I'm aiming for?

gandalf3@ If you mean, to use traditional maps (non animatible), then the problem is that the facial expressions will have wrinkles, which would be visualized by the animated maps. By the way, how would this be done with python (totally new to coding)


text:
Multiple material on a label!
I made a model of a cosmetics bottle with a label on it,

regarding my design the logo should be in Silver hot foil texture so I made the design picture as PNG.
Then applied it on the label then the silver material under it, then the last material should simple diffuse white material as the adhesive paper back
Now when I apply the three materials on the label, the silver foil material doesn't appears on the preview render but the paper back material do.
But when I remove the paper back material the silver foil appears,
but I need them all to appears cause the are a transparent bottles not only what plastic bottle,
thanks in advance.

It's very confusing if you don't show any screenshot of your object + node organization

i showed up an image of my label with the silver foil material, the node are all of no problem in them,
but my problem is only how to organize the materials on the label to be the face design and then from inside to be paper back and the silver foil to be appears only through the logo

Is the texture transparent?

yes the design texture is transparent correctly, but when the paper back material appears it's appears also through the logo but i need the silver foil to be appears through the logo.

You could split the sub layers, so you can change separately both colors

I think I've understood what you asked.

What you need then is a mix node for your label/Silver using the backfacing of your label's material. Here is the node setup :

This allows you to use a specific material when your look at the back side of your material.

hey @Bithur
thank you very much for your answer, yes it's exactly what i need the silver material to appears through the logo on the label and the back face of the label to be white diffuse. thanks a lot


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What is the difference between the two properties panels?
In the Blender UI, what is the difference between the Properties region (the thing that can be opened with N) and the Properties editor (the thing at the very right)?
What do they apply to (e.g. current selection/viewport/globally) and what kind of settings can I expect in each of them? In other words, if I were a developer adding a feature, how would I decide whether to put the UI in the Properties panel or the Properties window?

The Properties region, or as it is commonly called the Properties panel, holds settings for the 3D view and the active object.
In the picture below of the properties region, all the selection specific items are at the top. The bottom seven in the red box are all settings for the 3D view. The grease Pencil can be either object specific or scene specific.

The Properties window, or Proprieties editor holds the settings for the entire scene and the active object. The first four contexts (aka "tabs"), in the red box, are for the scene and do not change with the active object. All the other tabs, with the exception of the Texture tab are dependent on the active object. The Texture tab, similar to the grease Pencil, can hold settings for more than just the active object.

Please don't confuse panels and regions - a panel is a collapsible box inside a region or editor (e.g. Sampling panel, Light Paths panel...); the properties region and toolshelf are both regions (show/hide them with T/N)

@GregZaal Because my question is not primarily about the terminology, I edited it to include the correct terms, please check.

@GregZaal Seeing as there is a lack of documentation on the proper terminology for panels, windows, editors, views etc. I used the name blender uses. https://i.sstatic.net/bSnqj.png

The manual was indeed wrong at the time I wrote that comment - but I've since corrected it: http://blender.org/manual/getting_started/basics/interface/introduction.html#anatomy-of-an-editor - also, that tooltip is definitely incorrect, will fix that too.

Oh and in future, please report issues with the manual - or better, fix it yourself! :) See: http://blender.org/manual/about/introduction.html

The properties panel contains options pertaining to the 3d view and the active object. The properties area contains options pertaining to the world/scene and a more extensive set of controls for the active object, including the ones contained by the panel.
 Both are partially relevant to the selection. In the area, the first four items apply to the scene (global),

The circled items apply to the selection
 and the remaining ones apply to the selection in the case of the panel, the transform and item section are relevant to the selection everything else pertains to the 3d view or the 3d cursor.

The circled items apply to the selection
Both the contents of the transform and item section can be found under the object section in the area (Orange cube icon).

I'd disagree that they are "largely the same", there is some crossover, but they are mostly different imo.

They are not "largely the same" the only similarities are found in the Object tab of the properties window.

@gandalf3, Fixed


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Is there a way to shrink particles to mesh surface?
I attempted to create a dripping effect like this:

On a curved surface using this technique, however the long particles don't conform to the surface, looking very unrealistic (it looks particularly bad on sharp corners).
Is there another way to get this effect, or a way to use this technique on a curved surface?
In other words, I want to make the particles stick to the surface (while still being able to slide freely) and somehow leave trails behind them.

Image from Blender Guru

As I recall he manually made a few drops and used a particle system to distribute them. For a still that would mean apply particle system and sculpt the drops to the uneven surface.

@sambler Is there a way to snap to the surface automatically? (shrinkwrap?) Sculpting each one seems incredibly tedious..

I can't think of a way to make it work automatically. Shrinkwrap would pull the entire droplet flat, vert groups would pull the back and leave the top way out. shrinkwrap a flat piece to the surface and then displacing would not create good looking drops. None of these help with a particle system, only after it was applied. Either sculpt or proportional edit in edit mode to an applied particle system is all I can think of. What we want is a shnkwrap that has a preserve volume option, allowing the closest edge to shrink down but still prevent the other sides from collapsing.

@sambler I guess in that case I will just try and sculpt the drops from scratch.. Thanks anyway.

Sardi Pax released a tutorial for applying metaball particles as raindrops to glass, I believe there is no reason that prevents his method from being applied to a curved surface.
If this method is used instead of sculpted particles, they should conform to a non planar surface.
http://www.youtube.com/watch?v=RDte-IzvHlg

Link only answers are discouraged, please add some more information to your answer. (If the link goes, so does the answer) Thanks

Thanks for your answer :) Is there any way to make this have long drips like the image above?

If you wanna know more about the application, features, advantages, main components, working principles, and other ways, you are welcome to this [page](https://www.allpackchina.com/the-definite-buying-guide-of-shrink-wrap-machine/) of allpackchina.


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How to animate noise texture "seed"?
It's possible to animate a change noise texture by animating the texture coordinates with a mapping node or by animating the texture space, however this only works on one axis at a time (on the other axes the texture will appear to be sliding across the object's surface).
For example, the top face has the desired effect but the other faces appear to be moving/sliding upwards:

Even with all three axes location and rotation animated it still appears to be sliding rather than statically changing.

Is there some way to make each face appear like the top face in the first gif but still be seamlessly blended with the other faces? This should work for other shapes as well.
In other words, I'm looking for a way to animate the "seed" of the texture.

You can not animate the seed of a 3D gradient noise texture because it´s usually all fixed in a permutation table. What you are basically looking for are 4D gradient noise textures.
Why do 3D gradient noise textures not work? Imagine a 3D procedural texture as a continuous grid in space containing colour or intensity values at any node. Also imagine your mesh inside this grid. For simplicity imagine that every point on the surface of the mesh gets the colour of the nearest point of the grid assigned to it. Now imagine moving the grid or the manifold mesh. Eventually the points will move along the normal of a few faces but they can usually not move along the normals of all faces at a given time. And if they don´t move perfectly along a normal they will slide along the surface.
To overcome this limitation we need to add a dimension which we can then animate.
So how can we do this in blender/cycles?
We can program it ourselves in OSL(Open Shading Language). First we need the code for our 4D texture shader (e.g. a very simple one):
#include "stdosl.h"

shader simple_noise_texture4d(
float Scale = 1.0,
float Time = 0.0,
output color Color = 0.0
)
{
    Color = noise( "uperlin", P * Scale, Time );
}

Use the internal text editor and name the above text block e.g. noise.osl. We use the builtin noise function with 4D unsigned perlin noise. The 4th component named Time will be used to animate the texture. Scale is used to scale the texture as usual. The output is named Color. For more information see the OSL specification osl-languagespec.pdf.
Edit: By the way, there already exists a script template "Noise" in the text editor called noise.osl. I didn´t know this by the time I posted this answer. It provides some more 4D noise algorithms.
Important
On the render tab of the properties panel enable "Open Shading Language". The Open Shading Language checkbox will only be available with CPU render mode.
Then add a material to the object as usual and add a script node and set the shader script to "noise.osl". Click the "Update shader.." button next to the shader name input. Use the output colour e.g. as input colour for a Diffuse BSDF shader.

Now Time can be animated as usual.

For more complex noise just edit the OSL code accordingly.

Excellent answer! +1 for OSL exposure ;-)

@hawkenfox make sure you are using "Cycles Render" in the engine dropdown menu.

@ user2859 Was on "Cycles Render" but the problem was that I need to use CPU render mode and not GPU for OSL check box to be available.

@hawkenfox Oh, of course OSL only works on CPU for now. Thanks for the edit.

This is exactly what I am trying to achieve too but I render my scenes with the GPU.  Is there the same shader which does not use Open Shading Language (CPU only) ?

@GeoffCoope Take a look at the Noise5D node group in this related answer https://blender.stackexchange.com/a/119604/29586. Essentially it’s a noise-like 5D noise function with separate ‘seed’, without using OSL.

If using the objects UV's is not a firm requirement you can use the following setup to animate noise.  Conceptually, this is like placing the object 'within' the 3D texture and then moving that texture.  It's seamless across the faces.  Using the i shortcut to set keyframes for Location, Rotation, and Scale is quick and works well.

EDIT:here's the animated .gif

Could you upload a gif of how this looks? The second gif in my answer is made by animating the location and rotation, but you can still tell the texture is sliding..

Unfortunately this seems to have the same problem as the second gif in my question, where the texture seems to "slide" across the surface of the object.

yeah, I know.  I did not understand your question properly.  The other answer given is really nice.  I didn't know that could be done.  I almost deleted this answer but decided to leave it since several people seem to think it's also useful to them.  I prefer the other solution as well.

Since version 2.82 there is a dropdown to enable the W parameter in the following textures:

Voronoi
Musgrave
Noise
White Noise


text:
How to get additive blending in cycles?
I want a semi transparent particle that adds to the color behind it. Stack enough on them on top of each other it will be brighter and brighter until it is pure white. It is of course volumetrics I really want.
Example image:

I have tried this but it only decreases transparency. Not much surprise there. Is it at all possible?

My result with the Add shader. Light isn't added (then it would be white). It is only the transparency that goes away.

My node setup with the Add shader. I have also tried it with reversing the colors of the two shaders I add. Similar result.

Start of a solution
Thanks to Gandalf3, I have begun to solve this with only a shader. This is the shader.

This is a test render. I need more geometry, tweek the alphas and some more, but basicly, it is what I want.

I had to increase bounces in light path settings. This is experimental values but work for now. If not changed, the central part of the flames would be black.

This setup will add the transparent shader to itself when seen by the camera. To avoid excess fireflies, an emission shader is used for non-camera rays.

I used two transparent shaders in this case, but if you don't need to control them separately then only one is needed.
Result with three overlapping objects:

Note that with many overlapping objects you may need to increase the max number of Transparent bounces in Render settings > Light Paths to avoid getting black spots where there are more overlapping transparent surfaces than the specified number of bounces.
Update
With the new transparent depth output of the light path node, you can avoid getting black when you run out of transparent bounces. This setup will replace the transparent shaders with an emission shader when the max number of bounces is reached:

This way you can use lower numbers of transparent bounces and not have annoying black spots.

Original answer:

This will make the emission shader become brighter the longer a ray travels through the object:

However, this only works with a single object, so it doesn't look too good with many overlapping particles.

More information about types of ray : https://docs.blender.org/manual/es/2.79/render/cycles/settings/scene/render/light_paths.html

I think the only way to make a material add to what's behind it is to use compositing. To separate the added material from the rest of the scene, your going to have to use RenderLayers.

Move the add object to a separate layer (M).
In the RenderLayer tab select the layer that the add object is on:

Select all layers (`) and hit render.
Open the compositor and Select your two render layers:

Add a mix node and set the Blend Type to Add:

Final Result:

And here is another way how to make additive material. Possibly it will be helpful for someone.

Neat space ship.

Actually, I continued fiddling with the Add shader and came up with this. I am not really sure why this works better than the others. It may not be true additive blending but it looks good.

You should post this as an edit instead of an answer.

@DantheMan from what I know it is absolutly ok to answer your own questions.

Ah, sorry. Didn't notice that it was an answer.

I did additive material like this:
SIMPLEST SETUP:

WITHOUT EMISSION:

WITH EMISSION:


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Object is weight painted in edit mode
When I go to edit mode my object is weight painted. It did have a armature, but I deleted it. How do I delete the weight painting. I can't apply my modifiers either, because of some shape keys.
Please help!

After deleting the Armature modifier go to the Mesh Data header and delete all vertex groups (click the black down arrow-->Delete All Groups) in Vertex Groups panel. Do the same with shape keys in the Shape Keys panel to be able to apply your modifiers.


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Can't select and transform faces in UV Editor
I want to move a face in UV Editor I but I can't. I can't even select different faces in UV Editor. I have cursor with red circle around it in UV Editor. In 3D View I can move any faces properly.
P.S. It stretches faces if I click and drag along them.

Probably you have the UV Editor's mode set to Paint. Set it to View.

It's set to View already.

You probably have the UV Sculpt enabled. Disable it via Uvs-->UV Sculpt or press Q.