text:
Is it possible to prevent a Displacement modifier from affecting certain parts of a mesh?
A Displacement modifier is doing a great job making a mesh look a realistic object, but there are certain spots, such as a dozen or so vertices at one corner of the mesh, where I don't want any displacement effect.  The displacment is making a mess of things in those spots.
I don't want to undo my brilliant sculpting work there and re-do it after applying the modifier, or to fix the mess afterward. In fact, I don't want to apply the modifier.  Never mind my particular reason, since other Blender modelers may have the same question and want to animate, adjust the Displacment settings later, copy the object but have different ripples in the objects (using global coords), or whatever.
What would be nice is a way to modulate the "strength" setting with a grayscale image or painting in a UV map, but I'm not seeing how to do that.  I'm one of: unlucky at Google today, stupid, or ignorant of some non-obvious feature in Blender.  Maybe there's a nodes editor way to build a processing pipeline for modifier parameters?

As for your second question, I would suggest splitting it into a second question. Stack Exchange works best where there is one question per post.

You can achieve this by applying your displace modifier to a vertex group.

Just ensure that the vertices you don't want it applied to are not a part of your vertex group.
Example:

Ah, vertex groups - one of many important features I haven't gotten around to using much.  Perfect solution to the problem.

@DarenW glad to help :)
Don't forget if (and only if!) this answer answered your question, to mark it as answered by clicking the tick next to the answer.

The Texture and/or Vertex Group settings of the Displace modifier controls the influence.
It seems you are already using a texture and want to mask out areas of that. Doing this with texture nodes is currently not possible and has been on the development todo list for a while:

Texture nodes disabled for displacement now, conflict in using it with render (needs owner for stack).

Remaining options:

If using a image texture, add/use a alpha channel.
Use a vertex group in addition to the texture (as suggested by RolandiXor).
Use Cycles materials displacement, where textures can be mixed (but obviously this will only be visible at render time).

As for modulating the strength value, the way to control individual values in blender is either through keyframes or drivers.
By right-clicking on the value you can 'Insert Keyframe' or 'Add Driver'
The blender wiki has a short tutorial that can get you started.

This doesn't seem to answer the question, which was about altering the effects on different parts of mesh, not on different parts of animation.

The main question involves preventing the displacement modifier from altering some vertices which RolandiXor answered. In the last paragraph DarenW asks for a way to modulate the strength of the modifier to which I added the keyframe and driver options.

The strength value is applied uniformly across the displacement. For modulating, you'd want to use the Wave modifier, an animated texture, animated texture coordinates or animated vertex weight.


text:
How to make a menu like the Sculpt Brush/MatCap menu with Python?
I'd like to make a menu with images like the sculpt brush menu and MatCap menu in Blender with Python. Can anybody walk me through it? Thanks.

The matcap menu is written in C, so you can't define your own menu in Python for showing arbitrary images.
To see where the menu is called...

Open the text editor view.
Right click on the menu, select Edit Source
the line of python script that shows the matcap is displayed.

See that this is a template which means its a preset UI.

source: Stack Exchange

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

sort: votes


text:
Why texturing in game engine looks different than in render mode?
I am learning Blender, and at the moment I am trying to create very simple game. The point I am stuck at is texturing problem. I have created a simple maze and added two different materials for floors and walls. Walls are supposed to be white, and floors a bit blue with cloud texture. The look I got in render mode is:

And in game mode it is:

Why is that? Are only UV textures available in Blender game engine? I am using a procedural texture.

The game engine is rather limited in this regard, as it only supports UV and GLSL textures, along with vertex colours of course.
You can bake your procedural textures to UV maps, but this is a time consuming process. If you don't, however, you will not see them in the Game Engine.

Sources: Google, Wikipedia, my limited experience with the game engine ;)

RolandiXor's answer solves the problem at hand here so i'm just adding this as the question title is broad enough.
In response to your first revision of the question where it was unknown what the cause was (as you didn't say), one other common problem people will run into when using textures and not having them show is starting the game engine in a mode other than Texture.
To fix this, simply change the viewport shading to Texture from the 3d view header or use Alt + Z. By default the game engine will launch in whatever shading mode you have it.

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


text:
How can I animate object properties in Blender?
I was wondering if there was a method to alter object settings at a set point in an animation in blender.
For example, I want to make the color of an object blue for the first 20 frames, but after 20 frames I want its color to change to green. Is there any known method of doing this? I could not find anything when I searched.

Possible duplicate of How can I animate my Cycles shaders? and Can modifiers such as “Subdivision” and “Array” be “animated”?. Welcome to Blender.SE, please search around thoroughly before asking.

Sorry, I did not know what keywords to search, and so I could not find it. Next time I will search harder.

Ok, np. also while an answer that is posted may be correct or suit your current need(s). Feel free to wait a while so your question can possibly attract more views and probably better or more indepth answers.

If you right click on a property and click Insert Keyframe, you can animate that property like you would the location, rotation, scale, etc.

This method works with almost all the properties including all values and most checkboxes.
EDIT: Gwenn commented and noted that you can also insert the keyframe by using the I key. Also, you can Remove keyframes with Alt + I

And where that is not possible, with the "I" hotkey

Can't animate layers anymore, though.

@hjaarnio whoa, when did that happen? Thanks for the heads up.

@CharlesL http://blender.stackexchange.com/questions/1067/how-to-animate-layers-in-blender-2-6


text:
Undo and Redo on Macbook not functioning
The CtrlZ and ShiftCtrl + Z combinations are essentially ignored on my Macbook. It's behaving like an unqualified Z key press.  How do I get that to work on Macbook or is there another means of performing undo/redo?

I'm locking this post, because while it has some useful information, it does not directly relate to Blender in any way.

On Mac OS X the keyboard shortcuts for undo and redo are CmdZ and ShiftCmdZ, consistent with other applications on this operating system.


text:
Is there a way to disable the grid in orthographic view?
I'd like to ask about grid lines in orthographic views. Can we somehow disable them from drawing? Right now I have to turn on "Render Only" which is not the best solution.

Open the properties region by pressing N. Then in the Display section uncheck the Grid Floor checkbox to turn off the display of the grid floor.

If you do not want to see the axis lines, untick the X and Y buttons as well.

It works like a charm in Perspective View, have even hotkey for this. Still the question is about an orthographic views

@Shader From your comment, I gather that you are actually talking about hiding the grid lines for the alined views. My method does hide the gird floor, and in orthographic view.

For anyone searching this feature in Blender 2.8 and onwards, its under viewport overlays:

I misread the question, thinking that the OP wanted to hide the grid visible in aligned views like Top, Side, Front, etc. If this is not the case, then David's answer is the optimal solution.

One hack you can do is change the 3D view grid color to match the background color, by copy/pasting the colors in ⎈ Ctrl⎇ AltU> User preferences > Themes:

Unfortunately it's not possible to get rid of the axis lines in the same way, as their color is controlled by a single global preference which affects the axis colors everywhere.

Yeah, I reached upon such a workaround. Looks like it's time to start IDE and tweak some blender code...
Thanks for that, man.

@gandalf3 I'd like it if it could work for gradient backgrounds...? An solutions...?

Check "Grid Floor" > set Scale to zero, the grid is removed.

Go to the desired view, then press 4 on the Numpad followed by 6.
This makes the view go into an ortographic view about 15 degrees to the left, then back.

Worth mentioning that this doesn't seem to work in top view, nor if you have Auto Perspective enabled in user preferences.

My hack is a bit basic but it was the only way in 2.76b that I could make it acceptable. Switch the grid floor back on first, then you can change the scale to 20 - trial and error to find a number that works for your model - and the subdivisions to 1:
This seemed to give me the easiest workaround in right, front, top and other aligned views. Note, the scale 20 worked on a small model but chances are good you may need to go up to 1000 to place the lines far enough part to be helpful.
Note, this hasn't gotten rid of all the grid lines in aligned views but spread them far enough part to get them mostly out of my way. It might help one of you here! Also switching grid back off makes no difference once you've done this, you just need it on to work the options.

The multiplicity of answers stems from loose use of terminology.  Perspective is not a view (point), its a view projection, as is orthographic (projection); however, for many engineering types of folks, saying 'ortho' generally means "orthogonal" i.e. having to do with right angles...which insinuates X, Y, Z (axes) most of the time.   So loose use of the terms "view" vs. "projection" has caused some confusion here....because clearly you can have some arbitrary camera view point in space, but that view can have an 'ortho' projection.  An aligned view in Blenderspeak generally means a camera view that that is aligned with one of the primary orthogonal axes (top, left, front, etc), but note that such a view can be exactly aligned with a primary axes, yet still have either a perspective or orthogonal view projection.  The inference of an 'aligned' view by most folks though, generally implies orthogonal projection, but not necessarily so.  You can have an 'aligned' view with a perspective projection.....technically.  If you look at the blender tip for perspective/ortho under the view menu...the tip does specifically use the term "projection" and not view.
One has to surmise that the original poster was referring to an 'camera aligned with orthogonal (insinuates X, Y, Z) axis view with orthogonal projection'
So all that being said, the correct answer (for blender 2.79 anyhow) is the one with the least votes, by Adam Krol, i.e. set the scale value of the grid to zero.  Do note that you cannot get rid of the primary axes lines in an "aligned view orthogonal projection" in 2.79.  In 2.8, you can get rid of everything in said view/projection by unchecking the 'grid' box...but in doing so, will lose your primary axes lines also.

Hello and welcome, Tom Kyler. This is obviously a well though out and explained post, but unfortunately it does not technically provide an answer to the original question, only validates the existing ones. It'd be a shame to take it down because of it since there is still valuable information here. If you could somehow rephrase it to address the original question, or provide a new answer (like say how to achieve this in 2.8) we'd be inclined to keep it. Could you do so and ping me so we can lift the flags please?

I believe the information to be relevant.  I myself followed the 'wrong'  (and most voted on) answer and it took me a 2nd read to understand why folks were voting the wrong answer up.  I had to "try them all" and see which one worked, which is not very efficient.   I won't rephrase it.  Its great info and in the right spot.   I came here to learn and just to read "do this...do that....try this and that"  is not very good I feel.  Fundamental learning of concepts and correct terminology usage is much more valuable.  Feel free to remove it, flag it,  it does not bother me.

Hi, Tom. You said: "...followed the 'wrong' (and most voted on) answer and it took me a 2nd read to understand why folks were voting the wrong answer up". I beleive you ment answer by cegaton. It IS correct and coincides with your proposal - set scale to zero (watch 2nd gif).

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


text:
How to use the new cycles mist pass in 2.68?
How to make cycles mist work in 2.68?
I turned on the render pass, then fiddled with the start and depth settings in Properties > World > Mist Pass, but with no result.

Not much documentation yet, but it looks like you could use it in the compositor to get a mist/fading effect.

just straight, it returns a black and white map based on the settings in Properties > World  > Mist

You can investigate this simple tutorial. It's only a few steps and you're ready to go with mist pass. By the way - great feature, we don't have to go back to blender render to set it up.
http://blog.yamandi.com/mist-pass-blender-268-how-use-it-cycles

Welcome to Blender.SE! Please see the Provide context for links section of the How do I write a good answer? page and make the appropriate edits to your answer.


text:
Why is there still a white background even though a transparent png image is used?
I have a very simple node set up as below for a leaf texture which is a transparent backgrounded png file. When I use the transparent shader with alpha node, I still get the white backround appearing as below, I can't figure out what's the problem here, please help.
Render view

nodes

PNG file
Blender file
thanks a lot
Ps. I went through questions already asked here for this subject, they didn't solve my problem, even though it's a very simple node set-up - sorry if it's a duplicate which I haven't seen yet

Open up the Node Editor, select the image texture node, then open the Properties Panel N and enable Use Alpha.

Hi Chis, welcome to blender.se :) For your next answers, see: http://meta.blender.stackexchange.com/questions/524/what-case-should-letters-inside-kbd-tags-be

Glad I could help :)

I opened your file, everything is OK, even in render view. In your photo it seems that the leaf is projecting a shadow on an object just underneath; is there a duplicate? I hope it can be helpful

it's only one leaf, but for some reason png files transparent parts didn't recognised by blender, then i open my png file and saved it as png again , it worked this time, i don't know how it didn't in the first place..thanks for the answer btw

@ideorium I have had the same issue, IDK if it is a bug or what


text:
Problem with paths in my script, relative to local python file
I'm trying to import data stored as a JSON. It works fine in stand-alone python, but I am having problems in Blender python console.
I have a folder Applications/blender.app/Contents/Resources/2.74/scripts/addons/uhoh and in it I have wowtest.py, a blank __init__.py, and test_data.txt which contains the JSON.
This is wowtest.py
def wowtest(fname):

    import json

    print('hmmm.... will this work?')

    with open(fname, 'r') as infile:
        xdic = json.load(infile)

    return xdic

And this is what happens in Blender's python console:
>> import uhoh.wowtest as wow
>>> wow.wowtest('test_data.txt')
hmmm.... will this work?

Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
  File "/Applications/blender.app/Contents/Resources/2.74/scripts/addons/uhoh/wowtest.py", line 9, in wowtest
    with open(fname, 'r') as infile:
FileNotFoundError: [Errno 2] No such file or directory: 'test_data.txt'

I have put a second copy of test_data' up one level (in/addons`) just in case, but this doesn't help. What am I missing?
NOTE: I will run this from a script next. If there are differences, please let me know.

Your problem is path based, search about it here and you'll find many answers: http://blender.stackexchange.com/questions/639/how-do-i-get-the-path-my-script-is-running-in?rq=1 print out where your script is running and then correct path accordingly..

I see! I typed import os and then  os.path and I see I am not in Kansas. This helps @Jerryno! I can now get it to work if I append the entire correct path name to the file_name: Q = wow.wowtest('Applications/blender.app/Contents/Resources/2.74/scripts/addons/uhoh/test_data.txt'). Are there easier, or more standard ways to do this (e.g. store special data for scripts)? I feel like I'm making a mess in the /addons folder.

@uhoh read the link suggested by jerryno,  __file__  is a special keyword in python that will stand for the current location of the python file. The base of this question has nothing to do with json.

Thanks for the help @zeffii. So it seems to me that what I needed to understand (weather I knew exactly how to phrase the question or not) is well beyond the other question "How do I get the path my script is running in?" Your answer below is very helpful! Is it still necessary for me to "please edit this question to explain how it is different..."?

my advice to you is to think of the shortest possible way to describe the problem and still have a problem, here the problem was not json, it was about finding the path of another file. Those kinds of questions have been asked on the mother site 'stackoverflow' many times and have good answers, it will never hurt to check stackoverflow first for python specific stuff.. it's a grey area but we try not to teach python here.

The current file's location is obtained using __file__
import os
current_file_path = __file__
current_file_dir = os.path.dirname(__file__)

to access a file in the same directory as this python file you do
other_file_path = os.path.join(current_file_dir, "other_file.ext")
with open(other_file_path) as f:
   ...

if there's a directory on the same path as the main python file you can get that by doing
other_file_path = os.path.join(current_file_dir, "directory", "other_file.ext")
with open(other_file_path) as f:
   ...

This is a concise and useful summary of how to manage paths in scripts. Thanks @zeffii for anticipating the rest of my question!


text:
Python script to print tooltip value when mouse is over a property
I want to get the tooltip value of a property when the mouse is over it (after pressing a shortcut), like the X location of an object or another value that can be animated in the scene.
In specific, I need the full data path of a property to automate the creation of a specific driver configuration.
I've tried to get the information from the right-click menu or the tooltip, but it doesn't seem to be accessible with python. For instance the path marked in green.

For recent Blender builds (daily builds), you can do this using shortcuts.
See: https://www.blender.org/manual/interface/buttons_and_controls.html#common-shortcuts

Ctrl-Shift-C - copy the data-path for this property(also available from the right-click menu).Useful when writing drivers or scripts.
Ctrl-Alt-Shift-C - copy the full data-path for this data-block and property.

Warning: This is typically bad practice when scripting, in most cases its best to access values based on bpy.context, accessing via string lookups in bpy.data is error prone since the user may rename objects.

I think this is a fair warning, and still being able to do this is a comfortable convenience in those scenarios (to demo, to experiment) where using the path directly is perfectly fine.


text:
How to increase camera frames view area?
The Camera view area is so small (see picture). How can I increase it?

You shouldn't increase area of the camera (and it isn't done in this way). Instead grab it further away of the objects so to see more of them or change its sensor / focal length options. If you zoom out a photo very much, it will become small (e.g. like here) but the objects captured in it will become too.

In camera view, I didn't uncheck the "lock camera to view" box. Once unchecked, scrolling the MMB does indeed increase or decrease the size of the camera area. If checked, it merely zooms in or out on the scene. Thanks for all other suggestions.

Use the mouse wheel to zoom in and out. Besides you are looking through a camera hence you have the semi-transparent letter box border around the it. Other view, top, left, front and others do not have the letter box.
The good news is you can turn it off if you absolutely hate it.

Select your camera.
Go to Camera object tab.
Look for "Passepartout" and turn it off.

A similar question with the same answer is found HERE.

thx, but I don't want to do away with the letterbox area, just make it smaller.

Well you can use the scroll mouse to zoom in and out? Have you try zooming?

As @MrZak suggests, you should grab the camera along local Z axis.

Select the camera
G + Z + Z
move mouse up to "zoom in" or move mouse down to "zoom out"

Open the Properties panel with N, under View rollout find and enable checkbox Lock camera to view.
Now if you press NUM0, you can zoom in and out with your mouse thus increasing the amount of scene captured by the camera (so actually you'll increase / decrease distance between camera and object/s). When you position the camera where you want, press NUM0 again to exit camera view.
Note that before changing something in scene further on you may want to uncheck that checkbox so not to change camera's new location again.

ok, idk if anyone has said this but go to the camera setting, and change the focal length. its somewhere around 30 to start i think. working down the scale makes it a larger frame size. working up the scale makes it a smaller frame size... yeah

That will not change the view size of the camera at all. Changing the focal length is changing the zoom of the camera. It has no bearing on the amount of the view the camera covers.


text:
Can people using different computers edit the same .blend file at once?
I was wondering if it was possible to make a multiplayer blender file, almost like Google Docs. If there is, can anyone help? thanks, sorry for the strange question

Currently this isn't possible and would require major changes to Blender.
Typically larger projects divide assets into many files so people can work on different parts simultaneously, this can be done so assets can be re-used in many places using Blender's library linking system.
Its also common to use a version control system, such as Git, Subversion, Mercurial... (or many others), to manage files for larger projects.
For reference, Mango Open Movie used this structure.

Guess this is the link for Mano Open Movie now... https://mango.blender.org/ .. can't see any blend files though - too bad, I would have loved to see how it's structured.


text:
How to find x,y,z coordinates of a mesh in edit-mode?
I have ply format mesh in edit mode in blender. When I select some vertices , I need the x y z coordinates to be printed as output. Is it possible?

The mesh being imported from a PLY seems irrelevant to the question being asked. Perhaps the question should be How to print the XYZ coordinates of all selected vertices in edit-mode?
Its also not clear if this is a single function you want to run, or if you want the select action to always print vertex locations.

As ideasman42 wrote in his comment, this will work for any mesh in edit mode, regardless of whether it was imported from PLY or any other format, or generated within Blender:
import bpy, bmesh

bm = bmesh.from_edit_mesh( bpy.context.object.data )
mw = bpy.context.object.matrix_world

selected_verts_coordinates = [ mw * v.co for v in bm.verts if v.select ]

print( selected_verts_coordinates )

This will only work for selected vertices when the mesh is in edit mode.


text:
How to check if an object has a uvmap with python?
How would I test if an object object has a uv map from Python?
Run some code in this case, otherwise throw an error.

In this case you'll need to check if the objects mesh data has any UV layers.
This works for vertex colors too.
import bpy
if bpy.context.object.data.uv_layers:
    print("We have UV's")
else:
    # if this runs from an operator, you may want to report an error instead.
    raise Exception("Missing UV's")

Where uv_layers can be replaced by vertex_colors, materials... or any other sequence you want to check is empty or not.
Note: In Python you could check: if len(bpy.context.object.data.uv_layers) > 0: however there is no need, since all sequences will evaluate to False when empty, infact, this is slower in some cases since counting all items can be avoided when we only need to check if its empty.

but how to check if the actual uvmap has any image assigned to it and select only those objects? you see: I do LEGO models in Blender and all the bricks (objects) has uvmap, but only some of them have actual image assigned to it, and I need to select all from the bunch (it can be hundreds of them!) that do not have any image in uvmap (that is: having empty uvmap) - can it be done?


text:
Difference between 'Bounding Box center' and 'median point' pivot?
In the options from pivot point, is the option 'Bounding Box center' the same as the option 'median point'?

This was 2 questions, please ask a separate questions re: BoundBox draw option

for the second question :

the bounding box center is not the same as median center :
-The Median center is calculated as the average of all selected points ( vertices or object centers ) so it depends on the density distribution of the mesh
-The bounding box : is the smallest box (Cube ) that can contain the mesh of an object while aligned to the local space
-The bounding Box center will always be at the center of this bounding box regardless of the density distribution of the mesh inside

I don't disagree with what you have written, Chebhou, except that there are instances when the bounding box center and the Median point are coincident. The simplest example of this is the cube in the default scene. If all vertices of the cube are selected, the median point and bounding box center will be located at the same point. Yes, I admit that this is a special case.

Blender also has a center of mass option when moving the origin of an object. Even if there is no physics settings for the object, the center of mass can still be used, but I'm not 100% sure how it's calculated. There is no option to move the origin to the object's bounding box, but it looks like moving it to the center of mass does this, whilst moving the origin to the geometry snaps to the average of the selected vertices (the median center). Hopefully some of these functions will be renamed for clarity in the future :)


text:
Generate an image from 3d model (server side)
I'm working on an application that needs to quickly render simple top view of 3D model on the server, and then return them as a JPEG via HTTP. Basically, I want to be able to simply include a dynamic 3D scene in an HTML page
Can Blender do that?

Reopening, because the question is asking if its possible, not asking for a tutorial.

Yes, independed from the web technology stack you're using on the server side you can invoke Blender from the command line.
Something like:
blender -b file.blend -a -x 1 --render-output <path>

should do the job. See the link above for a complete description of all available parameters. Note that Blender itself doesn't provide a HTTP server therefore you would need to make the rendered image available to your server (probably by simply copying the file or direct rendering into the web server's image resources directory).


text:
How to select a face closest to a point in space?
I use cursor depth to snap the 3d cursor on my object. I want select the face corresponding the 3d cursor. There is a tricks with Blender python API ?
Exemple (Before/After) :

Try this (requires you to have one selected and active mesh object):
import bpy

cur = bpy.context.scene.cursor_location
o   = bpy.context.object

bpy.ops.object.mode_set( mode = 'OBJECT' )
faceIdx = o.closest_point_on_mesh( cur )[-1]

if faceIdx != -1:
    o.data.polygons[ faceIdx ].select = True

bpy.ops.object.mode_set( mode = 'EDIT' )

AFAIK you cannot select a face with the 3D cursor, but Shift+S > Cursor to selected will put it at the center of the face or face group... I think this is what you're asking. Also Shift+S has other settings for direct placement in relation to 3D cursor. they are named

Cursor to grid
Cursor to center (origin)

they do exactly what they sound like.

I know these shortcuts. This is not what I want. I will see bpy_extras.view3d_utils.location_3d_to_region_2d(region, rv3d, coord)


text:
Is it possible to symmetric weight-paint an asymmetric mesh?
Is it possible to do symmetrical weight painting without manually splitting my mesh into two pieces? I've already done building my mesh. I don't want to split it into two pieces because:
a) My mesh is not symmetrical to start with
b) It's gonna mess up the rigging on other parts
There are certain parts on the mesh that ARE symmetrical which I want to do symmetrical weight painting. What I mean is when I paint on the left side, Blender draws an imaginary line across middle of mesh and the right side will automatically get painted the exact same.
What I mean:

I want to be able to weight paint left side of that indicated area, then right side will automatically reflect same weight painting. But as you can see even though the upper part is symmetrical, entire object is not symmetrical. No this is not my object I just quickly drew it in MS Paint to show what I mean.

EDIT: According to person asking this question, this is the exact opposite of what they wanted, all i can say is just tick it on instead of off, but they said that doesn't work, i shall keep this up for those who find it though.
This is because X Mirroring is on, to turn it off go to into the Weight Painting mode on your desired object.
On the left Toolshelf T select the Options(1) tab.
Under Options(2) Uncheck the checkbox labeled as "X Mirror"(3)

Your weight painting should be fine now!
Tip: open up a new file, without changing anything (other than what i'm saying now), even moving the camera, repeat the steps above and then with the mouse over 3D view, press CTRL+U and then press "Save Startup File"
This makes your blender startup file have what you just did already done, so you don't have to do it again.

The (T) toolshelf, not the (N) Toolshelf facepalm, dont mind me im tripping

@eromod Don't worry about it. :P

Not sure if you read my question... I WANT mirroring, I think your answer is the exact opposite. Also turning on X-mirroring did nothing,

@Heartcloud Oh haha, sorry about that, i did read it, just read it wrong, it was past 3:00 Am. Anyway, not sure what to do, so to have me and others fully understand it, upload the .blend using blend-exchange.giantcowfilms.com and edit your post with the link.

This is not currently supported, while texture paint and sculpt support symmetrical painting (applying the brush on multiple axis at once), weight paint only supports mirroring weights, which requires each vertex to have a mirrored match.

Note that this is possible in to weight paint on asymetrical meshes as long as the topology is symmetrical, using the Topology Mirror option.
It does require the models have enough unique topology areas (most character models are fine), but it will fail for a cube or a grid for example.


text:
How can I tilt a mesh like this?
Consider:

How can I tilt a mesh like that? I have the mesh tilted, but I need to restore it so that it can be straight.

Hello :). There's a Shear Tool specifically for that.

Thank you so much!

That's a (Shift-Ctrl-Alt S) Shear. It defaults to operating in the View orientation, but that can be changed in its F9 panel.

You can enable the Snap > Vertex option:

Then select the top 2 vertices, move along the axis (here X), keep pressing Ctrl to snap and snap to the bottom vertex:

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


text:
How do I make a sphere become transparent when it is outside of a box that is transparent and have the sphere visible when inside the transparent box?
Consider:

How would I make a sphere transparent when it is outside of a box that is transparent and have the sphere be visible when it is inside the transparent box?

For Cycles: [Sphere Material setup]
This verson invalid in other side

This verson valid for all side

https://www.screentogif.com/  ;)  this is an elegant solution

Can't you plug directly the Is transmission ray into the alpha input since it's a 0/1 value ?


text:
Append function in menu is greyed. What can I do to fix it?
I'm trying to add an object from a previous project, but in the File menu bar the append option appears greyed out.
If I press Shift + F1, I can browse between the folder of my PC, but when I click on the file or press Enter that I need nothing happens.

The problem was that I was in Edit Mode where append can't be used ,so you need to switch to the Object Mode and it's done

Please use the edit link on your question to add additional information. The Post Answer button should be used only for complete answers to the question. - From Review

Sorry @Nate_Sycro27 , I wrote the answer in the wrong way, I hope in this way it's more clear what's the solution


text:
How can I create a 3D spacetime grid animation?
I want to make this kind of animation GIF.
It has to work in Eevee with multiple objects. Unfortunately I couldn't do it via wireframes modifier and proportional editing. Do you have any suggestions?

I think you want warp or hook modifiers instead of proportional editing. Wireframe should be okay.  I'll play around to see if I can get it to work.

Okay, I got it working with a negative cast modifier of all things.  I'm writing up my solution currently.

A similar (though not physically realistic) effect can be done using array modifiers and a wireframe modifier to create the 3 dimensional space-time lattice, and then a cast modifier to create the gravitational effect.

Start with a cube, and then add three array modifiers, one for each dimension, and then a wire frame modifier, as indicated:

This gives you the space time lattice. Apply these modifiers and then center the lattice on the origin, just to make everything else a little easier.

Add a sphere. Then add to the lattice a cast modifier, shape sphere, with a negative factor. The lower this factor is, the more gravitation is simulated.

Moving the sphere will distort the lattice as one might expect:

Note well however that this effect is applied linearly over space, while real gravity would fall off proportionally to the inverse square. A more physically realistic effect I believe is possible using vertex groups and the hook modifier, but would be more complicated than this solution, which should be acceptable for most aesthetic uses.

This is amazing!! I just fell in love with lattice and cast modifier! :D

Great answer from jwrush! - I'll add that with regards to texturing, this seems to do the trick. Make sure to select your "Warp sphere" as the Object basis for the Texture Coordinate. You may have to alter your mapping scale values and the ColorRamp sliders to accommodate the size of your objects.

Rad! I was wondering if there was an easy way to do this.

Why does this color ramp affect the whole Blender UI? :-)

Lol. Happy coincidence, I guess ;)

Is it possible to accept two answers?)

Na - only one accepted answer. It's all good though - leave it the way it is - the real "meat of the solution" is in jwrush's answer - all I added with this answer is that a "sphere texture" makes a "color sphere" around a sphere ;)


text:
Can I see two different frames on two different viewports of the same scene?
It is possible that I can see in two different viewports the same object, but on different frames?
E.g., I move a cube from frame 0 position 0/0/0 to frame 100 position 100/0/0.
So I would like to have two viewports open.
First on frame 0 where my cube is on 0,0,0.
Second on frame 50 where my cube is on 50,0,0.

A frame number is associated with a scene (bpy.data.scenes["Scene.rear"].frame_current), and all view-ports are associated with the selected scene.
So you could possibly create another (temp edit) scene (Link All), use menu: Window :: New Main Window, and set the scenes differently in each main window.   You can then also set the current frame numbers differently, (0 and 50 in your example).
Any edits in one will appear in the other, as they will both react to changes in the in-memory elements.   The downside is all of the window switching you may labor through, but unlike me you may be blessed with a second monitor or sufficient screen space.

I guess you can either live in New York or afford a second monitor, but not both.


text:
How can I make the file manager default to only list blend files?
I have to open up a lot of blend files in a row which are living in the same folder along with a lot of folders. When I open up the file browser I get a long list of folders first and have to scroll down a lot until I get to my blend files.
My current workaround is typing „.blend“ in search field:

Is there a way to display only the blend files within the current folder to save some time?

Comments are not for extended discussion; this conversation has been moved to chat.

There are dedicated properties in the Filter Settings for convenience to enable and disable all relevant types in the File Browser which will already speed things up (as mentioned):

Unfortunately, there is no way to save the Filter Settings along with your preferences at the moment, means that your settings are gone when starting a new Blender session.

In the past few years there have been a lot of requests allowing the user to store the file browser settings and there is even a well recieved Q&A from 6 years ago but it seems this feature is not that relevant for a wide range of users or there is no developer interested in implementing that functionality. The idea of the add-on provided by @Chebhou and @p2or from the Q&A mentioned, is basically to add (permanent) properties via AddonPreferences and use that properties to override each setting in the draw method.
The following add-on is a minimal version of the provided add-on to only address the Folder Setting. When installed and enabled properly, a new toggle is added to the header of the File Browser and stores your custom setting as long as the add-on is enabled:

display_folder_override.py
bl_info = {
    "name" : "File Browser - Display Folder Override",
    "version" : (0, 1),
    "blender" : (2, 80, 0),
    "location" : "File Browser",
    "category" : "User Interface" }

import bpy
from bpy.props import BoolProperty
from bpy.types import AddonPreferences

class FBO_AP_Preferences(AddonPreferences):
    bl_idname = __name__
    folder_override: BoolProperty(name="Show Folders (Override)", default=True)

def draw_filebrowser(self, context):
    prefs = context.preferences.addons[__name__].preferences
    browser = context.space_data
    row = self.layout.row(align=True)
    row.prop(prefs, "folder_override")
    if browser.params.use_filter_folder is not prefs.folder_override:
        browser.params.use_filter_folder = prefs.folder_override

def register():
    bpy.utils.register_class(FBO_AP_Preferences)
    bpy.types.FILEBROWSER_PT_directory_path.append(draw_filebrowser)

def unregister():
    bpy.utils.unregister_class(FBO_AP_Preferences)
    bpy.types.FILEBROWSER_PT_directory_path.remove(draw_filebrowser)

if __name__ == "__main__":
    register()

Related: How to make the file manager default to sorting by modification date?

Thanks! And works on 2.92 + 3.0.0alpha!! Hero status approved

You can display only .blend file by enabling Filter (icon in header), but your setup of Filter is not remembered when dialog window is open again (even when Saved as Startup File ... to be precise - it can be saved into Startup file while dialog window is opened whe saving as Startup File, but it bring this window open anytime you open Blender (that is not wanted) and even more this window is missing Cancel / Open buttons ... so totaly useless.

As workaround you can ...
Add a Workspace, name it "Open" (or what ever) and switch View3D editor to File browser editor.

Set Filters as wanted.

Switch back to default Layout workspace and go to File > Defaults > Save Startup File

For opening file click on Open workspace, drag&drop file to anywhere out of File Browser editor and choose Open command.

Edit
What looks like a bug here is the ignorance of saving the workspace changes made by user. I had to save file as regular .blend and switch this file with existing one called startup.blend.
Directory of this file depends on OS, for Mac it is
/Users/xy/Library/Application Support/Blender/2.9x/config/
Than it works like that ...

Right ... that is too much scratching :) Would be part of defaults.

Alternate solutions:

Copy/paste the strings of the files' you are hoping to find
Save the init file-browser search terms in a default, startup blend file (changes after init use do not always apply unfortunately)
You could state a default assets` path depending on what kind of file it is, e.g textures in the Preferences > File Paths
You could create a File Browser > Favorites (bookmark) for a certain folder that contains the assets` you are searching for easier access

Folders aren‘t my problem. Sorry for not being precise in my question. I updated my question.


text:
How to connect two circles on the same plane via tangent with geometry nodes
Given two circles on the same plane, how can I add a line which connects both circles on the tangent (so this would often be two lines)?

If I have these two black circles, I want to have the yellow line (which should end at the tangent points of the circles).

How they are defined? Object centers and radii, or they are just meshes?

Objects centers, sorry for that less info

Depending on where exactly you want to go..

... this might seem a good GN starting-point

Damn, that’s great!!!

that's already more than i wanted, thank you!!! i will now make my connection rod automatically with geometry nodes ;) just two empties given GN will do the rest for me ;)

Geometry answer.
Subtract one radius from the other and make a line between the new radius and the center point of the other. Then offset the line by the subtracted value:

The line between the point and circle is easy to get, because the tangent makes a 90° angle to the center of the circle, so you can use the Pythagorean theorem to find all pieces:

thank you Crantisz +1 - really great answer!

What do you mean by "offset the line on the subtracted value"? Do you mean "offset the line by the subtracted value"? Or something else?

@PeterMortensen Yep, thanks


text:
2D Face Animation on 3D Model: Transparent Texture?
I'm following this tutorial on YouTube: https://www.youtube.com/watch?v=5NlvgMYZgaY&list=PLJtehCu4iIj4T0dqawwRolg8B6DPzmu01&index=46&t=0s
The problem is that the character he is using is a single colour so when he applies the new UV map and texture there is no issue, however my character's texture is not one colour. I want to be able to add the 2D eyes for animation while being transparent and showing the original texture underneath. The picture below shows the texture and the eyes are 3D before I decided to animate them in 2D.
Does anyone know how I can animate the texture as a transparent texture so I can maintain the texture beneath?

First: looks great! Next, can you please provide screenshots of your node setup, the sprite map (texture used for facial animation) and a render(s) of the unwanted result(s)? It would be even better if you could upload your .blend file but I understand if you feel protective of your work

Really quick: Did you remember to hook up the alpha channel of the texture to the fac setting of the Mix shader?

No I got stuck at the part of the tutorial where he unwraps and creates a new UV map and then creates a copy of the texture to apply to the new area, the texture comes out strange because its not a single colour like the lego head. I will add the nodes in now and see if it fixes anything, thank you.

which version of Blender did you make this with? I am using 2.8

I tried that and its still not working. I'm using 2.79, should I update?

Not in the middle of a task like this, but when you are done, since you are learning, you are better off learning 2.8 b.c. it is the latest stable release with cool, useful new features and optimizations. Some previous workflows are deprecated too. I have a texture that is 95% done baking but I will look at your file as soon as its done

Ok, thank you, its much appreciated :)

Your problem is that the UVs for the face got moved away from the skin material. Further, the skin material is separate from the eye material, which is ok if you are following the tutorial, but note that he superimposes the eye material onto the skin material with the Mix Shader node. You only have 1 UV map--this makes it so the eyes will never be in the right place; they will always be floating out in space, away from the skin texture. We can fix that.I will record a gif or something, hang on...
...do you have a version of the file with the eye region still attached to the mesh? We should start from there. Please upload that file. Use https://blend-exchange.giantcowfilms.com/

Oh! I can just attach the animation :j

...animating the new UV map "_EyesUV" will not have any effect on the body texture now. Here is the .blend file:

NOTE: if you are no longer satisfied with your textures, there are a couple of solutions:

Export your UV layout for the eyes in the UV editor (I suspect you already know how to do this) and warp the eye textures you already have into proper orientation in Photoshop.
paint directly onto the model in Blender (see any quick-and-dirty Youtube tutorial for that). I find this technique expecially useful for high-contrast texture features I know will look warped if I try to eyeball it in Photoshop.

ALSO, IMPORTANT: Texture will be warped until you de-parent armature. I do not know yet why the armature was an issue.
I deparented the armature, recalculated the bone rolls, reset the pose, and re-parented, and it works now:
Baking the Eyes object silhouette onto an image using the Body's Ambient Occlusion.

The "Collections" panel replaces the "Outliner" panel in Blender 2.8. You can find these same options there:

If the bake takes longer than you (I) thought, it's because the second UV map also has coordinates for the rest of the body (not sure how to remove those for the bake, maybe just drag them outside the UV canvas?). Save this image:

File:

Here's the original file


text:
Where do the differences between render and baked texture come from and how to minimize them?
I'm playing with baked textures and do not understand the lighting differences between a pure render and a render using pre-baked lighting. The setup is simple:

cycles render of a cube on a plane

cycles render with pre-baked textures

differences between these two images

There are subtle differences of lighting between these two renders, but for more complex scence with more intense light, the differences become more important.
I'm guessing it can be due to color management (RGB / filmic) but I do not find relevant documentation about the proper way to do.


text:
How to clean the scan data in Blender?
sorry, absolutely beginner here.
I need advice how to fix some problem areas in the texture of scanned model.
see the attachment.
Thank you.
Gregory


text:
Subsurf modifier creating mesh irregularities
I'm working on an armchair, and I recently applied the Subsurf modifier to it. All was well until I noticed an irregularity that I simply cannot fix, here's a picture with and without the subsurf:

So I was wondering how I could take it away? Here's a link to the .blend file.

first steps are always: Remove Doubles, Recalc Normals. Then look around the mesh in Object mode without modifiers on to see if you have any double edges (they will show up as wires even in Object mode).
But here another problem is you have a whopping non-planar Ngon, a polygon with more than 4 verts, for the side. The ngon isn't flat, if you look carefully it tapers away into the back-rest (visible on the bottom left view).

Ngons as best avoided with subsurf, and especially avoid using them on areas that are non-planar. Why avoid them? Because you have no control over the underlying triangles, the ngon has abstracted away the real geometry.
Under the hood the real geometry of that ngon might look something like  this, and that is a problem for subsurf.

If you don't quite know what "planar" is, then imagine a sheet of paper, placed on a table. it is perfectly flat. now if you make one fold in it, and try to press it back into place - you know the fold will stay visible for a very long time, maybe forever. The sheet of paper has a discontinuity, the corner of that fold no longer lies on the same plane as the other corners. There will always be a bend. In geometry imagine something similar is happening when you join an edgeloop which isn't planar.
You need to guide your geometry at the back and maybe make an extra edge-loop. Fill this gap a different way. But exactly how depends a lot on the final shape you want.

assert some control over the underlying geometry of that side, and remove doubles, and you'll get reasonable results. adjust to taste of course.

you can clean up the geometry better than that...

agreed, i wasn't going to make suggestions as the desired form is unknown. Anything is better than an ngon.

Thanks for the answer! Also thank you for explaining it all to me, really helps!

@EspenSales we encourage you to show how you solved it, to show people a before and after, maybe narrate what you've learned. (you are not obligated to do any of this, but explaining stuff is a way to profoundly internalize techniques). Anyway, all the best!

Ok so this is how I solved it:

Please avoid putting text in images...

oh well ¯_(ツ)_/¯


text:
Reset property in toolbar for each script run
I would like to reset the string property in the toolbar every time I hit the "Object" in the Add.
In short, this is the code I'm using:
class primitive_object_add(bpy.types.Operator):
    bl_idname = "mesh.primitive_object_add"
    bl_label = "Add an object"
    bl_options = {'REGISTER', 'UNDO'}
    img_str = StringProperty(name="Image Name (example: name.png)", description="desc here", default="", subtype='FILE_PATH')

    def execute(self, context):
        #code here

def menu_func(self, context):
    self.layout.operator("mesh.primitive_object_add", text="Object", icon='OBJECT_DATA')

def register():
    bpy.utils.register_module(__name__)
    bpy.types.INFO_MT_mesh_add.append(menu_func)

def unregister():
    bpy.utils.unregister_module(__name__)
    bpy.types.INFO_MT_mesh_add.remove(menu_func)

if __name__ == "__main__":
    register()

I've tried using self.img_str = "" However if I'm not fully sure where I could put this in the code to have it run when I press "Object"

I think that should be in premitive_minecraft_item_add() where you initiate a call to this operator and pass the arguments ( including this string )

This is going to sound like a really noobish questions, but how would I call img_str = "" from that, any chance you could give a quick example? Thanks!

I meant calling the operator : bpy.ops.mesh.primitive_object_add(img_str  = "some string")


text:
Audio Visualizer Script Error
I knows lots of people have been having problems with this tutorial but I haven't found anyone with the specific problem that I have (I've been looking for a while).
The script I have so far:
import bpy

rows = 5
columns = 5

r = 0
c = 0

for i in range(0, rows*columns):
    if c == columns:
        r += 1
        c = 0

    bpy.ops.mesh.primitive_cube_add(location = (r, c, 0))
    bpy.context.scene.cursor_location = bpy.context.active_object.location
    bpy.context.scene.cursor_location.z -= 1
    bpy.ops.object.origin_set(type='ORIGIN_CURSOR')
    bpy.ops.object.transform_apply(scale=True)

    bpy.context.active_object.scale.x = 0.5
    bpy.context.active_object.scale.y = 0.5
    bpy.context.active_object.scale.z = 5

    bpy.ops.anim.keyframe_insert_menu(type='Scaling')

    bpy.context.active_object.animation_data.action.fcurves[0]. lock = True

    bpy.context.active_object.animation_data.action.fcurves[1]. lock = True

    bpy.context.area.type = 'GRAPH_EDITOR'

    step = 100000/ (rows*columns)

    bpy.ops.graph.sound_bake(filepath="C:\Users\Stephen\Music\Arcade Blaster - Reboot.wav", low=i*step, high=i*step + step)

    bpy.context.active_object.animation_data.action.fcurves[2]. lock = true

    c += 1

I don't understand any of the error.
Can someone help solve/explain the error?
Thanks!

try changing  "C:\Users\Stephen\Music\Arcade Blaster - Reboot.wav" to "C:/Users/Stephen/Music/Arcade Blaster - Reboot.wav"

what happens if you stick an r infront of your filepath, it will escape the backslash and make them double-backslashes.  filepath=r"C:\...."

Sorry I just copied how windows said the filepath was :P Thanks for the help!

@Chickenator you should not delete the question , post an answer for future reference

@Chebhou I haven't deleted it. Zeffni put up and answer and I'll keep the question up in case someone else encounters the same problem.

@Chickenator the other one not this

@Chebhou oh right okay. I thought it was stupid of me that I didn't look around enough for the answer so I just closed the question.

is it because your filepath is not a valid filepath?
Either use a prefix r to make the path raw, or use forward slashes. Backslashes have special meaning in programming languages like python. valid paths are
   # windows
   filepath = "C:\\some\\folder\\file.mp3"
   filepath = r"C:\some\folder\file.mp3"
   filepath = "C:/some/folder/file.mp3"

   # posix style (linux, osx)
   filepath = "/home/folder/file.mp3"

This bug is fixed as of today: this error will now return 'File not found', which is better:
https://developer.blender.org/rB39b85e452faae543d10831e4fa66fdffbc22e0a1

authors: Максим Московко


text:
Get the DEF property of a x3d node
Currently when Blender loads an .x3d file it does not load the correct DEF attribute, i.e., each shape doesn't get its designated name, and instead is called ShapeIndexedFaceSetXXX.
Is there some way to fix this bug via Python scripting, or is it something deeper?

it is in python you can find it in ,\scripts\addons\io_scene_x3d\import_x3d.py

You should file a bug report olamundo: https://developer.blender.org/ , or, if you do fix it submit a bug patch.

This question appears to be off-topic because it is about Blender's source code.
These questions are considered outside the scope of this StackExchange as defined in the help center. Development questions should be asked of the developers directly instead, see the contacting developers page of the blender wiki.

Found the problem: In Blender 2.74, inside
def getDefName(self):
        data = self.x3dNode.getAttributeNode('DEF')
        if data:
            data.value  # XXX, return??
        return None

Does not return the name in case it found it, changing it to
def getDefName(self):
        data = self.x3dNode.getAttributeNode('DEF')
        if data:
            return data.value  # XXX, return??
        return None

worked for me, however I don't know how to suggest it as a bug fix nor am I sure that it is indeed a worthy fix as clearly someone already noticed that this function doesn't return anything in case there is a DEF.


text:
How can I set the distance between repeated textures?

In the extension settings mainly you choose repeat, right? But can you change the distance between that repeat texture without stretching or adding more geometry lines? Using nodes maybe?

There has to be a color in the "space" between textures so why not just ad a rimm of that color around the texture in the image file? (Transparency is also posssible using an alpha channel)

@vklidu: Robin will come in 5 mins with the perfect nodegroup and just need 2 nodes to create it ;) but i don't think the brick texture will help, because it doesn't output vectors....but i am curious. maybe Robins finds a way...

But i think, it is also a good use case for python ;) So Batfinger is in the game ;)

@Chris Brick texture node is commonly used UV shift (like for a plank floor) ... Just plug node between Texture coordinates and Image node to see a magic ... :)

@vklidu: ok, now the brick texture makes sense ;) buuuut it cannot do what OP wants...isn't it?

Using default plane unwrapping the plane will be mapped 1:1 to the texture, so I multiply the coordinates so they go outside the boundaries. Then I apply modulo, to get a repeating 0..x range, where x is the the value in modulo node. To get spacing, use modulo > 1 to get some values outside the texture, and of course set "repeat" mode to "clip".

That was easy. Now i learnt that too ;) Great solution!

Awesome ... pure frustration :) sometimes I feel like from a different planet.

@vklidu: nope, you aren't. They are....!!!! ;)

You can achieve this by this (I didn't complete it, because I was too lazy):

But you would have to copy the mapping + image node and mix node for every tile you need and adapt the x/y coordinate accordingly. Of course, you could also make a node group from this to make it easier to use and reduce some nodes. But Filip's suggestion is quicker...except you need this for hundreds of pictures. Then mine might be reasonable.
If it wasn't clear what I meant, here is the node tree for three tiles:

I'm considering downvoting you for laziness. :)

NIKEEEEEEE -just do it!!! I deserve it!

@MarkusvonBroady buuuuut, with my solution I helped people to help themselves because they don‘t just copy it and it works but they have to think themselves and then really understand the solution. So maybe it is even better than a ready made solution


text:
Add a new edge snapping to a vertex and with an angle constraint?
How would you add a horizontal line without interference to the other edge?
As shown on the image,

The thing is that I want to create annother edge, that is starting from the existing vertex that would be conected to the other edge, but the new created edge to be horisontal and the right edge to remain the same - as shown on the image.

In edit mode press K, that will start the knife tool. Simply LMB  click on the vertex you want the cut to start from, and left click again on the other edge. Snapping for the cut is enabled by default. If you want the new edge to be straight then activate angle constrain by pressing C.  Once you like how the new cut is press Enter to finish the cut and exit the knife tool.
If you look at the 3d view header, you will see all the options for the knife tool and what button to press.
(click on image for full size)


text:
How can I turn a set of edges into a curve?
I'm trying to make a curve from a set of angled edges, but I can't seem to find the right tool to do so.
Replicating this curve

Trying to turn selected Edges into a Curve

I tried using the LoopTools addon making a curve, but that didn't work. So is it possible?

You could do it another way:

Create some loop cuts on each face (CtrlR):

Move up the top central edges with the Proportional Editing enabled:

Extrude up and right click > LoopTools > Circle:

Add some edge loops to rearrange the shape and sharpen some edges:

this seems to have solved the problem yes, thanks!


text:
How can I create a round handle from a cylinder object?
I'm trying to create a 3D model of a key in Blender made from a single cylinder object only. But I'm having trouble to think of a way of how to extend a round handle from the cylinder as seen from the image. I'm still a beginner and I haven't learned all the modifiers yet, so maybe there is a technique of how to achieve this.

This looks like it would involve the bridge edge loops operator, and possibly the subdivision surface modifier or just subdividing and then smoothing the desired area by operator.

Extrude the cylinder and scale up the new face on the X axis (s+x), then extrude straight, after that extrude it again but scale it down on the X axis. Then select the center face on both sides and make a hole with "bridge edge loops". Finally use subdivision surface and use edge loops/or edit the mesh to refine the shape.
It should look like something this:

This one helped me a lot! Especially when trying to make the most out of a single cylinder object. Thank you so much!

If you want to get persnickety about the exact shape and profile of the key's loop, and have control over curvatures in the transition to the shaft, this workflow might save work, tweaking...

You could start with a Curve > Circle, its control points set to 'Free' so you can scale them in X and Y, object-bevelled with a profile curve of your choice. (Here, a rectangle)
Convert a copy to a mesh. andCtrlR cut loops into the sides, and scale the front vertical in Z, to accommodate..
.. an I inset of the front faces, beginning to approximate a circle..

use Loop Tools > Circle to round the inset, and set the shaft radius
Move the inset out a bit, and E extrude it further
V cut the mesh down its axes of symmetry, and delete 3/4, so you can save work while ..

.. bevelling  edge-loops and tweaking vertex positions,  working under a mirror in 2 axes, and possibly a couple of levels of subdivision, with a metallic matcap, so you can see the effect of small adjustments.

For making tiny tweaks, I often find it helpful to use the Z of the 'Normal' transform orientation, and be ready to ShiftAltZ turn viewport overlays on and off, while working.
Your reference topology would be nearly impossible to edit. By contrast, adjustments to 1/4 of a quad loop topo are a pleasure...it will be easy to change the shapes to exactly what you want.

A key that also serves as a bottle cap opener. Genius!

... @NumLock unfortunately, my ref.for this key is to wind up a clock. So a teeny-tiny bottle..:(

Whoa, I think this one is the cleanest and most efficient way to do it. Thank you so much!

Create a plane, stretch it, delete its face, bevel its corners:

Extrude outwards, right click > LoopTools > Circle, scale the circle:

Extrude up:

Bevel the edges:

Cut a hole:

Extrude inwards and right click > LoopsTools > Circle:

Extrude, move a bit the topology:

My approach:
Create a torus

Select faces

Extrude

Use Looptools (enable in preferences, if not already done) → circle

Extrude again

Add a subdivision modifier


text:
How can I make a distorted UV map rectangular?
I have the following UV map which I need to make rectangular and somewhat symmetrical as shown below:

I tried many options in the UV context menu, like Follow Active Quads, but I am unable to achieve the desired results. How can I do this?

To make the Follow Active Quads work you need to select a rectangular face in the UV Editor, or make it rectangular if it's not, then unwrap, or use the UV Squares addon as Evripidis Lalissidis recommends. But as Evripidis Lalissidis says it looks like you have triangles, you need to convert to quads.

It looks like your UV consists of Triangles instead of quads, try the command Tris to quads.
For these kind of actions i use the UV Squares* Addon by Radivarig.
In Github, just press Code and then Zip.
After installing you can select all your UVs and open the tab with  N.

For this example i made my UV into equal squares.
You might notice, that some UVs are weirdly scaled and morphed.
If you have the same problem, you have to add seams in the relative problem areas.


text:
How to import a .mtl file?
I am new to Blender. I downloaded a .obj file of a plant model. When I unzipped it I found two files (.obj and .mtl).
I imported the .obj file and I couldn't do the same with the .mtl to apply the material and the textures.

When you import the obj it should read the associated .mtl file by default. Are you sure you aren't in wireframe view? Press Z to toggle this on/off.

@swim You probably don't have a texture on the object.

When you import the .obj file, Blender will also import the associated .mtl file* by default as well which is usually the same name. The colors applied to the model will show in the viewport and to see the texture(s) (if any), enable texture shading with AltZ.
* This is the file that should be generated alongside the obj when it was created and will hold color data and paths to textures if any. Opening the obj file in a text editor should show this near the top.

Also note, the textures won't show in the model editor. You need to go to "Shading" to see them

You may need to edit the plain text .mtl file. I just ran into this as the delivered .mtl file referred to two texture images with a hard coded Windows path.


text:
How to assign random numbers to phase value for all noise F-Curves modifiers?
I think that the question is pretty straightforward. I been trying to do it by my self for a while but I'm stuck.
This is the script I've made:
import bpy
import random

for i in bpy.data.objects:
    i.types.FModifiers.phase = random.random*5

... which of course fails.
Thanks in advance.

Explained in the inline comments:
import bpy
from random import random

# Only selected (thus visible), editable objects
# bpy.data.objects would affect all objects in all scenes!
for ob in bpy.context.selected_editable_objects:

    # OPTIONAL: Ignore object types other than mesh
    if ob.type != 'MESH':
        continue

    # Is there an animation?
    if ob.animation_data is not None and ob.animation_data.action is not None:
        action = ob.animation_data.action

        # Iterate over all F-Curves
        for fcu in action.fcurves:

            # Iterate over all F-Curve modifiers
            for mod in fcu.modifiers:

                # Only act upon Noise modifiers
                if mod.type == 'NOISE':
                    mod.phase = random() * 5


text:
How can I improve viewport performance when using Dyntopo?
I'm doing a Blendercookie course on how to sculpt a Scifi weapon with dyntopo. The fact is that when some piece reach a certain level of compleiity (about 1.1 million tris) the systems starts to lags too much and is so frustrating.
I've tried the several options:

Disable double sided lighting
Enable VBO

I've so also reduced the topology of hidden faces. But that´s how far I've reached.
I'm using a late Imac Intel I5 Nvidia GPU GTX 680mx
any tips out there?

The worst part is Undo...

Here is an answer by Sanctuary from Dynatopo test thread:
Some performance tips about Dyntopo

Do not use Matcap, while it does not show while you're still blocking out your sculpt and you are in early stage of it, Matcap will very noticably impact performance when you're starting to reach mid/high poly . Use that addon instead , gives full control on the Blender existing opengl lights and does not impact performance.
Make sure you have Double Sided disabled in the Object Data panel, it's not a nvidia problem only, at higher poly stage the difference in performance with it being enabled or disabled is very noticable on every hardware.
Check the Detail level in the Dyntopo setting, too low (like less than 5) that can lead in a -very- lot of triangles generated by your brush strokes , while sometime you may want that, in other time that amount of tris could be really unneeded and can degrade performance. For most of the sculpt time getting detail between 15/20 is good, and for fine detailling, around 10 or a bit less should be enough (remember that when you zoom in you're fine detailling anyways)
Less than 10 can be really overkill due the amount of generated tris.
You can optimise some part of your sculpt for which you think there are way too many triangles (enable Wire + Display All Edge to see what's going on while you sculpt) by either enabling the Collapse Short Edges button , increasing the detail setting and enabling for your brush the "Simplify" tool (in the bottom header Brush -> Sculpt Tool -> Simplify
You can press H and drag a selection to hide those parts while in Sculpt mode, it can help performance really a very lot depending on the kind of polycount you're having of course (ALT+H to unhide)
some people have mentionned that the regular freeze/pausing could be related to Blender autosaving (a function enabled by default for each 5 minutes) , you can disable or change the delay for that in File -> User Preferences -> File
additionally in freeze/pausing moment, clicking on "Optimise" in the Dyntopo settings may help so it recalculate whatever it has to recalculate
If rotating/zooming the view become painfully slow, press Z to switch to wireframe, rotating will then be very fast, press again Z to switch back to solid shading
Dyntopo can't currently reach (while keep performance good ) the same kind of polycount you can reach under Multiresolution, fortunately the "detail where needed" system of Dyntopo generating topology only where you work allows for detailled sculpt at a much lower polycount than an equivalent multires would require.
So don't be surprised if you can get a workable million in Multires and an unworkable million in Dyntopo.
Of course powerfull computers will get higher than less powerfull ones (and if i remember well, Dyntopo isn't multithreaded, while Multires is multithreaded).

Consider revising this answer for 2.79+ as the setting for detail has changed, a higher value is used for detail.

I've found this in the blenderartist forum

Enabling VBOs
Don't have a Subdivision Surface or Multires Modifier at the bottom of your Modifier Stack
Drawing of Outlines is very expensive
non-GLSL Textured modes are slow
(NVIDIA Geforce users only) Disable Double-Sided shading
Non-Power-Of-Two Textures are slow for Texture Painting
Sculpting on lowres meshes can hurt performance
GUI regions can slow down the viewport
Enabling "Show Diffuse Color" can hurt performance

For more detail it's here

Thanks folk! I´ve previosly followed all  those steps. It helped, but not enough.

I would add under 'User Preferences'->Editing disabling global undo and setting steps to 0 seem to help. VBO was notorious for adding artefacts (peaks and pits) in random part of the mesh. So if you experience these try to switch VBO off. There was a related bug which is partially fixed (2013-10-25) http://blenderartists.org/forum/showthread.php?264568-Dyntopo-tests&p=2499175&viewfull=1#post2499175


text:
Why is the view header showing triangle count when my mesh is all quads?
I know for a fact I don't have any tris so this thing is wrong, however, I notice that it's the same number as edges. I also find it hard to believe I only have 2 more vertices than I do faces. It takes 4 vertices to make one face and after that 2 for every adjoining face.

Sry for the noob question but I can't find the answer in the manual

Without getting too technical, in 3d, there is no such thing as a true quad. Quads and ngons are mere abstractions to make objects easier to manipulate (imagine modeling a car or face using triangles only). At the very core however, every object is comprised of triangles. Blender and other modeling packages abstract these away but they are there.
You might have seen proof of this if you've ever badly transformed a face for example, if you were to paint all 4 vertices of a plane and move a vertex out of place, you will see evidence that there is supporting geometry somewhere holding that "quad" together.

To test, just add a plane and check the header again, you will see that it shows 2 tris, this is accurate because a flat plane in its simplest form is two triangles. If you were to cut it diagonally with say the knife tool, it would still show 2 because now it is still 2 triangles.

Now if you were to create an actual triangle, it would show 1.

In a perfect sphere without any actual triangles, say a cube morphed into a sphere (by subdividing and using To Sphere AltShiftS), the amount of triangles will always be twice that of faces, because remember, by default a quad is 2 triangles.
This might not be the case for edges however, that count depends on how uniform your object is, toplogy etc.

Ok gotcha. Thanks for the answer. I had read that I should avoid tris and ngons so I was worried I was doing something horrible by having over 3000 tris lol

Also suddenly something makes sense. For example in the ear of my image there are pats where the quad looks like its folded in half, because the vertices don't allow for a solid face. Now I realize that triangles make it possible

About the relation between vertex, edge and face counts:
For a simple closed surface, essentially a "deformed" sphere as in your example, but without handles, such as (the surface of) a donut, we have the Euler formula:

vertices + faces = edges + 2

Additionally, in your example we have essentially as many vertices as faces. Just associate each face with its top left vertex, this will pair off most faces and most vertices successfully. Only in a few weird places you will have some vertices left out or being the top left of two faces (or it is unclear where top left is meant to be).
But if vertices are approximately the same as faces, then by Euler's equation, edges are approximately twice as numerous as either of them.
Now if we subdivide all your faces into triangles, we have triangle = 2 faces because all your faces are in fact quadrangles. Consequently triangles are approximately the same as edges .

The reason you have fewer vertices than expected is because vertices that are in the exact same place as other vertices can often be treated as just one vertex.
This is where index tracking comes in.  It's the sort of thing that GPU's rely on to reduce calculations since many of the calculations done on one vertex are also valid for the vertices which are also in the same spot.
Now the information that has already been calculated for one vertex can be fetched from cache memory and reused for all vertices that have matching index numbers.


text:
Procedurally weight a mesh based on the face angles of an animated mesh
I would like to procedurally emit particles (fluid mode) from the 'steepest' parts of animated 'waves' created by a Ocean modifier to attempt to emulate foam and splashes. I assume frame by frame normals values could be used, but cant figure out how.
So how would I go about procedurally weighting a mesh based on the face angles of an animated mesh? (ocean modifier in displace mode).

While this isn't impossible to do with blender at the moment, but its not something you can do easily, and doing this via a script would be very slow.
It would involve 2x modifier stack calculations per frame change.

Add a frame-change-post handler.
this handler must update the scene - scene.update() so the data it deals with is valid before you start to operate on it.
get the final calculated mesh and inspect its normals.
modify the original meshes vertex groups how you like.
throw away the copy of the mesh, only generated to inspect normals.
tag the mesh to be updated mesh.update_tag()
and run scene.update() again.

So officially this kind of thing isnt supported, and what I have suggested is very much a hack. Ideally modifier plugins would much more easily allow this functionality.

Thank you for your thoughtful reply. I will take a look at a scripted soultion. Cheers


text:
Bending an object into a circle
I wanted to create a ring around my planet. Unfortunately the bend tool does not work. It does not work when I type in the bend value (360) and the menu option is greyed out.
I downloaded earlier versions of Blender (all the way back to 2.67 when it was still called Warp) and it turns my mesh into an hourglass shape rather than creating a ring. Any solutions?

I removed the references to 'modifier' in your question as you are using the 'Bend' tool not a modifier.

Use the curve modifier with a circle

Bend tool, which is a newer operator than Warp, and take Warp's shortcut Shift W, works a bit different from Warp. I think here you just need the old Warp tool. You can still find it in the menu.

Another way for bending objects is to use Simple Deform modifier. It will bend along the Local Z axis. You can also give it a try.

You can use the Curve Modifier.
First, add a Circle, by pressing Shift + A and then going Curve>Circle. Then select the object you want to convert to a ring, go to the Properties panel, and under the Modifiers tab, add a Curve modifier.

Select your Circle (default name "BezierCircle") under the Object field and select -Y for the deformation axis (I don't really understand how this works, so just try them all :P).

At first, the Curve modifier was not working, then I played with the scaling of the Bezier circle and found out that scaling the curve to the ring's radius was enlarging the ring mesh (way beyond the clipping distance of the camera). I remember when a planetary ring could be made by scaling a plane to length, and then pressing Shift + W. The devs made some changes under the hood. By all rights the bend tool should do the same thing  (I am not the only one having a problem with it based on what I seen at developer.blender.org). The curve modifier works, with some tweaking. Thanks! :)


text:
How can I create a hollow sphere with regularly spaced holes?
My latest attempt has involved a hexagon shape repeated with array modifiers.

I then tried wrapping this over a sphere with the shrinkwrap modifier, but that didn't seem to work so well.

I couldn't get any better results by playing with the modifier offset or moving the two objects around.
Basically, I want to model something like this, with smaller holes:

one of the best variety of answers I have ever seen

Related: http://blender.stackexchange.com/questions/65395/repetitive-carvings-around-a-sphere

Also related: http://blender.stackexchange.com/questions/67334/how-to-turn-my-honeycomb-pattern-into-the-sphere

Another technique in video I did in less than 1 minute. It sounds exactly like what you want. https://www.youtube.com/watch?v=YBrhTXSOBLY&t=0s I hope this will help you Antoine 3Da

One way is to Add an Icosphere, select all verts, bevel (Ctrl + Shift + B), extrude, and delete the extruded faces.
This will result in N-Gons but may be okay if you don't need to smooth.

To get the shape looking more like the one in the image, try playing with Ctrl + F > Wireframe.

@User320 Actually, first the OP tries with only hexagons. I think he is content with both. :)

@MarkBTomlinson Sweet solution. However, you should just hit delete faces after the second image. Then add the solidify modifier. It gives you mesh thickness. This way it will have a solid inside.

@Gunslinger yep that would have been more like it, still interesting if you don't mind nGons.

Hi, this looks great! But I'm stuck at the first step. When I use the bevel command, it doesn't look anything like yours: http://imgur.com/h7x5dMT

Problem solved! I needed 'Shift+Ctrl+B', instead of 'Ctrl+B' to only bevel vertices. Sorry, I'm still really new to modelling

@Gunslinger, thanks for the tip. Deleting faces after the second step also meant that the extrusion closed the inside faces properly, which I needed for 3d printing

Instead of the shrinkwrap, there's an older but more precise tool to turn verts into a sphere.

Put the 3D-Cursor where the center of your sphere whould be
Select all verts
Hit Space, type 'to sphere' or press AltShiftS, select that tool and hit 1, Return to make it completely spherical. Most subsurfed spheres aren't really precise, so this tool changes that.

Here's my approach to this:

Making the cookie cutter

Create a mesh that has faces where you want the holes to be (I).
Parent a Cylinder to the Sphere and enable Duplifaces for the sphere (II)
Scale the Cylinder to the desired width
Select the sphere and hit CtrlShiftA to make the duplis real.
Select all Duplis and Shift-Select the middle one, then hit CtrlJ to join them into one single mesh

Making the sphere

Make a sphere to your liking. I used an Icosphere with applied subsurf modifier and 'To Sphere. While in Editmode I gave it depth by duplicating it, scling it in and flipping the normals, so the boolean modifier will be happy.
Put the Cylinder object right where your sphere is and scale it so the cylinders intersect with both inner and outer surface of the sphere. Save your file.
Give the sphere a boolean modifier, set it to Difference and put the cylinder mesh in the Object field to perform the task.
Hit Apply.
Delete, hide or move the Cylinder mesh
Give your sphere an Edge Split modifier and set the shading to smooth.

The advantage is that it works with irregular shapes too.
Try this to get close to the example image
(Bevelling like Mark did is much faster. Do it like he suggested and skip to the bucky ball.)
Start with a level one icosphere

Subdivide it twice

Select one corner vert and use Select (or ShiftG) >> Select Similar >> Amount of Adjacent Faces

Dissolve the verts with X >> Dissolve Vertices.

Enter Face Select Mode.
Select one pentagon and this time use ShiftG> Select Similar >> Polygon Sides.
Invert the selection with CtrlI

Get rid of the excess faces with X >> Limited Dissolve

Select everything and hit the Smooth vertex button a few times. (This is the point to which you could jump if you followed Marks Tutorial. My approach is pre-vertex beveling)
In vertex select mode, subdivide two times. This extra topology is useful to get a round sphere.

Inset individual faces (II)
Delete the big faces with the help of ShiftG> select similar.

Subdivide again. Select everything and use AltShiftS> To Sphere with factor of 1.0

Extrude it four times and scale inwards each time.

Give it a subsurf modifier and enjoy the result.

Hm, too much work to delete, but the images of the question loaded after I finished the 'answer'. I'm not only starving, I also have only 64kbit internet. Sorry

on the other hand, if you use six sided cylinders...

Thanks very much for your answer! It's great to see the difference between dupli-faces and dupli-verts, but I think I like the dupli-verts a little better

Ok, I think I have something that will get you pretty much that same result. First create an icosphere and set the subdivide to 5.

Then find a five sided pole and select it. Then hit Shift+G and select from the dropdown, "Amount of Adjacent Faces". You should have several isolated vertices selected throughout the mesh. The hit Ctrlnumpad+ 4 times to expand your selection.

Delete the selected vertices. You will notice several six sided shapes left. Select the interior vertices like this,

and delete them until you have a mesh that looks like this.

After this, just add a skin modifier and a subsurf modifier.

You should have something that by now, looks a bit like this.

If the "Tubes" are a bit large, you have to select all vertices in the mesh and hit Ctrl+A and "scale" the vertices to your liking. After you are happy with the result, just apply the skin modifier. I hope this works how you want it to.

Here's a flexible approach using dupliverts and a boolean modifier to create patterned circular holes in any object:

Add Ico sphere object

Add Cylinder object

Rotate Cylinder 90 degrees on X axis, apply Rotation

Parent Cylinder to Ico sphere

In the Properties Object tab for the Ico sphere, select Duplication-> Verts and check Rotation. After that, apply Make Duplicates Real

Delete Ico sphere and original Cylinder, Join the remaining cylinders in to one object
Add the target sphere you want to poke holes in (for this example, a UV sphere), then add a Boolean modifier for the new sphere, using Difference based on the new Cylinder object created

Apply the modifier, delete the new Cylinder object

which is exactly what I proposed yesterday (:

Oh cool, that's awesome! That's similar to my first attempt, which involved cylinders, array modifier + rotation, and the boolean modifier. But this is pretty much exactly what I wanted. The answer above had a mix of pentagons and hexagons, but this means I can cut out regular holes in any shape.

I suppose I'll add one as well,
A) Add any shape you like.
B) Use a variation of Extrude, accessed with (alt-e) and select Edges Only.  Now drag out the newly created edges far enough away from the original so that they do not overlap.
C) Select the old geometry in Wireframe mode and use (x) then (e) to delete the edges.  Now select the points which remain and this time use (x) then (d) to delete those points.
D) Now what you are left with is a wireframe of the original model.
E) Add a Skin modifier.
F) Use (ctrl-a) to scale the weight of each point. This tool will puff out, or contract, the geometry that this modifier creates.
G) Apply the Skin modifier and then add a Subdivision Surface modifier.

Steps B and C are just needlessly complicated way of doing x -> only faces


text:
unchangeable properties of new meshes
i have been using blender 2.8 for a couple of months but now i am stuck with a problem. I cant alter the properties of a new mesh in object mode. i need to reduce the vertices of a sphere but the properties are kind of frozen. please help!

Suggest downloading the 2.80 release candidate. (From screenshot your version appears earlier, given the location of tools settings.)

Maybe check in the Preferences > System > Memory & Limits, you need to activate the Global Undo option (but you need to recreate your object).

Thanks it works now :)


text:
how to make a group of Objects
I have this problem.. i want to combine the objects into a group so that it becomes one object and when i move it (the group of objects), it moves as a single object/model. I know that we need to press ctrl + J to join the objects but this is not i want to do. I want to keep the materials separate. when i press ctrl + J everything becomes one and shares one material.
It might be a very basic thing for some but for me, i have never needed to do it before. so.. kindly guide!

Are you using Blender 2.79b or Blender 2.8 (or another version)?

Both.. It didn't work this way in 2.8 but it did in 2.79..

You can parent objects:

In 3D view, select the objects you want to group. The first objects will be "children" and the last object will be "parent" (the active one).
So in 3D view header go to Object > Parent > Object (Ctrl+P) to unite them.
Done! (just move the parent)

Note that:
a. Child objects will be sub items of the parent in Outliner.
b. You can move/rotate/scale the children independently, but when you do the same with the parent, all children will follow along.
c. To view links in the viewport, enable ~ Relationship Lines ~ in Overlays (2.8).

So the materials will remain separate?

Ok it works. Thanks a lot


text:
vertices don't move or extrude properly
i have this problem with my model as i was following a character modeling tutorial and suddenly my vertices are stuck on their positions.. and i do not remember what settings i changed(may be its because i once selected all pressed W and smooth), but now whenever i try to move/extrude a vertex it either doesn't move at all or moves only when i drag the mouse far away.. like in the picture. Please help.

if your object is small it might be because you've enable the snapping and it makes the vertices stick to the grid?

I don't remember doing that but how can I un snap it??

https://blender.stackexchange.com/questions/46305/everything-snapping-to-grid-after-some-accident-hotkey-precise-changes-availabl  https://blender.stackexchange.com/questions/35235/how-to-turn-off-jumping-by-parts-when-moving-snapping

Try to disable the Snap option, it might be because your vertices stick to the grid:

Oh alright thanks I will try that :)

Thanks, that was the problem.. I don't know when did i do that. But its fixed now.. thanks again :)


text:
Blender 2.80 system Req + GPU req
Can someone please let me know the minimum system requirements and GPU requirement to run blender 2.80 and eevee smoothly?
Also please let me know the optimum system requirements for the purpose of

environment modeling
Game development
charachter modelling and animation

Also if someone can suggest me a good desktop/laptop for personal use that is compatible with blender 2.80 in a low budget.
Any help will be much appreciated.
Thanks in advance!

This sort of opinion based question is likely to be closed here. Try https://blenderartists.org/ for a more traditional forum.

Oh ok.. i did not know that

Blender's hardware requirements are documented here. As of now for Blender 2.80 this is:

Minimum

32-bit dual core 2Ghz CPU with SSE2 support
4 GB RAM
1280×768 display
Mouse, trackpad or pen tablet
Graphics card with 1 GB RAM, OpenGL 3.3

Recommended

64-bit quad core CPU
16 GB RAM
Full HD display
Three button mouse
Graphics card with 4 GB RAM

Optimal

64-bit eight core CPU
32 GB RAM
Full HD displays
Three button mouse and pen tablet
Graphics card with +12 GB RAM

Supported Graphics Cards
These requirements are for basic Blender operation, rendering using
  the GPU requires slightly different requirements. Always make sure to
  install the latest drivers from the graphics card manufacturer
  website.

NVIDIA: GeForce 200 and newer, Quadro Tesla architecture and newer, with NVIDIA drivers (list of all GeForce and Quadro GPUs)
AMD: GCN 1st gen and newer (list of all AMD GPUs)
Intel: Haswell and newer (list of all Intel GPUs)
macOS: version 10.12 or newer with supported hardware

In order to use the GPU for rendering your hardware needs to fulfill the requirements listed in the documentation. GPU rendering on macOS with AMD graphic cards has been discontinued due to Apple deprecating their OpenCL compiler.
Benchmarking information are available at Blender Open Data.


text:
Can I make 3D spheres to deform/pulse in sync with audio?
How can I make a sphere-like object pulsate with the beat of a song? Is this possible to do in Blender, or do I need to get Adobe After Effects?
Here is an example of what I mean:
https://www.youtube.com/channel/UC_aEa8K-EOJ3D6gOs7HcyNg

Yes, most certainly! I've made my own take on the effect, and I'll render it overnight to test it out (just for clarity, you are referring to a sphere as in this video, correct?). Hopefully I'll be able to write up a proper answer tomorrow

Thanks! Is it possible to make it similarly transparent like in the video?

I had so much fun re-creating this effect that I ended up doing it twice. You can see the final results (with sound) here.

Unfortunately a step-by-step guide to creating exactly what I made would be a bit long for an answer, so instead I'll summarize the process, with lots of links to other more specific answers.
The basic idea is this:

Create an empty (⇧ ShiftA> Empty) and keyframe an arbitrary transform channel (I) (using an empty's transform makes setting up drivers a little quicker later on)

Use Graph editor > Bake Sound to Fcurve.
If you want to get fancy you can bake several empties (or several transform channels) with different frequency ranges (for example, if you want to change the scale with the amplitude of bass sounds while changing the color with higher pitched sounds)

Use drivers to control whatever settings you want (object scale, subdivision levels, or even cycles materials) based on the empty's baked transform channel.
The reason for baking to an intermediate empty rather than directly to the property you want to animate is solely for ease of tweaking. With a driver you can e.g. use an expression to adjust the amplitude later on, or use multiple drivers to drive multiple properties off of a single empty.

With that in mind, I used a cube with some modifiers to create the sphere:

Subsurf To add more geometry to the cube
Cast To make the subsurfed cube spherical (note the Factor is set to 1)
Displace To produce the actual distortions. The texture used for this modifier is on the top right. The empty used for the texture's coordinate space has a random rotation animation generated with a noise fcurve modifier.
Cast (again) To flatten the displacements back towards a sphere a bit, but not all the way. Note the Factor on this one is < 1
Smooth Just to smooth out annoying wrinkles

Other points of interest in this screenshot:

The material used for the main sphere
The material used for the duplispheres (small dots)
The driver expression used to drive the displacement modifier strength (the referenced empty's Y location is driven by a sound-baked fcurve). To add a little "pep", the raw value is multiplied by 5 (totally arbitrary choice on my part) then taken to the second power. min() provides a quick way to limit the maximum value the driver will produce; e.g. min(somenumber, 1) can only ever return numbers < 1.

To create the dots I duplicated this cube and used dupliverts to render the second cube's vertices as icospheres, and added a driver to the subdivision level on the subsurf modifier.

To do the rotating and scaling close to yours, do I make bake it with each rotation and scale? (Sorry, I have not done baking before)

Could you record a tutorial?

This is super easy & Fun:

in the 3D viewport Add >> Mesh >> Sphere.
With the Sphere selected hit I >> Scale.
Split your 3D view and in the next view goto the Graph Editor.
on the menu bar: Key >> Bake Sound to F-Curves.
Browse to your song.
Select it, and click "Bake Song to F-Curves".
Hit play on the timeline and watch your sphere bump.

Cool! Can you do other things also, like spin or use sculpt mode to make spikes appear?

Yes you can do a lot, especially with drivers. I'm not quite sure about sculpt mode, but definitely with displacement modifiers, shapekeys, etc... (e.g. just about anything with a slider value).


text:
How can I output a counter or/and progress bar in the UI?
When I batch operations such as exportings, I'd like to know when it will be over.
Having a progress bar or indicator and something like "X of Y" (X is number of objects processed; Y is total number of objects) would be useful.
Does Blender have a way to accomplish this?


text:
How to create a custom property on an object by pressing UI button?
I'm writing a tool with a very simple panel with buttons.
On pressing a button a custom property with a specific name is to be assigned to the active object.
The UI should have 2 buttons Target and Clear

Pressing Target button in the UI should create a custom property.
Pressing Clear button in the UI should delete customer property that was created by the Target button (if such customer property is present).

For example, I have Cube and Sphere (names) objects. I would select Cube, then Sphere, press Target button, and Cube will have custom property names "target" with value "Sphere".
Selecting both of them in any manner and pressing Clear button would remove that custom property.
How do I go about making such basic add-on?
EDIT: Here is a mock-up that should explain it all :)

Link to full screen image: https://i.sstatic.net/aWyLc.png

Question isnt really clear about whats needed, is this about creating custom properties, or creating UI's?... How do I write an addon that does ***** is likely too vague for a question. Also did you try to do this already? - if so, what was the issue that stopped you from getting it working?

The question seems to be asking for an add-on to be written from scratch? which is too specific.
The answer is yes, this is possible.

Create an addon (see addon template).
Create a panel, (see template for making a panel).
Create an operator (see templates for creating those)
The operator can assign a custom property, see the Quick Start section on Custom Properties

So all of this is documented, best try to put this together to write your add-on.
Note, to access templates, see:Text Editor (Header) -> Templates -> Python

Where do I find all the templates and documentation?

Edited answer to include "how to access templates".

you want ID properties, they can be set per object
obj = bpy.data.objects['whatever']
obj['some_property_name'] = 'some_value'
obj['some_property_name_2'] = 33

>>> obj['some_property_name_2']
... 33

Here's an example of adding Custom Properties from an Blender Add-on.  It can be modified to remove the properties as well: https://github.com/MarioDelgadoSr/AddBlenderCustomPropertiesFromCSV

please always include the relevant code in your answer. Links are always bound to become invalid over time.


text:
How to redirect output from 'bpy.ops.*'?
When calling operators such as bpy.ops.mesh.remove_doubles() it outputs how many vertices were removed into console.
In some cases its better to silence it, but you may also want to catch it and use it within the script.
How can I redirect or otherwise silence the text from printing into the terminal?

@ideasman42 dublicate ? http://blender.stackexchange.com/q/6119/5113

Asking to redirect output isn't quite the same as suppressing.

This can be done by temporarily overriding the output using redirect_stdout.
eg:
Short example:
from contextlib import redirect_stdout
import io
stdout = io.StringIO()
with redirect_stdout(stdout):
    bpy.ops.mesh.remove_doubles()

Commented answer with redirect:
# Python module to redirect the sys.stdout
from contextlib import redirect_stdout
# So we can create a file-like object
import io

# our new output
stdout = io.StringIO()

with redirect_stdout(stdout):
    # any printing or operator output within this block
    # will go into 'stdout'
    bpy.ops.mesh.remove_doubles()

# if you like to get the output and use it
# you can read it as if its a regular file.
stdout.seek(0)
output = stdout.read()
del stdout

print("We caught the output, it was %d long!" % len(output))

Note, that this can also be used to re-direct operator reports for your own use, and example of this is a benchmarking tool which extracts output from the draw timer.
https://gitlab.com/ideasman42/blender-fps-bench/blob/master/blender_fps_bench.py#L196