text:
Mirrored object doesn't match it perfectly?
Well I retopologized the object and now I am having trouble with the mirror of it. It keeps mirroring int he wrong area and is not matching up equally. Also my verticies at the end of my mesh that would connect the mirror are not alligned properly. Can someonehelp. I have pictures below.

this is very similar to How do I make the Mirror Modifier work right?

It looks like the origin of the mesh is not quite in the correct place.

Select the vertices that you wish to be the centre of your mirror (the vertical line of vertices which run from the nose all the way
back around the head and back up to the nose)
Press Shift+S and choose Cursor to Selected.
Go into object mode and choose Origin> Origin to 3D cursor from the Toolshelf (press T to show the toolshelf).

The mirror modifier should then be moved to be above the subsurf modifier to avoid having a visible seam.
Update: To make the centre line of vertices completely straight, select the centre loop and press S , Y then 0.

But how do I align all the verticies to the same so that my merging isnt so choppy?

@RayMairlot, you should have said "S,Y, then 0", since on the image we can see the mirror is on the Y axis.

Yeah you're right, I had meant to do that. You could have edited the answer yourself though :)


text:
How to prevent triangulation of models when importing models from sketchup to blender?
I want to import Sketchup models in blender. For that, I tried exporting models form sketchup in various formats using the built in exporter in Sketchup followed by import in blender. The model looked fine in Sketchup but when I imported it in blender using "Import Model", the model's body mesh gets triangulated. This is making the model useless for me as it is very hard to work with in blender. Especially circular parts gets triangulated to a number of portions and are very hard to scale/ rotate etc.
Please suggest how should I import/export the model correctly.
In sketchup

In Blender

I tried the procedure above for

Collada
obj
3dS Max

The model looks same with all formats.
Link to sketchup model: http://sketchup.google.com/3dwarehouse/details?mid=a91cb0fd50d4b2cc5599acd1021b314d&prevstart=0

perhaps link to the sketchup model, it is difficult to see if there is anything wrong with this import (and of relevance to Blender.StackExchange) . sketchup internally has n-gons and it seems to default to triangulating the meshes in the export process -- which is a valid thing to do.

In the exporter settings, there might have been an option to triangulate faces.

Models for games must be triangulated at som point. I see no distorsion, only triangulation. ITs not pretty but should be workable.

possible duplicate of Import SketchUp ".skp" files

Its doing triangulation without providing any option. Triangulated is workable but if we can somehow avoid triangulation, it could be much easier to work with. Especially circular parts are very hard to work with..

@gandalf this is not a duplicate, as the other question is not talking about triangulation..

@simar, it's useful to describe the bigger picture goal, instead of only the steps that are failing - one of us might have better ideas that way.

You can't (at least - not the way you want)
SketchUp very cleverly abstracts away the underlying geometry by rendering all connected faces on the same plane as one surface (unless you tell it not to). With this visual abstraction SketchUp allows surfaces to have gaps.
Blender's geometry model, known as BMesh, treats surfaces differently, it has a model of Tris, Quads and Ngons. BMesh does not allow holes in an Ngon (by design). By extension of this fact, you won't have exactly the same representation in Blender as you would in SketchUp for the same model. Blender won't magically abstract connected faces on the same plane into surfaces the way SketchUp does.

The loaded geometry will be correct, but in edit mode you will see the real geometry the way it exists in the .dae.
Blender is designed to let you edit the underlying geometry. it is a true polygon modeller. Ngon support with BMesh is a relatively recent development -- before that it was quads and tris only.
What you could do is:

enter Edit Mode for each object
select all
Delete -> Limited Dissolve

You will get a mesh that is perhaps more convenient.
Another option is to press Alt+J in edit mode, wich will transform all the triangles into quads.

You dont have to do this manually, See: Mesh -> Delete -> Limited Dissolve

awesome thx for Limited Dissolve I never know what is is for,just recenlly I started to work with game characters etc

source: Stack Exchange

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

sort: votes


text:
How to bake "full render" in blender
My objective is to make models for android so I want to bake textures on low poly (plane) in case of a high poly floppy disk. I want the textures to appear on both sides of the plane. I tried "Full render but all in vain".
EDIT: This is because I did not check "Selected To Active"
When I did a full render bake, this is what I got

Could you enlist steps to do this??
Secondly if instead of a plane, i make a cuboid and I want textures to appear on all sides of the cuboid as if someone take picture and apply on the faces of the cuboid. How is that possible??

Select the high poly then the low poly mesh. So the active will be the low poly. Check the option Selected to Active in the Bake panel. Here is an example:

To be able to do this you have to UV unwrap the plane or cuboid and assign
a texture for the UV to bake on. But you have already done this. :) To use
a cubeoid, you simply have to adjust it so that it represents the models
geometry as close as possible.

How should bake the other side as well??
Suppose I want to bake the other side of the floppy?

In case the plane is at the same position as the high poly model, it will be probably ok simply to Flip the normals (3D view > mesh tools (toggle it with T) > Flip Direction). But you cannot use two textures for the two sides when developing games. You will have to use two planes, with opposite normals. Generally I think a cuboid would be a better idea to use.

Usually when developing games nowdays you can use shaders, so you should bake normals, ambient occlusion and texture, and use those for the material setup in the game engine.

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


text:
Dark surface unchanged by light source changes
I have 3 lamps on the scene (the one on the left has 0 energy):

The rendered surfaces are supposed to look like shiny metal.  However, there's always a dark spot at the top of the large light orange surface, apparently no matter how the scene is lit:

I've also tried flipping normals, removing doubles in the mesh, changing specular and diffuse, horizon color, and turning off receiving shadows.
Has anyone seen something similar?

Can you share the .blend file so we can see it more closer ? I don't really understand your mesh...

Or just paste an image of the wireframe. It looks like there is something wrong with your mesh.

It seems from your render that the black/dark part is a reflection of the background (the environment). Try adding a large diffuse white plane above/in front of your objects so that there is something there to reflect instead of just the empty blackness of your world. Make this plane invisible to the camera or use the compositor to exclude it from the final render if it gets in the way of your scene (or move it far enough away so it isn't in view of the camera).


text:
Remove sharp or jagged edges in mesh
The problematic edges are small, convex, sharp protrusions on a larger concave, smooth surface.  Edge split, smooth, and subdivision modifiers do not achieve the smooth surface I'm looking for.  Is there a way to force edges with larger than, say 290 degrees to become less obtuse?  Note that I describe the edge this way because that is the side of the surface I'll be viewing (not side of the surface with the equivalent acute angle).  Here's an example:

The mostly horizontal lines are where thin, jagged protrude out of the otherwise smooth surface.  Close-up:

Using the Smooth brush in sculpt mode with dynamic topology and Collapse short edge enabled gives (applied on various scales for demonstration):

This is close but is there a way to now make the 'crumpled'-looking surface become more like the other smooth surface?

It looks to me like the faces on the other side of the mesh are intersecting. Are you looking for a way to fix this with sculpting?

@gandalf3-- I've updated the close-up so you can see that the larger, concave, smooth surface is bridged by regularly repeating smaller convex features.  A solution by sculpting or modifiers works

You could try going over them with the Smooth brush in sculpt mode (with dynamic topology and Collapse short edge enabled)

@gandalf3 Thanks! This very well may be a solution. Please let me test extensively real quick

@gandalf3-- Almost but can we take it a step further to smooth crumpling? (see edit)

you could try a smooth modifier and maybe some subsurf. If I was correct and the mesh has thickness and the edges were caused by the other side intersecting, (It's hard to tell from the screenshots) an alternative to trying to model both sides is to use a solidify modifier.

Another thing that could help is a Remesh modifier.

Wow, the Remesh Modifier let's me make a Lego Suzie!! Problem is that it's desirable to have few verts where there's less detail and large curves and more detail on creases and sharp corners. Remesh makes a very dense mesh. But the Blocks option is so cool. Thank's for mentioning it.

@Haunt_House I often add a Decimate modifier after a remesh to try to reduce density. (the wiki is a bit out of date, there is now an un-subdivide option, as well as a planar option which is actually the same as Limited dissolve.

This topology is so messed up (current Sculpt Mode will do that), it might need a retopology.
Either use a Shrinkwrap Modifier to get a clean result with a new mesh and far less verts (after the rough adjustments, you can enable the modifier to be active during Edit Mode which glues your verts to the surface) or use use the Bsurfaces addon. With it, you can convert Grease Pencil strokes into topology. You need to set the grease pencil to Surface or otherwise the strokes won't connect to the underlying mesh.

You might want to add surface snapping to your list

Surface Snapping? What witchcraft is this?

@Haunt_House Surface snapping equals the combination of snapping to face with projection to other objects enabled (all connected to the magnet icon in 3DView header). Basically the same effect as the shrinkwrap modifier but applied to each vertex you move while in edit mode.

@Haunt_House see the wiki. (it's actually called Face snapping, not surface snapping :P)

Already found it, tried it, didn't like it. The fact that only one vert at a time is affected means I have to select every single vert. The shrinkwrap seems to be more convenient so far.

@Haunt_House Yes, that is annoying.. I was actually going to ask if there was a way around that a while ago, but now I don't need to :) (the Shrinkwrap works beautifully)

@Haunt_House - snapping actually applies to all selected verts, you can select as many verts as you want and press G and click to have them all snap to the surface. It's only g,s,r that snap, other operators like subdivide ignore snapping. The difference would be that snapping moves from current location to the surface right below based on viewing angle, where shrinkwrap scales the object down until it hits the nearest surface.


text:
shrinkwrap ("decal") around entire object?
I just want to (shrink) wrap a plane with an image over (around) the entire object, not just one face / plane.
[EDIT, after two answers] Many have said that original question is unclear. So now that I understand what I was asking %-/, here's the translation:
How do I cover an object with a picture without using UV Mapping -> unwrap?
[EDIT] Skip down to the accepted answer from Duane Dibbley.

Perhaps superfluous details, an example of an only partially successful attempt:

Start Blender with factory defaults (will use default cube).
Create Plane.
Drag drop some arbitrary image onto plane.
Set parent of plane to cube (via drag drop plane to cube in Outliner).
Click plane.
Add Modifier: Shrinkwrap.
Set target to cube.

At this point, it's just on the top face of the cube. How can I get it to cover the entire cube (all faces), e.g. "folding" it around the whole thing? If this turns out to be more complicated, e.g. requiring some UV / mesh mapping things, can you please point out a link or two that might assist?  (I've looked a bunch of tutorials, blender wiki, and blender docs (which I wish had examples, not just parameters :)), but I seem to be denser than that cube! Thank you!
- H
[EDIT:] Requested Screenshot --- the "brain" should cover the entire cube, but not multiple same images on each face, i.e., the cube should look like a brain in the shape of a cube.

Please show your work with an image to improve the clarity of the question.

Here is a tutorial link https://www.youtube.com/watch?v=Tovu1A0LxeQ

Maybe you should volunteer to improve Blender documentation since your exact steps convey everything any reader would want.   Blender documentation needs people like you.

I am not clear what you want. Perhaps others are.  Do you want a cube with six different pictures on six different faces?  Do you want to model a 3D Brain? Something else? Blender is not designed to be simple.  Blender is designed to be expressive.  Why not show your actual work or state that cannot it cannot be disclosed?  You could present an equally complex substitute. Can you show a image from the internet similar to your goal?  People use seams to unwrap complex images.  Images can be projected on meshes.  This requires searching at BSE or other sites.

Perhaps you should tell people if wrapping a box with gift wrap is your goal.  Please see Cloth Simulation.  I can suggest nothing that could not be immediately by rejected as an unpleasant aesthetic or discontinuous image.  You could try texture painting you brain image on all sides.  In this case having six different images of a brain might be helpful or a finished 3D model.  Having one image of the brain seems inadequate.  The final choice is yours.

Tried texture painting, but need to learn more. Will also look into Cloth Sim. suggestion. Thx! Yes, one image is inadequate. This is only a test to get further, so it doesn't have to look real. Have other views, i.e. top side back front, but wanted to try out just one. I have a feeling cloth sim. also requires mesh unwrapping - or mesh overlaying ... hmmm ... if a feature like "snap picture around all surfaces" doesn't exist, maybe I need to write an add-on? :))

So you want the image of the brain on all sides of the cube? (Is there any reason you have to use the shrink wrap modifier?)

Interesting that a closed question has a bit more explanation. Its true that people downvote and do not state why.  Bad situation.  They talk about this in meta recently.  Its very difficult for someone to state why, perhaps because it makes them seem aggressive.  Clicking anonymously is quite easy to do.  I would like to see specific downvotes only such as ... No Research ... No Effort ... Please make clearer ...  Too many topics ... et cetera.  I would not take it too seriously.  Sometimes a downvote is really about the down voter. Maybe the did not a Pokemon today.

Do you want to see a brain on 5 sides ... 6 sides or  other?

Can  find a 3D model of a brain on some sharing website?  You can use shrink wrap , perhaps with difficulty, to beform it to a cube.  The surface normal information can be used during weight painting and used in the vertex group setting of shrink wrap.

thx @atomicbezierslinger --- appreciate the many thoughtful and supportive comments... I need to go catch a few pokemons. LOL. seems the answer below followed your suggestion of a 3D model ... was hoping it would be easier / faster. BTW, Blender is one of the best pieces of software out there (and I think I should know as I've been a developer > 30 years :-0 )  cheers!

Blender is not simple in general.  You are the final judge of the aesthetic.  The suggestions and solutions are not the most complicated.  That note can either be encouraging or just the opposite. The documentation or nonexistance of documentation can attest to that fact is not simple.  The suggestions were meant for you to have an journey.  Which computer languages do work with?  Perhaps we can set the record for the most comments for a closed question.


text:
Can object parameters be set from data file?
I would like to do 3D animations.
M spheres appear moving around and rotating along N frames (all spheres will appear in every frame).
For each sphere at every frame, these values are saved in a text file, which I'd like Blender to read:

position
angle rotation

Is it possible to read this file from blender, (so that Blender will create N frames and move and rotate at each frame the M spheres with the data read)?
I can write the file with the positions and angles in the most easily format to perform this. Eg. csv file:
time step | sphere number | x | y | z | mx | my | mz
(where m is refered to the rotation components)

The last sentence is unclear. Do you mean you can save the file in 'some easy to read' format?  E.g. JSON, XML, CSV ?

It looks like you are asking the same question as this one:  http://blender.stackexchange.com/questions/61605/import-a-csv-animation-path-using-animation-nodes

Using a data file to control position and rotation can be done using the animation nodes add-on.
If this is not installed, then install it from the Git repository
To install the animation nodes, see http://animation-nodes-manual.readthedocs.io/en/latest/user_guide/install/install.html
Tested in Blender 2.77

To start, create a simple scene with a sphere and a plane. Add a material to the sphere so rotation can easily be seen.

Open the node editor, switch to the animation node mode, then create a new animation node network.

Add the 'Compose Matrix' and 'Object Matrix Output' nodes. Connect the matrix output to the matrix input. In the 'Object Matrix Output' node, set the object to the sphere is the scene.

At this point, if you change any of the values in the 'Compose Matrix' you should see the sphere move, rotate, or scale.
Add a 'Combine Vector' node and a 'Combine Euler' node. This will expose scalar values that can be used set. In the 'Combine Euler' node set the 'Use Degree' check box.

Once again, changing these values will move and rotate the sphere.
The next couple of steps will add the logic to convert a string into a vector. Add a 'String Input' node, a 'Split Text' node, a 'Get List Element' node, and a 'Parse Number' node as shown. Also 'Debug' nodes can be added to see what values flow through the node network. The 'Split By:' value should be set to ',' (a comma).

Now changing the inputs string, which is CSV separated, will change the location of the sphere.
Create the input file for location and rotation. It should look something like the following. Save it to 'sphere-1.csv' in the current directory.

The next steps will replace the string with the input from a file. Delete the 'String Input' node. Add a 'Text File Reader', a 'Split Text' node, and a 'Get List Element' node. Change the 'Split Text' to use 'Lines' to separate the text file.

This will set the x position of the sphere to the value of the 1st line in the 'sphere-1.csv' file. To animate this, add a 'Time Info' and 'to Integer (floor)' node.

To see this animation work, open a timeline panel and set the start to 0 and the end as 12. This will then only animation the first 13 lines in the data file.

If animated, the result will be the following:

At this point, all of the pieces are in place to translate and rotate an object. The next step is to hook up all of the information from the file to the object. Extend the previous network into this one.

The result of this network should be the following animation.

To animate multiple spheres, the animation logic is converted into a 'group' which has a file name and object as the input.
Add a group to the network. Connect the output of the group to the path and to the object. Then add a group instance. This will behave just like the previous example. The difference is that that group instance passes the path name and the object to the group. This group can be reused.

Add three spheres to the scene and create the three more data files with location and rotation like 'sphere-1.csv'.
Add a 'Create String List' node and populate it with the files names with the data for each sphere. Add a 'Create Object List' node and populate it with the name of each sphere. Add two 'Get List Element' nodes. Add a 'Loop Input' node. Connect all of this so the 'Loop Input' is used to specify the 'Index' of the object and data file for each iteration of the loop. Finally, add a 'Invoke Subprogram' that points to the loop and has 4 iterations. The part of the network is shown below.

The entire network is shown here:

By adding more data to the input files and setting the last frame in the animation larger, an animation like the following is generated.

This blend file can be downloaded here:


text:
how to render a composite created by scripting?
I tried my best to find the answer browsing the API doc and forums but here I'm stuck with quite an odd problem.
I'm developping an import addon wich I'd like to work as follows:
it opens a directory containing subfolders corresponding to each sequence of a movie. In each of these subfolders are still images constituting my sequences.
For each sequence, it creates a new scene in blender and in each scene it adds and connects a bunch of compositing nodes (say one image sequence node , a keying node and a composite node ). Up to this point , the script works perfectly fine.
The problem is , when I try to render a scene the composite output is never taken into account and it only renders what's in the 3D view port, that is to say nothing.
I checked in my scene render options that compositor is enabled for post-processing. And when I create the scene I always set the use_nodes option to True.
Here is the function used to create the scene and composite nodes.
Doesn't anyone has a clue why the composite nodes won't render?
def import_sequences(self,context):
    for s in os.listdir(self.directory):
        if os.path.isdir(os.path.join(self.directory, s)):
            bpy.data.scenes.new(s)
            bpy.data.scenes[s].frame_end=len(os.listdir(os.path.join(self.directory,s)))
            bpy.data.scenes[s].render.resolution_percentage=100
            bpy.data.scenes[s].render.filepath=os.path.normpath(os.path.join(self.directory,"render",s))+os.sep
            bpy.data.scenes[s].use_nodes=True
            nodes=bpy.data.scenes[s].node_tree.nodes
            nodes.remove(nodes[nodes.find("Render Layers")])
            images_node=nodes.new("CompositorNodeImage")
            images=os.listdir(os.path.join(self.directory,s))
            images.sort()
            seq_im=load_image(images[0],os.path.join(self.directory,s))
            seq_im.source = 'SEQUENCE'
            seq_im.alpha_mode='PREMUL'
            images_node.image = seq_im
            images_node.frame_duration=len(os.listdir(os.path.join(self.directory,s)))
            if self.operation == "KEYING":
                keying_node=nodes.new("CompositorNodeKeying")
                bpy.data.scenes[s].node_tree.links.new(images_node.outputs[0],keying_node.inputs[0])
                bpy.data.scenes[s].node_tree.links.new(keying_node.outputs[0],nodes[nodes.find("Composite")].inputs[0])

    bpy.data.scenes.remove(bpy.data.scenes[bpy.data.scenes.find("Scene")])

Note: bpy.data.scenes.remove(bpy.data.scenes[bpy.data.scenes.find("Scene")]) is redundant, you can do bpy.data.scenes.remove(bpy.data.scenes["Scene"])

haha thanks, I think it was about 4 or 5 am or something when I coded this XD though I still can't figure out where the problem is with my rendering. I must be missing some Scene parameter setting somewhere


text:
export paper model in multiple pages
Link below gives a pepakura 3d model unwrap Python script by Adam Dominec (Thank you to him).
Is there a way to export or have it in multiple page format, so printing becomes easy?
paper model

I just tried it and it does export in multiple pages by default if you choose .pdf export. In svg it splits it by file (name_page1.svg, name_page2.svg) and so on as AFAIK svg doesn't support multiple pages natively.

Get it. See image above. Is it possible to reduce number of faces from 32 to 5, 5, 5, 5, 5, 7. So this will come on different pages.  Currently in pds too it gives 3 islands on two pages. I need more islands than 3 ( atleast 8-9 ).


text:
How to change the handle_type of a keyframe I've just inserted?
In the VSE, I create a new effect and a keyframe for a property (speed_factor):
scn = bpy.context.scene
sp = scn.sequence_editor.sequences.new_effect("speed",
        'SPEED', 7, start_frame, seq1 = s)
sp.speed_factor = 0
sp.keyframe_insert('speed_factor', frame = start_frame)

How do I then change the handle_type of the keyframe to VECTOR? It seems odd to me that keyframe_insert only returns a success flag rather than some kind of reference to the keyframe I've just created.

I figured out a way to do it but in my opinion it's not ideal:
keyframe = sp.id_data.animation_data.action.fcurves[-1].keyframe_points[-1]
keyframe.handle_left_type = 'VECTOR'
keyframe.handle_right_type = 'VECTOR'

It's not ideal because the action might have other fcurves but it solves my case because I know it doesn't for my particular problem.


text:
How can I tell what part of the model the UV map is from? (In Blender)
I have a model in blender, and when I unwrap it, I noticed that there is a lot of stretch in one section.  How can I tell what section of the model this is from?

As you can see, there is one Huge green area that shows a many more vertex's than I was expecting to see.
Also, those boxes look huge.  Is everything the same scale?

It may be useful to see the 3D mesh and the UV at the same time as indicated in the answer below.  How was texture created?  Texture painting?  Since the UV can be edited this is one way the faces could seem incorrect to you.  If this is a learning experience you may want to have more space between the UV islands.  Strive to create a UV Map where no faces overlap.

UV Face Identification and Coordination

Image above.  Open two windows. One with the mesh in [edit mode]. We assume one UV. One with the UV image editor with the texture selected.  If you select faces of the mesh model you will see them highlighted in the UV editor window with the default settings.  You can change the setting indicated by the yellow arrow are to keep the Selection in Sync.  You may select faces in either the UV Image Editor or The 3D View Window with mesh in edit mode.
Notice the face selection mode.  The red seam allows the blender user to move the islands.
Face Size
Relative Face size in the UV Map and face size of the mesh model can be different and this is a flexible feature. Same scale is not necessary. We might imagine we want more detail in the face of some character than we want on the bottom of the foot.
Changing Island Size

Thank you, I understand why they might be different.  But I do have some faces that are scaled differently (and so the texture is showing up different) but should really look the same, is there a way to make it scale the same?  Thanks for your answer.

Please see above.  There are some videos at some [famous] video site about UV mapping in detail.  I think a video may provide more general explanations and well worth 30 minutes.  Search ... Blender UV Mapping ....

Lastly anyone can have an unwanted UV unwrap. Blender has two meanings to uv unwrap.  Blender has uv unwrap user actions and uv unwrap denotes the final data stored in the file.   Blender allows one face at a time to be unwrapped as an action, updating the final piece of data representing the uv unwrap when the file is saved. This may seem not useful to some people.  So this is another source of potential error.  I might also suggest delete the UV unwrap and create a new one. UV Unwraps come and go and are meant to deleted and created again.  A New uv unwrap may give you a fresh start.

UV editor menu > uvs > average island scale. This would scale your uv to the match them relative to the scale of your meshes. Shortcut is Ctrl + A.

@hawkenfox  the concept of average scale island was in the answer prior to your comment. 10 hours ago. You appear to be repeating the information in the answer.


text:
How to smooth a specific edge?
I have had a problem dealing with this edge no matter what I do. As you can see I am trying to make a face and last time I checked nobody has a sharpish edge going down the side of their head. I've tried smooth, bevel, and subdivide and none have worked and if I move the vertices in it creates a indent instead. Do I just need to try harder to get the vertices right? Help.

My guess is that your normals are pointing to the wrong direction. Go to edit mode press T and click Recalculate in the normals section.

Adding a .blend may help get a good answer. You can upload it to http://blend-exchange.giantcowfilms.com/ and edit the file into your question.

As it appears from your screenshot you're doing a character; for making organic shapes sculpting is used in most cases. However there isn't Multires modifier in your stack rather than Subsurf one which generally isn't used for that purpose (though it may be too late to change). Try using Sculpt brushes, like Smooth, Clay etc.

Try 'Remove Doubles'. W -> Remove Doubles You may have two rings right next to each other. If that is the case, items like Bevel and Subdivide, will not smooth the crease any more, because there is no space between verts to divide.
But you will have to play with the settings in the Tool Panel, or you could remove too many vertices.

For me recalculate and remove doubles didn't work but after lots of zooming (you don't want to know how much) I found that there was, in fact, another edge very close to another. Removing this fixed it. For those who might find this, still try all the options because it may be different for you. Thanks to dval who pointed this out.
Also thanks to all of you who answered.


text:
Seams on normal map
so I have a arm model, and I baked a normal map for from a sculpt. However, when I apply this normal map in any program (Blender, Unreal, Unity) there are seams on it. (from the UVs). This is ugly and I'm not sure why its happening. Please help]1

I don't think the seams are particularly bad here, if you had any kind of texture applied you couldn't probably notice it. In the image the polygons being distinguishable in the silhouette is far more disturbing to the eye. But you could still look into it. Why is there are UV mapping seam there, is this animated model? Normals are seamless when geometry has the same normal and the normal map colors match, so one of those things is slightly off. Can you supply the model and the map for investigating the issue?

If it persist in other software, then your normal map is baked incorrectly. You'll need to show how you baked the map, what settings, how you prepared the meshes etc.

If you are using cycles you probably forgot to switch your image texture node from color to non-color data. This will hide the seam significantly. Also creating a higher resolution normals map will help as well.

If this problem persists on other platforms outside Blender it's not related to Cycles nodes?

I have the solution. Just put the mode of your Normal map node (image texture) from Srgb to Non-Color

If seen this several times. In my experience it is due to weird uv mapping. Try to unwrap your model different. I find these edges occur when some connected faces are not connected in the uv map

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


text:
How to achieve softer and more realistic lighting from a chandelier?
I created a crystal chandelier and wanted to use it to light up my scene, but I'm not getting the results I wanted. I want to achieve a more reflective and softer lightning. Now you can see the silhouettes of my lamps right through the chandelier. I am using small parts in the chandelier with emission materials on them. Has anyone got any tips or tricks for softer realistic lightning?

You can try adding images you can find on google images and describe the effect you are trying to achieve. I suspect  what you really need is to create area lights to recreate soft lighting and shadows around your scene.


text:
My object which throw flame does not appearing during rendering?
Dear experts my object which project flames on wall does not appearing during rendering I do not know why
things I have done
*all layers are in  unrestrict mode
thanks in advance :)
file is attached      Here is the link for file
https://drive.google.com/file/d/0B6EziauliLnTQ3hGWGlLcUJQSms/view?usp=sharing

You need to use a volumetric material on the domain object utilizing the voxel data from the smoke sim.  Since I am not a BI expert I will let someone else write a full answer, unless you are open to using Cycles?

For the issue of the flame not appearing during render, there are two things you might want to consider that caught my eye upon looking at your scene.
First, is the material. You haven't created or assigned a material to the particles for your flow object- 'Plane'. Create a material for your flame, and assign it in the render tab> materials drop down (highlighted in yellow)
Second, is the emitter type to display(highlighted in red). Currently it is set to none. Select another option (halo works well for fire), and you will see your flame in the final render.


text:
UV unwrap ignores mirror on part of the mesh?
So I made this character, or half of it while mirrored along X, as you can see here
But when I apply the mirror and try to unwrap the UV I get this
Notice how the mouth is different on one side, I don't understand it as it should be exactly the same. Everything else unwraps perfectly, and the only thing I did was work on that part of the mouth with the mirror invisible so I could see better from the inside. But I've looked at it and  it is definitely the exact same mesh on both sides. I've tested it a bunch of times now, same result every time. Mark seams, apply mirror, unwrap, and the mouth area is always wrong. Any ideas to why this would happen?

Daniel, uploading a copy of the blend file to Blend-exchange, or a similar site might be helpful to me, and perhaps others.

I had this same issue and it was doing my head in, but it turned out because the mouth and face were separate materials, the pinning of the face were messing with the mouth.


text:
How to redo an undo that deleted an object?
I was working on a project that took a long time. I have two meshes, one I put a lot of time in. I joined the two meshes together, and worked a bit on them, but then decided I wanted to disjoin them. Upon hitting Ctrl+Z, one of my meshes dissappeared. I tried redoing using Ctrl+Shft+Z but that didnt work. I tried recovering from autosave, but that failed too. I tried closing it and reopening it, but that didnt work either.
Is my mesh completely gone forever? :(

I think no one can't tell better what's going on in your file except for you. The mesh couldn't just dissappear even if it seemed like that. Keep checking what's going on in your scene with Outliner. As it's stated now it seems there were modifiers on mesh which probably caused some unexpected behaviour after unjoining or you moved new object either to another layer or you were in Local view. Provide your blend file to hopefully get more detailed answer; make sure to delete unneded parts to decrease its size.

Sounds like trouble with "object mode undo stack" and "edit mode" undo stack, the user probably joined the meshes into one object entered edit mode and and then used undo, and somehow Blender was unable to recreate the original object before being joined. Not sure though, just my guess. Sad part is, if you saved your file or already closed and reopened Blender it is probably gone for good. Try unhiding everything with Alt+H or opening one of the backup .blend1 files and see if it still there, but I wouldn't expect much luck with it. For the future try saving your file as more often.


text:
Rig is hidden in Weight Paint?
I have this rig Rigify made for me and this model I made, but when Im weight painting, the rig is hidden for some reason. Heres some pictures to explain my predicament.

Thats what the rig is supposed to be, but in weight painting it's gone:

Where has it gone? :o

In the second picture, I can still see the bone next to the right arm I think, outlined in black. Do you have X-ray turned on for the armature object?

Ah! The xRay was the problem! I feel a bit dumb now aha thank you!

Cool. : ) I'll put it in an answer then.

In order to have your armature (and any object actually) show through any object in any mode, turn on X-ray mode. You can do this by selecting the object and going to the Properties panel -> Object -> Display Panel.

Interestingly, for the armature specifically, you can also turn on X-ray, by going to the Properties panel -> Data -> Display.


text:
How to use Blender Internal to UV map AND Alpha map?
I've been searching for an answer to my question, but my Google-Fu isn't quite up to scratch to figure out what is likely a pretty simple question.
Anyways, I'm looking to improve my hair on my character models in Blender Internal. I am looking to use alpha maps to make hair strands appear nicer and rounder while conserving on polygons (as I'm trying to eventually do models for games and animations in a cartoony-stylistic approach, a low poly count is vital to me).
I was wondering if anyone knew how to have a colour map and an alpha map work together. For example; I want one map where all my strands are on top of eachother on a texture like this:

Where he has all of his locks of hair on the same spot of the texture so that all the strands go with the grain.
And then I also want a separate map like this:

Where I can control the alpha of each individual hair.
How can I do this?

I wouldn't do it that way since the pixels counts are so different between the two images BUT if you wanted to, you do have the ability to have more than one UV map - so where you normally reference the default UVMap in the Data panel of the Properties editor, you would use one map for the color image and then add a new one for unwrapping to use the alpha map.


text:
How to create a sword trail smear in Blender Internal with Particles?
I want to create a sword trail smear in Blender with Particles. I cannot figure it out, and googling doesn't seem to give me too much direction. Perhaps I'm googling incorrectly.
The sort of smear I'm talking about is this:

So far, I have gotten this far with mine:
https://gfycat.com/gifs/detail/RequiredThirdBedbug
The issues I'm having are mainly:

Emitter does not emit along the whole length of the emitter (which is a seperate object that follows the curvature of the sword).
I cant figure out how to change the emission particles; theyre way to big, bright and white.
I dont know how to set a minimum speed the sword must swing at to emit particles.

If you somehow decide to make this effect using a texture instead of particle system, here's a solution: https://blender.stackexchange.com/questions/24251/how-to-create-motion-trail-in-cycles


text:
Texture Rendering Black, but shows up in textured view
My sword looks fine in solid view, but when I go into rendered view, it turns completely black.
I have mipmaps off, texture solid on.
It looks fine in solid view:
;
But when I switch to rendered view, the sword is entirely grey.
.

You're going to have to give a bit more information. What rendering engine are you using? Can you give some relevent screenshots of your material settings? a .blend file? We would be happy to answer your question, but it's important that we have the information nesisary.

You can upload a blend file here: http://blend-exchange.giantcowfilms.com/

Screenshots me viewing the item (1st picture) then i change the viewport shading to rendered and looks like this (2nd picture) -just rendered POV-
http://imgur.com/R8Fivik,lscoBPT#0 Check the link for screenshots
I dont really understand "What rendering engine are you using?"

The blend file is likely to be of more use to those trying to help you than the screen shots. And when you upload the blend file, make sure to either pack the images you are using. One thing which might cause the phenomenon you describe is not having a lamp in the scene, or having one which is not oriented directly, or does not have enough strength.

The light is perfectly fine, i have linked other things into 1 scene so i can animate, the other objects are perfectly fine, but the sword is black.
Il send the file in a moment

"I don't really understand "What rendering engine are you using?" There are different engines you can use to render. If you look at the top of your screen, you'll see a drop down menu that says Blender Render. This dropdown is for choosing the rendering engine. The two options that are most used, are Blender Render, and Cycles. Cycles is more realistic, but don't worry about it right now.

Your going to have to post a .blend file. Use the service @GiantCowFilms linked to. We won't be able to help out with just screenshots, because you don't understand enough of the things that could be going wrong to show us what we need to see to help.

Are you sure you have lights in your scene? Thanks @brasshat for the edit :)

Since no one has yet done so yet, Alex, please let me welcome to the site. The part of your statement "...I have linked other things into one scene...", causes me to suggest that when you upload a ~.blend file, that you upload the file containing the original sword, not the scene containing the link. While there is a chance the problem may be the scene containing the link, the odds are the problem is in the vile which contains the native sword.

Your issue is that you don't have any lamps in your scene.
To add a lamp, you can press SHIFTA to go to the add menu. Then go to lamp drop down, and select point. This will add a point light which casts light in all directions. After you add your light, just position it until it lights your sword well.

Generally you don't want to answer with one sentance like this. You always want to try to help explain why something is happening, and what can be done to fix it, etc.

no in this scene, im just showing what happens. But in the other scene where i have all my objects everything is fine without the sword

Thanks for trying to change it! I just submitted an edit, to show what I think could have been done better. It's mostly cleaning up the english, but there are a few other things I added to it. I hope you can see what I'm looking for.


text:
Where are the modifier scripts in the Blender package contents folder?
I need to find where Blender has applied their modifiers and physics scripts within their program so that I can install and place my own that I have. Either it has been a very long day already or I am simply blind because I have looked through every file and every option available for several hours now and am about to go crazy. If someone has a file path or can send a screenshot of where it is it would be much appreciated.

Blender's modifiers and physics related routines are written in C/C++, you won't find them in the scripts directory. Download Blender's source here as an archive or use GIT


text:
Does a mesh need UV if there is no texture?
To be more specific, I'm making a glass table that consists of two parts: the legs part, which has a metallic material, and the glass top, which has a glass material. Do I have to UV unwrap them, or it's pointless if there is no texture applied to them?
As I know, if I want to import it to a game engine, they need at least one UV map for the lightmap. Though I'm not sure.
So please tell me if I need them or not.
Thank you

Have you figured out yet that objects can have multiple materials? Add a new slot and material with the "+" button to the right of the material slots. Select some vertices, click on a material in the list, then click "Apply" to apply the selected material to the selected vertices.

Yeah I know that. Though my question was about something else

You don't need to UV unwrap the mesh if you can use the procedural texture coordinates like Generated or Object to get the material you want. This applies mainly to within Blender. If you are exporting to another app, like a game engine, you'll need to use the most compatible texture coordinate mode, which may in fact, be UV.

As far as Unity is concerned, a UV map isn't necessary for your mesh. You should be able to import it just fine and even apply simple textures to your object and tile them. Furthermore, Unity can generate lightmaps on its own, so that's not an issue either.

You don't if you're using unity like others but im not sure about other game engines. I would think not because the only thing a uv is used for from my understanding is a texture . if you have no texture you need no uv.


text:
Alpha Mask a texture with a mask having a different UV Map
I have a textured model for which I would like to apply an alpha mask - it can contain several materials with several textures. The textures were applied using a given UV projection, and the mask I created needs another UV projection/unwrapping.
Can you tell me how to tell Blender to mask the object material (make it transparent) where the mask says so (values in [0, 1]), even if it uses a different UV maps than the texture (I cannot therefore use an RGBA texture). The ideal solution would not use Nodes, or should be as cross-render compatible as possible (switching from Blender internal to Cycles should bring no additional steps to get the same alpha mask effect). I am definitely open to Python scripting (I'd like to implement this functionnality in a script).
Any hints appreciated, Thanks !

In Cycles render use a texture with a selected uv input to determine a [factor] value with a mix node. The mix node has two inputs with a transparent shader and diffuse shader.
In Blender render use the material texture with a given uv to affect [influence] alpha.  The material alpha may need to be set to zero.

Thanks for your answer, this is what I was thinking of. However, if there is a more cross-render compatible solution, I would appreciate it. The thing is that I am scripting this material alpha masking with Python, and I am already working on complex material Node trees. So I would love to find a way not to use nodes.

authors: ຕົ້ນ ສໍຄົງສິນ


text:
Name a group of faces / hide the group / call the Name later and un-hide that group
I've been working on a human model for a bit now. It's my first.
I want to select a group of faces in the nostrils (or any part of the character like an ear or the lips to work on the tongue or teeth etc), name the group of faces I have selected, hide that named group so that I can un-hide them later and work on them if needed.
An inverse select would come in handy too. I took a break on this project and forgot quite a few shortcuts.
So I guess, what is the best way to accomplish this? Or how can I name a portion of mesh to work on in detail without seeing anything else. Does it involve layers, moving pieces of mesh to another layer, and if so how to do it that way as well?
Thanks!


text:
Better practices with subdivisions surface modifier
I'm learning blender with help of the wiki, and other articles around the web(including blenderguru and blender artists).
I'm trying to make a model for a character that I've sketched, but Im having some problens with the junctions of his neck, this makes me wonder what's the best practice for creating a junction such as this one.
First try render result

Mesh of the first try

Second try with subdivision modifier

Any light on this matter?

Could you upload your .blend using http://pasteall.org/blend/  or something like that.

If you just want to have a low poly character, the easiest way would be to select the lower vertices of the neck

and move them down into the chest.

A better way would be do have a connected mesh with good topology (this one was created by Make Human):

It is connected I have deleted the entire neck and did a bridge edge loop on the second try, yet I'm still getting those results.

It must be as you said, the topology, which I suck, since I'm new on 3D modeling.
I'll do your first suggestion, but will it imply in something having the body parts separated?
Well, for working with vector animation, it's good to make the body parts separated at last. But I have no

You could select a part of the mesh and separate it with 'P' (Separate/Selection in Edit Mode) this would create another object. I'm used to start several approaches from scratch ;-)

Yes, I've done it, thanks! I rigged it and all. But I still need some more practice. I'll make some other characters like that with all the differents approachs possible to see which one I feel more comfortable.
Thanks!

The often you do it the faster you get ;-)

It looks like your neck is not actually connected to the body. Try deleting the shoulder face, then select all the base neck vertices plus the 4 shoulder ones and hit "f" to create a face. Then try the subdivision again.


text:
Python show rig ui if armature is selected
I have different characters in an scene, each one with different bone layers numbers. It is possible, using python, to create a rig ui layer panel for each character based on the armature name, and it is only show when a specific character is selected?
I've been using the flex rig code to create the rig bone layers. But with multiple characters, it doesn't work as I expected. For example, if character A has 5 layers and character B has only 2, toggle the button for layer 1 affects the layers for both characters.

If you add a poll method to your panel class you can use whatever criteria you wish to decide if a panel should be shown.
@classmethod
def poll(cls, context):
    return context.active_object.type == 'ARMATURE' and
        context.active_object.name.startswith('myrig')

When you alter the bone layer visibility it should only effect the one active armature. You can perform tests in the panels draw function to decide if a layer button is shown.
def draw(self, context):
    layout = self.layout
    col = layout.column()

    if context.active_object.name.startswith('myrig'):
        row = col.row()
        row.prop(context.active_object.data, 'layers', index=0, toggle=True, text='head')

Unfortunately I don't think there is an easy way to check if there are bones on a layer, you need to loop through all bones and their layers array.
def used_layers(obj):
    ulayers = [False,]*32
    if obj.type == 'ARMATURE':
        for bone in obj.data.bones:
            for i in range(32):
                if bone.layers[i]:
                    ulayers[i] = True
    return ulayers

Then in the draw method -
def draw(self, context):
    layout = self.layout
    col = layout.column()
    show_layers = used_layers(context.active_object)

    if show_layers[0]:
        row = col.row()
        row.prop(context.active_object.data, 'layers', index=0, toggle=True, text='head')


text:
Linked scene in VSE doesn't run Python script
I'm making a short movie in which one scene, I hide part of the mesh of a character using some python code in a Register .py file, like this:
bpy.data.objects['spider_eye.L'].modifiers['Mask.001'].show_viewport = 1

which hides the mesh in the animation file (anim.blend). I also have another blend file (vse.blend) where I linked the scene from the anim.blend to edit it but in the sequencer viewer of the VSE, the mesh is not hidden.

I'm guessing that when a scene is linked, the added code is not executed.
Is there a way around this?
Thanks for your help.

I think it would depend on how the script does it's thing. A registered script is run when opening the blend, is it just a script of simple commands like shown or is it doing things within a handler or driver? You could link the script as well as your mesh.

mod.show_viewport property shows / hides the result of modifier in the 3D Area's view, whereas I think you need to use  mod.show_render to hide result from the VSE

Make sure, in the User Preferences (Ctrl+Alt+U) you have Auto Run Python Scripts selected in the File Tab at the very bottom.

I already had that option enable. I just want to know how the "Register" option in the text editor works.

Then you might ask a bit more specifically.


text:
How to pick an object in BGE and release it while using NLA actions
I am trying to a pick an object and release it, in BGE.
I am attempting to use the actions setup in the NLA.
While I can successfully pick and release the object (via Dynamic Parent addon) for rendering purposes, I cannot do the same for BGE as the plugin will not work when using BGE.
Here is what I am trying to achieve (Please ignore auto loop)

Here is my setup :

As of now, only the arm (parented to armature) rotates upon pressing SPACEBAR. This is because the cube only contains the animation curve for the parent influence.
How can I achieve the above animation in BGE ?
Regards,
pixelhaze

Have you looked at the parent actuator?

@sambler   I have come across the Parent Actuator but I am a bit lost on how to use it. If I use it, I need to set the parent in the initial few frames of the animation and then clear it in the last few frames. Any pointers to where I can find such information will be appreciated.

You use one to set the parent and one to clear it. You just need to figure a way to trigger the event, maybe send a message?


text:
Python API: bpy.context.selected_nodes gone?
It seems like in the 2.73a version (and 2.74), bpy.context.selected_nodes method is not available despite the documentation showing it up. Does anyone have an idea on what could be happening ?
thanks!

selected_nodes is only available in the Nodes space context (not the 3D view or any other). Make sure you run that from an operator with the right context from the nodes editor

You might be able to filter on node.select for your application:
mat = bpy.data.materials['checker']
nodes = [ n for n in mat.node_tree.nodes if n.select ]

Although, I'm not entirely sure how that works with node groups (where you have a compound node selected and tab into it and select other nodes).


text:
Compositor: Export movie files
I have a composition with multiple file out nodes, and I would like to output movies from some of them instead of an image sequence. Is this possible ?
If I use the video sequence editor, I can't find an easy way to different clips with unique names at once. If that's something do-able, then it would serve my needs as well
thank you!

File output node only saves separate image files per frame. To make a a movie file you would need to add the frame seq to a VSE timeline and recompress. There is no built in way for Blender to achieve multiple movie exports from one scene. You could set up many VSE scenes with a image seq strip in each then perform a command line render of them.


text:
Compositor: File output with custom range
I would like to have multiple file output nodes in my comp scene and want to render seperate ranges for each node. Is this possible ?
thank you

Unfortunately no. You might be able to do something like what you want with multiple scenes though

Create a frame change callback and drive the mute of those output nodes with script:
import bpy

def frame_change_handler(scene):
    nodes = scene.node_tree.nodes
    nodes['File Output 1'].mute = not (15 < scene.frame_current < 50)
    nodes['File Output 2'].mute = not (45 < scene.frame_current < 55)

bpy.app.handlers.frame_change_pre.append(frame_change_handler)

Adjust the names of the nodes and the ranges like you want. You can also insert a driver to mute property in outliner dataview but such drivers on nodes do not update correctly, that's why it needs to be frame change handler.
If you need to change something in the script and want to re-run it call bpy.app.handlers.frame_change_pre.clear() in console first. Enjoy:)


text:
How to merge two sculpted meshes?
Is it possible to merge two sculpted meshes?
If you want to make a 3d printable mesh, you want to make it hollow... so you copy the mesh and scale it down, inwards. Then you make faces between those two meshes... Is this realistic to make with an complex sculpted mesh, or should this be done, before you make the complex sculpting? Or should I retopology?
Also I sculpted the face/head and the hair in two seperate meshes, also the eyes are seperate... how do I efficient merging all those meshes into one?
Many thanks and happy modeling :)

Not sure I follow you "make faces" bit. Hollow objects don't need to be filled with faces that wouldn't be visible from the outside anyway. When I want to make something hollow, I typically add a "Solidify" modifier (and apply it, if necessary).

I think I see what you mean. Once you have everything combined in a single mesh, you need to make sure that the normals of the internal mesh are pointing in, and the normals of the outer mesh are pointing out.

It's possible to use Sculpt Tools addon for that, see example video https://www.youtube.com/watch?v=LTQNGWawAwo

I think boolean should be preferred for joining for 3D printing

You may use a Direct Union option of a BoolTool add on.
Activate it in User Preferences (Ctrl+Alt+U).

In my case I have four objects with different vertex count. Some of them were sculpted, some of them not.

In Object Mode select all the objects and press Shift+Ctrl+Num+ (or press Spacebar and type 'direct'-->Direct Union).

After this operation you'll achieve a joined mesh ready for sculpting.

Well just for the 'merging two meshes'. The best way I found is:

Ctrl + J (join meshes)
on Sculpt Mode with F Snake Hook Brush, mix the extremes of the two meshes until you make a kind a "soup" with it
smooth it out with the F Smooth Brush.

When 3D printing a closed "water tight" object, don't worry about making it "hollow"  Just take your single, sculpted mesh, and export it as a stl.  The slicer program will fill this with a grid to support (this is what the infill % setting does).
If you really are keen making something "hollow", just copy paste, scale down a bit, and then boolean subtract.
If you are having with the boolean operation, I suggest you use the Remesh modifier first.

You can join multiple objects with Ctrl+J.

Just letting you know this was flagged as "low-quality because of its length and content."

My answer was flagged? Or the question?

The answer. It might have been an auto-flag because of it's length

I wouldn't flag it. But I tried it and I think it's not so good for 3d printing. The topology of the meshes isn't changed (I don't know if an export to stl gets them as one object) and you get faces in the inside, you don't want to print, because you can't see them. But I discovered the Boolean modifier with the Option Union, that does the trick.

Should I delete this answer then? I feel the question could be more concise, which would help make for a more focused answer.

That's also not the answer for this question, joining two objects into one won't merge them and doesn't do any good for 3D printing.

It is definitely possible! I had the same question.
To do so, you can use a boolean modifier to create a Union between the two meshes. The two meshes will join beautifully with no internal faces and you can smooth out the seams (may need to re-enable dynotopo) to create a single mesh. I got this information from the following youtube video:
https://www.youtube.com/watch?v=4-aQHMIYapI
Tested it in Blender 2.78 without issue. Make sure to move/delete the original piece you merged after applying the modifier.


text:
Boolean Modifier Union produces non manifold edges
I'm working on a sculpted model, that will be 3d printed...
the problem is, I had 4 objects (the head, the two eyes, the hair) and merged them with the boolean modifier Union... but if I check for non-manifold edges, it shows, that exactly those edges between the former seperate objects are now non-manifold.
How can I fix this in a fast way? because I need this model finished today...

Try to remove doubles in those areas and increase merge distance.

What do you mean with merge distance? Where should change those? And is there an automatic process to remove doubles? Sorry, I'm a noob

Right after you executed remove doubles, hit F6 button, or you will see the operator panel in the bottom left of your screen.

That may not solve your problem, because it's very hard to see what's going on in your model.

Suggestion. See tutorials on video sites on the preparation of models for 3d printing. Try simple examples of Boolean union to increase your understanding. There are many simple union examples where Boolean might not be the full solution to a specific need.  Extra work may be needed.  Boolean union does not always produce a single solid closed volume.


text:
Mirror-Modifier applied, but still mirroring
I made my first sculpt model and I used a mirror modifier. But then I applied the mirror modifier, because I got a strange edge on the mirror line in sculpt mode.
Now I modeled it, but it still mirrors the model, what in the beginning was good, but sometime I want to do asymmetrical things.
What did I wrong?
Many thanks for your help!!
Happy modeling :D

Does the answer on this question help? http://blender.stackexchange.com/questions/26165/proportional-editing-vertices-moving-for-no-reason/26167#26167

Does it mirror when you sculpt only? Maybe you need to disable the symmetry in tools tab?

Thanks, but I looked in the options menu there and the X mirror option wasn't checked, but the model still mirroring :/
Is this a bug? I would prefer, that I have done something wrong :/

@Highstaker You could add that as an answer to take this off the unanswered list.

Never mind... for some reason my browser didn't show Vince's answer.

@pgmath I wasn't sure if it was the case or not, and didn't want to get downvotes if I were wrong

@Highstaker  I just meant once the problem is established it's usually good to put the solution as an answer.  As an aside, a downvote should be just for a blatantly wrong or very poor answer, in a case like this it was a pretty likely solution so I personally probably would have posted it as an answer.  But that's just personal preference, some people like to clear it up in comments first.

@PGmath maybe I should be less humble then XD

You need to disable symmetry lock. It only happens in sculpt mode, the option to turn it off or on can be found under tools  >  symmetry lock.
Click the shaded option to disable, x by default.

Don't worry, you did nothing wrong


text:
Cloud texture type in cycles?
where to find the clouds texture type in node editor while using cycles? it is there while using displace modifier but not in node editor.

Cycles doesn't use the same procedural textures as BI. See the wiki for a list of Cycles textures. The noise texture should be pretty much the same as clouds.

thanks, so is there a work around if i want to use the cloud texture i used in the displace modifier as a base for my texture??

blender internal clouds

all default settings, shadeless material.
cycles noise

Niose texture Scale set to 8. All rest left to defaults. Cycles shadeless material, with a RGB Curves node to boost the contrast in the Noise Texture.

With those few settings changed you can get the cycles noise texture look very much like the blender internal clouds texture.

if only i was using simple noise, i m using voronoi f2-f1. i have been using multiple displacement. thanks for your suggestion.


text:
How to allow Rigid Body Physics take over after follow path constraint?
I'm trying to get a car to crash into a wall after a couple curves. I've followed Jonathan Lampel's tutorial on http://www.blender.org/support/tutorials/ which worked well using keyframes for animation. But is there a way to use the "Follow Path" Constraint and get the same effect? Or do I need to work in keyframes instead?
I move to frame 70 (when object reaches end of path), keyframed the animation check box, moved to frame 71, unchecked the animation and keyframed the checkbox again (like done in the tutorial). When I run the animation the object goes down the path like I want, but as soon as hits frame 71, the object disappears and reappears really far away and just falls forever.
Anyone able to help me out? Don't want to make the whole thing with keyframes but can do that if no better way.

At the frame before you want to switch from the "follow path" to rigid body, keyframe the "Follow Path" Constraint influence to "1" by hovering over the influence slider and pressing "i". Then go ahead one frame and set the influence to "0" and keyframe the influence again.
Then to do the same thing on the same frames to your rigid body. (I believe the dynamic checkbox controls the rigid body the same way the influence slider would for the "follow Path", but I'm not 100% sure.)


text:
How to stop a rigid body sliding
I have a car going down a slope and would like it to turn. It rolls nicely using rigid body constraints, but when I turn the front tires it just continues in the same direction like it is on ice. There is a little bouncing like the tires are trying to grab, but mostly has no effect.
To attempt to figure it out I upped the friction of the front wheel and ground plane to 10 million, steps per second to 600 and solver iterations to 60.
Any ideas of what I am missing? Thanks!

  The relationship lines show where the car started. The back wheels have a motor constraints which is pushing it quite nicely, just won't turn no matter what I do.

Is it possible you could upload the .blend?


text:
How to change initial angle of rigid body Hinge Constraint?
My scene is a toggle of sorts that a ball falls on. A rigid body hinge constraint allows the toggle to pivot and a limit within the constraint keeps it within about 25 degrees to either side.
I want the hinge/toggle to start to one side at the beginning of the simulation, but rotating it in object mode also affects the limits. How can I offset the initial rotation?
(Blender 2.80)

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


text:
Render points only if visible from another camera
I am trying to find a way to render only parts of the objects and scene that are visible from another camera. As an example, imagine I have two cameras pointing towards an object, the second making, say, a 45° angle with the first one. I want to render the scene from the first camera, and then render on the second a mask with only points that are visible from the first camera (like a visibility mask).
I can do this either using Nodes or Python (or something else). What I can think of now is :

something similar to the Node Light Path output Is Camera Ray, used as a factor of a Mix Shader in Cycles. However, I would like to use another camera than the one being used for the render.
In Python, I can render a depth map from the second camera, and then for each pixel, use the camera matrix and the depth information to backproject-it to a 3D point, and evaluate the distance of the first camera to that 3D point. If that distance is greater than the depth of the pixel on the first camera, I know that this pixel is occluded. So I would render it on the mask.

Is there any simpler way to do so ? Thanks in advance for your time !

All you need - projection mapping. Just put additional UV layer on objects which you want to control, add UV project modifier, and add new logic to material. Second camera projects normalized UV coordinates [0;1][0;1], but we can calculate if some point is outside and apply different material to it. Emissive like on first screenshot, or Transparent like on second one.

OK, lets get really freaky!
Of course, you have to render Z-channel to some EXR file (or sequence if you have an animation). Then add more to material: drivers to get camera position, math nodes to calculate distance for sampling point, and little more to avoid another reincarnation of z-fighting problem.
Just one fix to previous: that UV projecting produces "square", so you have to correct aspect (based on projecting camera render), it was 1080/1920=0.5625 to ScaleY.
I love Cycles magic!

Thanks a lot. This is a great way to use the UV map, I haven't thought about it.
However, this is only doing truncation of parts of the objects that do not project on the screen of the first camera. This does not hide in the second render portions of objects that are hidden because behind objects closer to the camera. Thanks again for your help

@DanilRomanov That's awesome ! You just converted the words to nodes :) And as I've read your cycles setup, it should work exactly as I want it to. Thanks really.

Hi, I've finally had time to test it for real. The problem is that I have trouble manipulting the UV Projector modifier. I've done everything as I should (with the simple first case for now testing UV against 0-1), and I can see the test does not work as expected - it seems like the projection is not working as expected, see image http://imgur.com/DTzjuLH and blend file :  (cannot upload EXR z image, but not useful for the simple setup). Can you find what's the cause ?

@DanilRomanov And I was using a square camera to avoid the scale effect in the scaleY of the projector. And thanks again for your help !

Sorry for the several comments, but the updated link for a more simple version of the image and blend files are here : http://imgur.com/9xHATtP and http://blend-exchange.giantcowfilms.com/b/532/ And the weird thing is that the same UV projector works with an orthographic camera. May be a bug, can someone tell me where to fill a bug request ?


text:
Is there a way to update a scene that's been added as a video strip?
You can add another scene as a strip in the video sequencer, but it does not update when the original scene is changed. The typical advice is to delete and re-add the strip when the scene is updated. This requirement doesn't make sense to me because there's no additional copy of the scene anywhere, so I'm not even sure how Blender is retaining the old data.
I've tried various "reload" options like Alt-R (reload strips) with no effect. Is there a way to make this work?

What specifically is not updated in your scene strip? If it is a length could be related https://blender.stackexchange.com/a/88298/2214 or Refresh All https://blender.stackexchange.com/a/149200/2214

@vklidu I think it's actually caching a proxy of the scene. If I make the scene strip long enough I can see changes update if I move far enough away on the timeline. But the proxy control that work on movie/image strips don't work on Scenes.

So your issue is that changes in 3D viewport are not reflected in VSE, right? Because what I tried right now Alt+R or Refresh all works for scene strip for me. So probably if you can open a new blend, setup vse and share with us if the issue persists. https://blend-exchange.com/ Thanks

Ok, I did not realize Alt+R operated on the selected strip. I thought it was a global operation, so I didn't have my strip selected when I tried it. Ctrl+E/Refresh All does work like I expected Alt+R to, I just didn't find it.

Consider to delete your Q, otherwise system will poke your Q in periods ... and since you solve it there is nothing to answer :) Thank you keep this site organised.


text:
Right way to stop export operator from saving with empty filename?
If I have a basic save/export operator like this:
class SaveData(bpy.types.Operator):
    bl_idname = "my.save"
    bl_label = "Save"
    filepath: bpy.props.StringProperty(subtype="FILE_PATH")

    def execute(self, context):
        do_save(ensure_ext(self.filepath, ".mytype"))
        return {"FINISHED"}

    def invoke(self, context, event):
        context.window_manager.fileselect_add(self)
        return {"RUNNING_MODAL"}

What is the right/idiomatic way to prevent that that from saving a file named .mytype if the user just hits Save without supplying a filename? This bad behavior appears to be common behavior among many Blender plugins (whether they give a Python traceback or save a .ext file just depends on whether they happen to call ensure_ext() or something similar)
What I have tried:

The check method is not clearly documented, but it appears to be for checking parameters before invoke, not after.
The execute method could check for empty self.filepath but I've found zero examples of that. This would occur after the file selector has closed, so it would require popping another modal to warn the user that nothing happened.
The native Save/Save As for .blend files aggressively puts .blend into the filepath if you try to clear it, so I guess technically you can't save with no filename, but it will happily write a file named .blend. There also doesn't seem to be any way to turn on that behavior for other file selectors.
The FILE_OT_execute (which is the operator for the Save or Load button in the file selector) has a promising property named need_active which looks (from reading the C source) like it makes the button do nothing in case no file is selected. But I don't understand how I would set that property because that is used internally by fileselect_add(). This behavior would match other Windows programs I've tested.

ImportHelper and ExportHelper mixin classes.
If you look at either the import or export operator templates in the text editor will see they use the helper mixin classes ImportHelper and ExportHelper
Here is the code for export helper from bpy_extras.io_utils  find it in the scripts/modules folder of your blender installation.
class ExportHelper:
    filepath: StringProperty(
        name="File Path",
        description="Filepath used for exporting the file",
        maxlen=1024,
        subtype='FILE_PATH',
    )
    check_existing: BoolProperty(
        name="Check Existing",
        description="Check and warn on overwriting existing files",
        default=True,
        options={'HIDDEN'},
    )

    # subclasses can override with decorator
    # True == use ext, False == no ext, None == do nothing.
    check_extension = True

    def invoke(self, context, _event):
        import os
        if not self.filepath:
            blend_filepath = context.blend_data.filepath
            if not blend_filepath:
                blend_filepath = "untitled"
            else:
                blend_filepath = os.path.splitext(blend_filepath)[0]

            self.filepath = blend_filepath + self.filename_ext

        context.window_manager.fileselect_add(self)
        return {'RUNNING_MODAL'}

    def check(self, _context):
        import os
        change_ext = False
        change_axis = _check_axis_conversion(self)

        check_extension = self.check_extension

        if check_extension is not None:
            filepath = self.filepath
            if os.path.basename(filepath):
                filepath = bpy.path.ensure_ext(
                    filepath,
                    self.filename_ext
                    if check_extension
                    else "",
                )

                if filepath != self.filepath:
                    self.filepath = filepath
                    change_ext = True

        return (change_ext or change_axis)

which as you can see sets the name to "untitled." if not set.
Check out the templates to see other properties that are used to extend this
# ExportHelper mixin class uses this
filename_ext = ".txt"

filter_glob: StringProperty(
    default="*.txt",
    options={'HIDDEN'},
    maxlen=255,

Also a files collection bpy/file browser: get selected file names where directory is used to designate the folder the files reside in.
Set custom location for import/export helper


text:
What is the advantage of separate line and fill layers in grease pencil?
The default 2D animation setup starts with one layer for "Lines" and one for "Fills". This feels like a traditional 2D setup where fills are behind the lines. However, it is also possible to use materials which are both stroked and filled, which achieves the same (?) result.
What are the advantages of the separate layer for fills? What are the disadvantages of using materials with both "fill" and "stroke" enabled?

Hello. I use separate layers and use separate materials as I like the additional control. I like to detail with a plain stroke and fill on the layer below. Using the fill on the same layer thins your strokes so it really needs to be on a lower layer. As you mention you can setup a stroke with a fill but that's only really useful when drawing closed shapes. Drawing unusual shapes can cause some freak results I find. Its also important to remember Blender layers items on 1 layer by the order they were drawn so the last fill then stroke will overlap previous strokes which for me is undesirable.

Good question. I never ever use materials with both fill and stroke enabled so to me a toggle switch would be just as good. But maybe the devs thought there could be cases where it's useful so left it up to the user?


text:
Using To Sphere with Mirror modifier enabled
I'm editing a mesh with a Mirror modifier on the X axis. I want to apply To Sphere (Alt-Shift-S) to points that lie on the mirror boundary. I expect the whole shape (the part I'm editing and the mirrored part) to end up more spherical.
Here's a picture. In the foreground is the result you get if you apply it to half of the sphere. You can see that the boundary points turned into a circle but actually pinched in a bit. In the background, I just applied the mirror modifier and then used To Sphere.
Is there some way to get the more sphere-like result without applying the mirror first? (Keeping in mind the actual mesh is much more complicated: I'm not trying to just make a sphere-ized cube).

Put the 3D cursor at the center of your object and select 3D Cursor in the Transform Pivot Point panel:


text:
Colour Bleeding
I have made this circle for an eye. I would like the white to fill the selected faces only, but for some reason it is going way beyond. Any ideas what I could do? Many thanks!

It doesn't look like these are vertex colors painted on the mesh. Are you sure you ask about vertex painting but not about materials or something else ?

Sorry yes, I meant materials... However, I have now made some proper eyes with globes now so the problem is somewhat solved in that sense... Thanks for your reply!

If the problem is solved you could add the exact steps as an answer to your own question to show that you found solution. It's a good idea to include some screenshots along with description in your answer detailing what were the steps you made.

What I mean is that I made my eyes differently so I did not actually solve the issue, I just used spheres and put them in the eye sockets like so: (http://i.imgur.com/aFa3FAu.png)


text:
Modified mesh loses changes when leaving edit mode
Apologies if this has been asked, but I couldn't find it anywhere. I'm using Blender 2.49b to change some head meshes for Morrowind, and they're already animated. The lips move and the eyes blink. I'm editing the neck, but every time I do and back out of edit mode, the changes revert. I figured the animations had something to do with it. Any help would be appreciated.

Please include a screen image.  Show the mesh and vertex groups and modifiers.  What you have stated above can be improved with more information.

screenshot
sorry about that. hope that's what you needed
this is what it reverts to after i back out to object mode. i had moved the vertices at the bottom of head mesh to line up with the neck

Any special reasons to use that quite old version of Blender ? Things have changed very much since then, chanses to face a bug in there are much higher.

i couldn't get blender set up to import nifs on the newer versions and it was driving me crazy. i found a download on the morrowind nexus that had everything i needed

Various Explanations for the behaviour.
Incomplete list follows.

Shape Keys.  If there are multiple Shape Keys present,  then you may end up editing a shape key whose influence is zero 0 or close to zero. Blinking eyes could be done with various animation techniques including shape keys.
Modifiers.  Shrink Wrap or Armature modifier can change the mesh shape. That is the purpose of such modifiers.  For example small edits might be completely dominated by a Shrink Wrap Modifier and thus not visible.

so, its defintely shape keys, but luckily there are only 3 of them. do i need to change the shape for each key?


text:
Multiple GPUs in AWS G2-8X LARGE I can only use 1 out of 4 GPUs
Using cycles on AWS G2-8X large which has 4 GPUs however cannot get blender to use more than 1 GPU at a time even though I can get it to switch between GPUs any suggestions? I have the latest drivers and versions

I know this question is pretty old but posting this in case anyone is having similar issues.
The question is a bit vague. I'm assuming you're using python script to call and render something in blender. I'm also assuming that you're using the following lines in the python script for setting GPU as the render device:
bpy.context.scene.cycles.device = 'GPU'
bpy.context.user_preferences.system.compute_device_type = 'CUDA'
bpy.context.user_preferences.system.compute_device = 'CUDA_0'

where the CUDA_0 means to use the first graphics card, CUDA_1 for second graphics card and so on. To make use of all the graphics cards, all you have to do is to modify the third line to:
bpy.context.user_preferences.system.compute_device = 'CUDA_MULTI_0'

Unrelated: If you want to see what all options are available for this setting in your current system, use the following in the python script:
print (bpy.context.user_preferences.system.bl_rna.properties['compute_device'].enum_items.keys())

Please note that if you give only this line in the script, it will show only 'CPU'. Make sure you set the render device to GPU using the code sample I've shared, and then use this line.

I believe it depends on how you are sending the rendering to the farm. This must be done via a script IIRC. Renderbot may have a setting to accommodate this as well.
Dalai's post illustrates the issue:
https://www.dalaifelinto.com/?p=746


text:
Points only camera calibration?
1) I have a photo of an object, taken at a specific orientation and position of my camera.
2) I also have a 3D model of that same object.
I need to be able to calibrate the camera in Blender (or some other software which would allow me to easily export the results back into Blender), using only several reference points (whose corresponding coordinates are known both in the 2D space of the object's photo, and in the 3D space of the object's 3D model) so that it precisely matches the physical camera's orientation and position (and Focal Length, sensor size, etc.) as seen in the photo.
What I've tried so far:

Doing it manually
Quite hard and I can never get it right
BLAM (the camera calibration tool for Blender)
It seems to work only with "perspective" lines, and it my case I can only use several (4, 5, 6...) "reference" points (see above)
Python script
It does a "brute force" space search through millions of possible camera positions/orientations and outputs an approximate orientation and position of the camera, which, allegedly, match the physical camera ones.

Is there a better/easier way to do this in Blender?
I guess this is what I essentially need to do, but rather without (the several views of) a calibration pattern (again - I only have the above described "reference" points in both 2D and 3D space and my object is quite "irregular" so that no vanishing points can be defined for it)
P.S. First time asking a question on SE, so please excuse me if I messed up somehow! :)

I'd suggest use blam, but without seeing the image it's guessing... If possible please add it to your question.

I can add an image, but just imagine a photo of a ball, with some kind of texture mapped onto it (mother Earth, for example! :) ). Now imagine that you have a complete 3d model of the ball (let's say you 3d scanned it), and a photo of the ball at a specific position and direction of your camera. Now, your goal is to determine these two parameters (the "extrinsic matrix", and possibly the "intrinsic matrix" as well) by specifying several reference points on the 3d model of the ball (on its texture somewhere) and the corresponding 2d points on your photo of the ball. How would BLAM help? Thanks!

Here an exact example of what you want
http://www1.cs.columbia.edu/~atroccol/3DPhoto/3D-2D_registration.html
The math broken down step by step
https://dsp.stackexchange.com/questions/1727/3d-position-estimation-using-2d-camera
If you need help with UI code, such as picking 3d or 2d points with a python modaloperator, I am happy to help with that.
EDIT:  I have made a partially working module
code:  https://github.com/patmo141/odc_public/blob/master/image_object_registration.py
blend:  https://www.dropbox.com/s/rqk9rrh9a4rw9ez/image_object_registration.blend?dl=0
https://youtu.be/Edk9uA5Yl5k
-Patrick

I have made a modal operator which stores points clicked on the 3dView and poitns clicked by the user in the image editor.  So the UI for this is done, just need someone (or for me to find the time) to dig into setting up the math.

https://youtu.be/Nc6myGYntpU


text:
Z-Pass to After Effects
How can I get the Z Pass from an animation to After Effects?
The normalize node is only usable for Stills, so that's not it.
The map value node seems to sort of work, but I find it pretty tricky to setup, and I would love to find a solution that can be setup within a few clicks.
Also, it would be great if the focus point can be controlled by an object(empty) this would normally be the focus object in the Depth of field panel, but I cant get it to work with the Map value node.
In our company we use AE for compositing, otherwise i would just use Blender.
Also, the Mist pass works great, also the way you setup the limits.    fortunately there is no way to turn of the Anti-aliasing.

You can output the 32-bit Z-depth plane to an EXR image, if AfterEffects can handle that.

I've tried using both the normal EXR and Multi-Layer EXR.
But i cant get any visual information from them in AE.
perhaps there is a trick to this i'm not aware of?

The information isn't visual - it's the distance in Blender Units from the camera to the object.  I've no idea how AE makes use of this information.

What do you mean by "The normalize node is only usable for stills"?

You need to work in 32bit depth in AfterEffects to use floating point zdepth hdr images. AE can utilize your hardware much much better for compositing work than Blender can and is much richer in tools to do so, no wonders your company uses AE.


text:
Set GPU using python script no longer working
We have our own render queue manager at work, and i use a python script to set the compute device of each worker to GPU.
However, with 2.79 the script no longer works.
Here is the script i use:
import bpy
bpy.context.user_preferences.system.compute_device_type = 'CUDA'
bpy.context.user_preferences.system.compute_device = 'CUDA_MULTI_2'

Pretty simple right?
But in 2.79 i get the following error:
AttributeError: 'UserPerferencesSystem' object has no attribute 'compute_device_type'

Anyone knows what changed in 2.79 that causes this error?

your error message says that you try to access 'UserPerferencesSystem' instead of 'UserPreferencesSystem' which seems to be a typo?

Changes have been made in the Blender API.
You can retrieve 'compute_device_type' and 'devices' via the cycles addon preferences
prefs = bpy.context.user_preferences.addons['cycles'].preferences
print(prefs.compute_device_type)

for d in prefs.devices:
    print(d.name)

And as of version 2.81, it seems like the Blender API has once again changed, because @pistiwique's answer doesn't work for me. You can now use:
# Set the device_type
bpy.context.preferences.addons["cycles"].preferences.compute_device_type = "CUDA"

# Set the device and feature set
bpy.context.scene.cycles.device = "GPU"
bpy.context.scene.cycles.feature_set = "SUPPORTED"


text:
Sculpting with Dynamic Topology, using Inflate Brush, blue Artifacts appear

I sculpted with Dyntypo enabled, but then there appeared those strange blue artifacts. If I use the smooth brush, it minimize the problem, but some artifacts stay.
Why does this happen? And how can I fix this?
Many thanks!
And happy modeling :)

Thanks a lot :)
I had strange bubbles of thausends of knoted vertices in the mesh, I don't know, how I have done this... At this stage i think it's the easiest to start new from scratch :D
But thanks a lot :)

There have been several bug reports posted on the tracker over the past couple years because of this.  Code-wise, nobody is sure how to fix it yet. :)

His brain exploded, its perfectly normal.

This is because of bleed through from the inner faces, facing the opposite direction. The darker color indicates the Normals direction. Try to never have interior faces near the sculpting surface while sculpting. If the hair is a separate object, you can completely remove inner faces, as they serve no purpose.

Notice that you will have to do this before you begin sculpting, as sculpting directly affects changes to the mesh. In order to salvage your mesh, you will have to just clean up as carefully as possible, using the Smooth brush and such tools.

Thanks a lot!
I ended up with strange bubbles of thausends of tangled vertices in the mesh... I don't know how I have done this by sculpting O.O
But I will start from scratch for the hair!
Thanks again, you are a lifesaver :D

No problem! I think the reason that the many bubbles were forming is that the previous strokes had made the two sides approach each other, and had subdivided them using Dynotopo, making it possible for the next action to affect both sides. However, the reversed normals (tells which way a face is facing) mean that the opposite side goes up instead of down, thus they intersected.


text:
Multiple UV Maps For 1 Object
I have a problem that is occurring when I try to add multiple UV maps to one object. When I select a vertex group and unwrap, it works fine, unwrapping just that vertex group to a UV map. The problem is when I select another vertex group and make a new UV map then unwrap, it unwraps that vertex group, but in the UV editor it still shows the previous unwrap in that UV map. I know that it is not just showing up because of "keep mesh in sync" because when I select the previous UV map, the vertex group from the UV map made after that one does not show up in the previous one. It seems every time I make a new UV map, the UV map from before automatically shows up in the new one, regaurdless of using a different texture. I am also making sure that I have just the faces that I want selected when I unwrap. Any help would be greatly appreciated.

You should keep one UV map, but create two materials. Assign the wanted faces to each material.

Blender allows multiple images to be assigned in one UV Map. If I'm not mistaken you want one set of UVs, just across multiple textures. To do this select only the faces you want to use a specific texture, and in the UV/Image Editor click the "browse image to be linked" rollout, and select the that texture.

This will map any faces you have currently selected to that texture in the "textured" viewport shading mode.
Alternatively, in the UV/Image Editor use "image > open image" to open an image file not already linked to the blender scene, or the + icon to make an internal image.
If you want to render this object or export it to another application, not just view it in the "textured" viewport, you will need to assign a material to your faces, and assign your texture to that material.


text:
How to create a node group with a custom node tree?
Is there a way to make node groups with a custom node tree? The option is grayed out in the node menu. I checked Sverchok's implementation, but it also seems like they don't support node groups.

No, as far as I know this is not supported yet, unfortunally.

sverchok has a node group  http://blender.stackexchange.com/questions/29226/how-to-group-nodes-in-sverchok

I can't figure out how to add sockets to the group inputs/outputs node in sverchok. The link didn't provide any instructions on how to use the node group after you create it. Anyway, I think I have an idea of how to implement node groups in custom node trees now. I'm going to try using node frames (bpy.ops.nodes.join) with custom operators that allow you to toggle between the frame view and collapsed view. Also, when creating the node frame, add an input and output node that can control the socket layout of the collapsed view.

Is this STILL not supported? I can't see a way to do it in v2.83.. There just doesn't seem to be a way for a custom tree to create a group?

There's a reference implementation for a custom Node Group for CustomNodeTrees, used in Lukas Toenne's object_nodes branch. While part of it is compiled, the UI is implemented using bpy's PyNodes ( A CustomNodeTree, same as Sverchok / AnimationNodes ).
If you are comfortable with Python then having a reference implementation may be enough, the whole concept is a little complex to try to convey as a single answer because it involves describing many sub problems. In short, it is possible, but it's not trivial. you'll have to deal implement a few things:

How does a node Group behave when copied/duplicated
Implement the code to generate a node Group from the selected nodes
Creating a NodeSocketInterface (What's that?!)

Most of these can be copied almost verbatim from the reference implementation but others will likely need some modifications to fit with your own CustomNodetree type.

Alternate implementation
In Sverchok we recently pushed a new group node implementation (codename Monads): see anything imported by /nodes/basic_data/monad.py. Warning, expect some complex dynamic programming.
It takes a slightly different approach, it is not final but includes a lot of the same functional Operators / UI behaviour:

socket recast
delete socket
rename socket
make nodegroup from selected.

I don't consider this a reference implementation, but it may be of some interest.


text:
How do i cut a black and white 2D image into a blender 3d object?
I want to cut this image
Into a 3D blender object, how do i do this?

I think you are asking about tehnique used in this tutorial - https://www.youtube.com/watch?v=pTfjrwYcY3g (if I understood correctly "cut"). You should create any mesh, drop all vertices and use Extrude tool by clicking LMB while holding Ctrl (you may also use curves in similar way). Then you should fill the faces between created edges (or  extrude faces instead).

convert it to a curve ( SVG from another tool)   then it would be easier


text:
How do you access the ruler?
No matter what I select or where I look I can't find the ruler anywhere. I'm using Blender 2.74, what am I doing wrong?

Open the toolbar in the 3D Viewport using T. Navigate to the Grease Pencil section and click the 'Ruler/Protractor' button. You can now click and drag in the 3D Viewport to create a ruler and or protractor measurement.

how to save this ?

@haidarvm how to save what . . ?

save the ruler so we can modiefied or render it ?

@haidarvm You can't turn it into a mesh or curve object as far as I am aware. You might be able to with some scripts

For those landing here after Blender 2.8 release: shift + spacebar + m. Or:

Plus: nice video (not mine) introducing how to use it: https://www.youtube.com/watch?v=OZECjQS5yVo

Thank you. I found the measure tool but wasn't able to accurately measure from point to point. Only after watching this video did I learn I was supposed to hold the ctrl button when clicking.


text:
Mirror modifier, but not quite. Is there a phantom modifier?
I need help, tried to google and seems I do not google the right keywords.
I need the thing like mirror, but not quite.
I want to mirror specific mesh object few exact places and edit the source mesh and see it reflected 3 other places.
Mirror modifier makes one copy - I need two, and each of them placed somewhere in space. I need that I can change position of each of the "phantom" meshes.
Is there such modifier or approach?
Any ideas much appreciated,

To make more copies with Mirror modifier add more Mirror modifiers. Modifier depends on object origin point (if with default settings) or Mirror object (if setting it in the settings). Change these and you will control behaviour of mirroring.

Perhaps linked meshes can help. You can duplicate object to share their meshes by pressing Alt+D

@HenrikD awesome, the one thing I needed. Thank you very much!

We'll start with this mesh (I extruded a face so it isn't symmetric):

Go to the object tab and add the object to a group:

Now, create an empty. Go to the object tab and set the duplication to the group you just created:

Now, to mirror the object, simply make the x-scale of the empty negative. It will become flipped. Since Blender is smart enough, the normals will be alright.

Now, you have a flipped copy of the object that will change if you change the original. You can repeat this if you need more copies, and you can position them as you wish:

Note that normals will look alright while actually not being. This can come up upon exporting or working with baking. It's best to apply scale which will freeze object transforms and inverted normals problem will become apparent

Duplicate your object using Alt+G to avoid creating a new mesh. Instead the same mesh data will be used and if you edit one you will also edit the other. You can also link mesh data between objects by selecting two objects and pressing Ctrl+L. Then select Object Data in the menu that appears. Or you could go to the mesh tab of the properties and right at the top select which mesh should be used by this object.