text:
Boolean Difference not showing
I know this is an often question. I tryed several solutions from other threads, but it didn't work so far. Also lots of shortcuts mentioned as solutions don't seem to work. Don't know if that's because of a different version, if the questions are older.
I'm very new to blender and did a tutorial to create a lion head. I wanted to cut a hohle in the back for wall hanging, bit the boolean difference does not work. The cutting of the back of the head was done in sculpt mode with the cutting box tool, as boolean for that also already didn't work. But maybe that created the problem?
The difference doesn't work on any other parts of the lion either, though.
I checked for manifolds. There was a tincy selection I deleted, but nothing changed.

As answer pointed out try switching between fast and exact solvers in modifier whenever boolean misbehaves

@BenedictsForester As my answer tries to point out, it is impossible to see if the modifier works or not in this screenshot, since the sphere is hiding the result.

The Boolean modifier has no shortcuts, unless you have the BoolTool add-on enabled. So for this part it's less a question of the version you are using but what add-ons you have enabled.
For your problem: sometimes the Solver set to Fast works better than Exact (although the name might suggest otherwise), have you tried this?
But: are you sure it is not working? Because the sphere object is set to be visible, so it will obstruct the hole created by the modifier. The BoolTool add-on automatically changes the visibility of the cutter object to wireframe or bounding box or whatever, so it does not obstruct the view.
The tool also has a destructive method where the modifier automatically gets applied and the cutter object deleted, which also gets rid of the sphere obstructing the view. But nothing of this happens automatically if you add the modifier manually, to see the effect you will have to either make the sphere invisible or apply the modifier and delete the sphere.
Boolean modifier with sphere visible in viewport:

Boolean modifier with sphere invisible in viewport:

I meant shortcuts for other things that were suggested as maybe solving the problem for other people. But I don't know if I was always in the right mode. I usually check that though, when it's not working.
As for my probem: I have tried fast mode, I have tried to apply, but nothing happens (I found an error note, though. It says: Modyfier disabled, failed to apply. Don't know where it is supposed to be disabled.)
Making the sphere invisible just makes the sphere invisible, no hole.

@Schneeleopard The error usually comes when a modifier is set to something which does not change anything on the object, for example when a Subdivision Surface modifier is set to Levels 0, it de facto does not subdivide anything so it is disabled. In this case, the modifier icon will show red. A Boolean modifier will show this message when no other object is selected, but this is not the case in your screenshot and the icon is not red either. So if it's nothing of that, I guess you will have to upload your file for further inspection - because in the screenshot everything looks fine.

OK, thanks for trieng to help. I ended up loading an older save file and for some reason boolean worked with that one. For both cutting the backside as well as putting a hole into it. I don't know what I did wrong the first time.

@Schneeleopard We would probably know, so it might still be interesting to inspect the file to avoid similar problems in the future.


text:
How to reset OpenGl for Solid lighting?
I read the original Reset OpenGL lights, I understand, but I don't do Python.
How would I "reset" my settings as shown?
I've had trouble with these forever, so my Solid lighting as I work is bizarre. Even with a new startup they're kaflooey.
Added bonus: How to "put back" the settings I have now if I screw up?

To see your current settings, Paste the first snippet into the text editor and press Run script. To reset to defaults, run the last snippet in the same fashion. To reset to the settings you printed before, replace the last three lines of the last snippet with the output of the first snippet and run it.

You can print the current settings to a console with a simple script:
import bpy

def round_vec3(vec): return tuple(map(lambda c: round(c, 3), vec))

solid_lights = bpy.context.user_preferences.system.solid_lights

for i, light in enumerate(solid_lights):
    print()
    print("Light %i:" % i)
    print("  Use:", light.use)
    print("  Direction:", round_vec3(light.direction))
    print("  Diffuse Color:", round_vec3(light.diffuse_color))
    print("  Specular Color:", round_vec3(light.specular_color))

Based on the settings for solid lights in startup.blend, here's a script to reset your current settings to the defaults:
import bpy

lights = [
    {
        'use': True,
        'direction': (-0.892, 0.3, 0.9),
        'diffuse_color': (0.8, 0.8, 0.8),
        'specular_color': (0.5, 0.5, 0.5)
    },
    {
        'use': True,
        'direction': (0.588, 0.46, 0.248),
        'diffuse_color': (0.498, 0.5, 0.6),
        'specular_color': (0.2, 0.2, 0.2)
    },
    {
        'use': True,
        'direction': (0.216, -0.392, -0.216),
        'diffuse_color': (0.798, 0.838, 1.0),
        'specular_color': (0.066, 0.0, 0.0)
    }
]

solid_lights = bpy.context.user_preferences.system.solid_lights

for s, l in zip(solid_lights, lights):
    for k, v in l.items():
        setattr(s, k, v)

If you don't want to deal with Python, just install this addon version of the script and click the Reset Solid Lights button in the User Preferences header (where the Save settings button is) while you are on the System tab:
bl_info = {
    "name": "Reset Solid Lights",
    "author": "CoDEmanX",
    "version": (1, 0),
    "blender": (2, 65, 0),
    "location": "User Preferences > System",
    "description": "Reset OpenGL Solid Lights to factory defaults",
    "warning": "",
    "wiki_url": "",
    "category": "User Interface"}

import bpy
from bpy.types import Operator

# OpenGL solid lights settings like in factory startup.blend
lights = [
    {
        'use': True,
        'direction': (-0.892, 0.3, 0.9),
        'diffuse_color': (0.8, 0.8, 0.8),
        'specular_color': (0.5, 0.5, 0.5)
    },
    {
        'use': True,
        'direction': (0.588, 0.46, 0.248),
        'diffuse_color': (0.498, 0.5, 0.6),
        'specular_color': (0.2, 0.2, 0.2)
    },
    {
        'use': True,
        'direction': (0.216, -0.392, -0.216),
        'diffuse_color': (0.798, 0.838, 1.0),
        'specular_color': (0.066, 0.0, 0.0)
    }
]

class WM_OT_solid_lights_reset(Operator):
    __doc__ = bl_info["description"]
    bl_label = bl_info["name"]
    bl_idname = "wm.solid_lights_reset"
    bl_options = {'REGISTER'}

    def execute(self, context):

        solid_lights = bpy.context.user_preferences.system.solid_lights

        for s, l in zip(solid_lights, lights):
            for k, v in l.items():
                setattr(s, k, v)

        return {'FINISHED'}

# Add button to user pref header (conditionally)
def userpref_button(self, context):
    if context.user_preferences.active_section == 'SYSTEM':
        self.layout.operator(WM_OT_solid_lights_reset.bl_idname)

def register():
    bpy.utils.register_class(WM_OT_solid_lights_reset)
    bpy.types.USERPREF_HT_header.append(userpref_button)

def unregister():
    bpy.utils.unregister_class(WM_OT_solid_lights_reset)
    bpy.types.USERPREF_HT_header.remove(userpref_button)

if __name__ == "__main__":
    register()

Not sure, but it could be that the OP isn't looking for a python solution. They said that they had already read this post..

Well, there's no alternative IMO. If you right-click and Reset to Default Value on the direction widgets, you'll end up with all directions set to Vector((0.0, 1.0, 0.0)). Colors reset to black. You probably don't want to create a new file derived from startup.blend to inherit the OpenGL solid light settings, then copy and paste all your stuff from the original .blend.

Added addon version of script to reset solid lights. Copy, paste to text file and save as .py script. Install via User Preferences > Addon > Install from file and enable. A new button will show up when you are on the System tab.

Using CoDEmanX .py script installed via UP>Addon>Install seems to have done the trick. Bravo!

There is also the quickPrefs in addons contrib that can change the GL lights to a list of presets including the default.

Have you tried changing these settings to get things looking the way you would like.
Click and drag over the spheres to change the light direction and click the color bars to activate a color selector popup.

I did know about these, and in prior versions did change them. But I longed for a reset/default after fiddling with them. Thus I'm now all set. Thx.

source: Stack Exchange

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

sort: votes


text:
Why Driver driven Node based material switch dose not reflect in 3D view?
I have used mix node to switch between materials in node editor and have used driver to control the switch. It renders properly i mean with correct material when switched but does not show in 3D viewport.

Switched

Why it dose not refresh in 3D viewport?

Probably a bug...

Dependency graph bug, if I recall.

@someonewithpc, NoviceInDisguise, Polosson, zeffii, SixthOfFour.
I am new to blender and can not understand whether something is bug or mistake. Thanks for clarification that its bug.
Now the question remains if some has found some hack to refresh the scene so that the right texture loads. It's very crucial for animation

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


text:
Can blend files be queued for animation rendering?
I would like to be able to render several files one after the other, when I am not using my computer, e.g. at night. Is there a way of doing this?

possible duplicate of Is there a way to batch render multiple scenes?

@Aldrik they are a bit different IMO. One is asking about different files, the other is about scenes in a file.

@iKlsR I did notice that, and it's normally good to point out the difference. But the procedure is much the same and both are covered by answers in the other question.

@Aldrik yes, we cannot help that, but for now, it's ok and best to keep them separate. We can't mark as dupe as the titles and intentions are different and we can't merge them because not all the answers apply to both questions.

I'm actually working on an application to do this.

Sounds like a job for Command Line Rendering. Sounds intimidating if you've never done it, but it's a simple matter of stealing someone's template and adjusting the parameters:
Windows: blender -b "C:\path\to\file.blend" -x 1 -a
Linux/Mac: blender -b "/path/to/file.blend" -x 1 -a
That's the simplest form of it which will use all the settings in the blend itself.
To make a cue of it, simply put '&&' between the commands:
blender -b "C:\path\to\file.blend" -x 1 -a && blender -b "C:\some\other\project.blend" -x 1 -a && blender -b "C:\yes\another\one.blend" -x 1 -a
To adjust settings like start and end frames, path of the outputed images/video, whether to render the animation or a single frame, check out the wiki page on Command Line Rendering.
It's also useful to tell it to shutdown your computer when it's finished simply by adding this at the end:
Windows: && shutdown /s /t 0
Linux/Mac: && sudo shutdown -h now
And here's one with start/end frame set, output path and format and shutdown when done:
blender -b "C:\En Passant\08-08\shots\s1\awake\awake.blend" -x 1 -o "C:\En Passant\bear_render\awake\img_#" -F PNG -s 119 -e 150 -a && shutdown /s /t 0
Note that if it doesn't recognize the 'blender' command, you just need to cd into the directory of the blender executable before it'll understand you. E.g:
Windows: cd "C:\Program Files\Blender Foundation\Blender"
Linux/Mac: cd "/home/user/Downloads/Blender"

All these commands are for Windows - if someone has the linux and mac versions please edit this answer.

thanks for that, yes it's intimidating. :) I used to program in Basic back in the early '80s and now I only use a Mac!

I think the commands work on Unix systems too, except, instead "C:\path" you write somthing like "/Users/[yourusername]/Path/To/File.belnd".

Yes, almost the same except for the commands marked "windows only" when you run blender --help

This appears to be what I'm looking for, I'll have to do some experimenting. Thank you.

Ok, now this one is driving me nuts! First I tried it in Terminal but it didn't recognise the 'blender' command so I typed in the cd "/etc./", as suggested, and the Terminal window changed its name to 'blender - bash'.
From here I was able to open Blender with a .blend file ok, so I quit Blender and tried again and got: -bash: blender: command not found. I tried removing 'blender' and got: -bash: -b: command not found! What am I doing wrong?? It could be the operating system - since I upgraded to OSX Mountain Lion, so many things have been going wrong! :(

in case the blender command is not in the system path, you have to enter the path to the application in the command, like /some/mac/path/blender.app -b etc etc.

also noting that the shutdown for mac and linux is not terribly useful, since you have to still be around to give the sudo password. Any solution to this, sudoing before the command is not an option, since it would run all the blenders as root?

@hjaarnio thanks. I tried that but still no joy! It seems that it does not recognise the 'blender' or the '-b' commands: command not found

In command line mode it seems to work even faster (approximately 30%).

@Brain totally depends on the scene, but it should never be slower.

https://docs.blender.org/manual/en/latest/advanced/command_line/ This should work..

The Brender renderfarm addon to Blender allows you to queue multiple renders, both from within the same file and from different .blend files. You can download the most recent version from this site.
The installation procedure is a little complicated, but once you have it set up, all you have to do is press the "New Job" button in the Render menu.

This looks great, although I must admit it looks a bit too advanced for me at this stage! :)

First see documentation on Blender from the command line
Once you can run blender --version. You can then setup a queue.
You only have to launch blender once, then pass it all the files you want to render.
blender --background foo.blend -a  bar.blend -a  baz.blend -a

This renders (foo.blend, bar.blend, baz.blend).
You can pass other arguments such as setting the output path or number of threads, be sure to position these after the blend file and before the -a.
This example uses the number system threads and reads to //path_to_render.
blender --background foo.blend -t 0 -o //path_to_render -a

I just finished writing a little Python app because I got sick of writing the same command line options over and over again to accomplish this.  Feel free to use it.
http://blenderq.readthedocs.io/en/latest/index.html

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


text:
What is the technical difference between an Ngon and a bunch of Triangles?
I read somewhere that Ngons were nothing more than triangles masked as an Ngon.
Some testing reveals this is not true, at least to some extent.
Here are two sub-surfed cylinders, one with an Ngon, the other with a Triangle Fan.

The things that look like 6 sided Ngons in the Triangle Fan example are really quads, and the cap on top is really a lot of tris:

As you can see, they are definitely different, but what is the difference technically?

in the first example there are still 6 sided ngons, the ones directly adjacent to the cap at the top.

@zeffii those are quads, I checked in edit mode.. I guess that is some error with object mode wire frame view?

This question is very generic - but you give a very specific example (Subsurf) which happens to treat ngons differently to many triangles (to be clear - differently to a triangulated ngon).
The answer is something like ... it depends: each modifier, tool, export-format and rendering engine can choose to use ngons / quads / triangles - differently. There are no fixed rules here, some tools triangulate internally to perform their calculations, others are able to handle ngon data.
Here are some general rules that mostly apply.

Rendering typically converts everything into triangles.
For OpenGL display, quads/ngons are also triangulated.
Some formats (OBJ, FBX for example) support ngons.
For Blender's tools - ngon support varies, but most tools support them.

Note that even in cases where ngons are triangulated, the normals from the ngons/quads are often used. So you may get a better looking model when smoothing is applied on the non-triangulated mesh data.

subsurf actually doesn't treat tri/quad/ngon differently. See my answer.

So it seems the answer to my question is, Ngons themselves are really ngons, but some tools/formats/etc. don't support them and they will be triangulated..

@Alistair Buxton, Think you misunderstood, added some clarification.

Subsurf does not treat tri, quad and ngon differently:

In each case the result follows exactly the same pattern:

Every edge is subdivided into exactly two edges.
Every face is subdivided into n faces where n = original number of vertices. Every new face is a quad.
A new vertex is created at the centre of the face. Every new face shares this vertex.

The difference in topology of the two results you showed can be more easily seen if we use simple subsurf (which does not smooth) and then apply the modifiers and look at the wireframes:

The result from subdividing the triangle fan has the extra edges (selected.) These extra edges are the result of subdividing the radial edges which connect the central vertex to the outside edges.
This does not demonstrate any fundamental difference between tris and ngons, because we can produce the same result using only triangles:

On the left is a triangle fan composed of three triangles. On the right our equivalent "ngon" is simply a normal triangle. The result of subdivision is different and follows the same pattern we saw before with the cylinders. The same results would be seen with a triangle fan composed of four triangles and a quad.
In general it's much better to think of tris and quads as special cases of the ngon than to consider an ngon a "bunch of triangles" like a triangle fan or triangle strip.

So if i understand correctly,  sub-surf seems to support Ngons, as it's different from when you sub-surf a triangle fan.. (it's not converting to tris before subdividing)

Yes, but even if it did convert the ngon to triangles first it would produce a third different result different to either of the results we have already seen. This is because triangulating an ngon will not produce the triangle fan that the cylinder tool does. Triangulating an ngon will not change the number of vertices, but the triangle fan has one more vertex (at the centre) than the equivalent ngon.

When you use N-gons you are essentially saying "I don't care how this geometry is arranged -- for now", and you relinquish control of the underlying geometry to Blender's tessellator. If you do an N-gon fill of a profile (edge-loop) you won't be able to control how faces are tessellated under the hood for display or rendering. If you need the N-gon to behave a certain way then you have to edit it manually, e.g., do a face-inset or convert it to triangles/quads manually to control the geometry.
See the example below:left side N-gon, right side underlying geometry that you don't have to worry about(until it becomes necessary).
.. or you may never be concerned about the underlying tessellation... or the final output may not be tessellated (in rare cases).
It depends on your use-case.

Your post makes the assumption that all n-gons will eventually be triangulated. While this is often the case its not necessarily true. You may output to a format that supports ngons, or you may perform some modifier that supports handling n-gons - or its even possible to render n-gons, though I'm not sure if there are any popular rendering engines that do this.

How do you propose I make this clearer?

Added note that final result may not depend on tessellation.

At the end of the day, it's all triangles - however the idea of NGons is an abstraction that helps the software deal with certain situations that come in handy when modelling (such as being able to slice a plane any which way you like, then extrude it)

This isn't always the case, some calculations are done directly on ngons (without triangulations). - booleans for example & some aspects of the knife tool.


text:
Why does Cycles sampling give diminishing returns?
This may seem like a obvious/basic question, but I am still curious, and I don't know the answer.
There will obviously be a big difference between an image rendered with a single sample and one rendered with 500 samples, but there will be a smaller difference between an image rendered with 1000 samples and 1500 samples.
What is the technical reason for this?
From what I understand of how cycles works, it fires one ray per pixel from the camera, which bounces and translates through objects at random angles.
It would make sense that samples would bounce in directions that have already been sampled, but I would think it would be possible to skip sampling "duplicate samples" by skipping bounces that are at a similar angle to previous bounces?

"skipping bounces that are at a similar angle" that would create banding, and would also just not be what you want.

@WChargin how would it create banding? (only skipping bounces similar to other bounces that occurred in the same pixel)

Sub-pixel banding, that is. You would have to define some threshold as "a similar angle." In reality, there would be slight variation (a gradual gradient) within that angle. As soon as you get out of that angle, you've jumped a bit, and there's a new color.

@WChargin I'm not sure I understand.. sampling the same bounce (angle) twice would not change the pixel, would it? so if you skip it it should not change it.

Sense the more samples, the more grainy it is, there would have to be a point in witch the human eye can not tell that it's grainy, so I would think probably not.

Cycles and all other path tracing render engines use Monte Carlo integration. The probabilistic error after N samples of Monte Carlo integration is:

This means that to halve the noise you have to take roughly 4x more samples.
Actually, we can do a bit better. You mention skipping samples in directions that have already been sampled, and we do this to an extent. Cycles uses Quasi-Monte Carlo integration, which means it uses a sequence of random numbers that is distributed well over all directions to avoid such duplicate samples.
Quasi-Monte Carlo has better convergence than basic Monte Carlo sampling, but it's difficult to quantify and depends on the scene and settings. The integral for global illumination is high dimensional which makes things quite complicated.
To halve noise you need somewhere between 2x and 4x more samples in practice.

  1500/1000 Samples is only 1.5 times more. 500/1 is 500 times more samples. It's the same with astrophotography. Several pictures are stacked to reduce noise in the picture and the improvement in quality is the square root of the amount of exposure time. That means if you want to double the quality, you have to quadruple the amount of data.
  Let's take a closer look at the numbers:
If we take the quality of 1 sample as a base, then 500 samples are sqrt(500 times the effort) = 22 times less noisy. If you now take 1000 as a base, then 1500 is 1.5 times the effort and only sqrt(1.5)=1.2 times better which I think fits the visual perception quite nicely.

It's not really a matter of how cycles works, more of a matter of logic. Think of it relatively, the difference between 1 and 500 is nearly 100% difference, whereas the difference between 1000 and 1500 is only 33.3% relative to the total. So logically, there won't appear to be as much of a difference.
However, developers recently implemented a "Square Samples" option (r58424):

With this enabled, all Sample values will be squared. So 10 Samples become 100 Samples.

Thus, by enabling this option, there is a much greater difference between sample count, and the difference between 1-500 (1-22 squared) and 1000-1500 (32-39) will be much closer together.

I think you meant that 500 is exactly 500% more than 1.

Not really. I meant is as a percentage of the total samples, though I can see how that's unclear

From a mathematical point of view, a cycles render would be a function which converges to an ideal soultion over time. So the more samples, the closer the render looks to the 'solution image', which would be the result with infinite samples thrown.

I don't think this actually answers the question about diminishing returns.


text:
How do I recalculate normals for all objects in the scene?
How do I recalculate normals for all objects in the scene? Normally, I select an object at a time, press Tab, press a to select all vertices/faces and press Ctrl-n. If I have 20+ objects in the scene, can do it in one hit combo?

No. You'll have to use python.

Here is a quick script to do this.


text:
Problems extruding a circle along circular path
I'm trying to extrude a circle along a circular path, ending up with a torus.
First, I added a Bezier circle centered at 0,0,0 and made it 10x10 in width and height (to form the path), then I added another circle, also at 0,0,0, and made it 2x2 in size.
When I select the smaller circle as the Bevel Object of the larger circle, the resulting shape resembles a swollen torus with a slight depression in the centre (where the hole would be) and becomes 20x20, larger than I expect.
I've tried positioning the smaller circle in different places, and at different angles before setting it as the Bevel Object, with similar results.
Any ideas what I'm doing wrong?
Here's an image of the two curves, then the end result:

Update
Just in case it helps anyone else, I think my problem occurred because I was scaling the larger circle (the path for the extrusion) via the Transform panel in Object mode rather than Edit mode.
Instead, if you add the (larger) circle, change to Edit mode and scale it to the correct size, and then change back to Object mode and set the Bevel Object, everything works perfectly.
Not sure if it's related, but a response on another site implies that you could also scale in Object mode, then Apply -> Scale, though this didn't work for me.

Because the OP wants a curve object. Adding a torus results in a mesh object.

This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post.

If all you want is a torus, then iKlsR's answer is the way to go.
To answer your question, it sounds like the beveled curve is only scaled in the X and Y axes.
To create a torus with a bevel object:

Add two Circle curves.
Set the bevel object of one curve to the other curve
Since the curves are both 2x2, there won't be any hole because the thickness (the diameter of the bevel object) is equal to the diameter of the main curve.
To fix this simply scale the curve set as the bevel object down.

Note that the location and rotation of the bevel object does not matter, so you could position the bevel object like this to prove that the thickness of the torus is equal to the diameter of the bevel object:

Thanks for this, scaling the object down does give me a torus. It does seem a bit hit-and-miss to make the object then re-size it though: I guess I expected the dimensions of the smaller circle to be respected in the cross-section. Thanks again.

@user2950747 They are. See my edits. Perhaps the scale of one of your objects is messed up in some way? Try resetting the scale on your main curve (Alt+S)

Thanks – just added an update at the end of my question. Think the larger circle's scale was messed up.

gandalf3's answer is the most likely answer and solution to the problem. Another thing you could try is shrinking the bevelled object with AltS. However, I see no advantages in obtaining a torus from curves that way. Why not just add a Curve > Circle and tweak the settings. To fatten, increase the depth and to get it smoother/rounder, increase the resoulution. Much easier to tweak and less work.

Thanks for the suggestion. That would definitely be easier (or even add a mesh torus), but I'd like to know why my approach produces unexpected results. If I can get that working, I've got a more complicated curve I want to use as an extrude path in the future.

@user2950747 Oh, thought you were just trying to get a torus from curves. Updated.

Just to add a tip here: the rotation of the Bevel Object is irrelevant; if you insist on rotating the Bevel Object circle a certain way, and then doing Ctrl-A "Apply" + "Rotation & Scale": then you might end up with Dimensions X (or Y) as 0 - in which case the beveled object will be "flat" and not "cylindrical". The fix is to restore the X and Y dimensions both to be different from zero.

I have found this old question searching another thing on the internet... Both other answers by gandalf3 and iKlsR are good and fit to the question. This is just a little complement.
The bevel object is extruded with its center following the main curve and relatively to its vertices positions compared to its own center.
For instance, you can obtain the torus by shifting the bevel circle inner geometry :

Grab Y moves the curve and grab Z seems to do "nothing" :

And a try about rotations :


text:
How to increase the scrollback history of the Python console/terminal within Blender?
How can I increase the size of the command history in the Python console?
The console options don't provide any option for doing this.
Like Maya's unlimited output section in the script editor.

You can do this by going to User Preferences > System and changing the value in Console Scrollback under the General category. It's set to 256 by default.

Anyway of setting it to unlimited. Plus, since it doesn't provide text area for increase the value to something extreme high, therefore unlimited, is there a way to programmatically change that value?

@BleedingFingers Some fields in Blender can be overwritten with custom values but others are built in such as this. One would also think that the limit (32768) is pretty much 'umlimited' in terms of history.

Coming from Maya I don't find that number quite high. Although it was quite easy to set it to that value.

What do you need such a large history for? If you really need it, increase the maximum value here: blender\source\blender\makesrna\intern\rna_userdef.c and compile

@CoDEmanX (You forgot the the @ ping ;)). 1). The software or its plugin starts malfunctioning, having the entire history would be quite helpful for inspection by the dev team 2). Scene file (GBs in size) gets corrupt, reconstruct as much as possible by evaling its content in pieces and have the peace of mind that nothing is lost is eaten up. 3). testing an intersection finding program on a large scene overnight, coming back to see if anything went wrong then what was the sequence of things and the traces. 4). Run a large loop on 4M edges and use the result for whatever reason.

@BleedingFingers: 1.) I doubt devs will be amused by giant logs 2.) Serialization of actions is not possible, but if all you do is to run Py code line by line, why don't you replace the execute operator shortcut to intercept it, log to an external file and call execute()?


text:
Why subdivided faces with smooth shading acting weird?
I have this model, and when I add the subdivision-modifier:

it seems to be okay, for me (I guess those bumps are there, because of the triangle faces instead of quads):

but when I add the smooth-shading I'm having this:

I think this is something really obvious -- but I just can't figure out the reason..
Thanks in advance,

The most likely reason for this is your object normals are facing the different directions at these edges. To fix, go into Edit mode, select the mesh and recalculate normals with CtrlN, Or you could manually select faces and flip the normals.
You can often confirm or investigate most most odd looking artifacts on your models by enabling a normal display type under Mesh Display in the Toolshelf (N). On a clean model, depending on the use case, both the vertex and face normals should point outwards.

Thanks, I figured out, a few minutes before you, although I started to flip the normals manually -- thanks for the global recalculate tip:)

Enabling backface culling is also a good way to quickly spot flipped normals.


text:
Understanding mirroring and inverting an object
When you look in the mirror you see your face flipped left to right. What you don't see is your skin turned inside-out. That would be horrific! Now if we take the gorgeous Suzanne (Monkey) and tab into Edit Mode, and then enable the Normal direction indicators:

we see all faces and vertices are facing outward:

Now, if I chop off half of the mesh, set the Pivot Center to 3D Cursor:

and select all A. Then duplicate shift+D and mirror ctrl+M along the X axis, the faces and vertices on the mirrored half are facing inward:

This could be a programing error, or a bug, or maybe theres a very good reason for it. It can be quite irritating to have to keep flipping the Normals:

I know that the Mirror Modifier doesn't have this problem, but what about ctrl+M, can anyone please enlighten me on this?

Very interesting, in emulating this, I noticed that if you mirror on the combination of any two axes the normals don't flip. Tick all 3 and it flips again. -- Also, doing this in object mode preserves the normals.

somewhat related: http://blender.stackexchange.com/questions/1020/how-is-the-normal-direction-determined-when-i-use-make-edge-face

The mirror tool (CTRLM) actually inverts the model by scaling it -1. This will flip the model, but will also invert the normals.
Here's what the docs say:

The mirror tool in Edit mode is similar to Mirroring in Object mode.
  It is exactly equivalent to scaling by -1 vertices, edges or faces
  around one chosen pivot point and in the direction of one chosen axis,
  only it is faster/handier.

I'm not exactly sure what the mirror modifier is doing, but I'm assuming it copies the vertices location along the axis and puts it in the negative location. Here's what the docs say:

The Mirror modifier automatically mirrors a mesh along its local X, Y
  and/or Z axes, which pass through the object’s center (the mirror
  plane is then defined by the two other axes).


text:
How do I measure a distance between two points?
I would like to measure the distance between the yellow points in this image:

How can I do it?
My goal is to cut the cube using the plane, but I must set a precise distance between the plane and the square's corner.

You can use the Ruler/Protractor. As of Blender 2.80 the operator was renamed to Measure but it acts like the same way. Good news is that the Measure tool is now directly accessible from 3d View as part of the main Tool Shelf (T) and via ShiftSpacebarM hotkey.

Measure (Blender 2.80+) vs Ruler/Protractor (Blender 2.79)

If you hold down Ctrl while dragging the second marker, the cursor should snap to the intersection point in order to measure the correct distance. With this you can also snap to the edge of the cube and set the desired length:

After that switch into Edit Mode and insert a new Edge Loop (Ctrl+R) into the right spot:

Note: For illustration purposes I've chosen Perspective Views, but Orthographic Views probably more useful to work with in this situation.

Thanks a lot @poor, I could not find the Ruler/Protactor tool first because I had an old version of Blender. So I downloaded the last one (2.72 version) and now it works perfectly ! What a useful tool !

I have a question. If I use ctrl+click I can snap second marker on a vertex. But I don't know how I can snap first marker.

If the section of the cut-off happens to be an isosceles triangle, you can simply use Bevel tool to "cut" precisely.

CtrlB to bevel selected edge;
Use Offset as bevel type, the amount is how much you want to cut off the edge.

If both lengths are different, you may consider manually translate or slide one of them after beveling.

Another way to do this precisely is as follow: (I'll try to make a text version asap)
Assuming you want different offsets for both sides, one is 0.5, another one is 0.3:

Another related answer is worth to read:
How to set a specific edge length numerically

Nice. Simple and easy, but it only works if both sides have the same lenghts. Although 2 lengths are shown in the picture it is unclear whether they are the same.

@poor see my updates. :)

Thanks a lot @LeonCheung, I'm not using the Bevel tool because my triangle isn't isoscele. The second method is very precise too and pretty straightforward. I finally used the Ruler/Protector tool and then added a difference Boolean modifier. It works fine.
Thanks again

Not related to the question, but how do you create those gif demonstration? Is there a tool in blender to do this? I find it incredibly useful.

@Gimly Blender has a built-in screencast recorder. After that, you can pick whatever frames you want  then edit in Gimp or PS, then merge and in other GIF software. I personally use GIF Animator. Hope it helps.

You could also do a Difference Boolean Modifier. It's fairly straight forward and useful for creating things like holes though solid geometry (windows is one good example).
The great thing here is that it can be done with a few clicks without taking into accounting measuring sides, just position the two objects as you want them to be.
Process:

Cube and Plane

Add Boolean Modifier and change to Difference, then select the Plane as the object to Boolean the Cube with. I had to flip the normal of the plane to get it to work like you want it to.

Apply Modifier and hide the Plane.

In Edit Mode enable Edge Info on the Mesh Display section.

Note: I rarely use the Boolean Modifier until after I'm finished texturing all objects in the scene. This is because the Boolean modifier preserves the Materials and UVs from both objects. This saves me some time because I don't have to spend so much time UV mapping complex geometry and can instead work with more primitive shapes and large, simple UV islands.

This isn't really answering the question as it stands, but method here could be useful to the op in addition to a measuring tool as the the plane can be moved even after the boolean modifier is enabled

Ah, I need to read more carefully. Either way, the options given in all the responses would work splendidly. As you say, the Boolean is mostly for adjusting geometry after measurement, alongside adding extra details to models.

Thank you @FSLuaGuy, I followed this method to cut the rectangle and it works perfectly! I also measured the distance between the rectangle's corner and the plane, which was my first problem, by using the Ruler/Protactor tool.


text:
How to move a complex object to the origin without destroying it?
I have a complex object far away from the origin of the scene itself.
If I mark all parts and use the Geometry to Origin function, the complex object gets crumbled, because all parts are set at the origin and the relations are destroyed.
Is there a way to move the object as a whole?
The object was an import from an STL file.

Go into edit mode, select all and press Shift-S and Cursor to selected.
Then go back to object mode, press Ctrl-Alt-Shift-C, Origin to cursor, and then press Alt-G (clear location).

If you need to keep the origin in the same place, you can select the object, press Shift+S > Cursor to Selected. Now press Ctrl+Shift+Alt+C > Origin to Geometry and then press Shift+S > Selection to cursor. You do not need to be in edit mode at any time to do this, and the origin will end up in the same place, just with the mesh centered around it.
Also you can just press Ctrl+Shift+Alt+C > Origin to Geometry or any of the other options, just this one command has the same result as Christy James process.

I do not have the option Origin to Center of Geometry

@Wandang It is just plain Origin to Geometry then, does the same thing

This is better than my answer actually, I thought that 'origin to geometry' and 'geometry to origin' did the same thing but backwards, but evidently not!

Add an empty ShiftA > Empty > Plain Axes, then position it at the proper position to your object with G.
Select all the pieces of your object, then select the empty last.
Parent the object(s) to the empty with CtrlP > Object.
Select just the empty and press AltG to clear the location, which moves it to the scene origin.

*Optional step* if you do not want your object(s) parented to a empty

Again select both the empty and your object(s), then press AltP > Clear and Keep Transformation. If you want to, you can now delete the empty.

Or, in edit mode, select all A
Shift+s > cursor to center
Shift+s > selection to cursor (offset)


text:
Is there a way to know camera information from an image (visually, without Exif data)?
I want to use photos in Blender, but I need to know camera information (sensor, focal, etc. for camera that was used to capture these photos), there is no Exif data inside these photos. I wonder if there is an equation or way to detect camera information visually (not exact, but near enough), depending on distance or perspective, etc.

You can get the angle of view with the Blam add-on
You can get them both (sensor size and focal length) at one time, but only the common factor of the equation.
With the mentioned add-on, that you can freely download, you are able to match the camera look starting from a bunch of grease pencil layers. If your photo has three vanishing points as the one below, you should provide three different layers, one per axis.

After that you can start the camera calibration with the button on the left, and you'll get the focal length value automatically applied to the active camera.

You can see from this quick modeling that the geometry is following the correct perspective deformation.

And even the length of the edges results in more or less the same as you expect from a cube.

Now comes the hardest part, as there is no uniform relation between the focal length of a lens and the angle of view, since the size of the camera sensor also determines the angle of view.
So in order to get the right value showed in the Exif data of the camera's focal length you must at least know the size of its sensor... (I may be wrong; there are a lots of things to consider. I hope someone who has more knowledge can help here. A related question is https://photo.stackexchange.com/questions/21616/how-can-i-calculate-focal-length-from-a-photograph).
Here's the scene after feeding the fields with the camera's real sensor size and focal length: the camera has to be slightly moved away from the subject to match the previous result.

Sorry, the properties panel is in my own language, anyway it's saying:

Camera Model NIKON D32000
Focal length = 38 mm
Focal length 35 mm = 57 mm
....

Image credits to Miguel Á. Padriñán, you can download it here.

BLAM is a fantastic add-on. :-) And you explained this well.

Thanks for your answer, I'm using this addon, but your answer was really helpful, ....thanks again


text:
How do I make an abstract 3D waveform-deformed surface?
I really like this 3D waveform-like approach for this logotype, and I want to create a mesh something like that. Any thoughts/tutorials/approaches I could use?

Proportional Edit of a moderately high density Cylinder with less extreme shape.  No Caps. Top extruded with loop cuts.  Consider Layers of these types of shapes.

Multiple Meshes.  Curve Deform and Proportional Edit.

This can be done using a Displace modifier.

Add a sphere.
Add a Displace modifier.
Create a new texture for it.
Choose the texture type "Distorted noise" and play with the options to get something you like.
Copy the Displace modifier and change the Strength and Midlevel for more sharper edges.
Add a Subdivision Surface modifier and set type of subdivision to Catmull-Clark (default).

I have a different method, and I think it will give you a better sense of control, but it will take some experimenting.

Add a Mesh >> Circle.
Tab into edit mode.
F to fill.
i to inset (Set amount to something like 0.1).
Repeat 7 times (Shift+R).
Now with the center ring selected turn on proportional editing and set the mode to random.
Pull the inner ring downward on Z (Adjust the strength with the scroll wheel on the mouse as desired.
change your proportional type to something like sphere or root, and scale, rotate, etc... (Have Fun).

NOTE:
On every one of these I applied a SubSurf Modifier, so if you are not getting similar results, it's because I left it out of the steps above. But you can add it at any time.

authors: Фантазер Петрухин


text:
How to join vertices of two objects
Is there is more automated and accurate way to connect two vertices of neighbouring objects?
I tried to move them manually, but it is a bit difficult to do it just in point.
I'd like to make flat and smooth faces for the bottom and sides. The top face is going to climb a bit to align with vertices of the other - higher object...

You can use Snap during transform tool set to Vertex.
Then you can snap directly one point to another or just choosen axis for example G > Z then hover desired vertices.
And if you want to trully connect them then you should have meshes joined and after Snap hit W and Remove Doubles.

Try different option as well like edge or face snap, it's really useful tool and if my answer was good enough, consider accepting it or/and upvoting ;)

After joining them, don't forget to remove the extra edges or at least the internal faces

Another option is to select the two vertices you want to connect/merge (you can use the circle select by pressing C or border select by pressing B) and then press Alt + M (shortcut for merging vertices).
Then choose where to merge - center of the distance between the two, at cursor or collapse (I am not quite sure what the difference is between collapse and center). There is no need to later delete extra vertices.


text:
Should I wait when Blender isn't responding?
By error I placed the angle of the smart uv unwrap to 1 and now Blender is not responding. I guess it calculates the uv. The problem is that I have a lot of unsaved changes on the mesh.
Should I wait it to come back to life or is there no point? Are there any possible solutions to save my unsaved data?

You can wait if you want, but it's probably going to take a long time before it will start responding. If you close it there is a way to recover you data; Blender autosaves your projects every 5 minutes, and you can change it if you want.
When you open Blender, go to 'File', then in the option, click 'Recover Auto save', wait for some time, and Blender will show all the autosaves it has taken according to the date. Click the unsaved projects, and save it when it opens.

In cases like this, I always look at CPU, RAM and HDD usage. Also I take into consideration the last task which I gave Blender to do. This helps me decide what's better: terminate Blender or wait.
There are no right answers that work in every case. All depend on the particular situation. In your case: how fast is your CPU, how much memory you have and how many vertices your model has (consider also subdivision modifiers).
PS: Here you can find three ways for recover your work:
Window close button [x] ignores changes

From experience, things like this (accidentally setting some setting to an insane value) will usually come back eventually, unless you run out of memory or blender crashes. Depending on what it is, on my machine these sorts of incidents are usually over within a few seconds, or perhaps a few minutes.
Only once or twice have I ended up giving up after letting it sit for a few hours.
However, you needn't wait around.
Open up a new instance of blender, click File > Recover Auto Save..., and try opening the most recent auto-saves (thumbnail view can be useful here). Chances are one of them is within a minute of the moment of disaster, and you can happily resume near where you left off.
See How to setup Auto Save? for more detail on the auto save system.

If you are loading a very large project onto blender, it may be best to wait for your output.
For example, i loaded 53,000 chunks of a minecraft world into blender, waited, and got my country loaded block by block.

It's a very particular situation. You gotta know what you did last and check the resource usage of blender.exe and see if the RAM getting higher slowly in small batches with CPU not that high. If it is, probably there some lazy-ass unoptimized script trying to calculate something not in the best way so you can wait in this kind of situations. But if your CPU and/or GPU all locked in high percentages you better unplug it right away because it's probably not worth it and you can go back and do it in a better way.
Like when you try to bool complex shapes with self enabled. It's like using 80s tech and almost like you can feel how script gets the vertices one by one and takes its time to calculate the new value. My setup is Ryzen9+RTX3060 but still having a lot of difficulties because of these neglected script pieces.


text:
How to cut a cube in half
I've had difficulty trying to cut a cube in half. I tried the knife tool at first, but that didn't work. I also tried using the loop cut too, but it just extrudes. I'd like to be able break it off into two entirely separate objects.

It is fairly simple, but it does utilize the obscure Rip tool (V). Here are the steps:

Tab into Edit Mode.
Key Ctrl + R and move the cursor around until the pink suggested loop cut is dividing the cube in half in the manner that you want it to (X, Y, or Z).
 LMB, then immediately  RMB to add the loop to the actual mesh. Make sure it remains selected; nothing else should be selected.
Key V to rip the vertices (opposite of Alt + M / W > Remove Doubles) and once again immediately  RMB. You should now have two identical copies of the loop cut that you previously added in the same place and one of them selected.
Key Ctrl + L to select the rest of one half of the cube.
Key P to open the Separate menu and select By Selection.
Tab out of Edit Mode. You should now have two identical halves of a cube.

The Procedure:

Edit (Optional Steps 6.5, 8, 9, and 10):
  6.5. Use Alt +  RMB to select the loop cut on the remaining half of the cube and key F to create a face.
  8. Select the other cuboid half and Tab into Edit Mode.
  9. Use Alt +  RMB to select the loop cut on the remaining half of the cube and key F to create a face.
  10. Tab out of Edit Mode.
Steps 6.5-10:

You actually don't need to use the Rib tool, seperating into different objects will automatically split the edges.

@Ezra Good idea!


text:
How can I hide hidden topology with a hologram shader?
I have a hologram shader that is mapped out like this in Eevee 2.9:

I've tried toggling Backface culling and other options. However, I still have a good of unseen topology being rendered through my hologram material:

How can I minimize this in the material?

Cycles
Light Path > Transparent Depth

Eevee
Material Properties > Settings > Blend Mode > Alpha Blend
Show Backface > OFF

Related https://blender.stackexchange.com/questions/15766/transparent-lines-for-a-hologram-like-effect

@Gorgious Thanks :) Updated.

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


text:
3D Mesh Vertex to 2D Pixel Coordinates
I can obtain the coordinate of a mesh vertex with python via
wco = mesh.vertices[mesh_vert_idx].co

Further, it is possible to convert this coordinate system to the camera system with
cco = bpy_extras.object_utils.world_to_camera_view(bpy.context.scene, bpy.data.objects['Camera'], wco)

But I am interested in the 2D position of the vertex in the image captured by the camera 'Camera'. In other words, is there a python method the projects the 3D point of the model to the 2D point in the image?


text:
How to model effectively using exact measurements?
I always struggle when trying to create a floor plan or furniture. How do I model using exact measurements.

If someone more experienced could elaborate on those tips: http://www.blender3darchitect.com/2008/07/tips-for-precision-modeling-with-blender-3d/ (shortcuts, maybe a few images) for recent version.

I think the (beginner) tag is meta, these are frowned upon for sites like these. Don't use any 'user' or 'question' level tags.

http://www.rab3d.com/tut_blender.php contains a tutorial which walks you through the creation of a (to scale) 608 bearing. While written for blender 2.49, the precision modelling guide is also worth a mention: http://www.rab3d.com/tut_blen_precision_guide.php

The absolute first step is to set the real-world units in the scene tab. This will make Blender's arbitrary units relate to something you can actually measure, like feet or meters.
Lines/Edges that Follow an Axis
You can click on a vertex, press E to extrude, press X, Y, or Z to choose the direction, then type in 1 and hit Enter. This will produce a line of length 1 (scene units) in that direction.
Lines/Edges at Arbitrary Angles
If your line needs to be at an angle, and you know how long it needs to be, then you could:

Create an edge with that length. Position the 3D cursor on one of
the vertices of the edge.

Set the pivot centre to be on the 3D cursor. (important)

Rotate the edge: (select the edge, hit R, hit (X,Y, or Z for axis) and type in the angle to rotate on that axis) , then Enter to finalize

Rinse and repeat until all axis of that edge are dealt with.

Extruding Edges/Faces
Edges and Faces can also be extruded and knowing how to do it can save you a lot of time:

select an edge or face, hit E and choose an axis using X,Y, or Z and type in the distance, then Enter.
Faces will start to extrude along their normal if no X,Y, or Z direction is given.

Directly entering coordinate values (global / local)
Get familiar with entering exact coordinates into this box. (found on the right hand panel, the N-panel). In Global mode when you change the position of a selected vertex using those fields then the coordinate will be relative to the world origin (0,0,0). When in Local mode the coordinate will be relative to the origin of the Object.

If the math is easy enough - also going X then Y is a possibility

After some research I found that there are options in in the transform panel (N) named Numerics. When Edge Length is ticked the exact measure is displayed in the viewport.

This only works in the mesh editing mode right?

@HRJ Yes, the edge length is only shown in Edit mode. The value is also in object-space -- meaning, if you scale your object and go into edit mode, the edge length will still be the same.
To measure world-space edge length you need to apply scale (Ctrl + A) (similar to "Freeze Transforms" in Maya).

Along with the default 'in Blender' tips already posted, there are several scripts/addons you can use to assist you too. The website Blender3DArchitect has alot of content tuned to this.
The addons are..
- EdgeTools (for 2.63 at the time of writing)

Edge Tools is designed to bring some CAD-style edge-based modeling
  tools to Blender. These tools are predominately inspired from several
  tools found in CATIA's "Geometric Design" workbench.

..More Info.

- Caliper

This addon incorporates the basic Caliper functionality of creating an
  object which displays the distance between 2 points in Blender’s 3d
  space and can be rendered. Then this functionality can be expanded
  with more detailed measurements and live updating.

..More Info.

I also wrote tinyCAD VTX (does: extend edge towards, project towards edge, and intersect edges) and also tinyCAD X ALL (does: intersect all selected edges)

I just tried your tinyCAD VTX, zeffii, and I have to say it is awesome.  It's just what I was looking for, but didn't even realize it.  Nice work!

The link to Caliper seems to be broken, I can't download from google code archive without some kind of user (with no obvious way of getting one)

@DanielVestøl Link has been updated, thanks.

To add to the other answers . . .
Another thing that you can do to help you model accurately is to use a unit system other than the Blender unit system. You could use the metric or imperial system. Doing so helps you to remember what distance means.
For example, instead of seeing 13.63 when using the BU system, you'll see 13m 63cm if using the metric system, and 44' 22" if using the imperial system.
more info here: https://blender.stackexchange.com/a/258/14

This is still a big problem in my world (CAD + BIM + CNC/CAM), and Included in this is a mix of metric & imperial.
So I have just learned to get practical about it.
For metric cases, its pretty easy, because default Blender units equate to meters.
AutoCAD for instance truly takes on a "None" unit, and if you model in inches or mm you just keep track of the 25.4 scale factor.
As far as this goes, I use these experiences to give me two major different answers inside the context of Blender.

I often import what I call a "Tape Measure Mesh" (I will explain it further down the page).
I also often model in my own psuedo-imperial system within Blender, get my whole scene done, then apply a global scale factor to it. Most of the time, I can get away with this method because coordinate systems are linear. Better yet for me, many times I don't have to care, because Blender is just the final resting place for the geometry.

Method #1:
For the first method that I mentioned ("Tape Measure Mesh"), Here's how I go about using it:

I Model a Large Column (A cube or circle scaled up the Z-Axis) to a known amount. Luckily for me, Blender makes this part easy, because I can just enter the math directly into the Dimension Fields: Here is what I enter

Starting with X & Y - I Enter: 24*25.4/1000
For Z - I Enter: 12*25.4/1000

Here's how the breakdown of what I am entering looks like (lets look at them all):
For X & Y my first number is my desired unit in imperial inches (24).
The scale factor from inches to mm is exactly 25.4 so we multiply this.
Because a mm is 1/1000 of a meter and the Blender units are in meters we divide by 1000.
So the format is always as follows:
[known unit in inches] * 25.4 / 1000
So now looking at my Z Value I'm changing the dimension to 1 Feet tall (1*12 = 12inches):
12*25.4/1000
Next:
I Apply the Scale to this Column mesh: Ctrl + A >> S.
I Enter Edit mode with this mesh selected using TAB,
I then add Loop Cuts to this mesh (specifically 12 of them). I do this by placing my mouse cursor over about the mid point of one of the four edges that run up and down the Z-Axis of the column mesh, and hitting Ctrl + R >> 1 >> 2 >> ENTER >> ENTER.
I then change my snap to Ctrl+Shift+Tab and Selecting Vertex on the menu that pops up. I personally Just hold Ctrl to temporarily activate snapping when I'm dragging, but if you wish to toggle it on and off use Shift+TAB.
The result is that I have a 1' Long mesh that I can snap to all the way down to 1" increments. Then I can Copy/Array them on top of each other for what ever height/width/depth I need.
I then Also copy this mesh and rotate them to lay down parallel to each of the horizontal axis' (X & Y) So I can snap my widths and depths of objects as well.
Here's what this method looks like:

Method #2:
Most times I use this because, I know that I can always globally scale all of this when needed.

NOTE: there is a drawback to this method!!!
  If you change the scale all of your objects globally later, your material scales may not automatically keep up, so keep this in mind and be careful. (This will largely depend on what kind of input coordinates you are using in your materials).

The easiest thing for me to do is to work in a decimal inch system, with one minor difference.
The difference here is that I move the decimal place over one.
So 1-1/2" would normally be 1.5 - In Blender I just enter it in at: 0.15
For 1-1/16" normally: 1.0625 - Blender: 0.10625
For 1'7-5/8" normally: 19.625 Blender: 1.9625
And so on...
The reason for sliding the decimal back 1/10 is because it keeps the default scene/camera comfortable without clipping, until you just get too big, but hey we all deal with that anyway when our scenes get large, and we adjust our camera's and views accordingly.
This method just allows me to work like I'm used to (in inches), without trying to line up to some mesh rig, or worry too much about the nuances of this while I'm modelling.
To apply the global scale when you are done, the formula used in method one is ever so slightly modified. It is as follows:
10 * 25.4 / 1000 = 0.254
To apply it, select all by using A then use S then type in: 0.254 >> ENTER.
Here's what the result of this looks like:

One note-worthy mention for method #1 here. You can create these in a file that keeps all of your standards and turn them into a group. That way when you need to use it in a new model you can use Shift+F1 >> Select Groups >> Pick your Group Name -  to append it into your active file. Once its inside your active file move the instance of it to a hidden layer, and add group instances of them as needed through the Add Menu.

If Group instances bother you, or hinder the snapping, you can always use Ctrl+Shift+A to 'Make Duplicates Real'. This will cause any instance that you did this to, to act just like when you originally created them. Just delete the Empty Objects they were attached to to clean up.

First determine your units in Properties panel > Scene > Units.
Use Grab or Extrude with x,y,z constraint and type your measurements and validate. You can also type in the transform panel of the properties shelf (3D window) but most of the time it is slower and less practical.
Use the snap tool in the 3D window header. Snap to increment can be really useful.

Like in real drawing, it can help and speed to draw construction lines. Sometime you can hijack some tools:
Use grid object as a template and snap.
In the special menu <W> use subdivide or merge at center to find some point.
The measure panel is more useful to check measurements than to draw exactly.

I know this discussion is old, but had similar problem, needed exact distance between a copied object and its original. Its possible to add operators (+,-) to existing position value.
Note: I am using the latest Sensei Format plugin, but operation most likely work without the plugin (have not tried that)

Set Units (Metric)
Go to local mode
Select object to copy
Press D to copy
Right-Click to exit move operation
Press N for properties
In the location properties panel you need (x,y,z) add an + or -
operator to the existing value, and will calculate the exact
position between two objects.
Eg: 44mm-10mm > press Enter

Hope this helps someone.


text:
Why are some buttons purple?
Basically to see this, all you have to do is hold down the d key and hover the mouse cursor all over a node or modifier and many of the active elements will change to a purple color.
This sometimes happens to me when I've been using the grease pencil to make notes and then move over some part of the UI quickly before I remember to release the 'd' key.
So what is this purple, and how can it be un-purpled?

Well, after doing some testing on this 'purple-controls' thing I started getting a message read-out at the top right statistics area.  A message prompt is showing up there and staying until I click on 1 of 2 choices that have something to do with a 'driver' error state.  So that much seems solved.  Purple fields would appear to be driver settings that are activated in a way that is similar to how keyframes are used to animate these values which then show up as yellow instead of purple.  I suppose this awaits confirmation, and also it would be nice to know how we get rid of this when it happens

By pressing D over an input field you are telling Blender to create a driver for that value. A driver is a way of controlling one value (the driven value) by another value (the driver). For example you  could drive the scale of one object by the rotational value of another.
To remove the driver you can either right-click on the value and choose 'Delete Drivers' or you could:
Navigate to the 'Graph Editor' from any screen area:

Change the view from 'F-Curve' to 'Drivers':

Shift select all the driven channels in the list and press X to delete them:

If you want to view and delete drivers for multiple objects at the same time make sure to toggle off the cursor icon which limits the view to currently selected objects:


text:
How to clear unused linked-data (libraries) quickly
I've got several assets files, which for some reason have unused linked-materials (from external other files). This results in a big list of useless "Libraries", visible in the Outliner, "Blender file" type of information.
I tried to delete the materials by hand, with Shift + Click on the "Unlink datablock" button, save the file, then reopen it, but materials are still there.

However, I tried to change the path of the linked libs by a non-existing file, directly in the Outliner, then saved the file and reopen it (twice). It worked. But too long and fastidious way to do that...

My question is : is there a quick way (with scripting or via UI) to auto-unlink unused things ?

Are you sure there aren't any 'fake' users - the F button next to the material name?

Yes I'm pretty sure... I added some images to the question to illustrate. BTW, the linked materials seems to have users. I guess it's the linked file's users, because in this scene there is no object who use those materials, just 1 object with the packed material ("Metal_Ancre").

Is there any progress with the script, is there anything so far, probably you Plosson are very busy I guess, I have similar issue - I would go forward, what you think, is there any possibility to change this path in .blend file direct in python, without opening in Blender. Cause in my case there is a kind of BUG which makes the .blend file crash on open.. What do you think guys?? http://blenderartists.org/forum/showthread.php?360517-Please-help

Hey @jay27flow and Ivaylo, the script I made to clean uninstanciated groups and their libraries is downloadable here. Use it carefully! Cheers!

Blender does not save unlinked datablocks. Thus linked datablock always has a user in the file it was linked from. To remove from your scene you must first click the make local button  and then it can be unlinked

Well, you're right, even if I knew it, I just realized that the users of those materials were some uninstantiated groups. By right-clicking on those groups in the Outliner, and choose "Unlink group" on each, then save, linked materials disappeared. Thx, btw!

Here's a script to auto-unlink groups that are not instantiated, and their libraries: http://www.polosson.com/public/scripts/AutoClean_groups.py.zip


text:
What is the Nested Animation time lines workaround?
File 1:

I create a blender file Name: Amenities
And i create 2 Animations

Animation 1 Tap scaling from 0 to 1 to appear and 1 to 0 to disappear. Between frames 1-100.
Animation 2 Water flowing down from a tap. Between frames 1-100. Water flows as particle animation (baked).

I group tap and water particle effect emitter as Amenities_Tap

File 2:
I have Some animation existing from frame 1 to frame 500. And i want to LINK Amenities_Tap group. And animation at frame 500.
PROBLEM 1 The animation of linked group plays between frame 1-100. But how do i make it play from frame 500?
How i am doing I am going to File 1 and offsetting animation to play between frames 500-600. And i come back to File 2 and update linked blend file and it works.
PROBLEM 2 It is becoming tedious to tweak animation timing in File 2
NOTE:

As Camera movement is continuous and part of File 2. So i cant isolate this and render separate and composite.

Even if i rig the Amenities, and LINK RIG and action file into FILE 2 and proxy it and apply action file. The particle animation plays only between frame 1 and 100.


text:
Create Kessler Syndrome in Blender?
anyone have a good process to create a earth/satellite debris field (aka Kessler Syndrome)?
Example:
https://www.youtube.com/watch?v=IOwv1j-fUbo&list=PLvjgztX_Uo3ZMUY9lGQZ6qIwZRiQw6LRR

Hello maybe check the particle boids?

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


text:
How to combine lighting while maintaining vibrant texture colours with toon shaders
I’m very new to creating materials in Blender and I’m trying an adaptive cel-shaded shader which allows me to change out material textures inspired by Borderlands 2 aesthetic.
I’m wondering if it’s possible to combine the lighting and hatching styles while also maintaining the colours of the materials?
From my limited knowledge, I believe the issue is with how I set up the texture by separating the RGB to create a 3-point lighting scene. The colours of the stylised materials are tied to these lights (which I don’t want), as this doesn’t allow for any room for changing the colour of the surrounding lights. The other extreme removes all of the vibrant colours and details out of the texture image to achieve the neon lighting and hatching.
Vibrant materials, but no neon lighting and hatching details:

Neon lighting and hatching details, but no material colours and minimal details:

Both this image and the one above use a marble texture seen in the first image in the top right
Separate RGB Node used for 3-point light:

Blender File: https://drive.google.com/file/d/1G34Ka-BzVFS3-j5UVxLtlGMTIOGUfG6V/view
Thanks


text:
How to save print-quality screenshots of the 3D view?
My question may look somewhat similar for the ones already answered on different forums "how to capture high resolution screenshots of blender"; although I don't care about the user interface at all!
What I want is only to create a screenshot of the 3D View itself with only a single object, that has a matcap shader turned on, with a custom resolution, eg. 4000px*4000px.
Is this possible? If not possible natively in blender, is there a non-photorealistic renderer that uses only a reflection map (matcap) to produce an image in custom resolution? (atm I could not find one)

NOTE: If a Python script is available for saving partial screenshots at a given zoom-level, one-after-another it also works, I guess. (at least when I want to capture the model in ortho projection).

Have you considered the OpenGL render? You can set the resolution in the render tab, then just click the render button in the toolbar at the bottom of the 3D viewport.:

It then renders an image of the viewport (without the grid) that you can save. It also works with animation.
The render anti-aliasing settings are used so for a higher quality result you can set it to 16, since its OpenGL the additional samples are typically still quite fast to render and help to give a smoother final image.
Here's a 4K render done with the OpenGL render:

I always wondered what OpenGL Render is good for.. well, it turned out again, Blender is simply the best. Thanks for the help!

Protip: if you want to keep the same render dimensions (e.g., 1920×1080) but just scale it up a bunch, you can enter values greater than 100% in the scale field. Just click it and type 500 and it'll be scaled to 500%.

Using the OpenGL quick render is the fastest way to go but blender can also use external matcap images as materials. Grab the ones Blender uses from the online repo here.
Create a new material and in the texture settings, load in the matcap image and just set Coordinates under Mapping to Normal. Set your viewport shading to GLSL to see these in realtime. This has several benefits such as being able to use multiple matcaps while still having the full internal renderer at your disposal.
More free matcaps here from zBrush's free library.

Render > OpenGL Render Image sounds like what you're looking for to me.


text:
How to rig a rotary counter?
I would like to know if is possible to create a simple python script to rotate these dials. What I want is something like this:
The first ring from the left is rotated around the Y axis by 40 degrees and when it reaches 40 degrees, the second ring is also rotated by 40 degrees and so on.
It could possibly be done with a Copy Rotation constraint but what i'd also like is to create a sudden shift of the dial every 40 degrees or so.

Drive rotation of Empty2 by the rotation of Empty1

In Properties panel (N to toggle):

Right click on Y-Rotation axis of Empty2 and select Add Single Driver.

In the Drivers section of the Graph Editor:

Add a variable yrot, set Object to Empty1 and type to "Y-Rotation".
Set driver scripted expression to: pi * ((180.0 * yrot / pi) // 40 * 10) / 180.0

This will give you an increase of 10° on Y-Axis of Empty2 for every 40° on Y-Axis of Empty1

Looking at your image you'd do this for the Y-Axis of your empties.
If you need increments of 10 on different rotation speeds, change the 40 in the above formula to i.e. 50
You can chain empties setup like this by making the next empty always driven by the previous. So the variable you add should be chosen from the correct object. The formula stays the same.
The main driving power behind this step-wise driving is the // floor division operator, which does integer division.

it works like magic

When I tried this it did not increment correctly. I am currently troubleshooting it and wondering: why is the number 40 given in your example? If there are ten digits (0~9) in a circular formation, and a 360 degree circle divided by ten is 36, should that be 36 instead? If you could explain a little more about how you got that formula it would be helpful.

Update: I got it working. In my case I changed the code to be: pi * ((180.0 * xrotone / pi) // 360 * 36) / 180.0   ...but I still don't know why. Anyway my blend ticks one numerical increment every frame, at 30fps. The tick rate and frame rate may come into play here. Also the orientation of the numbers on the wheel - do they increase rotating in from the top or bottom, etc. Because I think the rotation needs a positive value to work.


text:
How to create submenus with dynamic content?
I am trying to loop over all the cameras in my scene to populate a menu, and be able to access properties of each camera from the submenu of each menu item. For the minute, I'm just trying to get it to work with one property, the focal length:

I am able to loop over each camera and create a menu item by simply using the camera.name property in the text property of the menu item:
def draw(self, context):
    layout = self.layout

    for camera in bpy.data.cameras:

        row = layout.row()

        row.menu(CamerasSubMenu.bl_idname, text=camera.name)

However, what I don't really know how to do is make each submenu's properties relate to whichever camera I selected in the first menu. I managed to pass the camera_name to the submenu class with this in the last line of the camera loop:
CamerasSubMenu.camera_name = camera.name

And then access it with:
class CamerasSubMenu(bpy.types.Menu):
    bl_label = "Camera Properties"
    bl_idname = "view3d.camera_properties_menu"

    camera_name = bpy.props.StringProperty()

    def draw(self, context):
        layout = self.layout

        row = layout.row()
        row.prop(bpy.data.cameras[self.camera_name], "lens")

But the lens property (the focal length) is always the focal length of whichever camera name got passed in last in the loop, e.g. 'Camera.001'. So all submenus are accessing Camera.001's focal length instead of the individual focal lengths.
I presume I'm going about this completely the wrong way, but I attempted it in a similar way I would pass data to an operator (which works).
So, is there a way to have a unique submenu per camera or should I just try something completely different?
Full code:
import bpy

class CamerasSubMenu(bpy.types.Menu):
    bl_label = "Camera Properties"
    bl_idname = "view3d.camera_properties_menu"

    camera_name = bpy.props.StringProperty()

    def draw(self, context):
        layout = self.layout

        row = layout.row()
        row.prop(bpy.data.cameras[self.camera_name], "lens")

class CamerasMenu(bpy.types.Menu):
    bl_label = "Cameras"
    bl_idname = "view3d.cameras_menu"

    def draw(self, context):
        layout = self.layout

        for camera in bpy.data.cameras:

            row = layout.row()

            row.menu(CamerasSubMenu.bl_idname,text=camera.name)

            CamerasSubMenu.camera_name = camera.name

def register():
    bpy.utils.register_module(__name__)

def unregister():
    bpy.utils.unregister_module(__name__)

if __name__ == "__main__":
    register()

bpy.ops.wm.call_menu(name=CamerasMenu.bl_idname)

You are changing the class attribute (on line 29) and that changes it for all the instances. See: http://www.python-course.eu/python3_class_and_instance_attributes.php

@Jerryno I don't know if that solves my problem, but if it does it would be good to see that as an answer.

You can make each submenu have its own context by setting a variable in the UILayout.
The script can be made to work as expected with only minor changes.

Define a context member for each menu, using UILayout.context_pointer_set
In the menus draw function, access this variable directly.

Modified example script:
import bpy

class CamerasSubMenu(bpy.types.Menu):
    bl_label = "Camera Properties"
    bl_idname = "view3d.camera_properties_menu"

    # <-- Line removed (menu's don't store properties)

    def draw(self, context):
        layout = self.layout

        row = layout.row()
        row.prop(context.my_camera, "lens")  # <-- Changed from original

class CamerasMenu(bpy.types.Menu):
    bl_label = "Cameras"
    bl_idname = "view3d.cameras_menu"

    def draw(self, context):
        layout = self.layout

        for camera in bpy.data.cameras:

            row = layout.row()

            row.context_pointer_set("my_camera", camera)  # <-- Added to original
            row.menu(CamerasSubMenu.bl_idname, text=camera.name)
            # <-- Line removed (camera set above)

def register():
    bpy.utils.register_class(CamerasSubMenu)
    bpy.utils.register_class(CamerasMenu)

def unregister():
    bpy.utils.unregister_class(CamerasMenu)
    bpy.utils.unregister_class(CamerasSubMenu)

if __name__ == "__main__":
    register()

bpy.ops.wm.call_menu(name=CamerasMenu.bl_idname)

Thank you, that's brilliant. Had no idea about context_pointer_set


text:
Quick way to get current opened filename in a script?
I'm looking for an efficient way to get the current .blend file name, in a python script.
I know how to get its path, with bpy.path.abspath('//'), but it returns only the current path, without the file name. I'm sure it's possible, but I can't find out how.

It's in bpy.data.filepath.
This is the absolute path to the currently open blend file, see is_saved, and is_dirty too.

You can get the filename with bpy.path.basename(bpy.context.blend_data.filepath). This will return it as a string without the path attached. Use for Windows compatibility and some more info here.

If you run Python script directly from a Unix Shell with a Blender as interpreter you may use one of below:
#!blender -P
import os,sys

print("OS.PATH.ABSPATH(__FILE__): "+ os.path.abspath(__file__))
print("SYS.ARGV[-1]: " + sys.argv[-1])

os.path.abspath(__file__) will give you an absolute path (relpath() available as well).
sys.argv[-1] will give you a relative path.


text:
Rotating around two z axes
I have created two spheres (earth and moon) and am trying to get the moon to rotate around the earth and spin on it's own axis. I set the moons origin to the earth and got it rotate around but when I try to get the moon to spin on its own axis it rotates at odd angles when I render it, it is clearly noticeable.
Is there anyway to spin an object on two different z axis.(hope that makes sense) cheers.

You'll probably want to use an extra empty object that you rotate the moon around. That way you can rotate the earth and the moon independently from each other. Before starting, reset the origins of your objects (ShiftCtrlAltC).
To do so:

Start by adding an empty object in the same location as your earth object (you can snap your cursor to the earth by using ShiftS > Cursor to Selected)
Select your moon object, then select your empty and parent it (CtrlP). You will notice that you can now rotate the moon with the empty, but the earth rotates separately.
Rotate the earth at the speed you want.
Rotate the moon.
To make the moon orbit around the earth, rotate the empty.

If you want to make the moon orbit copy the speed of the earth, you can use a copy rotation constraint on the empty (you can also set the percentage of the speed by adjusting the influence).


text:
Offsetting animation
I have grouped together (CtrlG) aome animated meshes (9 of them) and I have used the graph editor (F-curve modifier) to cycle them through my animation but is there a way to offset them so they move at different intervals to create a more realistic effect. Cheers.

Are you wanting to offset the animation within a group instance? This is not possible.

Animate one of the objects. Then select all other objects, selecting the first animated object last (so that it's active) and hit Ctrl+L > Animation Data. This will make all those objects use the same "Action" for animation. Then in the NLA editor you can move these actions around per object to offset the animation.
Seems tedious, so there's probably an addon that does most of this stuff for you (?)

Another way. You can animate one of the objects, make it parent for the second, the second parent of the third....in the Properties Editor (Object Tab) of each child, check the Slow Parent option in the Relation Extras panel and type number in "offset".
An example: slow parent
Full tutorial and more: other link

Not quite animation offset, but still pretty damn cool.

You probably want to use AreWo and let the addon duplicate the object, if they're different you can change the mesh data after you're done. https://www.blenderdiplom.com/en/downloads/537-arewo-gui-a-detailed-description.html


text:
Can I use Cycles materials with Blender Internal?
Is it possible to have a mesh coloured and textured in cycles and then have it displayed in internal?
The only reason I ask is because I am building a log cabin and want to put some windows in. When I have done glass in cycles (Nodes) it looks much better (realistic) but when I try to do this and go back into blender internal to finish the rest of the log cabin off the window and the mesh surrounding the window becomes undefined and discoloured.
Is this because I am trying to put cycles into internal or because I am doing something wrong?

You can do something like what your asking with multiple scenes. Bear in mind, you will have a lot of extra work/tweaking/headaches when you have to adjust two scenes, but if it's necessary it's worth the trouble. Just link objects that shouldn't change between scenes (i.e. camera/lights)
Scene Setup

Create a new scene
Move your cycles object (the windows) to "Scene.001" (CtrlL > Objects to Scene > Scene.001 and and delete the object from "Scene")
Select "Scene.001" and go to the world settings:

Add a new world
Set your render engine to Cycles
Switch back to "scene". You should notice that the render engine will change between the two scenes.
Link your camera and lights to "Scene.001" (but don't delete them from "scene"). You can now move your camera and lights around and they will have the same location/rotation/scale in both of the scenes.

Render both scenes with transparent skies.
Compositing

Go to the compositor.
Enable Compositing Nodes
Add a new Render Layers node and select "Scene.001" from the drop down.
Add an alpha over node and plug them in so that one scene is on top of the other.

You will now have a Cycles object rendered in a Blender Internal scene.

you say render both scenes with a transparent skies, this is easy in cycles as the option appears but in internal how is this done? Thank you for the step through guide most helpful.

You can set it by changing the output RGBA, but it doesn't really matter because you'll be mixing the cycles scene on top of the BI scene.

@Lindsey, I added a relevant link as to how to do this.

You can't use cycles and blender internal materials in the same scene.
You can make a copy or link from the current scene, change render engine and materials in it and use the compositor to combine the two scenes. Adjusting renderlayers in the cycles one so that only the glass is visible, and hiding it in internal should be possible. You can have nodes of both render engines in the same material setup, but you need a scene for both engines to render both.

Actually you can assign materials for both engines in the same scene, using nodes. See this post by the Urchn studio for details.

@Aldrik, I know, you can't use them both at the same time though, which was the point here. Rewording a bit to make that clearer.

I had a similar problem, so I cobbled together a quick script.
I like my final renders to be in cycles, but I like to work in Blender Internal. The script swaps materials on selected objects. All materials named Cycles.whatever or GLSL.whatever will be replaced with the one appropriate for the current rendering engine. Note, this doesn't make the materials for you, just swaps from one to the other.
Takes more time up front, because I have to make two sets of materials, but it saves me a lot of time in the project because Blender Internal is so much faster than cycles and looks better during modeling.
# This script should go through all the materials in the SELECTED objects and replace them with another material (that you made) who's name is prefixed with Cycles or GLSL accordingly

# Switch the renderer, select some objects, then run this script.
# You'll need two copies of every material, one for cycles and one for GLSL.
# Just name the materials CYCLES.whatever and GLSL.whatever

# eg: Cycles.black.glossy <-> GLSL.black.glossy

import bpy
context = bpy.context # only selected items

print(bpy.data.scenes["Scene"].render.engine)

RenderEngine = bpy.data.scenes["Scene"].render.engine

if RenderEngine == "BLENDER_GAME" or RenderEngine == "BLENDER_RENDER":
    DesiredMaterialNamePrefix = "GLSL"
    UndesiredMaterialNamePrefix = "Cycles"
elif RenderEngine == "CYCLES":
    DesiredMaterialNamePrefix = "Cycles"
    UndesiredMaterialNamePrefix = "GLSL"

print("---------------------------------------")

mesh_objs = [ob for ob in context.selected_objects if ob.type == 'MESH']

print("Materials in scene")
print(dir(bpy.data.materials))

for mesh in mesh_objs:

    print(repr(mesh))

    print("active_slot:", mesh.active_material_index)
    if mesh.active_material is not None:
        #print("active_material:", repr(mesh.active_material) )
        print("active_material:", mesh.active_material.name)

    for materialSlot, mat in enumerate(mesh.material_slots):
        if not materialSlot:
            print("material_slots")
        if mat is not None:
            print("\t[%d] = %s" % (materialSlot, mat.name))

            # figure out if the undesired renderer is in the material name
            # if so, change the material to match the desired renderer
            # (but verify that the material actually exists before you try to make the swap)

            if (mat.name.find(UndesiredMaterialNamePrefix) != -1):
                print("Found material: ", mat.name)
                desiredMaterialName = mat.name.replace(UndesiredMaterialNamePrefix, DesiredMaterialNamePrefix)
                print("Change to: ", desiredMaterialName)
                print("finding material")
                newMaterial = bpy.data.materials.get(desiredMaterialName)
                if newMaterial is not None:
                    print(repr(newMaterial))
                    mesh.material_slots[materialSlot].material = newMaterial
                    #print(newMaterial.name)
                else:
                    print("No equivalent Material found for ", desiredMaterialName)

            elif (mat.name.find(DesiredMaterialNamePrefix) != -1):
                print("Found Desired Renderer: ", DesiredMaterialNamePrefix)
                print(repr(mat))
                print("No change necessary")

        else:
            print("\t[%d] is None" % materialSlot)

    print()


text:
Final render not showing full node setup
I am learning how to use the node editing but have come up with a problem. I have followed the instructions that were give on a tutorial but I cannot get the effect to work there are 2 effects that I want to appear in the final render but only one appears. Here is a screen shot of my node set up. If anybody knows what i have done wrong could you please tell me . Thank you. If you need any more information please just let me know. If I am asking wrong questions or asking for the wrong information i am sorry but I am new to this site and am just learning how to use the site properly. (larger image here)

I have tried attaching the compositor in different places to the star nodes and the nova nodes and i lose all effects. I have tried to place it at the end of the effects node frame as well but again I lose all effects, where it is placed now I can get the effect of the light in the star.

No worries Lindsey, we all try. Your questions are ok but can you please be as specific as possible when asking? For example, what tutorial? It makes it easier for us to see where you might have went wrong. Also, try to put all the information you think we need in the actual question and not in the comments. :)

If you haven't already, I would recommend reading the through the "Tips on asking Questions" (http://blender.stackexchange.com/help/how-to-ask) and the post on meta about what questions are off-topic: http://meta.blender.stackexchange.com/questions/1/what-questions-should-be-definitely-off-topic . The main thing to keep in mind when asking questions is "Can this be answered with solid facts?", if so, your question is probably valid. :)

Lindsey, based on the issue we spoke about in the chat, what you ask in the question and what you want are two different things. Please clarify it when you get the time, I also recommend that you rewatch the compositing part(s) of the tutorial.

I re-did the tutorial once again on 2.67b with no joy, then decided to do it on older version 2.62, to test, and everything worked fine. So I have reported it as a bug.

Looking at your node setup, I think it is because you have the wrong socket plugged into the Composite node. It should be coming from the same Add node that the Viewer node is also plugged into. Maybe you were testing earlier and forgot to change it back?
Also, you can enable Backdrop while in the compositor to update your changes as you work, this can save you the time of rendering everytime you need to try a certain setup or see changes.
See What is the difference between a Viewer and a Compositor node? for more information.

Thank you ikIsR I tried to plug the composite into the place that you suggested and I lost all of the effects again. Sorry for not mentioning the tutorial, it was http//cgcookie.com/blender/cgc-courses/creating-a-nova-explosion/ Sorry for not linking it but I don't know how to on a comment. Also when putting in a comment regarding the question I thought I had hit edit question. My aplogies

@Lindsey no worries. :) Can you attach the .blend to your question up above.

@ikIsR if you let me know how to attach blend file to a comment I will do so. cheers

@Lindsey you can use PasteAll.org. Just pack the blend file, upload it there and paste the link in the question so we can see it.

@iKIsR blend file uploaded but be warned uploading speed is slow so I don't know when you will be able to acces it. [http://PasteAll.org]

@Lindsey that 'link' is invalid.

[http://www.PasteAll.org/blend/supanova.blend]

let us continue this discussion in chat

@ikIsR thankyou i wil re-watch the tutorial and thank you for the help


text:
How can I move faces together in UV editor?
It is possible to move faces together, as solid island, but not as separated:

In sync mode.

Select more than one and then hit "g" to move them.

@BentleyCarpenter, I know this way.
Maybe I'm confusing something, but there was a case when the whole island moved when moving one face

There are a couple of ways to select entire islands for manipulation.
First, we could just select one face, then select linked, in the UV editor.  This will select all faces that are part of the same island.  Select linked, for me, is ctrl L.  (We could also sync our UV selection and select linked in the 3D editor, limiting by seams in the operator panel, if our seams represent our current islands.)
Second, we could island select mode.  Currently, we can see that you're in face select mode, with synced selection enabled.  If you disable synced selection, there will be an extra selection mode enabled, which is island selection mode.  In this mode, you can select and manipulate entire islands:

It it moves like one the left, but you want it to move like on the right, change Sticky Selection Mode in top-left corner:

If you just want to select more faces more easily, as Nathan says, hover over an island and press L or change selection mode to islands, or after selecting a single face, press Ctrl+ Numpad Add. If that still doesn't work, you may want to merge vertices (in edit mode in 3D viewport editor, not UV editor), by pressing A, M, B and maybe also F9 and adjusting distance.

Markus von Broady has the true-to-Blender answer. However, IMO, Textools is a must-have addon for UV unwrapping in Blender. Almost like Node Wrangler, like if you don't have that enabled then what are you even doing basically.
This addon comes with things like "Select By Island" as the default UV select mode.

Not to mention two dozen other awesome features built-in.


text:
How to iterate over custom properties?
I have a number of custom string properties that I added to my scene with:
bpy.types.Scene.prop1 = bpy.props.StringProperty()
bpy.types.Scene.prop2 = bpy.props.StringProperty()
# etc...

I want to be able to iterate over these properties to change their values.
I was hoping I would be able to do something like this:
for prop in bpy.types.Scene:
    prop = "new value";

This doesn't work but I would be iterating over all Scene properties instead of only mine anyway.
I also tried adding my properties' names to a list so that I might be able to access only my custom properties and not all the scene properties:
prop_names = ["prop1", "prop2", etc...]

But then I didn't know how to use these, I was hoping to do:
for prop in prop_names:
    bpy.types.Scene. + prop = "new value";

This also didn't work. So how might I achieve something like this?

There are a few ways to use Python to inspect an objects properties, but in this case you're best off using getattr, setattr.
In the case you describe I think the best option is to store a list of properties,
mainly because there isn't a good way to know which properties you created. (Blender doesn't track a properties owner).
for prop_id in prop_names:
    setattr(scene, prop_id, value)

... for completeness, to copy scene_src -> scene_dst
for prop_id in prop_names:
    setattr(scene_dst, prop_id, getattr(scene_src, prop_id))

Note, theres nothing spesific to custom propertes here, this is typical Python and world with any properties (called attributes in Python)

Thanks, but using seattr is currently reporting in the console that my property is read-only?

@Ray Mairlot, if you have read-only properties you need to either remove them from the list, or write more advanced code that handles them. For example bpy.data.Object.modifiers will report as readonly, not because you can't edit each modifier in the collection, you just cant assign the property directly, I assume you are getting this error on a Collection or PointerProperty. It would be best if you made a small example that fails for the purpose of this question.

I'm actually going to mark this question as solved, as your code does allow me to iterate over my properties as I wanted. I didn't realise having bpy.types.Scene.my_prop="new_value" after it's initial creation but before setattr would cause it to become read-only? I have now corrected this with bpy.context..instead of bpy.types.. but setattr makes this obsolete anyway. Thanks for your help.

@Ray Mairlot, not sure your understanding properties correctly? - but I think it would be best to ask this as a separate question. bpy.types.Scene.my_prop = "new_value" is not something your normally would want to do.

It was more a facepalm moment than anything else, I'm probably not aware of all the facts when dealing with properties, but I think my mind just went blank when I was trying to assign to bpy.types...not a mistake I've made before ;)