Dynamic paint dissolve time affects render result #42003

New Issue

gandalf3 · 2014-09-29T08:20:22+02:00

gandalf3 commented

2014-09-29 08:20:22 +02:00

System Information
Archlinux

Blender Version
Broken: 2.72 RC1

Short description of error

Cycles vertex color interpolation is not very smooth with fast dynamic paint dissolve times.
It looks better in solid view.

Exact steps for others to reproduce the error

Open cycles_vertex_weight_interpolation.blend.
Run the animation a bit.
Turn on rendered view. The interpolation isn't very smooth, even though it's smooth in solid view.
Set the dissolve time to 250 in properties > physics > dynamic paint advanced and re-run the animation.
Turn on viewport render. Now the interpolation is smooth.

**System Information** Archlinux **Blender Version** Broken: 2.72 RC1 **Short description of error** Cycles vertex color interpolation is not very smooth with fast dynamic paint dissolve times. It looks better in solid view. **Exact steps for others to reproduce the error** 1. Open [cycles_vertex_weight_interpolation.blend](https://archive.blender.org/developer/F113531/cycles_vertex_weight_interpolation.blend). 2. Run the animation a bit. 3. Turn on rendered view. The interpolation isn't very smooth, even though it's smooth in solid view. 4. Set the dissolve time to 250 in *properties > physics > dynamic paint advanced* and re-run the animation. 5. Turn on viewport render. Now the interpolation is smooth.

gandalf3 commented

2014-09-29 08:20:22 +02:00

Changed status to: 'Open'

gandalf3 commented

2014-09-29 08:20:22 +02:00

Added subscriber: @gandalf3

Sergey Sharybin was assigned by Bastien Montagne

2014-09-29 12:34:42 +02:00

Sergey Sharybin removed their assignment 2014-09-29 14:18:04 +02:00

Miika Hamalainen was assigned by Sergey Sharybin

2014-09-29 14:18:04 +02:00

Sergey Sharybin commented

2014-09-29 14:18:04 +02:00

Added subscribers: @LukasTonne, @miikah, @ideasman42, @Sergey

Sergey Sharybin commented

2014-09-29 14:18:04 +02:00

That's not an issue with cycles, it's something with applying the dynamic modifier to the mesh. That said, applying the modifier, then going to the vertex paint mode will give you the same "pixelated" result.

I'm not sure how this is intended to work, @miikah might know.

Also CCing @ideasman42 and @LukasTonne since they are also familiar with vertex color and physics.

That's not an issue with cycles, it's something with applying the dynamic modifier to the mesh. That said, applying the modifier, then going to the vertex paint mode will give you the same "pixelated" result. I'm not sure how this is intended to work, @miikah might know. Also CCing @ideasman42 and @LukasTonne since they are also familiar with vertex color and physics.

Miika Hamalainen commented

2014-09-29 14:40:38 +02:00

It's a Cycles "todo" sort of. Dynamic paint relies on vertex color alpha but Cycles is currently able to only access RGB values of vertex colors.

It's a [Cycles "todo" ](http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/ToDo) sort of. Dynamic paint relies on vertex color alpha but Cycles is currently able to only access RGB values of vertex colors.

Sergey Sharybin commented

2014-09-29 14:55:09 +02:00

@miikah, but shouldn't at least paint mode be correct then?

Miika Hamalainen commented

2014-09-29 15:03:49 +02:00

No, Vertex Paint mode doesn't use vertex alpha either and I guess thats why it doesn't even display it in the viewport.

IIRC, dynamic paint was first Blender tool to make use of the alpha component of vertex colors. Only then was support added for Blender Internal as well. Before that there was alpha component but it simply wasn't used for anything. I personally thought Cycles had vertex color alpha implemented already as it would be just matter of connecting the value to a node socket, but apparently not.

No, Vertex Paint mode doesn't use vertex alpha either and I guess thats why it doesn't even display it in the viewport. IIRC, dynamic paint was first Blender tool to make use of the alpha component of vertex colors. Only then was support added for Blender Internal as well. Before that there was alpha component but it simply wasn't used for anything. I personally thought Cycles had vertex color alpha implemented already as it would be just matter of connecting the value to a node socket, but apparently not.

Sergey Sharybin commented

2014-09-29 15:06:53 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2014-09-29 15:06:53 +02:00

Sergey Sharybin commented

2014-09-29 15:06:53 +02:00

Well, ok. Let's consider a TODO then. Thanks for the feedback and report.

gandalf3 commented

2014-09-29 20:12:48 +02:00

Then why does it kindof work with the slower dissolve speed?

Miika Hamalainen commented

2014-09-29 20:38:06 +02:00

@gandalf3 Hmm. I investigated the file a bit more and there are two things happening here:

First of all, your file works okay without dissolve because you have set white initial color for the canvas. That means from the first frame its solid white (1.0 alpha) and adding paint to it will create a mix of colors (without alpha changes) so it looks good in the Cycles render.

The confusing part here is that dissolve also dissolves the initial color. In your file it immediately dissolves canvas back to 0.0 alpha -> render fails. I suppose one could expect it to dissolve back to initial color, but the way it currently works makes most sense IMHO. At least as long as alpha was working correctly... :/

@gandalf3 Hmm. I investigated the file a bit more and there are two things happening here: First of all, your file works okay without dissolve because you have set white initial color for the canvas. That means from the first frame its solid white (1.0 alpha) and adding paint to it will create a mix of colors (without alpha changes) so it looks good in the Cycles render. The confusing part here is that dissolve also dissolves the initial color. In your file it immediately dissolves canvas back to 0.0 alpha -> render fails. I suppose one could expect it to dissolve back to initial color, but the way it currently works makes most sense IMHO. At least as long as alpha was working correctly... :/

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Dynamic paint dissolve time affects render result #42003