Smoke renders as transparent in OpenGL render #37834

New Issue

gandalf3 · 2013-12-16T21:05:42+01:00

gandalf3 commented

2013-12-16 21:05:42 +01:00

System Information
Archlinux
Nvidia 7900GT

Blender Version
Broken: Blender 2.69 Release (from arch repos)

Short description of error
Smoke appears transparent when rendered with the OpenGL render.

Exact steps for others to reproduce the error
Based on opengl_smoke.blend

Simulate the smoke
Render with the openGL render
Smoke is rendered as transparency

**System Information** Archlinux Nvidia 7900GT **Blender Version** Broken: Blender 2.69 Release (from arch repos) **Short description of error** Smoke appears transparent when rendered with the OpenGL render. **Exact steps for others to reproduce the error** Based on [opengl_smoke.blend](https://archive.blender.org/developer/F42191/opengl_smoke.blend) 1. Simulate the smoke 2. Render with the openGL render 3. Smoke is rendered as transparency

gandalf3 commented

2013-12-16 21:05:42 +01:00

Changed status to: 'Open'

gandalf3 commented

2013-12-16 21:05:42 +01:00

Added subscriber: @gandalf3

Thomas Dinges commented

2013-12-16 22:30:18 +01:00

Added subscriber: @ThomasDinges

Thomas Dinges commented

2013-12-16 22:30:18 +01:00

I cannot confirm this on Windows 7 x64 with Geforce 540M, both the smoke sim and the OpenGL render look fine.

Also looks fine on Mac OS X 10.9 with Intel Iris Pro.

I cannot confirm this on Windows 7 x64 with Geforce 540M, both the smoke sim and the OpenGL render look fine. Also looks fine on Mac OS X 10.9 with Intel Iris Pro.

gandalf3 commented

2013-12-16 22:43:11 +01:00

Here's a related post blender stack exchange .

Tested with an official blender.org build, still happens.

Here's a [related post blender stack exchange ](http://blender.stackexchange.com/q/5579/599). Tested with an official blender.org build, still happens.

Shane Ambler commented

2013-12-17 02:39:47 +01:00

Added subscriber: @sambler

Shane Ambler commented

2013-12-17 02:39:47 +01:00

I'm on FreeBSD -

While a smoke only sim renders fine, when the inflow is set to fire or fire & smoke it shows up as transparent in an opengl rendering. Be sure to update the cache or bake after changing inflow type.

Maybe this is *nix opengl issue.

I'm on FreeBSD - While a smoke only sim renders fine, when the inflow is set to fire or fire & smoke it shows up as transparent in an opengl rendering. Be sure to update the cache or bake after changing inflow type. Maybe this is *nix opengl issue.

Shane Ambler commented

2013-12-17 03:51:08 +01:00

This began in 2.67 - 2.66 did not exhibit this issue.

Looking more at this, what is happening is that the fire is cutting the alpha channel through the entire opengl render even the background. Like it's using the fire for a mask. The full colour exists in the rgb only display.

What I see is this

Steps -

Load Factory defaults
select cube and apply quick smoke
select original cube and change smoke inflow to fire
click opengl render

This began in 2.67 - 2.66 did not exhibit this issue. Looking more at this, what is happening is that the fire is cutting the alpha channel through the entire opengl render even the background. Like it's using the fire for a mask. The full colour exists in the rgb only display. What I see [is this ](http://www.pasteall.org/pic/show.php?id=64111) Steps - - Load Factory defaults - select cube and apply quick smoke - select original cube and change smoke inflow to fire - click opengl render

gandalf3 commented

2013-12-17 04:35:41 +01:00

Tested with different settings on arch.

Setup steps are the same as @sambler's:

Load factory settings
Apply Quick smoke on cube
Simulate to frame 30

With the flow cube set to smoke I see this:

For Fire+Smoke I get:

And for only Fire I get:

So it seems fire is okay, only smoke is rendered transparent.

In addition to sambler's note about masking anything behind the smoke, it even seems to mask object in front of it:

Tested with different settings on arch. Setup steps are the same as @sambler's: 1. Load factory settings 2. Apply *Quick smoke* on cube 3. Simulate to frame 30 With the flow cube set to *smoke* I see this:![examp10.png](https://archive.blender.org/developer/F42811/examp10.png) For *Fire+Smoke* I get:![examp11.png](https://archive.blender.org/developer/F42820/examp11.png) And for only *Fire* I get:![examp12.png](https://archive.blender.org/developer/F42822/examp12.png) So it seems fire is okay, only smoke is rendered transparent. In addition to sambler's note about masking anything behind the smoke, it even seems to mask object in front of it:

Paul B. commented

2013-12-17 10:29:46 +01:00

Added subscriber: @Paul.Brachmann

Paul B. commented

2013-12-17 10:29:46 +01:00

My system: Windows 7 Profesional x64, nVidia Geforce GTX 660

With the attatched file everything works fine.
Just when using fire or fire+smoke it renders some parts as transparent.

Smoke:

Fire:

Fire+Smoke:

I also noticed that the domain renders (if you set alpha to transparent) not transparent as it should. Instead it renders as a big black box:

My system: Windows 7 Profesional x64, nVidia Geforce GTX 660 With the attatched file everything works fine. Just when using fire or fire+smoke it renders some parts as transparent. Smoke: ![smoke.png](https://archive.blender.org/developer/F43292/smoke.png) Fire: ![fire.png](https://archive.blender.org/developer/F43294/fire.png) Fire+Smoke: ![fire_smoke.png](https://archive.blender.org/developer/F43297/fire_smoke.png) I also noticed that the domain renders (if you set alpha to transparent) not transparent as it should. Instead it renders as a big black box: ![domain_render.png](https://archive.blender.org/developer/F43306/domain_render.png)

Campbell Barton commented

2013-12-18 16:08:59 +01:00

Added subscriber: @ideasman42

Campbell Barton commented

2013-12-18 16:08:59 +01:00

Viewport rendering is convenient and using alpha can work too, but drawing volumetrics with correct alpha for opengl render is just not supported and its not needed for using smoke in the viewport.

The problem is caused by draw_smoke_volume Using glBlendFunc(GL_SRC_ALPHA, GL_ONE); but from what I can see this is needed to draw smoke correctly.

Closing, this as an unsupported feature.

Viewport rendering is convenient and using alpha can work too, but drawing volumetrics with correct alpha for opengl render is just not supported and its not needed for using smoke in the viewport. The problem is caused by `draw_smoke_volume` Using `glBlendFunc(GL_SRC_ALPHA, GL_ONE);` but from what I can see this is needed to draw smoke correctly. Closing, this as an unsupported feature.

Campbell Barton commented

2013-12-18 16:14:16 +01:00

Changed status from 'Open' to: 'Archived'

Campbell Barton closed this issue

2013-12-18 16:14:16 +01:00

Campbell Barton self-assigned this 2013-12-18 16:14:16 +01:00

blender-admin commented

2013-12-18 17:24:52 +01:00

This issue was referenced by blender/blender-addons-contrib@355c699dc6

This issue was referenced by blender/blender-addons-contrib@355c699dc6b6e95ef9305100a62efa7e70ae93ec

blender-admin commented

2013-12-18 17:24:52 +01:00