Shadow caustics visible through colored glass has intensive, solid color for directional/sunlight and are probably too dark for spotlight/pointlight #100352

New Issue

Alex P · 2022-08-11T21:24:00+02:00

Alex P commented

2022-08-11 21:24:00 +02:00

System Information
Operating system: Windows 11
Graphics card: GTX 1070 Ti

Blender Version
Broken: 3.22 master
Worked: none

Short description of error
This happens when transparent object intersects with diffuse one and caustics are visible though volume. I know that MNEE doesn't work with volumes, but I think this might be a bug.
For directional light and sunsky system caustics are colored to pure red, green or blue or are just white. No other colors are possible. Spotlight and pointlight work, but color of intersected primitives differs substantially from not intersecting ones when looking thought them. This is especially visible on the left upper sphere that has only slight tint. Hope this is useful.

mnee nishita sunsky:

mnee directional light:

mnee spotlight:

Exact steps for others to reproduce the error

Create an object casting caustics like sphere over default cube.
Create transparent material for sphere that consists of two shaders, glass and volume, adjust volume color to something darker then white
Turn on caustics for light and for objects, render in viewport.
Move the sphere so it intersects with the cube, see the result.
Switch light into directional mode and try to adjust volume absorption color.

...or just open attached file and render. Lighting is set to nishita sky, but both spotlight and directional light are added and hidden.
mnee_test_master.blend

**System Information** Operating system: Windows 11 Graphics card: GTX 1070 Ti **Blender Version** Broken: 3.22 master Worked: none **Short description of error** This happens when transparent object intersects with diffuse one and caustics are visible though volume. I know that MNEE doesn't work with volumes, but I think this might be a bug. For directional light and sunsky system caustics are colored to pure red, green or blue or are just white. No other colors are possible. Spotlight and pointlight work, but color of intersected primitives differs substantially from not intersecting ones when looking thought them. This is especially visible on the left upper sphere that has only slight tint. Hope this is useful. mnee nishita sunsky: ![mnee_sunsky.jpg](https://archive.blender.org/developer/F13365545/mnee_sunsky.jpg) mnee directional light: ![mnee_direct.jpg](https://archive.blender.org/developer/F13365548/mnee_direct.jpg) mnee spotlight: ![mnee_spot.jpg](https://archive.blender.org/developer/F13365550/mnee_spot.jpg) **Exact steps for others to reproduce the error** 1. Create an object casting caustics like sphere over default cube. 2. Create transparent material for sphere that consists of two shaders, glass and volume, adjust volume color to something darker then white 3. Turn on caustics for light and for objects, render in viewport. 4. Move the sphere so it intersects with the cube, see the result. 5. Switch light into directional mode and try to adjust volume absorption color. ...or just open attached file and render. Lighting is set to nishita sky, but both spotlight and directional light are added and hidden. [mnee_test_master.blend](https://archive.blender.org/developer/F13365586/mnee_test_master.blend)

Alex P commented

2022-08-11 21:24:00 +02:00

Added subscriber: @Alex-9

Alaska commented

2022-08-12 01:18:21 +02:00

Added subscribers: @olivier.fx, @brecht, @Alaska

Alaska commented

2022-08-12 01:18:21 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Alaska commented

2022-08-12 01:18:21 +02:00

I can confirm there is some kind of issue goind on here. But I don't know if it's a limitation or not.

@olivier.fx or @brecht, are you able to comment on this?

Here is a video demonstrating the issue since I personally had trouble understanding the report:
Volume Asorption issue MNEE.mp4

I can confirm there is some kind of issue goind on here. But I don't know if it's a limitation or not. @olivier.fx or @brecht, are you able to comment on this? Here is a video demonstrating the issue since I personally had trouble understanding the report: [Volume Asorption issue MNEE.mp4](https://archive.blender.org/developer/F13366626/Volume_Asorption_issue_MNEE.mp4)

Zijun Zhou commented

2022-08-12 04:23:19 +02:00

Added subscriber: @Eary

Zijun Zhou commented

2022-08-12 04:23:19 +02:00

This is strange. AFAIK MNEE doesn't support volumes, so the cautics generated by MNEE should remain black and white regardless of volume absorption.

But the strangest point of all is that this is such a dim volume, the blue should look very subtle, but instead it is increadibly saturated. Just tried this with Path Guiding, and you can see the blue is barely noticeable:

This is just how dim the volume is, the fact that the saturated blue exists here is already strange.

This is strange. AFAIK MNEE doesn't support volumes, so the cautics generated by MNEE should remain black and white regardless of volume absorption. But the strangest point of all is that this is such a dim volume, the blue should look very subtle, but instead it is increadibly saturated. Just tried this with Path Guiding, and you can see the blue is barely noticeable: ![image.png](https://archive.blender.org/developer/F13367424/image.png) This is just how dim the volume is, the fact that the saturated blue exists here is already strange.

Alex P commented

2022-08-12 08:46:43 +02:00

@Eary @Alaska thank you! This PG version also shows, that MNEE floating cube doesn't cast caustics, but intersected one does. Let me know if this needs separate report.

Zijun Zhou commented

2022-08-12 10:14:26 +02:00

This comment was removed by @Eary

*This comment was removed by @Eary*

Philipp Oeser removed the

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Shadow caustics visible through colored glass has intensive, solid color for directional/sunlight and are probably too dark for spotlight/pointlight #100352