jMonkeyEngine / jMonkeyEngine/jmonkeyengine

Shadow acne with PointLightShadowFilter

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Java
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Description

I found that PointLightShadowFilter has some trouble with shadow acne in 3.10-beta1 (not sure about previous versions) when the receiving geometry is close to the light source and the camera is not close to the same geometry.

Image

Excuse the mess, I've got several shadow-casting lights here. :P
The point light is located one unit above the acne area (one unit = width of a beam here). I was able to "resolve" the problem by switching to PointLightShadowRenderer. SpotLightShadowFilter and DirectionalLightShadowFilter don't have this issue afaik. I don't have an example app to show right now because I've since moved on to a custom shadow implementation (jme's shadows have pretty bad peter-panning), but just say if you'd like me to try to reproduce the issue.

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by comparing PointLightShadowFilter with PointLightShadowRenderer, then investigate how the filter handles receiving geometry near the light source. Reproduce the reported shadow acne with geometry close to the point light and the camera farther away, and verify that the filter no longer shows the artifact without introducing the peter-panning behavior noted in the report.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
computer-graphics, game-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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