Shadow acne with PointLightShadowFilter

[codex128]

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.

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.

[riccardobl]

does this happen with both ANGLE and OpenGL backends?

[codex128]

Ah, didn't try that. I'll go ahead and set up an example app.

[codex128]

public class ShadowIssueApp extends SimpleApplication {

    private FilterPostProcessor fpp;

    static void main(String[] args) {
        var app = new ShadowIssueApp();
        AppSettings settings = new AppSettings(true);
        //settings.setFrameRate(0);
        //settings.setVSync(false);
        settings.setRenderer(AppSettings.LWJGL_OPENGL45);
        app.setSettings(settings);
        app.start();
    }

    @Override
    public void simpleInitApp() {

        GLRenderUtils.initialize(this);

        viewPort.setBackgroundColor(ColorRGBA.Black);
        flyCam.setMoveSpeed(5);

        viewPort.addProcessor(fpp = new FilterPostProcessor(assetManager));

        var level = (Node)assetManager.loadModel("Scenes/level1.glb");
        rootNode.attachChild(level);
        rootNode.setShadowMode(RenderQueue.ShadowMode.CastAndReceive);
        //rootNode.addLight(new AmbientLight(new ColorRGBA(1f, 1f, 1f, 1f).multLocal(0.2f)));

        for (Spatial child : new SceneGraphIterator(level)) {
            for (Light l : child.getLocalLightList()) {
                if (l instanceof DirectionalLight dl) {
                    createDirectionalShadows(dl);
                } else if (l instanceof SpotLight sl) {
                    createSpotShadows(sl);
                } else if (l instanceof PointLight pl) {
                    createPointShadows(pl);
                }
            }
        }

    }

    private void createDirectionalShadows(DirectionalLight dl) {
        // disregard this
        //shadows.addDirectionalLightSource(new Attribute<>(dl), 2048, 1);
    }

    private void createSpotShadows(SpotLight sl) {
        // disregard this
        //shadows.addSpotLightSource(new Attribute<>(sl), 1024);
    }

    private void createPointShadows(PointLight pl) {
        System.out.println("create point shadows");
        var shadow = new PointLightShadowFilter(assetManager, 2048);
        shadow.setLight(pl);
        //shadow.setShadowZExtend(0.1f);
        //shadow.setShadowIntensity(1f);
        //shadow.setShadowZFadeLength(1f);
        //shadow.setEdgeFilteringMode(EdgeFilteringMode.PCFPOISSON);
        //shadow.setShadowIntensity(1f);
        fpp.addFilter(shadow);
        //viewPort.addProcessor(shadow);
    }

}

Here's the model: https://www.dropbox.com/scl/fi/j2ixxydbxrd1sl1gcl9ek/level1.glb?rlkey=hs3668dnirer54qje2bq5o16f&st=8t1vo71m&dl=0

The problem happens on both LWJGL_OPENGL45 and ANGLE_GLES3 for me.