Instanced objects are culled when using WaterFilter

[foxcc2021]

It seems there is a bug in culling checks of instanced objects.

The tree model should not be culled.

The correct scene expected．

After some debugging, I found that, it seems the instanceCullingFunction used the wrong camera to cull checks in the InstancedGeometry。
Because the WaterFilter has a reflectionCam, the default camera will be replaced when waterFilter rendering.

I've solved my problem using this way,pass the render camera from the instanced node to the instanced geometry for culling checks.
Hope this can helps.

JME version:3.6.0-stable
System: win10

[foxcc2021]

The code in the InstancedGeometry I have modified in my project.

[Ali-RS]

I can not reproduce this issue, can you provide a simple test case demonstrating the issue?

Edit:
Btw, InstancedGeometry gets the camera passed in the checkCulling method:

jmonkeyengine/jme3-core/src/main/java/com/jme3/scene/instancing/InstancedGeometry.java

Lines 420 to 423 in 25a3407

	public boolean checkCulling(Camera cam) {
	this.cam = cam;
	return super.checkCulling(cam);
	}

it is called from the RenderManager that also uses the viewport camera

jmonkeyengine/jme3-core/src/main/java/com/jme3/renderer/RenderManager.java

Lines 791 to 794 in 25a3407

	// check culling first.
	if (!scene.checkCulling(vp.getCamera())) {
	return;
	}

[foxcc2021]

I made a video to show the issue.

https://youtu.be/fbHqHQu6js8

The simple test case is:

public class TestWaterAndInstanced extends SimpleApplication {
    
    public static void main(String[] args) {
        TestWaterAndInstanced test = new TestWaterAndInstanced();
        test.start();
    }
    
    private Box mesh;
    private Material mat;
    private InstancedNode instanceNode;
    
    @Override
    public void simpleInitApp() {
        flyCam.setMoveSpeed(10);
        
        DirectionalLight light = new DirectionalLight();
        light.setDirection(new Vector3f(-1, -1, -1));
        rootNode.addLight(light);
        
        mat = new Material(assetManager, "Common/MatDefs/Light/Lighting.j3md");
        mat.setBoolean("UseInstancing", true);
        
        mesh = new Box(0.5f, 0.5f, 0.5f);
        
        FilterPostProcessor fpp = new FilterPostProcessor(assetManager);
        WaterFilter waterFilter = new WaterFilter();
        waterFilter.setReflectionScene(rootNode);
        fpp.addFilter(waterFilter);
        viewPort.addProcessor(fpp);
        
        instanceNode = new InstancedNode("TestInstancedNode");
        rootNode.attachChild(instanceNode);
        
        for (int i = 0; i < 1000; i++) {
            Geometry obj = new Geometry("TestBox" + i, mesh);
            obj.setLocalTranslation(0, 10, 0);
            obj.setLocalScale(1, 1, 1);
            obj.setMaterial(mat);
            obj.setLocalTranslation(i, i, 0);
            instanceNode.attachChild(obj);
        }
        instanceNode.instance();
    }
}

[foxcc2021]

public boolean checkCulling(Camera cam) {
this.cam = cam;
return super.checkCulling(cam);
}

I think maybe the problem is with checkCulling method, cam will be replaced by reflectionCam of WaterFilter.
InstancedNode renders the instance object in its render method, but the cam has been replaced.
But I just found out, that there is something wrong with my solution, causing the whole InstancedNode to disappear.
It may need more research.

[Ali-RS]

Thanks for the test and video, I am going to try it soon.

By the way, you can also disable instance culling by setting InstancedGeometry.setInstanceCullingFunction(null); (note that this is a static method) and it should resolve the issue.

[foxcc2021]

Thank you!
Culling check of the instancing object is very useful for large scenes.
Hope it can be fixed.

[Ali-RS]

I can reproduce the issue with the test case you provided. Passing the camera from InstancedNodeControl as you suggested seems to resolve the issue.

Would you like to submit a PR?

[foxcc2021]

I did some more testing and "pass camera from InstancedNodeControl" seems to fix the issue.

But I just found out, that there is something wrong with my solution, causing the whole InstancedNode to disappear.
It may need more research.

Another problem seems to be related to my project only. I just copied InstancedNode and InstancedGeometry into my project and renamed them to "MyInstancedNode" and "MyInstancedGeometry" for testing, causing InstancedNode to disappear and I don't know why yet.

[foxcc2021]

Would you like to submit a PR?

I'm sorry, I don't know how to make the PR.