Geometry Shader Lighting

[SpiderPig]

I'm getting mixed and seemingly random results with the lighting of my grass.  The line between light and dark moves with the camera.  This is what I'm passing out of my geometry shader to the default PBR fragment shader.  The grass is green as I'm setting the vertex color to green.  The fragment shader is just doing the lighting.  I've looked at the fragment shaders to see what it needed but might have missed something?

layout(location = 25 ) out uint outEntityID;
layout(location = 5 ) out flat uint outMaterialID;
layout(location = 8 ) out vec4 outVertexPosition;
layout(location = 1 ) out vec3 normal;
layout(location = 7 ) out vec4 worldPosition;
layout(location = 0 ) out vec4 vertexColor;

First it was this;

Now at random it is this;

 

[Josh]

Here are the inputs for the lighting function:

RenderLighting(material, materialInfo, vertexWorldPosition.xyz, n, v, NdotV, f_diffuse, f_specular, renderprobes, ibldiffuse, iblspecular);

 

[SpiderPig]

Oh, that reminds me.  Inside that function in Lighting.glsl, RenderLight() was using the input vertexWorldPosition rather than the argument "position".

RenderLight(lightIndex, material, materialInfo, vertexWorldPosition.xyz, normal, v, NdotV, f_diffuse, f_specular, renderprobes, ibldiffuse, iblspecular);

I thought it should use the argument 'position' seeing as it is passed to it but not sure... I don't know if it's something the user could end up editing in the UserFunction?

[Josh]

You are correct, but since that was the variable being passed to the function anyways, it won't make any difference.

[SpiderPig]

Just thought I'd check.

If I turn off Image Based Lighting I get a darker grass but no more artifacts.  Not sure if that's the cause or it's just hiding it. 

EDIT: I think IBL is the cause, though I have no idea why.

[SpiderPig]

Hmm, actually I don't think my normals are right... I'm multiplying the local vertex positions by a local matrix to rotate the blades but the normals are unchanged.  Can I rotate normals by multiplying by the same matrix as I do the vertices?

[Josh]

You need to multiply normals by a 3x3 matrix, not a 4x4.

[SpiderPig]

That seemed to have done the trick.

[havenphillip]

That looks rad.

[SpiderPig]

It's a bit slow using the geometry shader.  FPS drops from 800 to 300.  I think compute shaders might help here.