[SOLVED] Vertex Color not set in standard shader vertex pass

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1

Hello there,

I’m trying to change the Z position of the vertices via the shader chunk “transformVS”. here is the slightly modified code:

#ifdef PIXELSNAP
    uniform vec4 uScreenSize;
#endif

mat4 getModelMatrix() {
    #ifdef DYNAMICBATCH
        return getBoneMatrix(vertex_boneIndices);
    #elif defined(SKIN)
        return matrix_model * (getBoneMatrix(vertex_boneIndices.x) * vertex_boneWeights.x +
               getBoneMatrix(vertex_boneIndices.y) * vertex_boneWeights.y +
               getBoneMatrix(vertex_boneIndices.z) * vertex_boneWeights.z +
               getBoneMatrix(vertex_boneIndices.w) * vertex_boneWeights.w);
    #elif defined(INSTANCING)
        return mat4(instance_line1, instance_line2, instance_line3, instance_line4);
    #else
        return matrix_model;
    #endif
}

vec4 getPosition() {
    dModelMatrix = getModelMatrix();
    vec3 localPos = vertex_position;
     
    #ifdef NINESLICED
        // outer and inner vertices are at the same position, scale both
        localPos.xz *= outerScale;

        // offset inner vertices inside
        // (original vertices must be in [-1;1] range)
        vec2 positiveUnitOffset = clamp(vertex_position.xz, vec2(0.0), vec2(1.0));
        vec2 negativeUnitOffset = clamp(-vertex_position.xz, vec2(0.0), vec2(1.0));
        localPos.xz += (-positiveUnitOffset * innerOffset.xy + negativeUnitOffset * innerOffset.zw) * vertex_texCoord0.xy;

        vTiledUv = (localPos.xz - outerScale + innerOffset.xy) * -0.5 + 1.0; // uv = local pos - inner corner

        localPos.xz *= -0.5; // move from -1;1 to -0.5;0.5
        localPos = localPos.xzy;
    #endif

    vec4 posW = dModelMatrix * vec4(localPos, 1.0);
    float zPosChange =  vVertexColor.x;
    posW.z += zPosChange;
    
    #ifdef SCREENSPACE
        posW.zw = vec2(0.0, 1.0);
    #endif
    dPositionW = posW.xyz;

    vec4 screenPos;
    #ifdef UV1LAYOUT
        screenPos = vec4(vertex_texCoord1.xy * 2.0 - 1.0, 0.5, 1);
    #else
        #ifdef SCREENSPACE
            screenPos = posW;
        #else
            screenPos = matrix_viewProjection * posW;
        #endif

        #ifdef PIXELSNAP
            // snap vertex to a pixel boundary
            screenPos.xy = (screenPos.xy * 0.5) + 0.5;
            screenPos.xy *= uScreenSize.xy;
            screenPos.xy = floor(screenPos.xy);
            screenPos.xy *= uScreenSize.zw;
            screenPos.xy = (screenPos.xy * 2.0) - 1.0;
        #endif
    #endif

    return screenPos;
}

vec3 getWorldPosition() {
    return dPositionW;
}

The interesting part is

vec4 posW = dModelMatrix * vec4(localPos, 1.0);
float zPosChange =  vVertexColor.x;
posW.z += zPosChange;

This sadly does not work. When accessing the vertex color in the chunk emissivePS it does work (and shows me the vertex color of my mesh), so the variable vVertexColor should be correct. Why is this not working? I really can’t wrap my head around it.

All the best
Johannes

2

Can you post a URL to a public minimal scene that shows the problem. It’s difficult to diagnose otherwise.

3

Hi @will, thanks for your answer. I actually found the problem: vVertexColor is actually the parsed variable from the vertex shader, in the vertex shader itself you can access the vertex color with vertex_color.

More documentation on shader chunks and the default variables of the Standard Shader would help a lot.

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