AddZColorShader.metal

gistfile1.txt

struct SceneConstants {
    ...
    float3 bottomColor;
    float bottomColorBorder;
  };
  
  vertex VertexOut vertex_main(uint vertexID [[vertex_id]],
                               constant VertexIn *vertices [[buffer(0)]],
                               constant ModelConstants &modelConstants [[buffer(1)]],
                               constant SceneConstants &sceneConstants [[buffer(2)]]) {
    
    ...
    out.color = in.color;
    
    if (distorted_pos.z < 0) {
      float4 diff = sceneConstants.bottomColor - in.color;
      float d = saturate(distorted_pos.z / sceneConstants.bottomColorBorder);
      float4 b = diff * d;
      out.color = in.color + b;
    }
    ...
    
    return out;
}