anchor.diff:     List<double> positions;
      List<double> normals;
      List<double> texcoords;
  -   List<double> indices;
  +   List<int> indices;
      
      
      // fill cube vertex position
  
positive.code:      -1.0,  1.0, -1.0,   // index 23
     ];
     
     _gl.bufferDataTyped(wgl.RenderingContext.ARRAY_BUFFER, new Float32List.fromList(positions), wgl.STATIC_DRAW);
    
  }
  
  void onFrame(time)
  {
    
    _gl.viewport(0, 0, vpWidth, vpHeight);
    _gl.clear(wgl.RenderingContext.COLOR_BUFFER_BIT | wgl.RenderingContext.DEPTH_BUFFER_BIT);
    
  }
  
  
  void main()
  {
    
  }
negative.code: // index buffer
  wgl.Buffer indexBuffer;
  
  wgl.Program shaderProgram;
  
  int positionLoc;
  
  // uniforms
  wgl.UniformLocation worldMatrixLoc;
  wgl.UniformLocation cameraMatrixLoc;
  wgl.UniformLocation projectionMatrixLoc;
  void init()
  {
    glCanvas = document.querySelector("#drawArea");
  