anchor.diff:    // attribute vars
     // This should also contain an alpha channel
     aColors: new ShaderVarDesc("vec3", "per vertex color"),
  +  aColorAlpha: new ShaderVarDesc("vec4", "per vertex color"),
     aVertexPosition: new ShaderVarDesc("vec3", "vertex coordinates"),
     aTextureCoordinates: new ShaderVarDesc("vec2", "texture uvs"),
     aNormal: new ShaderVarDesc("vec3", "vertex normals"),
     aBinormal: new ShaderVarDesc("vec3", "vertex binormals"),
     aCenter: new ShaderVarDesc("vec4", "for wireframe"),
  +  aPointSize: new ShaderVarDesc("float", ""),
     
     iaRotatation: new ShaderVarDesc("vec4", ""),
     iaTranslation: new ShaderVarDesc("vec3", ""),
  
positive.code: // Used both as enum and as string. The latter allows for a limited form
  // of syntax checking inside shader programs.
  const String aColors = "aColors";
  const String aVertexPosition = "aVertexPosition";
  const String aTextureCoordinates = "aTextureCoordinates";
  const String aNormal = "aNormal";
  const String aBinormal = "aBinormal";
  const String aCenter = "aCenter";
  
  // Instancer
  const String iaRotatation = "iaRotation";
  
negative.code: 
      return out.join("\n");
    }
  }
  