code: func (td *TrianglesData) Update(t Triangles) {
  	if td.Len() != t.Len() {
  		panic(fmt.Errorf("(%T).Update: invalid triangles length", td))
  	}
  	td.updateData(t)
  }
docs: // Update copies vertex properties from the supplied Triangles into this TrianglesData.
  //
  // TrianglesPosition, TrianglesColor and TrianglesTexture are supported.