code: func (i *Image) QuadVertices(sx0, sy0, sx1, sy1 int, a, b, c, d, tx, ty float32, cr, cg, cb, ca float32) []float32 {
  	if i.backend == nil {
  		i.allocate(true)
  	}
  	ox, oy, _, _ := i.region()
  	return i.backend.restorable.QuadVertices(sx0+ox, sy0+oy, sx1+ox, sy1+oy, a, b, c, d, tx, ty, cr, cg, cb, ca)
  }
docs: // QuadVertices returns the vertices for rendering a quad.
  //
  // QuadVertices is highly optimized for rendering quads, and that's the most significant difference from
  // PutVertices.