func (i *Image) Pixels() []byte {
	c := &pixelsCommand{
		result: nil,
		img:    i,
	}
	theCommandQueue.Enqueue(c)
	theCommandQueue.Flush()
	return c.result
}
func (i *Image) Pixels() []byte {
	c := &pixelsCommand{
		result: nil,
		img:    i,
	}
	theCommandQueue.Enqueue(c)
	theCommandQueue.Flush()
	return c.result
}
// Pixels returns the image's pixels.
// Pixels might return nil when OpenGL error happens.