code: func (t *Texture) SetPixels(x, y, w, h int, pixels []uint8) {
  	if len(pixels) != w*h*4 {
  		panic("set pixels: wrong number of pixels")
  	}
  	gl.TexSubImage2D(
  		gl.TEXTURE_2D,
  		0,
  		int32(x),
  		int32(y),
  		int32(w),
  		int32(h),
  		gl.RGBA,
  		gl.UNSIGNED_BYTE,
  		gl.Ptr(pixels),
  	)
  }
docs: // SetPixels sets the content of a sub-region of the Texture. Pixels must be an RGBA byte sequence.