I wish to draw an image to the screen, but I also want to adjusts its alpha value’s with a slider control.
I am using OpenIL so the Texture is loaded and passed to Opengl without a pointer to the textures pixels.
Is the best and most efficient way to do this:
use glGetTeximage to get a pointer to the pixels of the texture.
then manually manipulate the pixels alpha value in a loop.
And finally use glTextSubImage to place the altered texture over the top of the old one?
does this sound right?