Updating a texture in OpenGL with glTexImage2D

Question

Are glTexImage2D and glTexSubImage2D the only ways to pass a buffer of pixels to a texture?

At the moment I use in a setup function glTexImage2D passing null as the buffer, and then on the render loop I call glTexSubImage2D with the new buffer data on each iteration.

But knowing that the texture will not change any property such as the dimensions, is there any more efficient way to pass the actual pixel data to the rendering texture?

Answer 1

In modern OpenGL there are 4 different methods to update 2D textures:

1. glTexImage2D - the slowest one, recreates internal data structures.

2. glTexSubImage2D - a bit faster, but can't change the parameters (size, pixel format) of the image.

3. Render-to-texture with FBO - update texture entirely on GPU, very fast. Refer to this answer for more details: https://stackoverflow.com/a/10702468/1065190

4. Pixel Buffer Object PBO - for fast uploads from CPU to GPU, not supported (yet) on OpenGL ES.