Transformations

OpenGL OpenGL: Advanced Coding
1

When I load a model from file, then I perform glRotate and glTranslate functions. Is it possible to get transformed vertices data back ? If yes, is it faster or slower than doing this on PCU ? I have a GeForce card.

Blecha

2

Hi Blecha,

You can’t get the vertices that the GPU has transformed back. You definitely want to do this in your own software.

Thanks -
Cass

3

In general, it’s a very slow (when possible) to get data back from GL, like the matrix stack, or whether state like lighting or the z-buffer is enabled. It’s typically best, as Cass has mentioned, to keep track of such state yourself. It’s typically better to unconditionally change the state, and best to conditionally change the state based on the state that you’re tracking yourself.