"If" with Vertex shader

OpenGL OpenGL: Basic Coding
1

If i have understood the documentations, it seems to be impossible to use “if”,“else”… with the ARB_Vertex_program extension (?)

Do i have to use GLSL if i want to use “if” in a vertex shader ? (using ARB extension only)

Thanks.

2

Often you can multiply the result of a code segment by 1 or 0 where that operand is derived from the parameter you want to branch on.

3

Ok.
Thanks.

4

Yes, when it comes about math you can emulate branching by using SGE and SLT instructions combined with things like x1=x and x0=0.

And if you want more advanced branching, you can take a look at the GL_NV_vertex_program2_option (only supported on NVIDIA hardware for now).