mapping coords

OpenGL
1

anyone want to tell me how to map coords from [-1,1] to [0,1]? much appreciated

2

Actually there are infinitely many mappings from [-1,+1] to [0,1], but I assume you mean the affine transformation T specified by T(-1)=0 and T(+1)=1.

In general you can do an affine mapping T: x->x’ specified by T(a)=p and T(b)=q like this:

x'=p+(x-a)*(q-p)/(b-a)

or in your specific case:

x'=(x+1)/2