Building a projection matrix without api

Are you wondering how the matrix look like?
You could look up the function in the DirectX SDK, to see how it
looks like.
This is ripped directly from the DX SDK 9.0



where:
h is the view space height. It is calculated from
h = cot(fovY/2);
w is the view space width. It is calculated from
w = h / Aspect.
fovY is in radians
zf is far view-plane
zn is near view-plane
Aspect is the view space height divided by width

- Patrik Willbo

Quote:

Original post by Malmer How does one really go about building a projection matrix? In Direct3D and OpenGL there are various functions for building them, but how does one do it in software? And what difference will the matrix have if the coordinate system is a right-handed one. Thanks! Malmer

If you are working with OGL then download the Mesa/3D source code and have a look at the glu functions. Such as gluPerspective, gluLookAt, etc its all there.

And straight from the docs on glFrustum:

    E  0  A  0    0  F  B  0    0  0  C  D    0  0  -1 0        A = (right+left)/(right-left)    B = (top+bottom)/(top-bottom)    C = -(far+near)/(far-near)    D = -2*far*near/(far-near)    E = 2*near/(right-left)    F = 2*near/(top-bottom)