I have the following two matrix creation methods:
GLK_INLINE GLKMatrix4 GLKMatrix4MakePerspective(float fovyRadians, float aspect, float nearZ, float farZ)
{
float cotan = 1.0f / tanf(fovyRadians / 2.0f);
GLKMatrix4 m = { cotan / aspect, 0.0f, 0.0f, 0.0f,
0.0f, cotan, 0.0f, 0.0f,
0.0f, 0.0f, (farZ + nearZ) / (nearZ - farZ), -1.0f,
0.0f, 0.0f, (2.0f * farZ * nearZ) / (nearZ - farZ), 0.0f };
return m;
}
GLK_INLINE GLKMatrix4 GLKMatrix4MakeOrtho(float left, float right,
float bottom, float top,
float nearZ, float farZ)
{
float ral = right + left;
float rsl = right - left;
float tab = top + bottom;
float tsb = top - bottom;
float fan = farZ + nearZ;
float fsn = farZ - nearZ;
GLKMatrix4 m = { 2.0f / rsl, 0.0f, 0.0f, 0.0f,
0.0f, 2.0f / tsb, 0.0f, 0.0f,
0.0f, 0.0f, -2.0f / fsn, 0.0f,
-ral / rsl, -tab / tsb, -fan / fsn, 1.0f };
return m;
}
Is there a good way to create an Orthographic matrix from a given perspective matrix so that the transition will be as smooth as possible?