frustum
inline fun <T : Number, Comparable<T>> frustum(left: T, right: T, bottom: T, top: T, near: T, far: T): Mat4<T>
fun <T : Number, Comparable<T>> frustum(left: T, right: T, bottom: T, top: T, near: T, far: T, type: KClass<T>): Mat4<T>
Creates a projection matrix for a perspective projection defined by a given frustum.
The frustum is defined by its near and far depth clipping planes, and its left, right, bottom and top clipping planes (specified at the near depth).