lookat_rotate2

NAME

lookat_rotate2() - build a viewing-rotation matrix from explicit eye
and look points

SYNOPSIS

float *lookat_rotate2(float *matrix, float eye_x, float eye_y,
                      float eye_z, float look_x, float look_y,
                      float look_z)

DESCRIPTION

Replaces the 4x4 transformation `matrix` (a 16-element flat array of
floats, as produced by id_matrix()) with a viewing-rotation matrix
that looks from the eye point (`eye_x`, `eye_y`, `eye_z`) toward the
look point (`look_x`, `look_y`, `look_z`).

This is like lookat_rotate(), except both the eye point and the look
point are given explicitly as arguments rather than being read from
the current matrix. The world up vector is fixed at (0, 1, 0); the
prior contents of `matrix` are ignored and fully overwritten.

The passed `matrix` array is modified IN PLACE: its 16 elements are
overwritten with the computed matrix, and that same array is left on
the stack as the return value. lookat_rotate2() mutates its first
argument; the return value is the very array you passed in, not a copy.

SEE ALSO

lookat_rotate(3), id_matrix(3)