matmul.c

vec4 mat4_col(const mat4 *m, int c)
{
	vec4 res;
	res.x = m->frows[0][c];
	res.y = m->frows[1][c];
	res.z = m->frows[2][c];
	res.w = m->frows[3][c];
	return res;
}

mat4 mat4_transpose(const mat4 *m)
{
	mat4 res;
	int i, j;
	for (i = 0; i < 4; ++i)
		for (j = 0; j < 4; ++j)
			res.frows[i][j] = m->frows[j][i];
	return res;
}
mat4 mat4_mul(const mat4 *l, const mat4 *r)
{
	/* rows act as columns */
	mat4 res;
	int i;
	for (i = 0; i < 4; ++i)
		res.rows[i] = mat4_vecmul(l, mat4_col(r, i));
	return mat4_transpose(&res);
}

vec4 mat4_vecmul(const mat4 *l, vec4 r)
{
	vec4 res;
	res.x = vec4_dot(l->rows[0], r);
	res.y = vec4_dot(l->rows[1], r);
	res.z = vec4_dot(l->rows[2], r);
	res.w = vec4_dot(l->rows[3], r);
	return res;
}