1 files changed, 80 insertions, 0 deletions
diff --git a/glm/affine.ha b/glm/affine.ha
new file mode 100644
index 0000000..e36cdd9
--- /dev/null
+++ b/glm/affine.ha
@@ -0,0 +1,80 @@
+use math;
+
+export fn translation_make(v: *v3) m4 = {
+	const mat = m4_new_ident();
+	v3_copy_to(v, m4_col(&mat, 3): *v3);
+	return mat;
+};
+
+export fn translate(m: *m4, v: *v3) void = {
+	const mat = translation_make(v);
+	const orig = *m;
+	m4_mul_to(&mat, &orig, m);
+};
+
+export fn rotation_make(angle: f32, axis: *v3) m4 = {
+	const r = m4_new_ident();
+	const c = math::cosf64(angle): f32;
+
+	let axisn = v3_new_zero();
+	let v = v3_new_zero();
+	let vs = v3_new_zero();
+
+	v3_normalize_to(axis, &axisn);
+	v3_scale_to(&axisn, 1.0 - c, &v);
+	v3_scale_to(&axisn, math::sinf64(angle): f32, &vs);
+
+	v3_scale_to(&axisn, v[0], m4_col(&r, 0): *v3);
+	v3_scale_to(&axisn, v[1], m4_col(&r, 1): *v3);
+	v3_scale_to(&axisn, v[2], m4_col(&r, 2): *v3);
+
+	r[0][0] += c;
+	r[1][0] -= vs[2];
+	r[2][0] += vs[1];
+
+	r[0][1] += vs[2];
+	r[1][1] += c;
+	r[2][1] -= vs[0];
+
+	r[0][2] -= vs[1];
+	r[1][2] += vs[0];
+	r[2][2] += c;
+
+	return r;
+};
+
+export fn rotate(m: *m4, angle: f32, axis: *v3) void = {
+	const rot = rotation_make(angle, axis);
+	const orig = *m;
+	m4_mul_to(&rot, &orig, m);
+};
+
+export fn rotate_at(m: *m4, pivot: *v3, angle: f32, axis: *v3) void = {
+	const pivot_inv = v3_new_fill(0.0);
+	v3_negate_to(pivot, &pivot_inv);
+	translate(m, &pivot_inv);
+	rotate(m, angle, axis);
+	translate(m, pivot);
+};
+
+export fn scale_make(v: *v3) m4 = {
+	let res = m4_new_ident();
+	res[0][0] = v[0];
+	res[1][1] = v[1];
+	res[2][2] = v[2];
+	return res;
+};
+
+export fn scale(m: *m4, v: *v3) void = {
+	const mat = scale_make(v);
+	const orig = *m;
+	m4_mul_to(&mat, &orig, m);
+};
+
+export fn affine_mul_v3(a: *m4, b: *v3) v3 = {
+	return v3_new(
+		a[0][0] * b[0] + a[1][0] * b[1] + a[2][0] * b[2] + a[3][0],
+		a[0][1] * b[0] + a[1][1] * b[1] + a[2][1] * b[2] + a[3][1],
+		a[0][2] * b[0] + a[1][2] * b[1] + a[2][2] * b[2] + a[3][2],
+	);
+};