From b0675358c3971abe39c0d0b94f7aa7b85ea9b054 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Tue, 6 Feb 2024 14:09:05 +0000
Subject: [PATCH] Add `angle_between` and `matrix2_rotate`

---
 core/math/linalg/general.odin  | 25 +++++++++++++++++++++++
 core/math/linalg/specific.odin | 37 ++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/core/math/linalg/general.odin b/core/math/linalg/general.odin
index 24bc4c7b3..4275dcb42 100644
--- a/core/math/linalg/general.odin
+++ b/core/math/linalg/general.odin
@@ -267,6 +267,31 @@ to_ptr :: proc{vector_to_ptr, matrix_to_ptr}
 
 
 
+vector_angle_between :: proc "contextless" (a, b: $V/[$N]$E) -> E {
+	a0 := normalize0(a)
+	b0 := normalize0(b)
+	return math.acos(dot(a0, b0))
+}
+quaternion64_angle_between :: proc "contextless" (a, b: $Q/quaternion64) -> f16 {
+	c := normalize0(conj(a) * b)
+	return math.acos(c.w)
+}
+quaternion128_angle_between :: proc "contextless" (a, b: $Q/quaternion128) -> f32 {
+	c := normalize0(conj(a) * b)
+	return math.acos(c.w)
+}
+quaternion256_angle_between :: proc "contextless" (a, b: $Q/quaternion256) -> f64 {
+	c := normalize0(conj(a) * b)
+	return math.acos(c.w)
+}
+angle_between :: proc{
+	vector_angle_between,
+	quaternion64_angle_between,
+	quaternion128_angle_between,
+	quaternion256_angle_between,
+}
+
+
 
 // Splines
 
diff --git a/core/math/linalg/specific.odin b/core/math/linalg/specific.odin
index 36783e1e2..4a0f5ee40 100644
--- a/core/math/linalg/specific.odin
+++ b/core/math/linalg/specific.odin
@@ -1270,6 +1270,43 @@ matrix2_adjoint :: proc{
 }
 
 
+@(require_results)
+matrix2_rotate_f16 :: proc "contextless" (angle_radians: f16) -> Matrix2f16 {
+	c := math.cos(angle_radians)
+	s := math.sin(angle_radians)
+
+	return Matrix2f16{
+		c, -s,
+		s,  c,
+	}
+}
+@(require_results)
+matrix2_rotate_f32 :: proc "contextless" (angle_radians: f32) -> Matrix2f32 {
+	c := math.cos(angle_radians)
+	s := math.sin(angle_radians)
+
+	return Matrix2f32{
+		c, -s,
+		s,  c,
+	}
+}
+@(require_results)
+matrix2_rotate_f64 :: proc "contextless" (angle_radians: f64) -> Matrix2f64 {
+	c := math.cos(angle_radians)
+	s := math.sin(angle_radians)
+
+	return Matrix2f64{
+		c, -s,
+		s,  c,
+	}
+}
+matrix2_rotate :: proc{
+	matrix2_rotate_f16,
+	matrix2_rotate_f32,
+	matrix2_rotate_f64,
+}
+
+
 @(require_results)
 matrix3_from_quaternion_f16 :: proc "contextless" (q: Quaternionf16) -> (m: Matrix3f16) {
 	qxx := q.x * q.x