From a8a5e80f416a09fa60279eea521351a54451bb40 Mon Sep 17 00:00:00 2001
From: Linklancien <123779978+Linklancien@users.noreply.github.com>
Date: Sun, 30 Nov 2025 11:55:41 +0100
Subject: [PATCH] math.vec: add tests for vec2,3,4 perpendicular (#25840)

---
 vlib/math/vec/vec2.v      |  2 +-
 vlib/math/vec/vec2_test.v | 21 +++++++++++++++++++++
 vlib/math/vec/vec3.v      |  2 +-
 vlib/math/vec/vec3_test.v | 25 ++++++++++++++++++++++++-
 vlib/math/vec/vec4.v      |  2 +-
 vlib/math/vec/vec4_test.v | 26 ++++++++++++++++++++++++++
 6 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/vlib/math/vec/vec2.v b/vlib/math/vec/vec2.v
index 786fecbcb..09983a0a5 100644
--- a/vlib/math/vec/vec2.v
+++ b/vlib/math/vec/vec2.v
@@ -258,7 +258,7 @@ pub fn (v Vec2[T]) perp_ccw() Vec2[T] {
 	return Vec2[T]{-v.y, v.x}
 }
 
-// perpendicular returns the `u` projected perpendicular vector to this vector.
+// perpendicular returns the `v` projected perpendicular vector to the 'u' vector.
 pub fn (v Vec2[T]) perpendicular(u Vec2[T]) Vec2[T] {
 	return v - v.project(u)
 }
diff --git a/vlib/math/vec/vec2_test.v b/vlib/math/vec/vec2_test.v
index d8da8cdd4..9e8135544 100644
--- a/vlib/math/vec/vec2_test.v
+++ b/vlib/math/vec/vec2_test.v
@@ -299,3 +299,24 @@ fn test_vec2_project_negative_components() {
 	assert tolerance(proj.x, 4.68, vec.vec_epsilon)
 	assert tolerance(proj.y, -6.24, vec.vec_epsilon)
 }
+
+// Test for perpendicularity
+// 'u' and 'v' are already perpendicular so it must return v
+fn test_vec2_perpendicularity_angle() {
+	u := vec.vec2(1.0, 0.0)
+	v := vec.vec2(0.0, 3.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, v.x, vec.vec_epsilon)
+	assert tolerance(per.y, v.y, vec.vec_epsilon)
+}
+
+// 'u' and 'v' are collinear so it must return the null vector
+fn test_vec2_collinear() {
+	u := vec.vec2(1.0, 0.0)
+	v := vec.vec2(3.0, 0.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, 0.0, vec.vec_epsilon)
+	assert tolerance(per.y, 0.0, vec.vec_epsilon)
+}
diff --git a/vlib/math/vec/vec3.v b/vlib/math/vec/vec3.v
index ce21d22a6..5fac7a0e2 100644
--- a/vlib/math/vec/vec3.v
+++ b/vlib/math/vec/vec3.v
@@ -253,7 +253,7 @@ pub fn (v Vec3[T]) unit() Vec3[T] {
 	return Vec3[T]{v.x * invm, v.y * invm, v.z * invm}
 }
 
-// perpendicular returns the `u` projected perpendicular vector to this vector.
+// perpendicular returns the `v` projected perpendicular vector to the 'u' vector.
 @[inline]
 pub fn (v Vec3[T]) perpendicular(u Vec3[T]) Vec3[T] {
 	return v - v.project(u)
diff --git a/vlib/math/vec/vec3_test.v b/vlib/math/vec/vec3_test.v
index 42c3b3216..e41ba0f3c 100644
--- a/vlib/math/vec/vec3_test.v
+++ b/vlib/math/vec/vec3_test.v
@@ -1,4 +1,4 @@
-import math { veryclose }
+import math { tolerance, veryclose }
 import math.vec
 
 fn test_vec3_int() {
@@ -131,3 +131,26 @@ fn test_vec3_project_onto_angle() {
 	assert veryclose(proj.y, 0.0)
 	assert veryclose(proj.z, 0.0)
 }
+
+// Test for perpendicularity
+// 'u' and 'v' are already perpendicular so it must return v
+fn test_vec3_perpendicularity_angle() {
+	u := vec.vec3(1.0, 0.0, 0.0)
+	v := vec.vec3(0.0, 3.0, 2.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, v.x, vec.vec_epsilon)
+	assert tolerance(per.y, v.y, vec.vec_epsilon)
+	assert tolerance(per.z, v.z, vec.vec_epsilon)
+}
+
+// 'u' and 'v' are collinear so the result must be the null vector
+fn test_vec3_collinear() {
+	u := vec.vec3(1.0, 0.0, 0.0)
+	v := vec.vec3(3.0, 0.0, 0.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, 0.0, vec.vec_epsilon)
+	assert tolerance(per.y, 0.0, vec.vec_epsilon)
+	assert tolerance(per.z, 0.0, vec.vec_epsilon)
+}
diff --git a/vlib/math/vec/vec4.v b/vlib/math/vec/vec4.v
index 0638e74a2..523dbf5be 100644
--- a/vlib/math/vec/vec4.v
+++ b/vlib/math/vec/vec4.v
@@ -270,7 +270,7 @@ pub fn (v Vec4[T]) unit() Vec4[T] {
 	}
 }
 
-// perpendicular returns the `u` projected perpendicular vector to this vector.
+// perpendicular returns the `v` projected perpendicular vector to the 'u' vector.
 pub fn (v Vec4[T]) perpendicular(u Vec4[T]) Vec4[T] {
 	return v - v.project(u)
 }
diff --git a/vlib/math/vec/vec4_test.v b/vlib/math/vec/vec4_test.v
index 0335a4bb8..b0ff59c8c 100644
--- a/vlib/math/vec/vec4_test.v
+++ b/vlib/math/vec/vec4_test.v
@@ -1,3 +1,4 @@
+import math { tolerance }
 import math.vec
 
 fn test_vec4_int() {
@@ -123,3 +124,28 @@ fn test_vec4_project_onto_zero() {
 	assert proj.z == 0.0
 	assert proj.w == 0.0
 }
+
+// Test for perpendicularity
+// 'u' and 'v' are already perpendicular so it must return v
+fn test_vec4_perpendicularity_angle() {
+	u := vec.vec4(1.0, 0.0, 0.0, 0.0)
+	v := vec.vec4(0.0, 3.0, 2.0, 0.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, v.x, vec.vec_epsilon)
+	assert tolerance(per.y, v.y, vec.vec_epsilon)
+	assert tolerance(per.z, v.z, vec.vec_epsilon)
+	assert tolerance(per.w, v.w, vec.vec_epsilon)
+}
+
+// 'u' and 'v' are collinear so it must return the null vector
+fn test_vec4_collinear() {
+	u := vec.vec4(1.0, 0.0, 0.0, 0.0)
+	v := vec.vec4(3.0, 0.0, 0.0, 0.0)
+
+	per := v.perpendicular(u)
+	assert tolerance(per.x, 0.0, vec.vec_epsilon)
+	assert tolerance(per.y, 0.0, vec.vec_epsilon)
+	assert tolerance(per.z, 0.0, vec.vec_epsilon)
+	assert tolerance(per.w, 0.0, vec.vec_epsilon)
+}
-- 
2.39.5