From e0bd54742df6b1108131006e13fda28ca81baa18 Mon Sep 17 00:00:00 2001
From: Stephen Seo <seo.disparate@gmail.com>
Date: Mon, 6 May 2024 11:30:33 +0900
Subject: [PATCH] Add Scale Mat4 creation function

Also added some relevant UnitTests.
---
 src/sc_sacd.cpp |  5 +++++
 src/sc_sacd.h   |  2 ++
 src/test.cpp    | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/src/sc_sacd.cpp b/src/sc_sacd.cpp
index a67e620..f6f8e94 100644
--- a/src/sc_sacd.cpp
+++ b/src/sc_sacd.cpp
@@ -546,6 +546,11 @@ SC_SACD_Mat4 SC_SACD_Translate_Mat4(float x, float y, float z) {
                       0.0F, 0.0F, 1.0F, z, 0.0F, 0.0F, 0.0F, 1.0F};
 }
 
+SC_SACD_Mat4 SC_SACD_Scale_Mat4(float x, float y, float z) {
+  return SC_SACD_Mat4{x,    0.0F, 0.0F, 0.0F, 0.0F, y,    0.0F, 0.0F,
+                      0.0F, 0.0F, z,    0.0F, 0.0F, 0.0F, 0.0F, 1.0F};
+}
+
 SC_SACD_Vec3 SC_SACD_Closest_Point_Dir_Normalized(const SC_SACD_Vec3 *pos,
                                                   const SC_SACD_Vec3 *dir,
                                                   const SC_SACD_Vec3 *point) {
diff --git a/src/sc_sacd.h b/src/sc_sacd.h
index 9cb0e21..e0bddb5 100644
--- a/src/sc_sacd.h
+++ b/src/sc_sacd.h
@@ -119,6 +119,8 @@ SC_SACD_EXPORT SC_SACD_Mat4 SC_SACD_Rotation_Mat4_ZAxis(float z_radians);
 
 SC_SACD_EXPORT SC_SACD_Mat4 SC_SACD_Translate_Mat4(float x, float y, float z);
 
+SC_SACD_EXPORT SC_SACD_Mat4 SC_SACD_Scale_Mat4(float x, float y, float z);
+
 /// This variant of Closest_Point expects "dir" to be a unit vector.
 SC_SACD_EXPORT SC_SACD_Vec3 SC_SACD_Closest_Point_Dir_Normalized(
     const SC_SACD_Vec3 *pos, const SC_SACD_Vec3 *dir,
diff --git a/src/test.cpp b/src/test.cpp
index 77acd62..a759639 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -591,6 +591,48 @@ int main() {
     CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
   }
 
+  // Box with Scale Mat4.
+  {
+    SC_SACD_Generic_Box a = SC_SACD_Generic_Box_Default();
+    SC_SACD_Generic_Box b = SC_SACD_Generic_Box_Default();
+
+    a.x = 1.1F;
+    b.x = -1.1F;
+    CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(2.0F, 1.0F, 1.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(-2.0F, 1.0F, 1.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.x = 0.0F;
+    b.x = 0.0F;
+    a.y = 1.1F;
+    b.y = -1.1F;
+    a.transform = SC_SACD_Mat4_Identity();
+    CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(1.0F, 2.0F, 1.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(1.0F, -2.0F, 1.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.y = 0.0F;
+    b.y = 0.0F;
+    a.z = 1.1F;
+    b.z = -1.1F;
+    a.transform = SC_SACD_Mat4_Identity();
+    CHECK_FALSE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(1.0F, 1.0F, 2.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+
+    a.transform = SC_SACD_Scale_Mat4(1.0F, 1.0F, -2.0F);
+    CHECK_TRUE(SC_SACD_Generic_Box_Collision(&a, &b));
+  }
+
   std::cout << "Checks checked: " << checks_checked << '\n'
             << "Checks passed:  " << checks_passed << '\n';