From baf1a70fc68201a6e2ed00f8a6d1843b65a3a699 Mon Sep 17 00:00:00 2001
From: Ben Visness <bvisness@gmail.com>
Date: Sat, 9 Jun 2018 11:50:41 -0400
Subject: [PATCH] Add array subscript operators for all types

---
 HandmadeMath.h                   | 36 +++++++++++++++++++++++++++++
 test/categories/Initialization.h | 39 ++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/HandmadeMath.h b/HandmadeMath.h
index 5628d7e..2e09984 100644
--- a/HandmadeMath.h
+++ b/HandmadeMath.h
@@ -314,6 +314,13 @@ typedef union hmm_vec2
     };
 
     float Elements[2];
+
+#ifdef __cplusplus
+    inline float &operator[](int i)
+    {
+        return Elements[i];
+    }
+#endif
 } hmm_vec2;
 
 typedef union hmm_vec3
@@ -358,6 +365,13 @@ typedef union hmm_vec3
     };
 
     float Elements[3];
+
+#ifdef __cplusplus
+    inline float &operator[](int i)
+    {
+        return Elements[i];
+    }
+#endif
 } hmm_vec3;
 
 typedef union hmm_vec4
@@ -415,6 +429,13 @@ typedef union hmm_vec4
 #ifdef HANDMADE_MATH__USE_SSE    
     __m128 InternalElementsSSE;
 #endif
+
+#ifdef __cplusplus
+    inline float &operator[](int i)
+    {
+        return Elements[i];
+    }
+#endif
 } hmm_vec4;
 
 typedef union hmm_mat4
@@ -424,6 +445,21 @@ typedef union hmm_mat4
 #ifdef HANDMADE_MATH__USE_SSE
     __m128 Rows[4];
 #endif
+
+#ifdef __cplusplus
+    inline hmm_vec4 operator[](int i)
+    {
+        float* col = Elements[i];
+
+        hmm_vec4 result;
+        result.Elements[0] = col[0];
+        result.Elements[1] = col[1];
+        result.Elements[2] = col[2];
+        result.Elements[3] = col[3];
+
+        return result;
+    }
+#endif
 } hmm_mat4;
 
 typedef union hmm_quaternion
diff --git a/test/categories/Initialization.h b/test/categories/Initialization.h
index c2616e0..99d390d 100644
--- a/test/categories/Initialization.h
+++ b/test/categories/Initialization.h
@@ -18,6 +18,10 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v2.Height, 2.0f);
     EXPECT_FLOAT_EQ(v2.Elements[0], 1.0f);
     EXPECT_FLOAT_EQ(v2.Elements[1], 2.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v2[0], 1.0f);
+    EXPECT_FLOAT_EQ(v2[1], 2.0f);
+#endif
 
     EXPECT_FLOAT_EQ(v2i.X, 1.0f);
     EXPECT_FLOAT_EQ(v2i.Y, 2.0f);
@@ -29,6 +33,10 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v2i.Height, 2.0f);
     EXPECT_FLOAT_EQ(v2i.Elements[0], 1.0f);
     EXPECT_FLOAT_EQ(v2i.Elements[1], 2.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v2i[0], 1.0f);
+    EXPECT_FLOAT_EQ(v2i[1], 2.0f);
+#endif
 
     //
     // Test vec3
@@ -56,6 +64,11 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v3.UV.Elements[1], 2.0f);
     EXPECT_FLOAT_EQ(v3.VW.Elements[0], 2.0f);
     EXPECT_FLOAT_EQ(v3.VW.Elements[1], 3.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v3[0], 1.0f);
+    EXPECT_FLOAT_EQ(v3[1], 2.0f);
+    EXPECT_FLOAT_EQ(v3[2], 3.0f);
+#endif
 
     EXPECT_FLOAT_EQ(v3i.X, 1.0f);
     EXPECT_FLOAT_EQ(v3i.Y, 2.0f);
@@ -77,6 +90,11 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v3i.UV.Elements[1], 2.0f);
     EXPECT_FLOAT_EQ(v3i.VW.Elements[0], 2.0f);
     EXPECT_FLOAT_EQ(v3i.VW.Elements[1], 3.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v3i[0], 1.0f);
+    EXPECT_FLOAT_EQ(v3i[1], 2.0f);
+    EXPECT_FLOAT_EQ(v3i[2], 3.0f);
+#endif
 
     //
     // Test vec4
@@ -107,6 +125,12 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v4.RGB.Elements[0], 1.0f);
     EXPECT_FLOAT_EQ(v4.RGB.Elements[1], 2.0f);
     EXPECT_FLOAT_EQ(v4.RGB.Elements[2], 3.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v4[0], 1.0f);
+    EXPECT_FLOAT_EQ(v4[1], 2.0f);
+    EXPECT_FLOAT_EQ(v4[2], 3.0f);
+    EXPECT_FLOAT_EQ(v4[3], 4.0f);
+#endif
 
     EXPECT_FLOAT_EQ(v4i.X, 1.0f);
     EXPECT_FLOAT_EQ(v4i.Y, 2.0f);
@@ -130,6 +154,12 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v4i.RGB.Elements[0], 1.0f);
     EXPECT_FLOAT_EQ(v4i.RGB.Elements[1], 2.0f);
     EXPECT_FLOAT_EQ(v4i.RGB.Elements[2], 3.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v4i[0], 1.0f);
+    EXPECT_FLOAT_EQ(v4i[1], 2.0f);
+    EXPECT_FLOAT_EQ(v4i[2], 3.0f);
+    EXPECT_FLOAT_EQ(v4i[3], 4.0f);
+#endif
 
     EXPECT_FLOAT_EQ(v4v.X, 1.0f);
     EXPECT_FLOAT_EQ(v4v.Y, 2.0f);
@@ -153,6 +183,12 @@ TEST(Initialization, Vectors)
     EXPECT_FLOAT_EQ(v4v.RGB.Elements[0], 1.0f);
     EXPECT_FLOAT_EQ(v4v.RGB.Elements[1], 2.0f);
     EXPECT_FLOAT_EQ(v4v.RGB.Elements[2], 3.0f);
+#ifdef __cplusplus
+    EXPECT_FLOAT_EQ(v4v[0], 1.0f);
+    EXPECT_FLOAT_EQ(v4v[1], 2.0f);
+    EXPECT_FLOAT_EQ(v4v[2], 3.0f);
+    EXPECT_FLOAT_EQ(v4v[3], 4.0f);
+#endif
 }
 
 TEST(Initialization, MatrixEmpty)
@@ -163,6 +199,9 @@ TEST(Initialization, MatrixEmpty)
         for (int Row = 0; Row < 4; ++Row)
         {
             EXPECT_FLOAT_EQ(m4.Elements[Column][Row], 0.0f);
+#ifdef __cplusplus
+            EXPECT_FLOAT_EQ(m4[Column][Row], 0.0f);
+#endif
         }
     }
 }