add DirectXMath for rotation

PracticeDx/VertexShader.hlsl

@@ -6,7 +6,7 @@ struct VSOut
 
 cbuffer CBuf
 {
-	row_major matrix transform;
+	matrix transform;
 };
 
 VSOut main(float2 pos : Position, float3 color : Color)

PracticeDx/WinMain.cpp

@@ -10,6 +10,10 @@
 
 #include <wrl.h>
 
+#include <DirectXMath.h>
+
+namespace dx = DirectX;
+
 #include <array>    // to usd std::size
 #include <cmath>    // to use std::sin and std::cos
 #include "Timer.h"  // to use timer
@@ -72,22 +76,19 @@ Microsoft::WRL::ComPtr<ID3D11Buffer>            pConstantBuffer;
 // Create constant buffer struct
 struct ConstantBuffer
 {
-    struct
-    {
-        float element[4][4];
-    } transformation;
+    dx::XMMATRIX transform;
 };
 // create constant buffer
 const float heightWidthRatio = 0.3f / 0.4f;
 float angle = 0.0f;
 ConstantBuffer cb =
 {
-    {
-        heightWidthRatio * std::cos(angle),	    -std::sin(angle),	0.0f,	0.0f,
-        heightWidthRatio * std::sin(angle),	    std::cos(angle),	0.0f,	0.0f,
-        0.0f,					                0.0f,			    1.0f,	0.0f,
-        0.0f,					                0.0f,			    0.0f,	1.0f,
-    }
+    // transpose the matrix to change from row_major to column_major
+    dx::XMMatrixTranspose(
+        // rotate Z axis
+        dx::XMMatrixRotationZ(-angle)
+        * dx::XMMatrixScaling(heightWidthRatio, 1.0f, 1.0f)
+    )
 };
 
 // Define input layout
@@ -128,10 +129,15 @@ void DefineVertexBuffer()
 
 void DefineConstantBuffer(float angle)
 {
-    cb.transformation.element[0][0] = heightWidthRatio * std::cos(angle);
-    cb.transformation.element[0][1] = -std::sin(angle);
-    cb.transformation.element[1][0] = heightWidthRatio * std::sin(angle);
-    cb.transformation.element[1][1] = std::cos(angle);
+    cb =
+    {
+        // transpose the matrix to change from row_major to column_major
+        dx::XMMatrixTranspose(
+            // rotate Z axis
+            dx::XMMatrixRotationZ(-angle)
+            * dx::XMMatrixScaling(heightWidthRatio, 1.0f, 1.0f)
+        )
+    };
 
     D3D11_BUFFER_DESC cbd = {};
     cbd.BindFlags = D3D11_BIND_CONSTANT_BUFFER;