From 53cf8b96a349b5e3100e409e3acec8e0456dc822 Mon Sep 17 00:00:00 2001
From: David Hackbarth <david@lyrebird-studio.com>
Date: Wed, 17 Sep 2025 16:08:23 +0200
Subject: [PATCH] add world matrix add view matrix add projection matrix

---
 GDP/D3D9/Camera.cpp | 25 ++++++++++++++++++++++++-
 GDP/D3D9/Camera.h   |  2 +-
 GDP/D3D9/Mesh.cpp   | 12 ++++++++++++
 GDP/D3D9/main.cpp   |  2 +-
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/GDP/D3D9/Camera.cpp b/GDP/D3D9/Camera.cpp
index 882aac6..6f2139c 100644
--- a/GDP/D3D9/Camera.cpp
+++ b/GDP/D3D9/Camera.cpp
@@ -1,12 +1,35 @@
 #include "Camera.h"
 
+#include <DirectXMath.h>
+
+using namespace DirectX;
+
 UINT Camera::init(UINT width, UINT height)
 {
+    // view matrix
+    XMVECTOR position = XMVectorSet(0.0f, 0.0f, -2.0f, 0.0f); // camera position
+    XMVECTOR forward = XMVectorSet(0.0f, 0.0f, 1.0f, 0.0f); // camera forward vector
+    XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f); // camera up vector
+
+    XMMATRIX viewMatrix = XMMatrixLookToLH(position, forward, up);
+    XMStoreFloat4x4(reinterpret_cast<XMFLOAT4X4*>(&_viewMatrix), viewMatrix);
+
+    // projection matrix
+    FLOAT fov = XM_PI * 0.3333333f; // field of view
+    FLOAT aspectRatio = static_cast<FLOAT>(width) / static_cast<FLOAT>(height); // CAUTION: UINT / UINT => UINT
+    FLOAT nearClippingPlane = 0.3f;
+    FLOAT farClippingPlane = 100.0f;
+
+    XMMATRIX projectionMatrix = XMMatrixPerspectiveFovLH(fov, aspectRatio, nearClippingPlane, farClippingPlane);
+    XMStoreFloat4x4(reinterpret_cast<XMFLOAT4X4*>(&_projectionMatrix), projectionMatrix);
+
     return 0;
 }
 
-void Camera::update(FLOAT dt)
+void Camera::update(FLOAT dt, IDirect3DDevice9* pD3DDevice)
 {
+    pD3DDevice->SetTransform(D3DTS_VIEW, &_viewMatrix);
+    pD3DDevice->SetTransform(D3DTS_PROJECTION, &_projectionMatrix);
 }
 
 void Camera::deInit()
diff --git a/GDP/D3D9/Camera.h b/GDP/D3D9/Camera.h
index 3cc7e31..9227580 100644
--- a/GDP/D3D9/Camera.h
+++ b/GDP/D3D9/Camera.h
@@ -5,7 +5,7 @@ class Camera
 {
 public:
 	UINT init(UINT width, UINT height);
-	void update(FLOAT dt);
+	void update(FLOAT dt, IDirect3DDevice9* pD3DDevice);
 	void deInit();
 
 private:
diff --git a/GDP/D3D9/Mesh.cpp b/GDP/D3D9/Mesh.cpp
index 970568d..a40bc28 100644
--- a/GDP/D3D9/Mesh.cpp
+++ b/GDP/D3D9/Mesh.cpp
@@ -2,6 +2,10 @@
 #include "Utilities.h"
 #include "Vertex.h"
 
+#include <DirectXMath.h>
+
+using namespace DirectX;
+
 UINT Mesh::init(IDirect3DDevice9* pD3DDevice)
 {
     UINT error = 0;
@@ -12,6 +16,13 @@ UINT Mesh::init(IDirect3DDevice9* pD3DDevice)
     error = createIndexBuffer(pD3DDevice);
     CheckError(error);
 
+    // identity matrix
+    XMMATRIX identityMatrix = XMMatrixIdentity();
+    XMFLOAT4X4 worldMatrix;
+    XMStoreFloat4x4(&worldMatrix, identityMatrix);
+    D3DMATRIX* pWorldMatrix = reinterpret_cast<D3DMATRIX*>(&worldMatrix);
+    _worldMatrix = *pWorldMatrix;
+
     return 0;
 }
 
@@ -25,6 +36,7 @@ void Mesh::render(IDirect3DDevice9* pD3DDevice)
     pD3DDevice->SetStreamSource(0, _pVertexBuffer, 0, _vertexStride);
     pD3DDevice->SetFVF(FVF);
     pD3DDevice->SetIndices(_pIndexBuffer);
+    pD3DDevice->SetTransform(D3DTS_WORLD, &_worldMatrix);
 
     // 2. draw call
     //pD3DDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, _vertexCount / 3);
diff --git a/GDP/D3D9/main.cpp b/GDP/D3D9/main.cpp
index bd13e87..3900a51 100644
--- a/GDP/D3D9/main.cpp
+++ b/GDP/D3D9/main.cpp
@@ -65,7 +65,7 @@ int WINAPI WinMain(
 		// 8.1. update objects
 		time.update();
 		mesh.update(time.getDeltaTime());
-		camera.update(time.getDeltaTime());
+		camera.update(time.getDeltaTime(), d3d.getDevice());
 		light.update(time.getDeltaTime());
 
 		// 8.2. render objects