From e5451c10fc4ccbbadd659b0d8950b1f6f4917af8 Mon Sep 17 00:00:00 2001
From: David Hackbarth <david@lyrebird-studio.com>
Date: Wed, 17 Sep 2025 14:20:46 +0200
Subject: [PATCH] add mesh examples

---
 GDP/D3D9/Direct3D.cpp |  2 +-
 GDP/D3D9/Mesh.cpp     | 79 ++++++++++++++++++++++++++++++++++++++++++-
 GDP/D3D9/main.cpp     |  2 ++
 3 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/GDP/D3D9/Direct3D.cpp b/GDP/D3D9/Direct3D.cpp
index abadb5a..c51f322 100644
--- a/GDP/D3D9/Direct3D.cpp
+++ b/GDP/D3D9/Direct3D.cpp
@@ -61,7 +61,7 @@ void Direct3D::beginScene()
 	_pD3DDevice->Clear(
 		0, nullptr, // clear specific areas only
 		D3DCLEAR_TARGET, // what to clear
-		D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0xFFFFFFFF // how to clear
+		D3DCOLOR_XRGB(255, 255, 255), 1.0f, 0xFFFFFFFF // how to clear
 	);
 }
 
diff --git a/GDP/D3D9/Mesh.cpp b/GDP/D3D9/Mesh.cpp
index 2c47363..970568d 100644
--- a/GDP/D3D9/Mesh.cpp
+++ b/GDP/D3D9/Mesh.cpp
@@ -21,6 +21,16 @@ void Mesh::update(FLOAT dt)
 
 void Mesh::render(IDirect3DDevice9* pD3DDevice)
 {
+    // 1. set mesh data
+    pD3DDevice->SetStreamSource(0, _pVertexBuffer, 0, _vertexStride);
+    pD3DDevice->SetFVF(FVF);
+    pD3DDevice->SetIndices(_pIndexBuffer);
+
+    // 2. draw call
+    //pD3DDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, _vertexCount / 3);
+    //pD3DDevice->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, _vertexCount - 2);
+    //pD3DDevice->DrawPrimitive(D3DPT_TRIANGLEFAN, 0, _vertexCount - 2);
+    pD3DDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, _vertexCount, 0, _indexCount / 3);
 }
 
 void Mesh::deInit()
@@ -32,7 +42,7 @@ void Mesh::deInit()
 UINT Mesh::createVertexBuffer(IDirect3DDevice9* pD3DDevice)
 {
     // 1. define mesh structure
-    _vertexCount = 3;
+    _vertexCount = 4;
     _vertexStride = sizeof(Vertex);
 
     // 2. create vertex buffer WITHOUT data
@@ -44,12 +54,79 @@ UINT Mesh::createVertexBuffer(IDirect3DDevice9* pD3DDevice)
         &_pVertexBuffer,
         nullptr // not used anymore
     );
+    CheckFailed(hr, 300);
 
     // 3. fill vertex buffer with data
+    Vertex* pVertices = nullptr;
+    hr = _pVertexBuffer->Lock(0, 0, reinterpret_cast<void**>(&pVertices), 0);
+    CheckFailed(hr, 310);
+
+    // triangle
+    //pVertices[0] = Vertex(0.0f, 0.5f, 0.0f);
+    //pVertices[1] = Vertex(0.5f, -0.5f, 0.0f);
+    //pVertices[2] = Vertex(-0.5f, -0.5f, 0.0f);
+
+    // quad with trianglelist WITHOUT index buffer
+    //// triangle 1
+    //pVertices[0] = Vertex(-0.5f, 0.5f, 0.0f);
+    //pVertices[1] = Vertex(0.5f, 0.5f, 0.0f);
+    //pVertices[2] = Vertex(0.5f, -0.5f, 0.0f);
+
+    //// triangle 2
+    //pVertices[3] = Vertex(-0.5f, 0.5f, 0.0f);
+    //pVertices[4] = Vertex(0.5f, -0.5f, 0.0f);
+    //pVertices[5] = Vertex(-0.5f, -0.5f, 0.0f);
+
+    // quad with trianglestrip
+    //pVertices[0] = Vertex(-0.5f, 0.5f, 0.0f);
+    //pVertices[1] = Vertex(0.5f, 0.5f, 0.0f);
+    //pVertices[2] = Vertex(-0.5f, -0.5f, 0.0f);
+    //pVertices[3] = Vertex(0.5f, -0.5f, 0.0f);
+
+    // quad with trianglefan
+    // quad with trianglelist & index buffer
+    pVertices[0] = Vertex(-0.5f, 0.5f, 0.0f);
+    pVertices[1] = Vertex(0.5f, 0.5f, 0.0f);
+    pVertices[2] = Vertex(0.5f, -0.5f, 0.0f);
+    pVertices[3] = Vertex(-0.5f, -0.5f, 0.0f);
+
+    hr = _pVertexBuffer->Unlock();
+    CheckFailed(hr, 320);
+
+    pVertices = nullptr;
+
     return 0;
 }
 
 UINT Mesh::createIndexBuffer(IDirect3DDevice9* pD3DDevice)
 {
+    _indexCount = 6; // triangle * 3
+
+    HRESULT hr = pD3DDevice->CreateIndexBuffer(
+        _indexCount * sizeof(WORD),
+        D3DUSAGE_WRITEONLY,
+        D3DFMT_INDEX16,
+        D3DPOOL_MANAGED,
+        &_pIndexBuffer,
+        nullptr
+    );
+    CheckFailed(hr, 330);
+
+    WORD* pIndices = nullptr;
+    hr = _pIndexBuffer->Lock(0, 0, reinterpret_cast<void**>(&pIndices), 0);
+    CheckFailed(hr, 340);
+
+    // quad
+    // triangle 1
+    pIndices[0] = 0; pIndices[1] = 1; pIndices[2] = 2;
+
+    // triangle 2
+    pIndices[3] = 0; pIndices[4] = 2; pIndices[5] = 3;
+
+    hr = _pIndexBuffer->Unlock();
+    CheckFailed(hr, 350);
+
+    pIndices = nullptr;
+
     return 0;
 }
diff --git a/GDP/D3D9/main.cpp b/GDP/D3D9/main.cpp
index cc20ea5..bd13e87 100644
--- a/GDP/D3D9/main.cpp
+++ b/GDP/D3D9/main.cpp
@@ -32,6 +32,8 @@ int WINAPI WinMain(
 	error = d3d.init(window.getWindowHandle(), width, height, isFullscreen);
 	CheckError(error);
 
+	d3d.getDevice()->SetRenderState(D3DRS_CULLMODE, D3DCULL_CCW);
+
 	// 3. create a mesh
 	Mesh mesh = {};
 	error = mesh.init(d3d.getDevice());