From da92a49ed9251a0210b13a7f1c340f9bd16e26cc Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Mon, 22 Dec 2025 17:25:07 -0600
Subject: [PATCH] simple pixel shader

---
 main.cpp | 27 +++++++++++++++++++++++++++
 main.psh |  9 +++++++++
 main.vsh |  3 ++-
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 main.psh

diff --git a/main.cpp b/main.cpp
index d843aa2..2a97e56 100644
--- a/main.cpp
+++ b/main.cpp
@@ -29,6 +29,7 @@ IDirect3DVertexBuffer9 * g_pVB = NULL;
 IDirect3DVertexDeclaration9 * g_pVertexDeclaration = NULL;
 ID3DXConstantTable * g_pConstantTable = NULL;
 IDirect3DVertexShader9 * g_pVertexShader = NULL;
+IDirect3DPixelShader9 * g_pPixelShader = NULL;
 
 IDirectInput8 * g_pDI = NULL;
 IDirectInputDevice8 * g_pdiDevice;
@@ -149,6 +150,7 @@ void Render()
 
   g_pd3dDevice->SetVertexDeclaration(g_pVertexDeclaration);
   g_pd3dDevice->SetVertexShader(g_pVertexShader);
+  g_pd3dDevice->SetPixelShader(g_pPixelShader);
 
   g_pd3dDevice->SetStreamSource(0, g_pVB, 0, (sizeof (CUSTOMVERTEX)));
   g_pd3dDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 1);
@@ -374,6 +376,31 @@ int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PWSTR pCmdLine
     return 0;
   }
 
+  //////////////////////////////////////////////////////////////////////
+  // pixel shader
+  //////////////////////////////////////////////////////////////////////
+
+  res = D3DXCompileShaderFromFile(L"main.psh", // pSrcFile
+                                  NULL, // pDefines
+                                  NULL, // pInclude
+                                  "Main", // pFunctionName
+                                  "ps_3_0", // pProfile
+                                  dwShaderFlags, // Flags
+                                  &pCode, // ppShader
+                                  NULL, // ppErrorMsgs
+                                  &g_pConstantTable // ppConstantTable
+                                  );
+  if (FAILED(res)) {
+    fprintf(stderr, "D3DXCompileShader\n");
+    return 0;
+  }
+  res = g_pd3dDevice->CreatePixelShader((DWORD*)pCode->GetBufferPointer(), &g_pPixelShader);
+  pCode->Release();
+  if(FAILED(res)) {
+    fprintf(stderr, "CreatePixelShader\n");
+    return 0;
+  }
+
   //
 
   fprintf(stderr, "success\n");
diff --git a/main.psh b/main.psh
new file mode 100644
index 0000000..cacd727
--- /dev/null
+++ b/main.psh
@@ -0,0 +1,9 @@
+struct VS_OUTPUT
+{
+  float4 Position   : POSITION;   // vertex position
+  float4 Diffuse    : COLOR0;     // vertex diffuse color
+};
+
+float4 Main(VS_OUTPUT In) : COLOR {
+  return float4(1, 1, 1, 1) - In.Diffuse;
+}
diff --git a/main.vsh b/main.vsh
index a979cf4..14a28a5 100644
--- a/main.vsh
+++ b/main.vsh
@@ -16,7 +16,8 @@ VS_OUTPUT Main(VS_INPUT Input)
 {
   VS_OUTPUT Output;
 
-  Output.Position = mul(float4(Input.Position, 1.0), mWorldViewProj);
+  //Output.Position = mul(float4(Input.Position, 1.0), mWorldViewProj);
+  Output.Position = float4(Input.Position, 1.0);
   Output.Diffuse = Input.Color;
 
   return Output;