font.fx: geometry shaded text string

font.fx

@@ -13,7 +13,12 @@ SamplerState samPoint {
 
 struct VS_INPUT
 {
-  float2 Pos : POSITION;
+  float4 Pos : TEXCOORD;
+};
+
+struct GS_INPUT
+{
+  float4 Pos : SV_POSITION;
 };
 
 struct PS_INPUT
@@ -22,20 +27,44 @@ struct PS_INPUT
   float2 Tex : TEXCOORD0;
 };
 
-PS_INPUT VS(VS_INPUT input)
+
+GS_INPUT VS(VS_INPUT input)
 {
-  PS_INPUT output = (PS_INPUT)0;
+  GS_INPUT output;
 
-  float2 Pos = input.Pos * vGlyphScale + vPosition;
+  output.Pos = input.Pos;
-  Pos = Pos * vInvScreenSize + float2(-1, 1);
-  output.Pos = float4(Pos.xy, 0, 1);
 
-  float2 Tex = float2(input.Pos.x, -input.Pos.y);
-
-  output.Tex = (Tex + vCharCoord) * vTexScale;
   return output;
 }
 
+static const float2 vertices[] = {
+  float2( 0.0f,  0.0f), // -- top right
+  float2( 1.0f,  0.0f), // -- top left
+  float2( 0.0f, -1.0f), // -- bottom right
+  float2( 1.0f, -1.0f), // -- bottom left
+};
+
+[maxvertexcount(4)]
+void GS (point GS_INPUT input[1], inout TriangleStream<PS_INPUT> TriStream)
+{
+  PS_INPUT output;
+
+  for (int i = 0; i < 4; i++) {
+    float2 Pos;
+    //Pos = vertices[i] * vGlyphScale + vPosition;
+    Pos = vertices[i] * vGlyphScale + input[0].Pos.xy;
+    Pos = Pos * vInvScreenSize + float2(-1, 1);
+    output.Pos = float4(Pos.xy, 0, 1);
+
+    output.Tex = vertices[i] * float2(1, -1);
+    //output.Tex = (output.Tex + vCharCoord) * vTexScale;
+    output.Tex = (output.Tex + input[0].Pos.zw) * vTexScale;
+
+    TriStream.Append(output);
+  }
+  TriStream.RestartStrip();
+}
+
 float4 PS(PS_INPUT input) : SV_Target
 {
   float4 texColor = txDiffuse.Sample(samPoint, input.Tex);
@@ -50,7 +79,7 @@ technique10 Font
   pass P0
   {
     SetVertexShader(CompileShader(vs_4_0, VS()));
-    SetGeometryShader(NULL);
+    SetGeometryShader(CompileShader(gs_4_0, GS()));
     SetPixelShader(CompileShader(ps_4_0, PS()));
   }
 }

src/main.cpp

@@ -370,16 +370,8 @@ HRESULT LoadMesh()
   return S_OK;
 }
 
-struct FontVertex {
+const int g_iFontBufferLength = 512;
-  D3DXVECTOR2 Pos;
+typedef D3DXVECTOR4 FontVertex;
-};
-
-const FontVertex FontVertices[] = {
-  D3DXVECTOR2( 0.0f,  0.0f), // -- top right
-  D3DXVECTOR2( 1.0f,  0.0f), // -- top left
-  D3DXVECTOR2( 0.0f, -1.0f), // -- bottom right
-  D3DXVECTOR2( 1.0f, -1.0f), // -- bottom left
-};
 
 HRESULT InitFontBuffers()
 {
@@ -422,7 +414,7 @@ HRESULT InitFontBuffers()
   //////////////////////////////////////////////////////////////////////
 
   D3D10_INPUT_ELEMENT_DESC layout[] = {
-    {"POSITION", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 0 , D3D10_INPUT_PER_VERTEX_DATA, 0},
+    {"TEXCOORD", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 0 , D3D10_INPUT_PER_VERTEX_DATA, 0},
   };
   UINT numElements = (sizeof (layout)) / (sizeof (layout[0]));
 
@@ -443,16 +435,15 @@ HRESULT InitFontBuffers()
   //////////////////////////////////////////////////////////////////////
 
   D3D10_BUFFER_DESC bd;
-  D3D10_SUBRESOURCE_DATA initData;
 
   // position
-  bd.Usage = D3D10_USAGE_DEFAULT;
+  bd.Usage = D3D10_USAGE_DYNAMIC;
-  bd.ByteWidth = (sizeof (FontVertices));
+  bd.ByteWidth = (sizeof (FontVertex)) * g_iFontBufferLength;
   bd.BindFlags = D3D10_BIND_VERTEX_BUFFER;
-  bd.CPUAccessFlags = 0;
+  bd.CPUAccessFlags = D3D10_CPU_ACCESS_WRITE;
   bd.MiscFlags = 0;
-  initData.pSysMem = FontVertices;
+
-  hr = g_pd3dDevice->CreateBuffer(&bd, &initData, &g_pVertexBuffersFont[0]);
+  hr = g_pd3dDevice->CreateBuffer(&bd, NULL, &g_pVertexBuffersFont[0]);
   if (FAILED(hr)) {
     print("CreateBuffer\n");
     return hr;
@@ -899,6 +890,49 @@ void RenderModel(float t)
 
 void RenderFont()
 {
+
+  //////////////////////////////////////////////////////////////////////
+  // dynamic vertex buffer
+  //////////////////////////////////////////////////////////////////////
+
+  FontVertex * pData;
+  HRESULT hr;
+  hr = g_pVertexBuffersFont[0]->Map(D3D10_MAP_WRITE_DISCARD,
+                                    0,
+                                    (void **)&pData);
+  if (FAILED(hr)) {
+    print("g_pVertexBuffersFont->Map");
+  }
+
+  int advance = 10;
+  const char * s = "asdf";
+  int ix = 0;
+  const int charStride = (int)(g_FontSize.Texture.Width / g_FontSize.Glyph.Width);
+  while (ix < g_iFontBufferLength && *s) {
+    char c = *s++;
+
+    float px = (float)advance;
+    float py = -10.0;
+
+    float cx = 0;
+    float cy = 0;
+    if (c >= 0x20 && c <= 0x7f) {
+      c -= 0x20;
+      cx = (float)(c % charStride);
+      cy = (float)(c / charStride);
+      print("%c %f %f\n", c + 0x20, cx, cy);
+    }
+
+    pData[ix++] = FontVertex(px, py, cx, cy);
+
+    advance += g_FontSize.Glyph.Width;
+  }
+  g_pVertexBuffersFont[0]->Unmap();
+
+  //////////////////////////////////////////////////////////////////////
+  // effect variables
+  //////////////////////////////////////////////////////////////////////
+
   D3DXVECTOR2 invScreenSize = D3DXVECTOR2(2.0f / (float)g_ViewportSize.Width,
                                           2.0f / (float)g_ViewportSize.Height);
 
@@ -923,7 +957,7 @@ void RenderFont()
   UINT offset[] = { 0 };
   g_pd3dDevice->IASetInputLayout(g_pVertexLayoutFont);
   g_pd3dDevice->IASetVertexBuffers(0, g_dwVertexBufferCountFont, g_pVertexBuffersFont, stride, offset);
-  g_pd3dDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP);
+  g_pd3dDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_POINTLIST);
 
   D3D10_TECHNIQUE_DESC techDesc;
   g_pTechniqueFont->GetDesc(&techDesc);