FramebufferShaderGen: Migrate over to fmt

Continures the migration of the shader generators over to fmt.

1 files changed, 329 insertions, 321 deletions

diff --git a/Source/Core/VideoCommon/FramebufferShaderGen.cpp b/Source/Core/VideoCommon/FramebufferShaderGen.cpp
index 49c2ba3b16..0b4022239e 100644
--- a/Source/Core/VideoCommon/FramebufferShaderGen.cpp
+++ b/Source/Core/VideoCommon/FramebufferShaderGen.cpp
@@ -4,12 +4,12 @@
 
 #include "VideoCommon/FramebufferShaderGen.h"
 
-#include <sstream>
 #include <string_view>
 
 #include "Common/Logging/Log.h"
 
 #include "VideoCommon/FramebufferManager.h"
+#include "VideoCommon/ShaderGenCommon.h"
 #include "VideoCommon/TextureDecoder.h"
 #include "VideoCommon/VertexShaderGen.h"
 #include "VideoCommon/VideoCommon.h"
@@ -24,27 +24,27 @@ APIType GetAPIType()
   return g_ActiveConfig.backend_info.api_type;
 }
 
-void EmitUniformBufferDeclaration(std::ostringstream& ss)
+void EmitUniformBufferDeclaration(ShaderCode& code)
 {
   if (GetAPIType() == APIType::D3D)
-    ss << "cbuffer PSBlock : register(b0)\n";
+    code.WriteFmt("cbuffer PSBlock : register(b0)\n");
   else
-    ss << "UBO_BINDING(std140, 1) uniform PSBlock\n";
+    code.WriteFmt("UBO_BINDING(std140, 1) uniform PSBlock\n");
 }
 
-void EmitSamplerDeclarations(std::ostringstream& ss, u32 start = 0, u32 end = 1,
+void EmitSamplerDeclarations(ShaderCode& code, u32 start = 0, u32 end = 1,
                              bool multisampled = false)
 {
   switch (GetAPIType())
   {
   case APIType::D3D:
   {
+    const char* array_type = multisampled ? "Texture2DMSArray<float4>" : "Texture2DArray<float4>";
+
     for (u32 i = start; i < end; i++)
     {
-      ss << (multisampled ? "Texture2DMSArray<float4>" : "Texture2DArray<float4>") << " tex" << i
-         << " : register(t" << i << ");\n";
-      ss << "SamplerState"
-         << " samp" << i << " : register(s" << i << ");\n";
+      code.WriteFmt("{} tex{} : register(t{});\n", array_type, i, i);
+      code.WriteFmt("SamplerState samp{} : register(s{});\n", i, i);
     }
   }
   break;
@@ -52,10 +52,11 @@ void EmitSamplerDeclarations(std::ostringstream& ss, u32 start = 0, u32 end = 1,
   case APIType::OpenGL:
   case APIType::Vulkan:
   {
+    const char* array_type = multisampled ? "sampler2DMSArray" : "sampler2DArray";
+
     for (u32 i = start; i < end; i++)
     {
-      ss << "SAMPLER_BINDING(" << i << ") uniform "
-         << (multisampled ? "sampler2DMSArray" : "sampler2DArray") << " samp" << i << ";\n";
+      code.WriteFmt("SAMPLER_BINDING({}) uniform {} samp{};\n", i, array_type, i);
     }
   }
   break;
@@ -64,17 +65,17 @@ void EmitSamplerDeclarations(std::ostringstream& ss, u32 start = 0, u32 end = 1,
   }
 }
 
-void EmitSampleTexture(std::ostringstream& ss, u32 n, std::string_view coords)
+void EmitSampleTexture(ShaderCode& code, u32 n, std::string_view coords)
 {
   switch (GetAPIType())
   {
   case APIType::D3D:
-    ss << "tex" << n << ".Sample(samp" << n << ", " << coords << ')';
+    code.WriteFmt("tex{}.Sample(samp{}, {})", n, n, coords);
     break;
 
   case APIType::OpenGL:
   case APIType::Vulkan:
-    ss << "texture(samp" << n << ", " << coords << ')';
+    code.WriteFmt("texture(samp{}, {})", n, coords);
     break;
 
   default:
@@ -84,17 +85,17 @@ void EmitSampleTexture(std::ostringstream& ss, u32 n, std::string_view coords)
 
 // Emits a texel fetch/load instruction. Assumes that "coords" is a 4-element vector, with z
 // containing the layer, and w containing the mipmap level.
-void EmitTextureLoad(std::ostringstream& ss, u32 n, std::string_view coords)
+void EmitTextureLoad(ShaderCode& code, u32 n, std::string_view coords)
 {
   switch (GetAPIType())
   {
   case APIType::D3D:
-    ss << "tex" << n << ".Load(" << coords << ')';
+    code.WriteFmt("tex{}.Load({})", n, coords);
     break;
 
   case APIType::OpenGL:
   case APIType::Vulkan:
-    ss << "texelFetch(samp" << n << ", (" << coords << ").xyz, (" << coords << ").w)";
+    code.WriteFmt("texelFetch(samp{}, ({}).xyz, ({}).w)", n, coords, coords);
     break;
 
   default:
@@ -102,7 +103,7 @@ void EmitTextureLoad(std::ostringstream& ss, u32 n, std::string_view coords)
   }
 }
 
-void EmitVertexMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 num_color_inputs,
+void EmitVertexMainDeclaration(ShaderCode& code, u32 num_tex_inputs, u32 num_color_inputs,
                                bool position_input, u32 num_tex_outputs, u32 num_color_outputs,
                                std::string_view extra_inputs = {})
 {
@@ -110,19 +111,19 @@ void EmitVertexMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 n
   {
   case APIType::D3D:
   {
-    ss << "void main(";
+    code.WriteFmt("void main(");
     for (u32 i = 0; i < num_tex_inputs; i++)
-      ss << "in float3 rawtex" << i << " : TEXCOORD" << i << ", ";
+      code.WriteFmt("in float3 rawtex{} : TEXCOORD{}, ", i, i);
     for (u32 i = 0; i < num_color_inputs; i++)
-      ss << "in float4 rawcolor" << i << " : COLOR" << i << ", ";
+      code.WriteFmt("in float4 rawcolor{} : COLOR{}, ", i, i);
     if (position_input)
-      ss << "in float4 rawpos : POSITION, ";
-    ss << extra_inputs;
+      code.WriteFmt("in float4 rawpos : POSITION, ");
+    code.WriteFmt("{}", extra_inputs);
     for (u32 i = 0; i < num_tex_outputs; i++)
-      ss << "out float3 v_tex" << i << " : TEXCOORD" << i << ", ";
+      code.WriteFmt("out float3 v_tex{} : TEXCOORD{}, ", i, i);
     for (u32 i = 0; i < num_color_outputs; i++)
-      ss << "out float4 v_col" << i << " : COLOR" << i << ", ";
-    ss << "out float4 opos : SV_Position)\n";
+      code.WriteFmt("out float4 v_col{} : COLOR{}, ", i, i);
+    code.WriteFmt("out float4 opos : SV_Position)\n");
   }
   break;
 
@@ -131,36 +132,36 @@ void EmitVertexMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 n
   {
     for (u32 i = 0; i < num_tex_inputs; i++)
     {
-      ss << "ATTRIBUTE_LOCATION(" << (SHADER_TEXTURE0_ATTRIB + i) << ") in float3 rawtex" << i
-         << ";\n";
+      const auto attribute = SHADER_TEXTURE0_ATTRIB + i;
+      code.WriteFmt("ATTRIBUTE_LOCATION({}) in float3 rawtex{};\n", attribute, i);
     }
     for (u32 i = 0; i < num_color_inputs; i++)
     {
-      ss << "ATTRIBUTE_LOCATION(" << (SHADER_COLOR0_ATTRIB + i) << ") in float4 rawcolor" << i
-         << ";\n";
+      const auto attribute = SHADER_COLOR0_ATTRIB + i;
+      code.WriteFmt("ATTRIBUTE_LOCATION({}) in float4 rawcolor{};\n", attribute, i);
     }
     if (position_input)
-      ss << "ATTRIBUTE_LOCATION(" << SHADER_POSITION_ATTRIB << ") in float4 rawpos;\n";
+      code.WriteFmt("ATTRIBUTE_LOCATION({}) in float4 rawpos;\n", SHADER_POSITION_ATTRIB);
 
     if (g_ActiveConfig.backend_info.bSupportsGeometryShaders)
     {
-      ss << "VARYING_LOCATION(0) out VertexData {\n";
+      code.WriteFmt("VARYING_LOCATION(0) out VertexData {{\n");
       for (u32 i = 0; i < num_tex_outputs; i++)
-        ss << "  float3 v_tex" << i << ";\n";
+        code.WriteFmt("  float3 v_tex{};\n", i);
       for (u32 i = 0; i < num_color_outputs; i++)
-        ss << "  float4 v_col" << i << ";\n";
-      ss << "};\n";
+        code.WriteFmt("  float4 v_col{};\n", i);
+      code.WriteFmt("}};\n");
     }
     else
     {
       for (u32 i = 0; i < num_tex_outputs; i++)
-        ss << "VARYING_LOCATION(" << i << ") out float3 v_tex" << i << ";\n";
+        code.WriteFmt("VARYING_LOCATION({}) out float3 v_tex{};\n", i, i);
       for (u32 i = 0; i < num_color_outputs; i++)
-        ss << "VARYING_LOCATION(" << (num_tex_inputs + i) << ") out float4 v_col" << i << ";\n";
+        code.WriteFmt("VARYING_LOCATION({}) out float4 v_col{};\n", num_tex_inputs + i, i);
     }
-    ss << "#define opos gl_Position\n";
-    ss << extra_inputs << '\n';
-    ss << "void main()\n";
+    code.WriteFmt("#define opos gl_Position\n");
+    code.WriteFmt("{}\n", extra_inputs);
+    code.WriteFmt("void main()\n");
   }
   break;
   default:
@@ -168,7 +169,7 @@ void EmitVertexMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 n
   }
 }
 
-void EmitPixelMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 num_color_inputs,
+void EmitPixelMainDeclaration(ShaderCode& code, u32 num_tex_inputs, u32 num_color_inputs,
                               std::string_view output_type = "float4",
                               std::string_view extra_vars = {}, bool emit_frag_coord = false)
 {
@@ -176,14 +177,14 @@ void EmitPixelMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 nu
   {
   case APIType::D3D:
   {
-    ss << "void main(";
+    code.WriteFmt("void main(");
     for (u32 i = 0; i < num_tex_inputs; i++)
-      ss << "in float3 v_tex" << i << " : TEXCOORD" << i << ", ";
+      code.WriteFmt("in float3 v_tex{} : TEXCOORD{}, ", i, i);
     for (u32 i = 0; i < num_color_inputs; i++)
-      ss << "in float4 v_col" << i << " : COLOR" << i << ", ";
+      code.WriteFmt("in float4 v_col{} : COLOR{}, ", i, i);
     if (emit_frag_coord)
-      ss << "in float4 frag_coord : SV_Position, ";
-    ss << extra_vars << "out " << output_type << " ocol0 : SV_Target)\n";
+      code.WriteFmt("in float4 frag_coord : SV_Position, ");
+    code.WriteFmt("{}out {} ocol0 : SV_Target)\n", extra_vars, output_type);
   }
   break;
 
@@ -192,26 +193,26 @@ void EmitPixelMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 nu
   {
     if (g_ActiveConfig.backend_info.bSupportsGeometryShaders)
     {
-      ss << "VARYING_LOCATION(0) in VertexData {\n";
+      code.WriteFmt("VARYING_LOCATION(0) in VertexData {{\n");
       for (u32 i = 0; i < num_tex_inputs; i++)
-        ss << "  in float3 v_tex" << i << ";\n";
+        code.WriteFmt("  in float3 v_tex{};\n", i);
       for (u32 i = 0; i < num_color_inputs; i++)
-        ss << "  in float4 v_col" << i << ";\n";
-      ss << "};\n";
+        code.WriteFmt("  in float4 v_col{};\n", i);
+      code.WriteFmt("}};\n");
     }
     else
     {
       for (u32 i = 0; i < num_tex_inputs; i++)
-        ss << "VARYING_LOCATION(" << i << ") in float3 v_tex" << i << ";\n";
+        code.WriteFmt("VARYING_LOCATION({}) in float3 v_tex{};\n", i, i);
       for (u32 i = 0; i < num_color_inputs; i++)
-        ss << "VARYING_LOCATION(" << (num_tex_inputs + i) << ") in float4 v_col" << i << ";\n";
+        code.WriteFmt("VARYING_LOCATION({}) in float4 v_col{};\n", num_tex_inputs + i, i);
     }
 
-    ss << "FRAGMENT_OUTPUT_LOCATION(0) out " << output_type << " ocol0;\n";
-    ss << extra_vars << "\n";
+    code.WriteFmt("FRAGMENT_OUTPUT_LOCATION(0) out {} ocol0;\n", output_type);
+    code.WriteFmt("{}\n", extra_vars);
     if (emit_frag_coord)
-      ss << "#define frag_coord gl_FragCoord\n";
-    ss << "void main()\n";
+      code.WriteFmt("#define frag_coord gl_FragCoord\n");
+    code.WriteFmt("void main()\n");
   }
   break;
 
@@ -223,399 +224,406 @@ void EmitPixelMainDeclaration(std::ostringstream& ss, u32 num_tex_inputs, u32 nu
 
 std::string GenerateScreenQuadVertexShader()
 {
-  std::ostringstream ss;
-  EmitVertexMainDeclaration(ss, 0, 0, false, 1, 0,
+  ShaderCode code;
+  EmitVertexMainDeclaration(code, 0, 0, false, 1, 0,
                             GetAPIType() == APIType::D3D ? "in uint id : SV_VertexID, " :
                                                            "#define id gl_VertexID\n");
-  ss << "{\n"
-        "  v_tex0 = float3(float((id << 1) & 2), float(id & 2), 0.0f);\n"
-        "  opos = float4(v_tex0.xy * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), 0.0f, 1.0f);\n";
+  code.WriteFmt(
+      "{{\n"
+      "  v_tex0 = float3(float((id << 1) & 2), float(id & 2), 0.0f);\n"
+      "  opos = float4(v_tex0.xy * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), 0.0f, 1.0f);\n");
 
   // NDC space is flipped in Vulkan. We also flip in GL so that (0,0) is in the lower-left.
   if (GetAPIType() == APIType::Vulkan || GetAPIType() == APIType::OpenGL)
-    ss << "  opos.y = -opos.y;\n";
+    code.WriteFmt("  opos.y = -opos.y;\n");
 
-  ss << "}\n";
+  code.WriteFmt("}}\n");
 
-  return ss.str();
+  return code.GetBuffer();
 }
 
 std::string GeneratePassthroughGeometryShader(u32 num_tex, u32 num_colors)
 {
-  std::ostringstream ss;
+  ShaderCode code;
   if (GetAPIType() == APIType::D3D)
   {
-    ss << "struct VS_OUTPUT\n"
-          "{\n";
+    code.WriteFmt("struct VS_OUTPUT\n"
+                  "{{\n");
     for (u32 i = 0; i < num_tex; i++)
-      ss << "  float3 tex" << i << " : TEXCOORD" << i << ";\n";
+      code.WriteFmt("  float3 tex{} : TEXCOORD{};\n", i, i);
     for (u32 i = 0; i < num_colors; i++)
-      ss << "  float4 color" << i << " : COLOR" << i << ";\n";
-    ss << "  float4 position : SV_Position;\n"
-          "};\n";
+      code.WriteFmt("  float4 color{} : COLOR{};\n", i, i);
+    code.WriteFmt("  float4 position : SV_Position;\n"
+                  "}};\n");
 
-    ss << "struct GS_OUTPUT\n"
-          "{";
+    code.WriteFmt("struct GS_OUTPUT\n"
+                  "{{");
     for (u32 i = 0; i < num_tex; i++)
-      ss << "  float3 tex" << i << " : TEXCOORD" << i << ";\n";
+      code.WriteFmt("  float3 tex{} : TEXCOORD{};\n", i, i);
     for (u32 i = 0; i < num_colors; i++)
-      ss << "  float4 color" << i << " : COLOR" << i << ";\n";
-    ss << "  float4 position : SV_Position;\n"
-          "  uint slice : SV_RenderTargetArrayIndex;\n"
-          "};\n\n";
-
-    ss << "[maxvertexcount(6)]\n"
-          "void main(triangle VS_OUTPUT vso[3], inout TriangleStream<GS_OUTPUT> output)\n"
-          "{\n"
-          "  for (uint slice = 0; slice < 2u; slice++)\n"
-          "  {\n"
-          "    for (int i = 0; i < 3; i++)\n"
-          "    {\n"
-          "      GS_OUTPUT gso;\n"
-          "      gso.position = vso[i].position;\n";
+      code.WriteFmt("  float4 color{} : COLOR{};\n", i, i);
+    code.WriteFmt("  float4 position : SV_Position;\n"
+                  "  uint slice : SV_RenderTargetArrayIndex;\n"
+                  "}};\n\n");
+
+    code.WriteFmt("[maxvertexcount(6)]\n"
+                  "void main(triangle VS_OUTPUT vso[3], inout TriangleStream<GS_OUTPUT> output)\n"
+                  "{{\n"
+                  "  for (uint slice = 0; slice < 2u; slice++)\n"
+                  "  {{\n"
+                  "    for (int i = 0; i < 3; i++)\n"
+                  "    {{\n"
+                  "      GS_OUTPUT gso;\n"
+                  "      gso.position = vso[i].position;\n");
     for (u32 i = 0; i < num_tex; i++)
-      ss << "      gso.tex" << i << " = float3(vso[i].tex" << i << ".xy, float(slice));\n";
+      code.WriteFmt("      gso.tex{} = float3(vso[i].tex{}.xy, float(slice));\n", i, i);
     for (u32 i = 0; i < num_colors; i++)
-      ss << "      gso.color" << i << " = vso[i].color" << i << ";\n";
-    ss << "      gso.slice = slice;\n"
-          "      output.Append(gso);\n"
-          "    }\n"
-          "    output.RestartStrip();\n"
-          "  }\n"
-          "}\n";
+      code.WriteFmt("      gso.color{} = vso[i].color{};\n", i, i);
+    code.WriteFmt("      gso.slice = slice;\n"
+                  "      output.Append(gso);\n"
+                  "    }}\n"
+                  "    output.RestartStrip();\n"
+                  "  }}\n"
+                  "}}\n");
   }
   else if (GetAPIType() == APIType::OpenGL || GetAPIType() == APIType::Vulkan)
   {
-    ss << "layout(triangles) in;\n"
-          "layout(triangle_strip, max_vertices = 6) out;\n";
+    code.WriteFmt("layout(triangles) in;\n"
+                  "layout(triangle_strip, max_vertices = 6) out;\n");
+
     if (num_tex > 0 || num_colors > 0)
     {
-      ss << "VARYING_LOCATION(0) in VertexData {\n";
+      code.WriteFmt("VARYING_LOCATION(0) in VertexData {{\n");
       for (u32 i = 0; i < num_tex; i++)
-        ss << "  float3 v_tex" << i << ";\n";
+        code.WriteFmt("  float3 v_tex{};\n", i);
       for (u32 i = 0; i < num_colors; i++)
-        ss << "  float4 v_col" << i << ";\n";
-      ss << "} v_in[];\n";
+        code.WriteFmt("  float4 v_col{};\n", i);
+      code.WriteFmt("}} v_in[];\n");
 
-      ss << "VARYING_LOCATION(0) out VertexData {\n";
+      code.WriteFmt("VARYING_LOCATION(0) out VertexData {{\n");
       for (u32 i = 0; i < num_tex; i++)
-        ss << "  float3 v_tex" << i << ";\n";
+        code.WriteFmt("  float3 v_tex{};\n", i);
       for (u32 i = 0; i < num_colors; i++)
-        ss << "  float4 v_col" << i << ";\n";
-      ss << "} v_out;\n";
+        code.WriteFmt("  float4 v_col{};\n", i);
+      code.WriteFmt("}} v_out;\n");
     }
-    ss << "\n"
-          "void main()\n"
-          "{\n"
-          "  for (int j = 0; j < 2; j++)\n"
-          "  {\n"
-          "    gl_Layer = j;\n";
+    code.WriteFmt("\n"
+                  "void main()\n"
+                  "{{\n"
+                  "  for (int j = 0; j < 2; j++)\n"
+                  "  {{\n"
+                  "    gl_Layer = j;\n");
 
     // We have to explicitly unroll this loop otherwise the GL compiler gets cranky.
     for (u32 v = 0; v < 3; v++)
     {
-      ss << "    gl_Position = gl_in[" << v << "].gl_Position;\n";
+      code.WriteFmt("    gl_Position = gl_in[{}].gl_Position;\n", v);
       for (u32 i = 0; i < num_tex; i++)
-        ss << "    v_out.v_tex" << i << " = float3(v_in[" << v << "].v_tex" << i
-           << ".xy, float(j));\n";
+      {
+        code.WriteFmt("    v_out.v_tex{} = float3(v_in[{}].v_tex{}.xy, float(j));\n", i, v, i);
+      }
       for (u32 i = 0; i < num_colors; i++)
-        ss << "    v_out.v_col" << i << " = v_in[" << v << "].v_col" << i << ";\n";
-      ss << "    EmitVertex();\n\n";
+        code.WriteFmt("    v_out.v_col{} = v_in[{}].v_col{};\n", i, v, i);
+      code.WriteFmt("    EmitVertex();\n\n");
     }
-    ss << "    EndPrimitive();\n"
-          "  }\n"
-          "}\n";
+    code.WriteFmt("    EndPrimitive();\n"
+                  "  }}\n"
+                  "}}\n");
   }
 
-  return ss.str();
+  return code.GetBuffer();
 }
 
 std::string GenerateTextureCopyVertexShader()
 {
-  std::ostringstream ss;
-  EmitUniformBufferDeclaration(ss);
-  ss << "{"
-        "  float2 src_offset;\n"
-        "  float2 src_size;\n"
-        "};\n\n";
-
-  EmitVertexMainDeclaration(ss, 0, 0, false, 1, 0,
+  ShaderCode code;
+  EmitUniformBufferDeclaration(code);
+  code.WriteFmt("{{"
+                "  float2 src_offset;\n"
+                "  float2 src_size;\n"
+                "}};\n\n");
+
+  EmitVertexMainDeclaration(code, 0, 0, false, 1, 0,
                             GetAPIType() == APIType::D3D ? "in uint id : SV_VertexID, " :
                                                            "#define id gl_VertexID");
-  ss << "{\n"
-        "  v_tex0 = float3(float((id << 1) & 2), float(id & 2), 0.0f);\n"
-        "  opos = float4(v_tex0.xy * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), 0.0f, 1.0f);\n"
-        "  v_tex0 = float3(src_offset + (src_size * v_tex0.xy), 0.0f);\n";
+  code.WriteFmt(
+      "{{\n"
+      "  v_tex0 = float3(float((id << 1) & 2), float(id & 2), 0.0f);\n"
+      "  opos = float4(v_tex0.xy * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), 0.0f, 1.0f);\n"
+      "  v_tex0 = float3(src_offset + (src_size * v_tex0.xy), 0.0f);\n");
 
   // NDC space is flipped in Vulkan. We also flip in GL so that (0,0) is in the lower-left.
   if (GetAPIType() == APIType::Vulkan || GetAPIType() == APIType::OpenGL)
-    ss << "  opos.y = -opos.y;\n";
+    code.WriteFmt("  opos.y = -opos.y;\n");
 
-  ss << "}\n";
+  code.WriteFmt("}}\n");
 
-  return ss.str();
+  return code.GetBuffer();
 }
 
 std::string GenerateTextureCopyPixelShader()
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 1, false);
-  EmitPixelMainDeclaration(ss, 1, 0);
-  ss << "{\n"
-        "  ocol0 = ";
-  EmitSampleTexture(ss, 0, "v_tex0");
-  ss << ";\n"
-        "}\n";
-  return ss.str();
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 1, false);
+  EmitPixelMainDeclaration(code, 1, 0);
+  code.WriteFmt("{{\n"
+                "  ocol0 = ");
+  EmitSampleTexture(code, 0, "v_tex0");
+  code.WriteFmt(";\n"
+                "}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateColorPixelShader()
 {
-  std::ostringstream ss;
-  EmitPixelMainDeclaration(ss, 0, 1);
-  ss << "{\n"
-        "  ocol0 = v_col0;\n"
-        "}\n";
-  return ss.str();
+  ShaderCode code;
+  EmitPixelMainDeclaration(code, 0, 1);
+  code.WriteFmt("{{\n"
+                "  ocol0 = v_col0;\n"
+                "}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateResolveDepthPixelShader(u32 samples)
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 1, true);
-  EmitPixelMainDeclaration(ss, 1, 0, "float",
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 1, true);
+  EmitPixelMainDeclaration(code, 1, 0, "float",
                            GetAPIType() == APIType::D3D ? "in float4 ipos : SV_Position, " : "");
-  ss << "{\n"
-        "  int layer = int(v_tex0.z);\n";
+  code.WriteFmt("{{\n"
+                "  int layer = int(v_tex0.z);\n");
   if (GetAPIType() == APIType::D3D)
-    ss << "  int3 coords = int3(int2(ipos.xy), layer);\n";
+    code.WriteFmt("  int3 coords = int3(int2(ipos.xy), layer);\n");
   else
-    ss << "  int3 coords = int3(int2(gl_FragCoord.xy), layer);\n";
+    code.WriteFmt("  int3 coords = int3(int2(gl_FragCoord.xy), layer);\n");
 
   // Take the minimum of all depth samples.
   if (GetAPIType() == APIType::D3D)
-    ss << "  ocol0 = tex0.Load(coords, 0).r;\n";
+    code.WriteFmt("  ocol0 = tex0.Load(coords, 0).r;\n");
   else
-    ss << "  ocol0 = texelFetch(samp0, coords, 0).r;\n";
-  ss << "  for (int i = 1; i < " << samples << "; i++)\n";
+    code.WriteFmt("  ocol0 = texelFetch(samp0, coords, 0).r;\n");
+  code.WriteFmt("  for (int i = 1; i < {}; i++)\n", samples);
   if (GetAPIType() == APIType::D3D)
-    ss << "    ocol0 = min(ocol0, tex0.Load(coords, i).r);\n";
+    code.WriteFmt("    ocol0 = min(ocol0, tex0.Load(coords, i).r);\n");
   else
-    ss << "    ocol0 = min(ocol0, texelFetch(samp0, coords, i).r);\n";
+    code.WriteFmt("    ocol0 = min(ocol0, texelFetch(samp0, coords, i).r);\n");
 
-  ss << "}\n";
-  return ss.str();
+  code.WriteFmt("}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateClearVertexShader()
 {
-  std::ostringstream ss;
-  EmitUniformBufferDeclaration(ss);
-  ss << "{\n"
-        "  float4 clear_color;\n"
-        "  float clear_depth;\n"
-        "};\n";
-
-  EmitVertexMainDeclaration(ss, 0, 0, false, 0, 1,
+  ShaderCode code;
+  EmitUniformBufferDeclaration(code);
+  code.WriteFmt("{{\n"
+                "  float4 clear_color;\n"
+                "  float clear_depth;\n"
+                "}};\n");
+
+  EmitVertexMainDeclaration(code, 0, 0, false, 0, 1,
                             GetAPIType() == APIType::D3D ? "in uint id : SV_VertexID, " :
                                                            "#define id gl_VertexID\n");
-  ss << "{\n"
-        "  float2 coord = float2(float((id << 1) & 2), float(id & 2));\n"
-        "  opos = float4(coord * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), clear_depth, 1.0f);\n"
-        "  v_col0 = clear_color;\n";
+  code.WriteFmt(
+      "{{\n"
+      "  float2 coord = float2(float((id << 1) & 2), float(id & 2));\n"
+      "  opos = float4(coord * float2(2.0f, -2.0f) + float2(-1.0f, 1.0f), clear_depth, 1.0f);\n"
+      "  v_col0 = clear_color;\n");
 
   // NDC space is flipped in Vulkan
   if (GetAPIType() == APIType::Vulkan)
-    ss << "  opos.y = -opos.y;\n";
+    code.WriteFmt("  opos.y = -opos.y;\n");
 
-  ss << "}\n";
+  code.WriteFmt("}}\n");
 
-  return ss.str();
+  return code.GetBuffer();
 }
 
 std::string GenerateEFBPokeVertexShader()
 {
-  std::ostringstream ss;
-  EmitVertexMainDeclaration(ss, 0, 1, true, 0, 1);
-  ss << "{\n"
-        "  v_col0 = rawcolor0;\n"
-        "  opos = float4(rawpos.xyz, 1.0f);\n";
+  ShaderCode code;
+  EmitVertexMainDeclaration(code, 0, 1, true, 0, 1);
+  code.WriteFmt("{{\n"
+                "  v_col0 = rawcolor0;\n"
+                "  opos = float4(rawpos.xyz, 1.0f);\n");
   if (g_ActiveConfig.backend_info.bSupportsLargePoints)
-    ss << "  gl_PointSize = rawpos.w;\n";
+    code.WriteFmt("  gl_PointSize = rawpos.w;\n");
 
   // NDC space is flipped in Vulkan.
   if (GetAPIType() == APIType::Vulkan)
-    ss << "  opos.y = -opos.y;\n";
+    code.WriteFmt("  opos.y = -opos.y;\n");
 
-  ss << "}\n";
-  return ss.str();
+  code.WriteFmt("}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateFormatConversionShader(EFBReinterpretType convtype, u32 samples)
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 1, samples > 1);
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 1, samples > 1);
   EmitPixelMainDeclaration(
-      ss, 1, 0, "float4",
+      code, 1, 0, "float4",
       GetAPIType() == APIType::D3D ?
           (g_ActiveConfig.bSSAA ?
                "in float4 ipos : SV_Position, in uint isample : SV_SampleIndex, " :
                "in float4 ipos : SV_Position, ") :
           "");
-  ss << "{\n"
-        "  int layer = int(v_tex0.z);\n";
+  code.WriteFmt("{{\n"
+                "  int layer = int(v_tex0.z);\n");
   if (GetAPIType() == APIType::D3D)
-    ss << "  int3 coords = int3(int2(ipos.xy), layer);\n";
+    code.WriteFmt("  int3 coords = int3(int2(ipos.xy), layer);\n");
   else
-    ss << "  int3 coords = int3(int2(gl_FragCoord.xy), layer);\n";
+    code.WriteFmt("  int3 coords = int3(int2(gl_FragCoord.xy), layer);\n");
 
   if (samples == 1)
   {
     // No MSAA at all.
     if (GetAPIType() == APIType::D3D)
-      ss << "  float4 val = tex0.Load(int4(coords, 0));\n";
+      code.WriteFmt("  float4 val = tex0.Load(int4(coords, 0));\n");
     else
-      ss << "  float4 val = texelFetch(samp0, coords, 0);\n";
+      code.WriteFmt("  float4 val = texelFetch(samp0, coords, 0);\n");
   }
   else if (g_ActiveConfig.bSSAA)
   {
     // Sample shading, shader runs once per sample
     if (GetAPIType() == APIType::D3D)
-      ss << "  float4 val = tex0.Load(coords, isample);";
+      code.WriteFmt("  float4 val = tex0.Load(coords, isample);");
     else
-      ss << "  float4 val = texelFetch(samp0, coords, gl_SampleID);";
+      code.WriteFmt("  float4 val = texelFetch(samp0, coords, gl_SampleID);");
   }
   else
   {
     // MSAA without sample shading, average out all samples.
-    ss << "  float4 val = float4(0.0f, 0.0f, 0.0f, 0.0f);\n";
-    ss << "  for (int i = 0; i < " << samples << "; i++)\n";
+    code.WriteFmt("  float4 val = float4(0.0f, 0.0f, 0.0f, 0.0f);\n");
+    code.WriteFmt("  for (int i = 0; i < {}; i++)\n", samples);
     if (GetAPIType() == APIType::D3D)
-      ss << "    val += tex0.Load(coords, i);\n";
+      code.WriteFmt("    val += tex0.Load(coords, i);\n");
     else
-      ss << "    val += texelFetch(samp0, coords, i);\n";
-    ss << "  val /= float(" << samples << ");\n";
+      code.WriteFmt("    val += texelFetch(samp0, coords, i);\n");
+    code.WriteFmt("  val /= float({});\n", samples);
   }
 
   switch (convtype)
   {
   case EFBReinterpretType::RGB8ToRGBA6:
-    ss << "  int4 src8 = int4(round(val * 255.f));\n"
-          "  int4 dst6;\n"
-          "  dst6.r = src8.r >> 2;\n"
-          "  dst6.g = ((src8.r & 0x3) << 4) | (src8.g >> 4);\n"
-          "  dst6.b = ((src8.g & 0xF) << 2) | (src8.b >> 6);\n"
-          "  dst6.a = src8.b & 0x3F;\n"
-          "  ocol0 = float4(dst6) / 63.f;\n";
+    code.WriteFmt("  int4 src8 = int4(round(val * 255.f));\n"
+                  "  int4 dst6;\n"
+                  "  dst6.r = src8.r >> 2;\n"
+                  "  dst6.g = ((src8.r & 0x3) << 4) | (src8.g >> 4);\n"
+                  "  dst6.b = ((src8.g & 0xF) << 2) | (src8.b >> 6);\n"
+                  "  dst6.a = src8.b & 0x3F;\n"
+                  "  ocol0 = float4(dst6) / 63.f;\n");
     break;
 
   case EFBReinterpretType::RGB8ToRGB565:
-    ss << "  ocol0 = val;\n";
+    code.WriteFmt("  ocol0 = val;\n");
     break;
 
   case EFBReinterpretType::RGBA6ToRGB8:
-    ss << "  int4 src6 = int4(round(val * 63.f));\n"
-          "  int4 dst8;\n"
-          "  dst8.r = (src6.r << 2) | (src6.g >> 4);\n"
-          "  dst8.g = ((src6.g & 0xF) << 4) | (src6.b >> 2);\n"
-          "  dst8.b = ((src6.b & 0x3) << 6) | src6.a;\n"
-          "  dst8.a = 255;\n"
-          "  ocol0 = float4(dst8) / 255.f;\n";
+    code.WriteFmt("  int4 src6 = int4(round(val * 63.f));\n"
+                  "  int4 dst8;\n"
+                  "  dst8.r = (src6.r << 2) | (src6.g >> 4);\n"
+                  "  dst8.g = ((src6.g & 0xF) << 4) | (src6.b >> 2);\n"
+                  "  dst8.b = ((src6.b & 0x3) << 6) | src6.a;\n"
+                  "  dst8.a = 255;\n"
+                  "  ocol0 = float4(dst8) / 255.f;\n");
     break;
 
   case EFBReinterpretType::RGBA6ToRGB565:
-    ss << "  ocol0 = val;\n";
+    code.WriteFmt("  ocol0 = val;\n");
     break;
 
   case EFBReinterpretType::RGB565ToRGB8:
-    ss << "  ocol0 = val;\n";
+    code.WriteFmt("  ocol0 = val;\n");
     break;
 
   case EFBReinterpretType::RGB565ToRGBA6:
     //
-    ss << "  ocol0 = val;\n";
+    code.WriteFmt("  ocol0 = val;\n");
     break;
   }
 
-  ss << "}\n";
-  return ss.str();
+  code.WriteFmt("}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureFormat to_format)
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 1, false);
-  EmitPixelMainDeclaration(ss, 1, 0, "float4", "", true);
-  ss << "{\n"
-        "  int layer = int(v_tex0.z);\n"
-        "  int4 coords = int4(int2(frag_coord.xy), layer, 0);\n";
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 1, false);
+  EmitPixelMainDeclaration(code, 1, 0, "float4", "", true);
+  code.WriteFmt("{{\n"
+                "  int layer = int(v_tex0.z);\n"
+                "  int4 coords = int4(int2(frag_coord.xy), layer, 0);\n");
 
   // Convert to a 32-bit value encompassing all channels, filling the most significant bits with
   // zeroes.
-  ss << "  uint raw_value;\n";
+  code.WriteFmt("  uint raw_value;\n");
   switch (from_format)
   {
   case TextureFormat::I8:
   case TextureFormat::C8:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n"
-          "  raw_value = uint(temp_value.r * 255.0);\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(";\n"
+                  "  raw_value = uint(temp_value.r * 255.0);\n");
   }
   break;
 
   case TextureFormat::IA8:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n"
-          "  raw_value = uint(temp_value.r * 255.0) | (uint(temp_value.a * 255.0) << 8);\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(
+        ";\n"
+        "  raw_value = uint(temp_value.r * 255.0) | (uint(temp_value.a * 255.0) << 8);\n");
   }
   break;
 
   case TextureFormat::I4:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n"
-          "  raw_value = uint(temp_value.r * 15.0);\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(";\n"
+                  "  raw_value = uint(temp_value.r * 15.0);\n");
   }
   break;
 
   case TextureFormat::IA4:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n"
-          "  raw_value = uint(temp_value.r * 15.0) | (uint(temp_value.a * 15.0) << 4);\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(";\n"
+                  "  raw_value = uint(temp_value.r * 15.0) | (uint(temp_value.a * 15.0) << 4);\n");
   }
   break;
 
   case TextureFormat::RGB565:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n"
-          "  raw_value = uint(temp_value.b * 31.0) | (uint(temp_value.g * 63.0) << 5) |\n"
-          "              (uint(temp_value.r * 31.0) << 11);\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(";\n"
+                  "  raw_value = uint(temp_value.b * 31.0) | (uint(temp_value.g * 63.0) << 5) |\n"
+                  "              (uint(temp_value.r * 31.0) << 11);\n");
   }
   break;
 
   case TextureFormat::RGB5A3:
   {
-    ss << "  float4 temp_value = ";
-    EmitTextureLoad(ss, 0, "coords");
-    ss << ";\n";
+    code.WriteFmt("  float4 temp_value = ");
+    EmitTextureLoad(code, 0, "coords");
+    code.WriteFmt(";\n");
 
     // 0.8784 = 224 / 255 which is the maximum alpha value that can be represented in 3 bits
-    ss << "  if (temp_value.a > 0.878f) {\n"
-          "    raw_value = (uint(temp_value.b * 31.0)) | (uint(temp_value.g * 31.0) << 5) |\n"
-          "                (uint(temp_value.r * 31.0) << 10) | 0x8000u;\n"
-          "  } else {\n"
-          "     raw_value = (uint(temp_value.b * 15.0)) | (uint(temp_value.g * 15.0) << 4) |\n"
-          "                 (uint(temp_value.r * 15.0) << 8) | (uint(temp_value.a * 7.0) << 12);\n"
-          "  }\n";
+    code.WriteFmt(
+        "  if (temp_value.a > 0.878f) {{\n"
+        "    raw_value = (uint(temp_value.b * 31.0)) | (uint(temp_value.g * 31.0) << 5) |\n"
+        "                (uint(temp_value.r * 31.0) << 10) | 0x8000u;\n"
+        "  }} else {{\n"
+        "     raw_value = (uint(temp_value.b * 15.0)) | (uint(temp_value.g * 15.0) << 4) |\n"
+        "                 (uint(temp_value.r * 15.0) << 8) | (uint(temp_value.a * 7.0) << 12);\n"
+        "  }}\n");
   }
   break;
 
@@ -630,45 +638,45 @@ std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureF
   case TextureFormat::I8:
   case TextureFormat::C8:
   {
-    ss << "  float orgba = float(raw_value & 0xFFu) / 255.0;\n"
-          "  ocol0 = float4(orgba, orgba, orgba, orgba);\n";
+    code.WriteFmt("  float orgba = float(raw_value & 0xFFu) / 255.0;\n"
+                  "  ocol0 = float4(orgba, orgba, orgba, orgba);\n");
   }
   break;
 
   case TextureFormat::IA8:
   {
-    ss << "  float orgb = float(raw_value & 0xFFu) / 255.0;\n"
-          "  ocol0 = float4(orgb, orgb, orgb, float((raw_value >> 8) & 0xFFu) / 255.0);\n";
+    code.WriteFmt("  float orgb = float(raw_value & 0xFFu) / 255.0;\n"
+                  "  ocol0 = float4(orgb, orgb, orgb, float((raw_value >> 8) & 0xFFu) / 255.0);\n");
   }
   break;
 
   case TextureFormat::IA4:
   {
-    ss << "  float orgb = float(raw_value & 0xFu) / 15.0;\n"
-          "  ocol0 = float4(orgb, orgb, orgb, float((raw_value >> 4) & 0xFu) / 15.0);\n";
+    code.WriteFmt("  float orgb = float(raw_value & 0xFu) / 15.0;\n"
+                  "  ocol0 = float4(orgb, orgb, orgb, float((raw_value >> 4) & 0xFu) / 15.0);\n");
   }
   break;
 
   case TextureFormat::RGB565:
   {
-    ss << "  ocol0 = float4(float((raw_value >> 10) & 0x1Fu) / 31.0,\n"
-          "                 float((raw_value >> 5) & 0x1Fu) / 31.0,\n"
-          "                 float(raw_value & 0x1Fu) / 31.0, 1.0);\n";
+    code.WriteFmt("  ocol0 = float4(float((raw_value >> 10) & 0x1Fu) / 31.0,\n"
+                  "                 float((raw_value >> 5) & 0x1Fu) / 31.0,\n"
+                  "                 float(raw_value & 0x1Fu) / 31.0, 1.0);\n");
   }
   break;
 
   case TextureFormat::RGB5A3:
   {
-    ss << "  if ((raw_value & 0x8000u) != 0u) {\n"
-          "    ocol0 = float4(float((raw_value >> 10) & 0x1Fu) / 31.0,\n"
-          "                   float((raw_value >> 5) & 0x1Fu) / 31.0,\n"
-          "                   float(raw_value & 0x1Fu) / 31.0, 1.0);\n"
-          "  } else {\n"
-          "    ocol0 = float4(float((raw_value >> 8) & 0x0Fu) / 15.0,\n"
-          "                   float((raw_value >> 4) & 0x0Fu) / 15.0,\n"
-          "                   float(raw_value & 0x0Fu) / 15.0,\n"
-          "                   float((raw_value >> 12) & 0x07u) / 7.0);\n"
-          "  }\n";
+    code.WriteFmt("  if ((raw_value & 0x8000u) != 0u) {{\n"
+                  "    ocol0 = float4(float((raw_value >> 10) & 0x1Fu) / 31.0,\n"
+                  "                   float((raw_value >> 5) & 0x1Fu) / 31.0,\n"
+                  "                   float(raw_value & 0x1Fu) / 31.0, 1.0);\n"
+                  "  }} else {{\n"
+                  "    ocol0 = float4(float((raw_value >> 8) & 0x0Fu) / 15.0,\n"
+                  "                   float((raw_value >> 4) & 0x0Fu) / 15.0,\n"
+                  "                   float(raw_value & 0x0Fu) / 15.0,\n"
+                  "                   float((raw_value >> 12) & 0x07u) / 7.0);\n"
+                  "  }}\n");
   }
   break;
   default:
@@ -676,64 +684,64 @@ std::string GenerateTextureReinterpretShader(TextureFormat from_format, TextureF
     return "{}\n";
   }
 
-  ss << "}\n";
-  return ss.str();
+  code.WriteFmt("}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateEFBRestorePixelShader()
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 2, false);
-  EmitPixelMainDeclaration(ss, 1, 0, "float4",
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 2, false);
+  EmitPixelMainDeclaration(code, 1, 0, "float4",
                            GetAPIType() == APIType::D3D ? "out float depth : SV_Depth, " : "");
-  ss << "{\n"
-        "  ocol0 = ";
-  EmitSampleTexture(ss, 0, "v_tex0");
-  ss << ";\n";
-  ss << "  " << (GetAPIType() == APIType::D3D ? "depth" : "gl_FragDepth") << " = ";
-  EmitSampleTexture(ss, 1, "v_tex0");
-  ss << ".r;\n"
-        "}\n";
-  return ss.str();
+  code.WriteFmt("{{\n"
+                "  ocol0 = ");
+  EmitSampleTexture(code, 0, "v_tex0");
+  code.WriteFmt(";\n");
+  code.WriteFmt("  {} = ", GetAPIType() == APIType::D3D ? "depth" : "gl_FragDepth");
+  EmitSampleTexture(code, 1, "v_tex0");
+  code.WriteFmt(".r;\n"
+                "}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateImGuiVertexShader()
 {
-  std::ostringstream ss;
+  ShaderCode code;
 
   // Uniform buffer contains the viewport size, and we transform in the vertex shader.
-  EmitUniformBufferDeclaration(ss);
-  ss << "{\n"
-        "float2 u_rcp_viewport_size_mul2;\n"
-        "};\n\n";
-
-  EmitVertexMainDeclaration(ss, 1, 1, true, 1, 1);
-  ss << "{\n"
-        "  v_tex0 = float3(rawtex0.xy, 0.0);\n"
-        "  v_col0 = rawcolor0;\n"
-        "  opos = float4(rawpos.x * u_rcp_viewport_size_mul2.x - 1.0,"
-        "                1.0 - rawpos.y * u_rcp_viewport_size_mul2.y, 0.0, 1.0);\n";
+  EmitUniformBufferDeclaration(code);
+  code.WriteFmt("{{\n"
+                "float2 u_rcp_viewport_size_mul2;\n"
+                "}};\n\n");
+
+  EmitVertexMainDeclaration(code, 1, 1, true, 1, 1);
+  code.WriteFmt("{{\n"
+                "  v_tex0 = float3(rawtex0.xy, 0.0);\n"
+                "  v_col0 = rawcolor0;\n"
+                "  opos = float4(rawpos.x * u_rcp_viewport_size_mul2.x - 1.0,"
+                "                1.0 - rawpos.y * u_rcp_viewport_size_mul2.y, 0.0, 1.0);\n");
 
   // NDC space is flipped in Vulkan.
   if (GetAPIType() == APIType::Vulkan)
-    ss << "  opos.y = -opos.y;\n";
+    code.WriteFmt("  opos.y = -opos.y;\n");
 
-  ss << "}\n";
-  return ss.str();
+  code.WriteFmt("}}\n");
+  return code.GetBuffer();
 }
 
 std::string GenerateImGuiPixelShader()
 {
-  std::ostringstream ss;
-  EmitSamplerDeclarations(ss, 0, 1, false);
-  EmitPixelMainDeclaration(ss, 1, 1);
-  ss << "{\n"
-        "  ocol0 = ";
-  EmitSampleTexture(ss, 0, "float3(v_tex0.xy, 0.0)");
-  ss << " * v_col0;\n"
-        "}\n";
-
-  return ss.str();
+  ShaderCode code;
+  EmitSamplerDeclarations(code, 0, 1, false);
+  EmitPixelMainDeclaration(code, 1, 1);
+  code.WriteFmt("{{\n"
+                "  ocol0 = ");
+  EmitSampleTexture(code, 0, "float3(v_tex0.xy, 0.0)");
+  code.WriteFmt(" * v_col0;\n"
+                "}}\n");
+
+  return code.GetBuffer();
 }
 
 }  // namespace FramebufferShaderGen