Add a WebGPU compat option in the shader compiler

Come on...

engine/shadercompiler/include/shadercompiler.hpp

@@ -36,6 +36,8 @@ public:
     
     /// When compiling MSL, the result may differ whether or not we're targetting non-Mac Metal platforms.
     bool is_apple_mobile = false;
+
+    bool enable_wgpu_compat = false;
 };
 
 /// Represents the source code of a shader either in plaintext (GLSL, MSL) or bytecode (SPIR-V).
@@ -94,7 +96,7 @@ public:
      @param options Optional compilation parameters.
      @note Right now, only GLSL is supported as a source shader language.
      */
-    std::optional<ShaderSource> compile(ShaderLanguage from_language, ShaderStage shader_stage, const ShaderSource& shader_source, ShaderLanguage to_language, const CompileOptions& options = CompileOptions());
+    std::optional<ShaderSource> compile(ShaderLanguage from_language, ShaderStage shader_stage, const ShaderSource& shader_source, ShaderLanguage to_language, CompileOptions options = CompileOptions());
 };
 
 static inline ShaderCompiler shader_compiler;

engine/shadercompiler/src/shadercompiler.cpp

@@ -31,6 +31,14 @@ std::vector<uint32_t> compile_glsl_to_spv(const std::string_view source_string,
     
     newString += source_string;
 
+    if(options.enable_wgpu_compat) {
+        // in some wacky world the webgpu devs live in, push constants do not exist.
+
+        // alright, so to make webgpu happy we are going to hand-waive all of our push constant blocks
+        // away into UBOs. let's start by rewriting our GLSL. yay...
+        newString = replace_substring(newString, "push_constant", "binding = 10");
+    }
+
     const char* InputCString = newString.c_str();
     
     glslang::TShader shader(shader_language);
@@ -43,6 +51,9 @@ std::vector<uint32_t> compile_glsl_to_spv(const std::string_view source_string,
                        glslang::EShClientVulkan,
                        ClientInputSemanticsVersion);
 
+
+    prism::log("compiling {}", newString);
+
     // we are targeting vulkan 1.1, so that uses SPIR-V 1.3
     shader.setEnvClient(glslang::EShClientVulkan, glslang::EShTargetVulkan_1_1);
     shader.setEnvTarget(glslang::EShTargetSpv,  glslang::EShTargetSpv_1_3);
@@ -50,7 +61,6 @@ std::vector<uint32_t> compile_glsl_to_spv(const std::string_view source_string,
     DirStackFileIncluder file_includer;
     for(const auto& path : include_path)
         file_includer.pushExternalLocalDirectory(path);
-
     if (!shader.parse(&DefaultTBuiltInResource, 100, false, EShMsgDefault, file_includer)) {
         prism::log("{}", shader.getInfoLog());
         
@@ -77,7 +87,7 @@ std::vector<uint32_t> compile_glsl_to_spv(const std::string_view source_string,
     return SpirV;
 }
 
-std::optional<ShaderSource> ShaderCompiler::compile(const ShaderLanguage from_language, const ShaderStage shader_stage, const ShaderSource& shader_source, const ShaderLanguage to_language, const CompileOptions& options) {
+std::optional<ShaderSource> ShaderCompiler::compile(const ShaderLanguage from_language, const ShaderStage shader_stage, const ShaderSource& shader_source, const ShaderLanguage to_language, CompileOptions options) {
     if(from_language != ShaderLanguage::GLSL) {
         prism::log("Non-supported input language!");
         return std::nullopt;
@@ -96,6 +106,8 @@ std::optional<ShaderSource> ShaderCompiler::compile(const ShaderLanguage from_la
             break;
     }
 
+    options.enable_wgpu_compat = to_language == ShaderLanguage::WGSL;
+
     auto spirv = compile_glsl_to_spv(shader_source.as_string(), lang, options);
     if(spirv.empty()) {
         prism::log("SPIRV generation failed!");
@@ -103,6 +115,7 @@ std::optional<ShaderSource> ShaderCompiler::compile(const ShaderLanguage from_la
     }
     
     switch(to_language) {
+        case ShaderLanguage::WGSL:
         case ShaderLanguage::SPIRV:
             return ShaderSource(spirv);
         case ShaderLanguage::MSL: {
@@ -123,9 +136,6 @@ std::optional<ShaderSource> ShaderCompiler::compile(const ShaderLanguage from_la
         case ShaderLanguage::HLSL:
             prism::log("Unimplemented shader language: HLSL");
             return ShaderSource(spirv);
-        case ShaderLanguage::WGSL:
-            prism::log("Unimplemented shader language: WGSL");
-            return ShaderSource(spirv);
         default:
             return {};
     }