feat(platform): Centralize platform-specific WebGPU code and improve shader composition

2 files changed, 170 insertions, 1 deletions

diff --git a/src/platform/platform.cc b/src/platform/platform.cc
index 29b3af3..2b8529a 100644
--- a/src/platform/platform.cc
+++ b/src/platform/platform.cc
@@ -5,6 +5,7 @@
 #include "platform/platform.h"
 #include "glfw3webgpu.h"
 #include <GLFW/glfw3.h>
+#include <cstdio>
 
 // --- Callbacks ---
 
@@ -128,4 +129,88 @@ WGPUSurface platform_create_wgpu_surface(WGPUInstance instance,
 
 double platform_get_time() {
   return glfwGetTime();
-}
\ No newline at end of file
+}
+
+// --- WebGPU Request Helpers ---
+
+#if defined(DEMO_CROSS_COMPILE_WIN32)
+static void _platform_adapter_cb_win32(WGPURequestAdapterStatus status,
+                                       WGPUAdapter adapter, const char* message,
+                                       void* userdata) {
+  if (status == WGPURequestAdapterStatus_Success) {
+    *((WGPUAdapter*)userdata) = adapter;
+  } else {
+    printf("Request adapter failed: %s\n", message ? message : "Unknown");
+  }
+}
+
+void platform_wgpu_request_adapter(WGPUInstance instance,
+                                   const WGPURequestAdapterOptions* options,
+                                   WGPUAdapter* out_adapter) {
+  wgpuInstanceRequestAdapter(instance, options, _platform_adapter_cb_win32,
+                             out_adapter);
+}
+
+static void _platform_device_cb_win32(WGPURequestDeviceStatus status,
+                                      WGPUDevice device, const char* message,
+                                      void* userdata) {
+  if (status == WGPURequestDeviceStatus_Success) {
+    *((WGPUDevice*)userdata) = device;
+  } else {
+    printf("Request device failed: %s\n", message ? message : "Unknown");
+  }
+}
+
+void platform_wgpu_request_device(WGPUAdapter adapter,
+                                  const WGPUDeviceDescriptor* descriptor,
+                                  WGPUDevice* out_device) {
+  wgpuAdapterRequestDevice(adapter, descriptor, _platform_device_cb_win32,
+                           out_device);
+}
+
+#else
+
+static void _platform_adapter_cb_native(WGPURequestAdapterStatus status,
+                                        WGPUAdapter adapter,
+                                        WGPUStringView message, void* userdata,
+                                        void* userdata2) {
+  (void)userdata2;
+  if (status == WGPURequestAdapterStatus_Success) {
+    *((WGPUAdapter*)userdata) = adapter;
+  } else {
+    printf("Request adapter failed: %.*s\n", (int)message.length, message.data);
+  }
+}
+
+void platform_wgpu_request_adapter(WGPUInstance instance,
+                                   const WGPURequestAdapterOptions* options,
+                                   WGPUAdapter* out_adapter) {
+  WGPURequestAdapterCallbackInfo cb = {};
+  cb.mode = WGPUCallbackMode_WaitAnyOnly;
+  cb.callback = _platform_adapter_cb_native;
+  cb.userdata1 = out_adapter;
+  wgpuInstanceRequestAdapter(instance, options, cb);
+}
+
+static void _platform_device_cb_native(WGPURequestDeviceStatus status,
+                                       WGPUDevice device,
+                                       WGPUStringView message, void* userdata,
+                                       void* userdata2) {
+  (void)userdata2;
+  if (status == WGPURequestDeviceStatus_Success) {
+    *((WGPUDevice*)userdata) = device;
+  } else {
+    printf("Request device failed: %.*s\n", (int)message.length, message.data);
+  }
+}
+
+void platform_wgpu_request_device(WGPUAdapter adapter,
+                                  const WGPUDeviceDescriptor* descriptor,
+                                  WGPUDevice* out_device) {
+  WGPURequestDeviceCallbackInfo cb = {};
+  cb.mode = WGPUCallbackMode_WaitAnyOnly;
+  cb.callback = _platform_device_cb_native;
+  cb.userdata1 = out_device;
+  wgpuAdapterRequestDevice(adapter, descriptor, cb);
+}
+#endif
diff --git a/src/platform/platform.h b/src/platform/platform.h
index 0a98850..ddea7af 100644
--- a/src/platform/platform.h
+++ b/src/platform/platform.h
@@ -22,6 +22,9 @@
 #define WGPUCallbackMode_WaitAnyOnly 0
 
 typedef WGPUShaderModuleWGSLDescriptor WGPUShaderSourceWGSL;
+// Texture compatibility typedefs
+typedef WGPUImageCopyTexture WGPU_TEX_COPY_INFO;
+typedef WGPUTextureDataLayout WGPU_TEX_DATA_LAYOUT;
 
 static inline const char* str_view(const char* str) {
   return str;
@@ -39,10 +42,44 @@ platform_wgpu_set_error_callback(WGPUDevice device,
   wgpuDeviceSetUncapturedErrorCallback(device, callback, nullptr);
 }
 
+// Helper to create a WGPUShaderModuleDescriptor with platform-specific chain
+static inline WGPUShaderModuleDescriptor platform_create_shader_module_descriptor(
+    const char* shader_code) {
+  WGPUShaderSourceWGSL* wgsl_src = new WGPUShaderSourceWGSL();
+  wgsl_src->chain.sType = WGPUSType_ShaderSourceWGSL;
+  wgsl_src->code = str_view(shader_code);
+
+  WGPUShaderModuleDescriptor shader_desc = {};
+  shader_desc.nextInChain = &wgsl_src->chain;
+  shader_desc.label = label_view(nullptr); // Use label_view for cross-platform compatibility
+
+  return shader_desc;
+}
+
+// Macro to set the depth stencil state for render pipelines
+#define PLATFORM_SET_PIPELINE_DEPTH_STENCIL(pipeline_desc, depth_stencil_state_ptr) \
+  _Pragma("clang diagnostic push") \
+  _Pragma("clang diagnostic ignored \"-Wuninitialized\"") \
+  _Pragma("clang diagnostic ignored \"-Wmissing-field-initializers\"") \
+  do { \
+    if (depth_stencil_state_ptr) { \
+      if (defined(DEMO_CROSS_COMPILE_WIN32)) { \
+        (pipeline_desc).depthStencilState = *(depth_stencil_state_ptr); \
+      } else { \
+        (pipeline_desc).depthStencil = (depth_stencil_state_ptr); \
+      } \
+    } \
+  } while (0) \
+  _Pragma("clang diagnostic pop")
+
 #else
 #include <webgpu.h>
 #include <wgpu.h>
 
+// Texture compatibility typedefs
+typedef WGPUTexelCopyTextureInfo WGPU_TEX_COPY_INFO;
+typedef WGPUTexelCopyBufferLayout WGPU_TEX_DATA_LAYOUT;
+
 static inline WGPUStringView str_view(const char* str) {
   if (!str)
     return {nullptr, 0};
@@ -69,8 +106,55 @@ platform_wgpu_set_error_callback(WGPUDevice device,
   // Handled in descriptor for new API, but provided for compatibility if needed
   // elsewhere
 }
+
+// Helper to create a WGPUShaderModuleDescriptor with platform-specific chain
+static inline WGPUShaderModuleDescriptor platform_create_shader_module_descriptor(
+    const char* shader_code) {
+  WGPUShaderModuleDescriptor shader_desc = {};
+  // Need to dynamically allocate wgsl_src, as it needs to persist for the lifetime of shader_desc.
+  WGPUShaderSourceWGSL* wgsl_src = new WGPUShaderSourceWGSL(); 
+  wgsl_src->chain.sType = WGPUSType_ShaderSourceWGSL;
+  wgsl_src->code = str_view(shader_code);
+
+  shader_desc.nextInChain = &wgsl_src->chain;
+  shader_desc.label = label_view(nullptr);
+  return shader_desc;
+}
+
+// Macro to set the depth stencil state for render pipelines
+#define PLATFORM_SET_PIPELINE_DEPTH_STENCIL(pipeline_desc, depth_stencil_state_ptr) \
+  do { \
+    (pipeline_desc).depthStencil = (depth_stencil_state_ptr); \
+  } while (0)
 #endif
 
+// Helper to extract error message from platform-specific string type
+static inline const char* platform_wgpu_get_error_message(
+#if defined(DEMO_CROSS_COMPILE_WIN32)
+    const char* message
+#else
+    WGPUStringView message
+#endif
+) {
+#if defined(DEMO_CROSS_COMPILE_WIN32)
+  return message ? message : "Unknown";
+#else
+  // Warning: Returns raw pointer to view data, typically not null-terminated!
+  // Use '%.*s' printf format with message.length if possible.
+  // This helper is best effort.
+  return message.data;
+#endif
+}
+
+// Platform-agnostic WebGPU request helpers
+void platform_wgpu_request_adapter(WGPUInstance instance,
+                                   const WGPURequestAdapterOptions* options,
+                                   WGPUAdapter* out_adapter);
+
+void platform_wgpu_request_device(WGPUAdapter adapter,
+                                  const WGPUDeviceDescriptor* descriptor,
+                                  WGPUDevice* out_device);
+
 // Forward declare GLFWwindow to avoid including the full header here.
 struct GLFWwindow;