From d9ec84b327fd138e375fe1fdf8ae613e95252d0a Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Sat, 4 Dec 2021 21:18:06 +0000
Subject: [PATCH] gpu: implement C wrapper for Dawn Instance.discoverAdapters

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 gpu/src/dawn/dawn_native_mach.cpp | 39 +++++++++++++++++++++++++++----
 gpu/src/dawn/dawn_native_mach.h   | 14 +++++++++++
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/gpu/src/dawn/dawn_native_mach.cpp b/gpu/src/dawn/dawn_native_mach.cpp
index 5705cb9f..4dd7292a 100644
--- a/gpu/src/dawn/dawn_native_mach.cpp
+++ b/gpu/src/dawn/dawn_native_mach.cpp
@@ -1,7 +1,9 @@
 #include <dawn_native/DawnNative.h>
 #include <dawn_native/wgpu_structs_autogen.h>
 #include "utils/BackendBinding.h"
-
+#if defined(DAWN_ENABLE_BACKEND_OPENGL)
+#include <dawn_native/OpenGLBackend.h>
+#endif
 #include "dawn_native_mach.h"
 
 #ifdef __cplusplus
@@ -133,10 +135,37 @@ MACH_EXPORT void machDawnNativeInstance_discoverDefaultAdapters(MachDawnNativeIn
     dawn_native::Instance* self = reinterpret_cast<dawn_native::Instance*>(instance);
     self->DiscoverDefaultAdapters();
 }
-// TODO(dawn-native-mach):
-// // Adds adapters that can be discovered with the options provided (like a getProcAddress).
-// // The backend is chosen based on the type of the options used. Returns true on success.
-// bool DiscoverAdapters(const AdapterDiscoveryOptionsBase* options);
+MACH_EXPORT bool machDawnNativeInstance_discoverAdapters(MachDawnNativeInstance instance, WGPUBackendType backendType, const void* options) {
+    dawn_native::Instance* self = reinterpret_cast<dawn_native::Instance*>(instance);
+    switch (backendType) {
+    case WGPUBackendType_OpenGL:
+    #if defined(DAWN_ENABLE_BACKEND_DESKTOP_GL)
+    {
+        auto opt = reinterpret_cast<const MachDawnNativeAdapterDiscoveryOptions_OpenGL*>(options);
+        dawn_native::opengl::AdapterDiscoveryOptions adapterOptions = dawn_native::opengl::AdapterDiscoveryOptions();
+        adapterOptions.getProc = opt->getProc;
+        return self->DiscoverAdapters(&adapterOptions);
+    }
+    #endif
+    case WGPUBackendType_OpenGLES:
+    #if defined(DAWN_ENABLE_BACKEND_OPENGLES)
+    {
+        auto opt = reinterpret_cast<const MachDawnNativeAdapterDiscoveryOptions_OpenGLES*>(options);
+        dawn_native::opengl::AdapterDiscoveryOptionsES adapterOptions;
+        adapterOptions.getProc = opt->getProc;
+        return self->DiscoverAdapters(&adapterOptions);
+    }
+    #endif
+    case WGPUBackendType_WebGPU:
+    case WGPUBackendType_D3D11:
+    case WGPUBackendType_D3D12:
+    case WGPUBackendType_Metal:
+    case WGPUBackendType_Null:
+    case WGPUBackendType_Vulkan:
+    case WGPUBackendType_Force32:
+        return false;
+    }
+}
 MACH_EXPORT MachDawnNativeAdapters machDawnNativeInstance_getAdapters(MachDawnNativeInstance instance) {
     dawn_native::Instance* self = reinterpret_cast<dawn_native::Instance*>(instance);
     auto cppAdapters = self->GetAdapters();
diff --git a/gpu/src/dawn/dawn_native_mach.h b/gpu/src/dawn/dawn_native_mach.h
index 5f455b10..ffcc900e 100644
--- a/gpu/src/dawn/dawn_native_mach.h
+++ b/gpu/src/dawn/dawn_native_mach.h
@@ -81,11 +81,25 @@ typedef struct MachDawnNativeInstanceImpl* MachDawnNativeInstance;
 MACH_EXPORT MachDawnNativeInstance machDawnNativeInstance_init(void);
 MACH_EXPORT void machDawnNativeInstance_deinit(MachDawnNativeInstance);
 MACH_EXPORT void machDawnNativeInstance_discoverDefaultAdapters(MachDawnNativeInstance);
+
+// Adds adapters that can be discovered with the options provided (like a getProcAddress).
+// You must specify a valid backend type corresponding to the type of MachDawnNativeAdapterDiscoveryOptions_
+// struct pointer you pass as options.
+// Returns true on success.
+MACH_EXPORT bool machDawnNativeInstance_discoverAdapters(MachDawnNativeInstance instance, WGPUBackendType backendType, const void* options);
+
 MACH_EXPORT MachDawnNativeAdapters machDawnNativeInstance_getAdapters(MachDawnNativeInstance instance);
 
 // Backend-agnostic API for dawn_native
 MACH_EXPORT const DawnProcTable* machDawnNativeGetProcs();
 
+// Backend-specific options which can be passed to discoverAdapters
+typedef struct MachDawnNativeAdapterDiscoveryOptions_OpenGL {
+    void* (*getProc)(const char*);
+} MachDawnNativeAdapterDiscoveryOptions_OpenGL;
+typedef struct MachDawnNativeAdapterDiscoveryOptions_OpenGLES {
+    void* (*getProc)(const char*);
+} MachDawnNativeAdapterDiscoveryOptions_OpenGLES;
 
 // utils
 #include <GLFW/glfw3.h>