Expose launch args to render sessions

Summary: This is an alternative implementation of D50209756. Read that diff and discussion for all the context on this change.

Reviewed By: corporateshark

Differential Revision: D50285937

fbshipit-source-id: 450c1a30de21cb3293b765d95823f0a8e13c1e98

shell/ios/main.m → shell/ios/main.mm

@@ -7,7 +7,11 @@
 
 #import "AppDelegate.h"
 
+#import <shell/shared/platform/Platform.h>
+
 int main(int argc, char* argv[]) {
+  igl::shell::Platform::initializeCommandLineArgs(argc, argv);
+
   @autoreleasepool {
     return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
   }

shell/mac/main.m → shell/mac/main.mm

@@ -7,6 +7,10 @@
 
 #import <Cocoa/Cocoa.h>
 
-int main(int argc, const char* argv[]) {
-  return NSApplicationMain(argc, argv);
+#import <shell/shared/platform/Platform.h>
+
+int main(int argc, char* argv[]) {
+  igl::shell::Platform::initializeCommandLineArgs(argc, argv);
+
+  return NSApplicationMain(argc, (const char**)argv);
 }

shell/shared/platform/Platform.cpp

@@ -10,6 +10,14 @@
 #include <shell/shared/imageLoader/ImageLoader.h>
 #include <shell/shared/platform/Platform.h>
 
+namespace {
+
+int g_argc = 0;
+char** g_argv = nullptr;
+bool g_argsInitialized = false;
+
+} // namespace
+
 namespace igl::shell {
 
 Platform::~Platform() = default;
@@ -40,4 +48,21 @@ std::shared_ptr<ITexture> Platform::loadTexture(const char* filename,
   return tex;
 }
 
+int Platform::argc() {
+  IGL_ASSERT_MSG(g_argsInitialized, "Accessing command line args before they are initialized.");
+  return g_argc;
+}
+
+char** Platform::argv() {
+  IGL_ASSERT_MSG(g_argsInitialized, "Accessing command line args before they are initialized.");
+  return g_argv;
+}
+
+void Platform::initializeCommandLineArgs(int argc, char** argv) {
+  IGL_ASSERT_MSG(!g_argsInitialized, "Must not initialize command line arguments more than once.");
+  g_argc = argc;
+  g_argv = argv;
+  g_argsInitialized = true;
+}
+
 } // namespace igl::shell

shell/shared/platform/Platform.h

@@ -48,6 +48,14 @@ class Platform {
       igl::TextureFormat format = igl::TextureFormat::RGBA_SRGB,
       igl::TextureDesc::TextureUsageBits usage = igl::TextureDesc::TextureUsageBits::Sampled);
 
+  // 'argc' and 'argv' are the exact arguments received in 'main()'.
+  static int argc();
+  static char** argv();
+
+  // Don't call this from the application level. The shell framework will use this API to expose
+  // command line arguments for the application.
+  static void initializeCommandLineArgs(int argc, char** argv);
+
  public:
   Extension* createAndInitializeExtension(const char* name) noexcept;
 

shell/windows/opengl/App.cpp

@@ -226,6 +226,8 @@ static void RunApplicationMode(uint32_t majorVersion, uint32_t minorVersion) {
 }
 
 int main(int argc, char* argv[]) {
+  igl::shell::Platform::initializeCommandLineArgs(argc, argv);
+
   uint32_t majorVersion = 4;
   uint32_t minorVersion = 6;
   if (argc == 2) {

shell/windows/opengles/App.cpp

@@ -157,6 +157,8 @@ igl::SurfaceTextures createSurfaceTextures(igl::IDevice& device) {
 }
 
 int main(int argc, char* argv[]) {
+  igl::shell::Platform::initializeCommandLineArgs(argc, argv);
+
   uint32_t majorVersion = 3;
   uint32_t minorVersion = 1;
   if (argc == 2) {

shell/windows/vulkan/App.cpp

@@ -168,6 +168,8 @@ igl::SurfaceTextures getVulkanSurfaceTextures(igl::IDevice& device) {
 }
 
 int main(int argc, char* argv[]) {
+  igl::shell::Platform::initializeCommandLineArgs(argc, argv);
+
   using WindowPtr = std::unique_ptr<GLFWwindow, decltype(&glfwDestroyWindow)>;
 
   WindowPtr vulkanWindow(initWindow(), &glfwDestroyWindow);