Verifying GLSL version and ARB_bindless_texture support.

Fixes #289.

src/xenia/gpu/gl4/gl_context.cc

@@ -10,6 +10,7 @@
 #include "xenia/gpu/gl4/gl_context.h"
 
 #include <mutex>
+#include <string>
 
 #include "xenia/base/assert.h"
 #include "xenia/base/logging.h"
@@ -196,6 +197,42 @@ std::unique_ptr<GLContext> GLContext::CreateShared() {
   return new_context;
 }
 
+void FatalGLError(std::string error) {
+  XEFATAL(
+      (error +
+       "\nEnsure you have the latest drivers for your GPU and that it supports "
+       "OpenGL 4.5. See http://xenia.jp/faq/ for more information.").c_str());
+}
+
+void GLContext::AssertExtensionsPresent() {
+  if (!MakeCurrent()) {
+    XEFATAL("Unable to make GL context current");
+    return;
+  }
+
+  // Check shader version at least 4.5 (matching GL 4.5).
+  auto glsl_version_start =
+      reinterpret_cast<const char*>(glGetString(GL_SHADING_LANGUAGE_VERSION));
+  auto glsl_version_end = std::strchr(glsl_version_start, ' ');
+  std::string glsl_version(glsl_version_start, glsl_version_end);
+  if (glsl_version.compare("4.50") != 0) {
+    FatalGLError("OpenGL GLSL version 4.50 is required.");
+    return;
+  }
+
+  if (!GLEW_ARB_bindless_texture) {
+    FatalGLError("OpenGL extension ARB_bindless_texture is required.");
+    return;
+  }
+
+  // TODO(benvanik): figure out why this query fails.
+  // if (!GLEW_ARB_fragment_coord_conventions) {
+  //   FatalGLError(
+  //       "OpenGL extension ARB_fragment_coord_conventions is required.");
+  //   return;
+  // }
+}
+
 void GLContext::DebugMessage(GLenum source, GLenum type, GLuint id,
                              GLenum severity, GLsizei length,
                              const GLchar* message) {

src/xenia/gpu/gl4/gl_context.h

@@ -28,6 +28,7 @@ class GLContext {
   ~GLContext();
 
   bool Initialize(HWND hwnd);
+  void AssertExtensionsPresent();
 
   HDC dc() const { return dc_; }
 

src/xenia/gpu/gl4/wgl_control.cc

@@ -63,10 +63,12 @@ bool WGLControl::Create() {
     XEFATAL(
         "Unable to initialize GL context. Xenia requires OpenGL 4.5. Ensure "
         "you have the latest drivers for your GPU and that it supports OpenGL "
-        "4.5.");
+        "4.5. See http://xenia.jp/faq/ for more information.");
     return false;
   }
 
+  context_.AssertExtensionsPresent();
+
   SetFocus(hwnd_);
 
   OnCreate();