[core] Refactor OpenGL extension loading mechanism

Previously, we initialized global variables that held pointers to the extension functions. While this seemed to work, the spec doesn't guarantee that the function pointers are identical for different OpenGL contexts. Therefore, we are now making them a member variable of the Context object.

1 files changed, 120 insertions, 0 deletions

diff --git a/src/mbgl/gl/debugging_extension.hpp b/src/mbgl/gl/debugging_extension.hpp
new file mode 100644
index 0000000000..c1835cfcdd
--- /dev/null
+++ b/src/mbgl/gl/debugging_extension.hpp
@@ -0,0 +1,120 @@
+#pragma once
+
+#include <mbgl/gl/extension.hpp>
+#include <mbgl/gl/gl.hpp>
+
+#define GL_DEBUG_OUTPUT_SYNCHRONOUS       0x8242
+#define GL_DEBUG_NEXT_LOGGED_MESSAGE_LENGTH 0x8243
+#define GL_DEBUG_CALLBACK_FUNCTION        0x8244
+#define GL_DEBUG_CALLBACK_USER_PARAM      0x8245
+#define GL_DEBUG_SOURCE_API               0x8246
+#define GL_DEBUG_SOURCE_WINDOW_SYSTEM     0x8247
+#define GL_DEBUG_SOURCE_SHADER_COMPILER   0x8248
+#define GL_DEBUG_SOURCE_THIRD_PARTY       0x8249
+#define GL_DEBUG_SOURCE_APPLICATION       0x824A
+#define GL_DEBUG_SOURCE_OTHER             0x824B
+#define GL_DEBUG_TYPE_ERROR               0x824C
+#define GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR 0x824D
+#define GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR  0x824E
+#define GL_DEBUG_TYPE_PORTABILITY         0x824F
+#define GL_DEBUG_TYPE_PERFORMANCE         0x8250
+#define GL_DEBUG_TYPE_OTHER               0x8251
+#define GL_MAX_DEBUG_MESSAGE_LENGTH       0x9143
+#define GL_MAX_DEBUG_LOGGED_MESSAGES      0x9144
+#define GL_DEBUG_LOGGED_MESSAGES          0x9145
+#define GL_DEBUG_SEVERITY_HIGH            0x9146
+#define GL_DEBUG_SEVERITY_MEDIUM          0x9147
+#define GL_DEBUG_SEVERITY_LOW             0x9148
+#define GL_DEBUG_TYPE_MARKER              0x8268
+#define GL_DEBUG_TYPE_PUSH_GROUP          0x8269
+#define GL_DEBUG_TYPE_POP_GROUP           0x826A
+#define GL_DEBUG_SEVERITY_NOTIFICATION    0x826B
+#define GL_MAX_DEBUG_GROUP_STACK_DEPTH    0x826C
+#define GL_DEBUG_GROUP_STACK_DEPTH        0x826D
+#define GL_BUFFER                         0x82E0
+#define GL_SHADER                         0x82E1
+#define GL_PROGRAM                        0x82E2
+#define GL_QUERY                          0x82E3
+#define GL_PROGRAM_PIPELINE               0x82E4
+#define GL_SAMPLER                        0x82E6
+#define GL_MAX_LABEL_LENGTH               0x82E8
+#define GL_DEBUG_OUTPUT                   0x92E0
+#define GL_CONTEXT_FLAG_DEBUG_BIT         0x00000002
+#define GL_DISPLAY_LIST                   0x82E7
+#define GL_VERTEX_ARRAY                   0x8074
+#define GL_TRANSFORM_FEEDBACK             0x8E22
+#define GL_TEXTURE                        0x1702
+#define GL_RENDERBUFFER                   0x8D41
+#define GL_FRAMEBUFFER                    0x8D40
+
+namespace mbgl {
+namespace gl {
+namespace extension {
+
+class Debugging {
+public:
+    typedef void (*Callback)(GLenum source,
+                             GLenum type,
+                             GLuint id,
+                             GLenum severity,
+                             GLsizei length,
+                             const GLchar* message,
+                             const void* userParam);
+
+    static void DebugCallback(GLenum source,
+                              GLenum type,
+                              GLuint id,
+                              GLenum severity,
+                              GLsizei /* length */,
+                              const GLchar* message,
+                              const void* /* userParam */);
+
+    template <typename Fn>
+    Debugging(const Fn& loadExtension)
+        :
+#ifndef NDEBUG
+          pushDebugGroup(
+              loadExtension({ { "GL_KHR_debug", "glPushDebugGroup" } })),
+          popDebugGroup(
+              loadExtension({ { "GL_KHR_debug", "glPopDebugGroup" } })),
+          pushGroupMarkerEXT(
+              loadExtension({ { "GL_EXT_debug_marker", "glPushGroupMarkerEXT" } })),
+          popGroupMarkerEXT(
+              loadExtension({ { "GL_EXT_debug_marker", "glPopGroupMarkerEXT" } })),
+#endif
+          debugMessageControl(
+              loadExtension({ { "GL_KHR_debug", "glDebugMessageControl" },
+                              { "GL_ARB_debug_output", "glDebugMessageControlARB" } })),
+          debugMessageCallback(
+              loadExtension({ { "GL_KHR_debug", "glDebugMessageCallback" },
+                              { "GL_ARB_debug_output", "glDebugMessageCallbackARB" } })) {
+    }
+
+#ifndef NDEBUG
+    const ExtensionFunction<void(GLenum source,
+                                 GLuint id,
+                                 GLsizei length,
+                                 const GLchar* message)> pushDebugGroup;
+
+    const ExtensionFunction<void()> popDebugGroup;
+
+    const ExtensionFunction<void(GLsizei length,
+                                 const GLchar* marker)> pushGroupMarkerEXT;
+
+    const ExtensionFunction<void()> popGroupMarkerEXT;
+#endif
+
+    const ExtensionFunction<void(GLenum source,
+                                 GLenum type,
+                                 GLenum severity,
+                                 GLsizei count,
+                                 const GLuint* ids,
+                                 GLboolean enabled)> debugMessageControl;
+
+    const ExtensionFunction<void(Callback callback,
+                                 const void* userParam)> debugMessageCallback;
+};
+
+} // namespace extension
+} // namespace gl
+} // namespace mbgl