From 54d176fed0931f802bf5060a09beffeeb797384b Mon Sep 17 00:00:00 2001
From: Leith Bade <leith@leithalweapon.geek.nz>
Date: Sun, 9 Nov 2014 01:22:38 +1100
Subject: [PATCH] Implement GL extensions

---
 android/cpp/NativeMapView.cpp | 28 ++++++++++++++++++++++++++++
 android/cpp/NativeMapView.hpp |  2 ++
 2 files changed, 30 insertions(+)

diff --git a/android/cpp/NativeMapView.cpp b/android/cpp/NativeMapView.cpp
index add3e3bdb..a59c59857 100644
--- a/android/cpp/NativeMapView.cpp
+++ b/android/cpp/NativeMapView.cpp
@@ -432,6 +432,8 @@ void NativeMapView::start() {
         log_gl_string(GL_SHADING_LANGUAGE_VERSION, "SL Version");
         log_gl_string(GL_EXTENSIONS, "Extensions");
 
+        loadExtensions();        
+
         if (!eglMakeCurrent(display, EGL_NO_SURFACE, EGL_NO_SURFACE,
                 EGL_NO_CONTEXT)) {
             LOG_ERROR("eglMakeCurrent(EGL_NO_CONTEXT) returned error %d",
@@ -444,6 +446,32 @@ void NativeMapView::start() {
     }
 }
 
+void NativeMapView::loadExtensions() {
+    const GLubyte* str = glGetString(GL_EXTENSIONS);
+    if (str == nullptr) {
+        LOG_ERROR("glGetString(GL_EXTENSIONS) returned error %d", glGetError());
+        return;
+    }
+
+    std::string extensions(reinterpret_cast<const char*>(str));
+    
+    if (extensions.find("GL_OES_vertex_array_object") != std::string::npos) {
+        LOG_INFO("Using GL_OES_vertex_array_object.");
+        gl::BindVertexArray = (gl::PFNGLBINDVERTEXARRAYPROC)eglGetProcAddress("glBindVertexArrayOES");
+        gl::DeleteVertexArrays = (gl::PFNGLDELETEVERTEXARRAYSPROC)eglGetProcAddress("glDeleteVertexArraysOES");
+        gl::GenVertexArrays = (gl::PFNGLGENVERTEXARRAYSPROC)eglGetProcAddress("glGenVertexArraysOES");
+        gl::IsVertexArray = (gl::PFNGLISVERTEXARRAYPROC)eglGetProcAddress("glIsVertexArrayOES");
+
+        if ((gl::BindVertexArray == nullptr) || (gl::DeleteVertexArrays == nullptr) || (gl::GenVertexArrays == nullptr) || (gl::IsVertexArray == nullptr)) {
+            LOG_ERROR("Could not load GL_OES_vertex_array_object functions.");
+            gl::BindVertexArray = nullptr;
+            gl::DeleteVertexArrays = nullptr;
+            gl::GenVertexArrays = nullptr;
+            gl::IsVertexArray = nullptr;
+        }
+    }
+}
+
 void NativeMapView::stop() {
     LOG_VERBOSE("NativeMapView::stop");
     if ((display != EGL_NO_DISPLAY) && (surface != EGL_NO_SURFACE)
diff --git a/android/cpp/NativeMapView.hpp b/android/cpp/NativeMapView.hpp
index 866365c6d..aafd76189 100644
--- a/android/cpp/NativeMapView.hpp
+++ b/android/cpp/NativeMapView.hpp
@@ -68,6 +68,8 @@ private:
     EGLConfig chooseConfig(const EGLConfig configs[], EGLint num_configs,
             bool use565) const;
 
+    void loadExtensions();
+
 private:
     JavaVM* vm = nullptr;
     jobject obj = nullptr;