diff --git a/cpp/display/display_glx.cpp b/cpp/display/display_glx.cpp
index 8f2dae1..2a79cc9 100644
--- a/cpp/display/display_glx.cpp
+++ b/cpp/display/display_glx.cpp
@@ -17,6 +17,7 @@
 
 #include "../display.hpp"
 #include "display_glx.hpp"
+#include "../events/events_x11.hpp"
 #include <cstdio>
 #include <cstring>
 
@@ -26,9 +27,6 @@ static bool rk_error_occured = false;
 #define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092
 typedef GLXContext (*rk_CreateContextAttribsFunc)(Display *, GLXFBConfig, GLXContext, Bool, int const *);
 
-rk_DrawElementsInstancedBaseInstanceFunc rk_DrawElementsInstancedBaseInstance = nullptr;
-rk_MultiDrawElementsIndirectFunc rk_MultiDrawElementsIndirect = nullptr;
-
 static int const rk_visual_attribs[] = {
     GLX_X_RENDERABLE, True,
     GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT,
@@ -51,19 +49,24 @@ static int const rk_context_attribs[] = {
     None
 };
 
+static void rk_x11_printf(
+    char const * messsage) {
+    printf("[X11] %s\n", messsage);
+}
+
 static void rk_glx_printf(
     char const * messsage) {
     printf("[GLX] %s\n", messsage);
 }
 
 static bool rk_extension_supported(
-    char const * extlist,
+    char const * extensions,
     char const * extension) {
     char const * where = strchr(extension, ' ');
     if (where || *extension == '\0') {
         return false;
     }
-    for (char const * start = extlist;;) {
+    for (char const * start = extensions;;) {
         where = strstr(start, extension);
         if (!where) {
             break;
@@ -77,6 +80,24 @@ static bool rk_extension_supported(
     return false;
 }
 
+rk_func_ptr rk_resolve_extension(
+    char const * extensions,
+    char const * extension,
+    char const * fn) {
+    if (!extensions || !extension || !fn) {
+        return nullptr;
+    }
+    if (!rk_extension_supported(extensions, extension)) {
+        printf("[GLX] Extension %s not supported\n", extension);
+        return nullptr;
+    }
+    rk_func_ptr const ptr = glXGetProcAddressARB(reinterpret_cast<GLubyte const *>(fn));
+    if (!ptr) {
+        printf("[GLX] Function %s::%s not found\n", extension, fn);
+    }
+    return ptr;
+}
+
 static int rk_error_handler(
     Display * display,
     XErrorEvent * event) {
@@ -97,7 +118,7 @@ rk_display_t rk_create_display(
     display->colormap = 0;
     display->context = nullptr;
     if (!display->display) {
-        rk_glx_printf("Failed to open X display.");
+        rk_x11_printf("Failed to open X display.");
         rk_destroy_display(reinterpret_cast<rk_display_t>(display));
         return nullptr;
     }
@@ -109,8 +130,15 @@ rk_display_t rk_create_display(
         rk_destroy_display(reinterpret_cast<rk_display_t>(display));
         return nullptr;
     }
+
     char const * const glx_exts = glXQueryExtensionsString(display->display, DefaultScreen(display->display));
     // rk_glx_printf(glx_exts);
+    rk_CreateContextAttribsFunc const glXCreateContextAttribs = reinterpret_cast<rk_CreateContextAttribsFunc>(
+        rk_resolve_extension(glx_exts, "GLX_ARB_create_context", "glXCreateContextAttribsARB"));
+    if (!glXCreateContextAttribs) {
+        rk_destroy_display(reinterpret_cast<rk_display_t>(display));
+        return nullptr;
+    }
 
     int fbcount;
     GLXFBConfig * const fbc = glXChooseFBConfig(
@@ -157,32 +185,22 @@ rk_display_t rk_create_display(
         0, 0, width, height, 0, vi->depth, InputOutput, vi->visual, CWColormap | CWEventMask, &swa);
     XFree(vi);
     if (!display->window) {
-        rk_glx_printf("Failed to create window.");
+        rk_x11_printf("Failed to create window.");
         rk_destroy_display(reinterpret_cast<rk_display_t>(display));
         return nullptr;
     }
     XStoreName(display->display, display->window, name);
     XMapWindow(display->display, display->window);
 
-    rk_CreateContextAttribsFunc const glXCreateContextAttribs =
-        reinterpret_cast<rk_CreateContextAttribsFunc>(
-            glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("glXCreateContextAttribsARB")));
-
-    if (!rk_extension_supported(glx_exts, "GLX_ARB_create_context") || !glXCreateContextAttribs) {
-        rk_glx_printf("glXCreateContextAttribsARB extension not found.");
+    rk_error_occured = false;
+    int (*oldHandler)(Display *, XErrorEvent *) = XSetErrorHandler(&rk_error_handler);
+    display->context = glXCreateContextAttribs(display->display, bestFbc, 0, True, rk_context_attribs);
+    XSync(display->display, False);
+    XSetErrorHandler(oldHandler);
+    if (rk_error_occured || !display->context) {
+        rk_glx_printf("Failed to create context.");
         rk_destroy_display(reinterpret_cast<rk_display_t>(display));
         return nullptr;
-    } else {
-        rk_error_occured = false;
-        int (*oldHandler)(Display *, XErrorEvent *) = XSetErrorHandler(&rk_error_handler);
-        display->context = glXCreateContextAttribs(display->display, bestFbc, 0, True, rk_context_attribs);
-        XSync(display->display, False);
-        XSetErrorHandler(oldHandler);
-        if (rk_error_occured || !display->context) {
-            rk_glx_printf("Failed to create context.");
-            rk_destroy_display(reinterpret_cast<rk_display_t>(display));
-            return nullptr;
-        }
     }
 
     if (!glXIsDirect(display->display, display->context)) {
@@ -190,25 +208,6 @@ rk_display_t rk_create_display(
     }
     glXMakeCurrent(display->display, display->window, display->context);
 
-    char const * const gl_exts = reinterpret_cast<char const *>(glGetString(GL_EXTENSIONS));
-    // printf("[GL] %s\n", gl_exts);
-    if (rk_extension_supported(gl_exts, "GL_EXT_base_instance")) {
-        rk_DrawElementsInstancedBaseInstance =
-            reinterpret_cast<rk_DrawElementsInstancedBaseInstanceFunc>(
-                glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("DrawElementsInstancedBaseInstance")));
-        if (rk_DrawElementsInstancedBaseInstance) {
-            rk_glx_printf("Using extension GL_EXT_base_instance::DrawElementsInstancedBaseInstance.");
-            if (rk_extension_supported(gl_exts, "GL_EXT_multi_draw_indirect")) {
-                rk_MultiDrawElementsIndirect =
-                    reinterpret_cast<rk_MultiDrawElementsIndirectFunc>(
-                        glXGetProcAddressARB(reinterpret_cast<GLubyte const *>("MultiDrawElementsIndirectEXT")));
-                if (rk_MultiDrawElementsIndirect) {
-                    rk_glx_printf("Using extension GL_EXT_multi_draw_indirect::MultiDrawElementsIndirectEXT.");
-                }
-            }
-        }
-    }
-
     return reinterpret_cast<rk_display_t>(display);
 }
 
diff --git a/cpp/display/display_glx.hpp b/cpp/display/display_glx.hpp
index 33bcbc4..80252a8 100644
--- a/cpp/display/display_glx.hpp
+++ b/cpp/display/display_glx.hpp
@@ -18,17 +18,17 @@
 
 #include "../types.hpp"
 #include "display_x11.hpp"
-#include "../events/events_x11.hpp"
 #include <GL/glx.h>
 
 struct rk_display_glx : public rk_display_x11 {
     GLXContext context;
 };
 
-typedef void (*rk_DrawElementsInstancedBaseInstanceFunc)(rk_uint, rk_uint, rk_uint, const void *, rk_uint, rk_uint);
-typedef void (*rk_MultiDrawElementsIndirectFunc)(rk_uint, rk_uint, const void *, rk_uint, rk_uint);
+typedef void (*rk_func_ptr)();
 
-extern rk_DrawElementsInstancedBaseInstanceFunc rk_DrawElementsInstancedBaseInstance;
-extern rk_MultiDrawElementsIndirectFunc rk_MultiDrawElementsIndirect;
+extern rk_func_ptr rk_resolve_extension(
+    char const * extensions,
+    char const * extension,
+    char const * fn);
 
 #endif // _RK_ENGINE_DISPLAY_GLX_H
diff --git a/cpp/render/render_opengles.cpp b/cpp/render/render_opengles.cpp
index cf1075c..73c51a1 100644
--- a/cpp/render/render_opengles.cpp
+++ b/cpp/render/render_opengles.cpp
@@ -19,9 +19,19 @@
 #include <cstdio>
 #include <cstring>
 
+typedef void (*rk_DrawElementsInstancedBaseInstanceFunc)(rk_uint, rk_uint, rk_uint, const void *, rk_uint, rk_uint);
+typedef void (*rk_MultiDrawElementsIndirectFunc)(rk_uint, rk_uint, const void *, rk_uint, rk_uint);
+
+static rk_DrawElementsInstancedBaseInstanceFunc rk_DrawElementsInstancedBaseInstance = nullptr;
+static rk_MultiDrawElementsIndirectFunc rk_MultiDrawElementsIndirect = nullptr;
+
 static rk_shader const * rk_current_shader = nullptr;
 static rk_vertices const * rk_current_vertices = nullptr;
 
+static void rk_gl_printf(char const * message) {
+    printf("[GL] %s\n", message);
+}
+
 static void rk_printf(char const * message) {
     printf("[RK] %s\n", message);
 }
@@ -42,14 +52,27 @@ static void rk_debug_message_callback(
 void rk_render_initialize() {
     GLubyte const * const vendor = glGetString(GL_VENDOR);
     GLubyte const * const renderer = glGetString(GL_RENDERER);
-    printf("[RK] vendor: %s, renderer: %s\n", vendor, renderer);
+    printf("[GL] vendor: %s, renderer: %s\n", vendor, renderer);
     GLubyte const * const version = glGetString(GL_VERSION);
     GLubyte const * const language = glGetString(GL_SHADING_LANGUAGE_VERSION);
-    printf("[RK] version: %s, language: %s\n", version, language);
+    printf("[GL] version: %s, language: %s\n", version, language);
 
     glDebugMessageCallback(rk_debug_message_callback, nullptr);
     glEnable(GL_DEBUG_OUTPUT);
 
+    char const * const gl_exts = reinterpret_cast<char const *>(glGetString(GL_EXTENSIONS));
+    // printf("[GL] %s\n", gl_exts);
+    rk_DrawElementsInstancedBaseInstance = reinterpret_cast<rk_DrawElementsInstancedBaseInstanceFunc>(
+        rk_resolve_extension(gl_exts, "GL_EXT_base_instance", "DrawElementsInstancedBaseInstance"));
+    if (rk_DrawElementsInstancedBaseInstance) {
+        rk_gl_printf("Using extension GL_EXT_base_instance::DrawElementsInstancedBaseInstance.");
+        rk_MultiDrawElementsIndirect = reinterpret_cast<rk_MultiDrawElementsIndirectFunc>(
+            rk_resolve_extension(gl_exts, "GL_EXT_multi_draw_indirect", "MultiDrawElementsIndirectEXT"));
+        if (rk_MultiDrawElementsIndirect) {
+            rk_gl_printf("Using extension GL_EXT_multi_draw_indirect::MultiDrawElementsIndirectEXT.");
+        }
+    }
+
     glDisable(GL_BLEND);
     glEnable(GL_DITHER);
     glEnable(GL_DEPTH_TEST);