From ee834a83860e614d565f5bb38cdfb8681ffa5f16 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sun, 17 Feb 2019 21:09:23 +0100
Subject: Add puglGetProcAddress for using OpenGL extensions

---
 pugl/pugl.h        | 11 +++++++++++
 pugl/pugl_osx.m    | 16 ++++++++++++++++
 pugl/pugl_win.cpp  |  6 ++++++
 pugl/pugl_x11_gl.c |  6 ++++++
 4 files changed, 39 insertions(+)

diff --git a/pugl/pugl.h b/pugl/pugl.h
index b2937e2..9e70100 100644
--- a/pugl/pugl.h
+++ b/pugl/pugl.h
@@ -629,6 +629,17 @@ puglProcessEvents(PuglView* view);
    @}
 */
 
+/**
+   OpenGL extension function.
+*/
+typedef void (*PuglGlFunc)();
+
+/**
+   Return the address of an OpenGL extension function.
+*/
+PUGL_API PuglGlFunc
+puglGetProcAddress(const char* name);
+
 /**
    Request a redisplay on the next call to puglProcessEvents().
 */
diff --git a/pugl/pugl_osx.m b/pugl/pugl_osx.m
index 8e40907..e56a1a7 100644
--- a/pugl/pugl_osx.m
+++ b/pugl/pugl_osx.m
@@ -702,6 +702,22 @@ puglProcessEvents(PuglView* view)
 	return PUGL_SUCCESS;
 }
 
+PuglGlFunc
+puglGetProcAddress(const char *name)
+{
+	CFBundleRef framework =
+		CFBundleGetBundleWithIdentifier(CFSTR("com.apple.opengl"));
+
+	CFStringRef symbol = CFStringCreateWithCString(
+		kCFAllocatorDefault, name, kCFStringEncodingASCII);
+
+	PuglGlFunc func = CFBundleGetFunctionPointerForName(framework, symbol);
+
+	CFRelease(symbol);
+
+	return func;
+}
+
 void
 puglPostRedisplay(PuglView* view)
 {
diff --git a/pugl/pugl_win.cpp b/pugl/pugl_win.cpp
index 2c092eb..048c0c3 100644
--- a/pugl/pugl_win.cpp
+++ b/pugl/pugl_win.cpp
@@ -631,6 +631,12 @@ wndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 	}
 }
 
+PuglGlFunc
+puglGetProcAddress(const char* name)
+{
+	return (PuglGlFunc)wglGetProcAddress(name);
+}
+
 void
 puglPostRedisplay(PuglView* view)
 {
diff --git a/pugl/pugl_x11_gl.c b/pugl/pugl_x11_gl.c
index 6c007b1..f9e3ce2 100644
--- a/pugl/pugl_x11_gl.c
+++ b/pugl/pugl_x11_gl.c
@@ -186,6 +186,12 @@ puglX11GlGetHandle(PuglView* view)
 	return NULL;
 }
 
+PuglGlFunc
+puglGetProcAddress(const char* name)
+{
+	return glXGetProcAddress((const GLubyte*)name);
+}
+
 PuglDrawContext puglGetX11GlDrawContext(void)
 {
 	static const PuglDrawContext puglX11GlDrawContext = {
-- 
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