Made FBO helper to work on OSX when using GL2

example/example_gl2.c

@@ -59,6 +59,7 @@ int main()
 	struct NVGcontext* vg = NULL;
 	struct PerfGraph fps;
 	double prevt = 0;
+	struct NVGLUframebuffer* fb = NULL;
 
 	if (!glfwInit()) {
 		printf("Failed to init GLFW.");
@@ -110,6 +111,8 @@ int main()
 	glfwSetTime(0);
 	prevt = glfwGetTime();
 
+	fb = nvgluCreateFramebuffer(vg, 600, 600);
+
 	while (!glfwWindowShouldClose(window))
 	{
 		double mx, my, t, dt;
@@ -129,6 +132,20 @@ int main()
 		// Calculate pixel ration for hi-dpi devices.
 		pxRatio = (float)fbWidth / (float)winWidth;
 
+		if (fb != NULL) {
+			int fboWidth, fboHeight;
+			nvgImageSize(vg, fb->image, &fboWidth, &fboHeight);
+			// Draw some stull to an FBO as a test
+			nvgluBindFramebuffer(fb);
+			glViewport(0, 0, fboWidth, fboHeight);
+			glClearColor(0, 0, 0, 0);
+			glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
+			nvgBeginFrame(vg, fboWidth, fboHeight, pxRatio, NVG_PREMULTIPLIED_ALPHA);
+			renderDemo(vg, mx, my, fboWidth, fboHeight, t, blowup, &data);
+			nvgEndFrame(vg);
+			nvgluBindFramebuffer(NULL);
+		}
+
 		// Update and render
 		glViewport(0, 0, fbWidth, fbHeight);
 		if (premult)
@@ -142,6 +159,15 @@ int main()
 		renderDemo(vg, mx,my, winWidth,winHeight, t, blowup, &data);
 		renderGraph(vg, 5,5, &fps);
 
+		if (fb != NULL) {
+			struct NVGpaint img = nvgImagePattern(vg, 0, 0, 150, 150, 0, fb->image, NVG_NOREPEAT, 1.0f);
+			nvgBeginPath(vg);
+			nvgTranslate(vg, 540, 300);
+			nvgRect(vg, 0, 0, 150, 150);
+			nvgFillPaint(vg, img);
+			nvgFill(vg);
+		}
+
 		nvgEndFrame(vg);
 
 		if (screenshot) {

src/nanovg_gl_utils.h

@@ -34,9 +34,20 @@ void nvgluDeleteFramebuffer(struct NVGcontext* ctx, struct NVGLUframebuffer* fb)
 
 #ifdef NANOVG_GL_IMPLEMENTATION
 
+#if defined(NANOVG_GL3)
+// FBO is core in OpenGL 3>.
+#	define NANOVG_FBO_VALID 1
+#elif defined(NANOVG_GL2)
+// On OS X including glext defines FBO on GL2 too.
+#	ifdef __APPLE__
+#		include <OpenGL/glext.h>
+#		define NANOVG_FBO_VALID 1
+#	endif
+#endif
+
 struct NVGLUframebuffer* nvgluCreateFramebuffer(struct NVGcontext* ctx, int w, int h)
 {
-#ifdef NANOVG_GL3
+#ifdef NANOVG_FBO_VALID
 	struct NVGLUframebuffer* fb = NULL;
 	fb = (struct NVGLUframebuffer*)malloc(sizeof(struct NVGLUframebuffer));
 	if (fb == NULL) goto error;
@@ -75,7 +86,7 @@ error:
 
 void nvgluBindFramebuffer(struct NVGLUframebuffer* fb)
 {
-#ifdef NANOVG_GL3
+#ifdef NANOVG_FBO_VALID
 	glBindFramebuffer(GL_FRAMEBUFFER, fb != NULL ? fb->fbo : 0);
 #else
 	NVG_NOTUSED(fb);
@@ -84,7 +95,7 @@ void nvgluBindFramebuffer(struct NVGLUframebuffer* fb)
 
 void nvgluDeleteFramebuffer(struct NVGcontext* ctx, struct NVGLUframebuffer* fb)
 {
-#ifdef NANOVG_GL3
+#ifdef NANOVG_FBO_VALID
 	if (fb == NULL) return;
 	if (fb->fbo != 0)
 		glDeleteFramebuffers(1, &fb->fbo);