require glew only on mac

openglcanvas.cpp

@@ -593,12 +593,14 @@ void OpenGLCanvas::setShaders() {
 
     char *vs,*fs;
 
-#ifdef GLEW_VERSION_1_5
+#ifndef __APPLE__
+  #ifdef GLEW_VERSION_1_5
     GLenum err=glewInit();
     if(err!=GLEW_OK){
         fprintf(stderr,"error in GLEW initialization: %s\n",glewGetString(err));
         exit(-1);
     }
+  #endif
 #endif
 
     GLuint v = glCreateShader(GL_VERTEX_SHADER);

openglcanvas.h

 #ifndef OPENGLCANVAS_H
 #define OPENGLCANVAS_H
 
-// GLew might not be needed if a recent version of OpenGL is present
-#include <GL/glew.h>
-#if (!defined GLEW_VERSION_1_5) || (!defined GL_VERSION_3_1)
+// GLew might not be needed on mac, or if a recent version of OpenGL is present
+#ifndef __APPLE__
+  #include <GL/glew.h>
+  #if (!defined GLEW_VERSION_1_5) || (!defined GL_VERSION_3_1)
     #error GLEW 1.5.2 is required
+  #endif
 #endif
 
 #define GL_GLEXT_PROTOTYPES 1