Check the glutDisplayFunc() callback for being a NULL pointer. This is

[freeglut] / src / freeglut_callbacks.c

diff --git a/src/freeglut_callbacks.c b/src/freeglut_callbacks.c
index b741a0c..da06283 100644 (file)
--- a/src/freeglut_callbacks.c
+++ b/src/freeglut_callbacks.c
@@ -48,7 +48,16 @@
  */
 void FGAPIENTRY glutDisplayFunc( void (* callback)( void ) )
 {
+    if( !callback )
+       fgError ("Fatal error in program.  NULL display callback not "
+           "permitted in GLUT 3.0+ or freeglut 2.0.1+\n");
     SET_CALLBACK( Display );
+
+    /*
+     * Force a redisplay with the new callback
+     */
+    fgStructure.Window->State.Redisplay = TRUE;
+
 }
 
 /*
@@ -100,7 +109,7 @@ void FGAPIENTRY glutTimerFunc( unsigned int timeOut, void (* callback)( int ), i
     /*
      * Create a new freeglut timer hook structure
      */
-    timer = calloc( sizeof(SFG_Timer), 1 );
+    timer = (SFG_Timer *)calloc( sizeof(SFG_Timer), 1 );
 
     /*
      * Remember the callback address and timer hook's ID