added needClear flag to take care of initial window clear and window resize clears

[freeglut] / progs / demos / Fractals_random / fractals_random.c

diff --git a/progs/demos/Fractals_random/fractals_random.c b/progs/demos/Fractals_random/fractals_random.c
index e401c70..8992d1e 100644 (file)
--- a/progs/demos/Fractals_random/fractals_random.c
+++ b/progs/demos/Fractals_random/fractals_random.c
@@ -50,6 +50,9 @@ float scale_factor = 1.0 ;
 /* The current point */
 float current_x = 0.0, current_y = 0.0 ;
 
+/* Signals when a glClear is needed */
+static GLboolean needClear = GL_TRUE;
+
 static void draw_level ( int num, double m00, double m01, double m10, double m11, double n0, double n1 )
 {
   /* Draw a fractal transformed by "M", "N" as passed in */
@@ -70,6 +73,11 @@ static void draw_level ( int num, double m00, double m01, double m10, double m11
 static void 
 Display(void)
 {
+  if (needClear) {
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    needClear = GL_FALSE;
+  }
+
   /* the curve */
   glPushMatrix();
   glScalef(2.5, 2.5, 2.5);
@@ -81,7 +89,7 @@ Display(void)
 
   glPopMatrix();
 
-  //  glutSwapBuffers(); /* Should NOT be here... This is a Single-Buffered Program! */
+  glFlush();
   glutPostRedisplay();  /* Needed so that this function will be called again */
 }
 
@@ -99,6 +107,7 @@ Reshape(int width, int height)
   xwin = -1.0 ;
   ywin =  0.0 ;
   glTranslatef(xwin, ywin, -5.0);
+  needClear = GL_TRUE;
 }
 
 static void 
@@ -119,7 +128,7 @@ Key(unsigned char key, int x, int y)
     break ;
   }
 
-  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+  needClear = GL_TRUE;
 
   glutPostRedisplay();
 }
@@ -169,7 +178,7 @@ Special(int key, int x, int y)
     break ;
   }
 
-  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+  needClear = GL_TRUE;
 
   glutPostRedisplay();
 }
@@ -188,6 +197,11 @@ void readConfigFile ( char *fnme )
 
   /* Read the window title */
   fgets ( inputline, 256, fptr ) ;
+  /* We assume here that this line will not exceed 79 characters plus a 
+     newline (window_title is 80 characters long). That'll cause a buffer 
+     overflow. For a simple program like  this, though, we're letting it 
+     slide! 
+  */
   sscanf ( inputline, "%[a-zA-Z0-9!@#$%^&*()+=/\\_-\" ]", window_title ) ;
 
   /* Read a comment line */
@@ -251,8 +265,6 @@ main(int argc, char *argv[])
 
   glClearColor(1.0, 1.0, 1.0, 1.0);
 
-  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
   glutReshapeFunc(Reshape);
   glutKeyboardFunc(Key);
   glutSpecialFunc(Special);