Updated demo for new GLU 1.3 tessellation. Added optimized rendering

by saving the output of the tessellation into display lists.

progs/demos/tessdemo.c

@@ -1,4 +1,4 @@
-/* $Id: tessdemo.c,v 1.2 1999/09/19 20:09:00 tanner Exp $ */
+/* $Id: tessdemo.c,v 1.3 1999/11/04 04:00:42 gareth Exp $ */
 
 /*
  * A demo of the GLU polygon tesselation functions written by Bogdan Sikorski.
@@ -8,9 +8,16 @@
    cc -g -ansi -prototypes -fullwarn -float -I../include -DSHM tess_demo.c -L../lib -lglut -lMesaGLU -lMesaGL -lm -lX11 -lXext -lXmu -lfpe -lXext -o tess_demo
  */
 
+/*
+ * Updated for GLU 1.3 tessellation by Gareth Hughes <garethh@bell-labs.com>
+ */
 
 /*
  * $Log: tessdemo.c,v $
+ * Revision 1.3  1999/11/04 04:00:42  gareth
+ * Updated demo for new GLU 1.3 tessellation.  Added optimized rendering
+ * by saving the output of the tessellation into display lists.
+ *
  * Revision 1.2  1999/09/19 20:09:00  tanner
  *
  * lots of autoconf updates
@@ -44,29 +51,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-#define MAX_POINTS 200
+#define MAX_POINTS	256
-#define MAX_CONTOURS 50
+#define MAX_CONTOURS	32
-
+#define MAX_TRIANGLES	256
-int menu;
-typedef enum{ QUIT, TESSELATE, CLEAR } menu_entries;
-typedef enum{ DEFINE, TESSELATED } mode_type;
-struct
-{
-	GLint p[MAX_POINTS][2];
-	GLuint point_cnt;
-} contours[MAX_CONTOURS];
-GLuint contour_cnt;
-GLsizei width,height;
-mode_type mode;
-
-struct
-{
-	GLsizei no;
-	GLfloat color[3];
-	GLint p[3][2];
-	GLclampf p_color[3][3];
-} triangle;
-
 
 #ifndef GLCALLBACK
 #ifdef CALLBACK
@@ -76,6 +63,34 @@ struct
 #endif
 #endif
 
+typedef enum{ QUIT, TESSELATE, CLEAR } menu_entries;
+typedef enum{ DEFINE, TESSELATED } mode_type;
+
+static GLsizei		width, height;
+static GLuint		contour_cnt;
+static GLuint		triangle_cnt;
+
+static mode_type 	mode;
+static int		menu;
+
+static GLuint		list_start;
+
+static GLfloat		edge_color[3];
+
+static struct
+{
+   GLint	p[MAX_POINTS][2];
+   GLuint	point_cnt;
+} contours[MAX_CONTOURS];
+
+static struct
+{
+   GLsizei	no;
+   GLint	p[3][2];
+   GLclampf	color[3][3];
+} triangles[MAX_TRIANGLES];
+
+
 
 void GLCALLBACK my_error( GLenum err )
 {
@@ -84,48 +99,71 @@ void GLCALLBACK my_error(GLenum err)
 
    glColor3f( 0.9, 0.9, 0.9 );
    glRasterPos2i( 5, 5 );
+
    str = (const char *) gluErrorString( err );
    len = strlen( str );
-	for(i=0;i<len;i++)
+
+   for ( i = 0 ; i < len ; i++ ) {
       glutBitmapCharacter( GLUT_BITMAP_9_BY_15, str[i] );
    }
+}
 
 void GLCALLBACK begin_callback( GLenum mode )
 {
-	triangle.no=0;
+   /* Allow multiple triangles to be output inside the begin/end pair. */
+   triangle_cnt = 0;
+   triangles[triangle_cnt].no = 0;
 }
 
 void GLCALLBACK edge_callback( GLenum flag )
 {
+   /* Persist the edge flag across triangles. */
    if ( flag == GL_TRUE )
    {
-		triangle.color[0]=1.0;
+      edge_color[0] = 1.0;
-		triangle.color[1]=1.0;
+      edge_color[1] = 1.0;
-		triangle.color[2]=0.5;
+      edge_color[2] = 0.5;
    }
    else
    {
-		triangle.color[0]=1.0;
+      edge_color[0] = 1.0;
-		triangle.color[1]=0.0;
+      edge_color[1] = 0.0;
-		triangle.color[2]=0.0;
+      edge_color[2] = 0.0;
    }
 }
 
 void GLCALLBACK end_callback()
 {
+   GLint	i;
+
    glBegin( GL_LINES );
-	glColor3f(triangle.p_color[0][0],triangle.p_color[0][1],
+
-		triangle.p_color[0][2]);
+   /* Output the three edges of each triangle as lines colored
-	glVertex2i(triangle.p[0][0],triangle.p[0][1]);
+      according to their edge flag. */
-	glVertex2i(triangle.p[1][0],triangle.p[1][1]);
+   for ( i = 0 ; i < triangle_cnt ; i++ )
-	glColor3f(triangle.p_color[1][0],triangle.p_color[1][1],
+   {
-		triangle.p_color[1][2]);
+      glColor3f( triangles[i].color[0][0],
-	glVertex2i(triangle.p[1][0],triangle.p[1][1]);
+		 triangles[i].color[0][1],
-	glVertex2i(triangle.p[2][0],triangle.p[2][1]);
+		 triangles[i].color[0][2] );
-	glColor3f(triangle.p_color[2][0],triangle.p_color[2][1],
+
-		triangle.p_color[2][2]);
+      glVertex2i( triangles[i].p[0][0], triangles[i].p[0][1] );
-	glVertex2i(triangle.p[2][0],triangle.p[2][1]);
+      glVertex2i( triangles[i].p[1][0], triangles[i].p[1][1] );
-	glVertex2i(triangle.p[0][0],triangle.p[0][1]);
+
+      glColor3f( triangles[i].color[1][0],
+		 triangles[i].color[1][1],
+		 triangles[i].color[1][2] );
+
+      glVertex2i( triangles[i].p[1][0], triangles[i].p[1][1] );
+      glVertex2i( triangles[i].p[2][0], triangles[i].p[2][1] );
+
+      glColor3f( triangles[i].color[2][0],
+		 triangles[i].color[2][1],
+		 triangles[i].color[2][2] );
+
+      glVertex2i( triangles[i].p[2][0], triangles[i].p[2][1] );
+      glVertex2i( triangles[i].p[0][0], triangles[i].p[0][1] );
+   }
+
    glEnd();
 }
 
@@ -135,13 +173,21 @@ void GLCALLBACK vertex_callback(void *data)
    GLint	*p;
 
    p = (GLint *) data;
-	no=triangle.no;
+   no = triangles[triangle_cnt].no;
-	triangle.p[no][0]=p[0];
+
-	triangle.p[no][1]=p[1];
+   triangles[triangle_cnt].p[no][0] = p[0];
-	triangle.p_color[no][0]=triangle.color[0];
+   triangles[triangle_cnt].p[no][1] = p[1];
-	triangle.p_color[no][1]=triangle.color[1];
+
-	triangle.p_color[no][2]=triangle.color[2];
+   triangles[triangle_cnt].color[no][0] = edge_color[0];
-	++(triangle.no);
+   triangles[triangle_cnt].color[no][1] = edge_color[1];
+   triangles[triangle_cnt].color[no][2] = edge_color[2];
+
+   /* After every three vertices, initialize the next triangle. */
+   if ( ++(triangles[triangle_cnt].no) == 3 )
+   {
+      triangle_cnt++;
+      triangles[triangle_cnt].no = 0;
+   }
 }
 
 void set_screen_wh( GLsizei w, GLsizei h )
@@ -156,20 +202,25 @@ void tesse(void)
    GLdouble		data[3];
    GLuint		i, j, point_cnt;
 
+   list_start = glGenLists( 2 );
+
    tobj = gluNewTess();
+
    if ( tobj != NULL )
    {
-		glClear(GL_COLOR_BUFFER_BIT);
-		glColor3f (0.7, 0.7, 0.0);
       gluTessCallback( tobj, GLU_BEGIN, glBegin );
+      gluTessCallback( tobj, GLU_VERTEX, glVertex2iv );
       gluTessCallback( tobj, GLU_END, glEnd );
       gluTessCallback( tobj, GLU_ERROR, my_error );
-		gluTessCallback(tobj,GLU_VERTEX,glVertex2iv);
+
+      glNewList( list_start, GL_COMPILE );
       gluBeginPolygon( tobj );
+
       for ( j = 0 ; j <= contour_cnt ; j++ )
       {
 	 point_cnt = contours[j].point_cnt;
 	 gluNextContour( tobj, GLU_UNKNOWN );
+
 	 for ( i = 0 ; i < point_cnt ; i++ )
 	 {
 	    data[0] = (GLdouble)( contours[j].p[i][0] );
@@ -178,17 +229,23 @@ void tesse(void)
 	    gluTessVertex( tobj, data, contours[j].p[i] );
 	 }
       }
+
       gluEndPolygon( tobj );
-		glLineWidth(2.0);
+      glEndList();
+
       gluTessCallback( tobj, GLU_BEGIN, begin_callback );
-		gluTessCallback(tobj,GLU_END,end_callback);
       gluTessCallback( tobj, GLU_VERTEX, vertex_callback );
+      gluTessCallback( tobj, GLU_END, end_callback );
       gluTessCallback( tobj, GLU_EDGE_FLAG, edge_callback );
+
+      glNewList( list_start + 1, GL_COMPILE );
       gluBeginPolygon( tobj );
+
       for ( j = 0 ; j <= contour_cnt ; j++ )
       {
 	 point_cnt = contours[j].point_cnt;
 	 gluNextContour( tobj, GLU_UNKNOWN );
+
 	 for ( i = 0 ; i < point_cnt ; i++ )
 	 {
 	    data[0] = (GLdouble)( contours[j].p[i][0] );
@@ -197,11 +254,13 @@ void tesse(void)
 	    gluTessVertex( tobj, data, contours[j].p[i] );
 	 }
       }
+
       gluEndPolygon( tobj );
+      glEndList();
+
       gluDeleteTess( tobj );
+
       glutMouseFunc( NULL );
-		glColor3f (1.0, 1.0, 0.0);
-		glLineWidth(1.0);
       mode = TESSELATED;
    }
 }
@@ -212,12 +271,17 @@ void left_down(int x1,int y1)
    GLuint	point_cnt;
 
    /* translate GLUT into GL coordinates */
+
    P[0] = x1;
    P[1] = height - y1;
+
    point_cnt = contours[contour_cnt].point_cnt;
+
    contours[contour_cnt].p[point_cnt][0] = P[0];
    contours[contour_cnt].p[point_cnt][1] = P[1];
+
    glBegin( GL_LINES );
+
    if ( point_cnt )
    {
       glVertex2iv( contours[contour_cnt].p[point_cnt-1] );
@@ -228,9 +292,11 @@ void left_down(int x1,int y1)
       glVertex2iv( P );
       glVertex2iv( P );
    }
+
    glEnd();
    glFinish();
-	++(contours[contour_cnt].point_cnt);
+
+   contours[contour_cnt].point_cnt++;
 }
 
 void middle_down( int x1, int y1 )
@@ -240,14 +306,19 @@ void middle_down(int x1, int y1)
    (void) y1;
 
    point_cnt = contours[contour_cnt].point_cnt;
+
    if ( point_cnt > 2 )
    {
       glBegin( GL_LINES );
+
       glVertex2iv( contours[contour_cnt].p[0] );
       glVertex2iv( contours[contour_cnt].p[point_cnt-1] );
+
       contours[contour_cnt].p[point_cnt][0] = -1;
+
       glEnd();
       glFinish();
+
       contour_cnt++;
       contours[contour_cnt].point_cnt = 0;
    }
@@ -257,15 +328,18 @@ void mouse_clicked(int button,int state,int x,int y)
 {
    x -= x%10;
    y -= y%10;
+
    switch ( button )
    {
    case GLUT_LEFT_BUTTON:
-			if(state==GLUT_DOWN)
+      if ( state == GLUT_DOWN ) {
 	 left_down( x, y );
+      }
       break;
    case GLUT_MIDDLE_BUTTON:
-			if(state==GLUT_DOWN)
+      if ( state == GLUT_DOWN ) {
 	 middle_down( x, y );
+      }
       break;
    }
 }
@@ -276,13 +350,17 @@ void display(void)
    GLuint point_cnt;
 
    glClear( GL_COLOR_BUFFER_BIT );
+
    switch ( mode )
    {
    case DEFINE:
       /* draw grid */
       glColor3f( 0.6, 0.5, 0.5 );
+
       glBegin( GL_LINES );
+
       for ( i = 0 ; i < width ; i += 10 )
+      {
 	 for ( j = 0 ; j < height ; j += 10 )
 	 {
 	    glVertex2i( 0, j );
@@ -290,11 +368,16 @@ void display(void)
 	    glVertex2i( i, height );
 	    glVertex2i( i, 0 );
 	 }
+      }
+
       glColor3f( 1.0, 1.0, 0.0 );
+
       for ( i = 0 ; i <= contour_cnt ; i++ )
       {
 	 point_cnt = contours[i].point_cnt;
+
 	 glBegin( GL_LINES );
+
 	 switch ( point_cnt )
 	 {
 	 case 0:
@@ -321,13 +404,23 @@ void display(void)
 	    }
 	    break;
 	 }
+
 	 glEnd();
       }
+
       glFinish();
       break;
+
    case TESSELATED:
-			/* draw lines */
+      /* draw triangles */
-			tesse();
+      glColor3f( 0.7, 0.7, 0.0 );
+      glCallList( list_start );
+
+      glLineWidth( 2.0 );
+      glCallList( list_start + 1 );
+      glLineWidth( 1.0 );
+
+      glFlush();
       break;
    }
 
@@ -338,9 +431,14 @@ void clear( void )
 {
    contour_cnt = 0;
    contours[0].point_cnt = 0;
+   triangle_cnt = 0;
+
    glutMouseFunc( mouse_clicked );
+
    mode = DEFINE;
-	display();
+
+   glDeleteLists( list_start, 2 );
+   list_start = 0;
 }
 
 void quit( void )
@@ -362,28 +460,32 @@ void menu_selected(int entry)
       quit();
       break;
    }
+
+   glutPostRedisplay();
 }
 
 void key_pressed( unsigned char key, int x, int y )
 {
    (void) x;
    (void) y;
+
    switch ( key )
    {
+   case 'c':
+   case 'C':
+      clear();
+      break;
    case 't':
    case 'T':
       tesse();
-			glFinish();
       break;
    case 'q':
    case 'Q':
       quit();
       break;
-		case 'c':
-		case 'C':
-			clear();
-			break;
    }
+
+   glutPostRedisplay();
 }
 
 void myinit( void )
@@ -391,27 +493,34 @@ void myinit (void)
    /* clear background to gray */
    glClearColor( 0.4, 0.4, 0.4, 0.0 );
    glShadeModel( GL_FLAT );
+   glPolygonMode( GL_FRONT, GL_FILL );
 
    menu = glutCreateMenu( menu_selected );
+
    glutAddMenuEntry( "clear", CLEAR );
    glutAddMenuEntry( "tesselate", TESSELATE );
    glutAddMenuEntry( "quit", QUIT );
+
    glutAttachMenu( GLUT_RIGHT_BUTTON );
+
    glutMouseFunc( mouse_clicked );
    glutKeyboardFunc( key_pressed );
+
    contour_cnt = 0;
-    glPolygonMode(GL_FRONT,GL_FILL);
    mode = DEFINE;
 }
 
 static void reshape( GLsizei w, GLsizei h )
 {
    glViewport( 0, 0, w, h );
+
    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glOrtho( 0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0 );
+
    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();
+
    set_screen_wh( w, h );
 }
 
@@ -424,20 +533,26 @@ static void usage( void )
 }
 
 
-/*  Main Loop
+/*
+ * Main Loop
  * Open window with initial window size, title bar,
  * RGBA display mode, and handle input events.
  */
 int main( int argc, char **argv )
 {
     usage();
+
     glutInit( &argc, argv );
     glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
     glutInitWindowSize( 400, 400 );
     glutCreateWindow( argv[0] );
+
     myinit();
+
     glutDisplayFunc( display );
     glutReshapeFunc( reshape );
+
     glutMainLoop();
+
     return 0;
 }