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-rw-r--r--progs/demos/tessdemo.c524
1 files changed, 524 insertions, 0 deletions
diff --git a/progs/demos/tessdemo.c b/progs/demos/tessdemo.c
new file mode 100644
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+++ b/progs/demos/tessdemo.c
@@ -0,0 +1,524 @@
+
+/*
+ * A demo of the GLU polygon tesselation functions written by Bogdan Sikorski.
+ * Updated for GLU 1.3 tessellation by Gareth Hughes <gareth@valinux.com>
+ */
+
+#include <GL/glut.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAX_POINTS 256
+#define MAX_CONTOURS 32
+#define MAX_TRIANGLES 256
+
+#ifndef GLCALLBACK
+#ifdef CALLBACK
+#define GLCALLBACK CALLBACK
+#else
+#define GLCALLBACK
+#endif
+#endif
+
+#ifdef GLU_VERSION_1_2
+
+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 {
+ GLfloat p[MAX_POINTS][2];
+ GLuint point_cnt;
+} contours[MAX_CONTOURS];
+
+static struct {
+ GLsizei no;
+ GLfloat p[3][2];
+ GLclampf color[3][3];
+} triangles[MAX_TRIANGLES];
+
+
+
+static void GLCALLBACK error_callback( GLenum err )
+{
+ int len, i;
+ char const *str;
+
+ glColor3f( 0.9, 0.9, 0.9 );
+ glRasterPos2i( 5, 5 );
+
+ str = (const char *) gluErrorString( err );
+ len = strlen( str );
+
+ for ( i = 0 ; i < len ; i++ ) {
+ glutBitmapCharacter( GLUT_BITMAP_9_BY_15, str[i] );
+ }
+}
+
+static void GLCALLBACK begin_callback( GLenum mode )
+{
+ /* Allow multiple triangles to be output inside the begin/end pair. */
+ triangle_cnt = 0;
+ triangles[triangle_cnt].no = 0;
+}
+
+static void GLCALLBACK edge_callback( GLenum flag )
+{
+ /* Persist the edge flag across triangles. */
+ if ( flag == GL_TRUE ) {
+ edge_color[0] = 1.0;
+ edge_color[1] = 1.0;
+ edge_color[2] = 0.5;
+ } else {
+ edge_color[0] = 1.0;
+ edge_color[1] = 0.0;
+ edge_color[2] = 0.0;
+ }
+}
+
+static void GLCALLBACK end_callback()
+{
+ GLuint i;
+
+ glBegin( GL_LINES );
+
+ /* Output the three edges of each triangle as lines colored
+ according to their edge flag. */
+ for ( i = 0 ; i < triangle_cnt ; i++ ) {
+ glColor3f( triangles[i].color[0][0],
+ triangles[i].color[0][1],
+ triangles[i].color[0][2] );
+
+ glVertex2f( triangles[i].p[0][0], triangles[i].p[0][1] );
+ glVertex2f( triangles[i].p[1][0], triangles[i].p[1][1] );
+
+ glColor3f( triangles[i].color[1][0],
+ triangles[i].color[1][1],
+ triangles[i].color[1][2] );
+
+ glVertex2f( triangles[i].p[1][0], triangles[i].p[1][1] );
+ glVertex2f( 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] );
+
+ glVertex2f( triangles[i].p[2][0], triangles[i].p[2][1] );
+ glVertex2f( triangles[i].p[0][0], triangles[i].p[0][1] );
+ }
+
+ glEnd();
+}
+
+static void GLCALLBACK vertex_callback( void *data )
+{
+ GLsizei no;
+ GLfloat *p;
+
+ p = (GLfloat *) data;
+ no = triangles[triangle_cnt].no;
+
+ triangles[triangle_cnt].p[no][0] = p[0];
+ triangles[triangle_cnt].p[no][1] = p[1];
+
+ triangles[triangle_cnt].color[no][0] = edge_color[0];
+ 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;
+ }
+}
+
+static void GLCALLBACK combine_callback( GLdouble coords[3],
+ GLdouble *vertex_data[4],
+ GLfloat weight[4], void **data )
+{
+ GLfloat *vertex;
+
+ vertex = (GLfloat *) malloc( 2 * sizeof(GLfloat) );
+
+ vertex[0] = (GLfloat) coords[0];
+ vertex[1] = (GLfloat) coords[1];
+
+ *data = vertex;
+}
+
+
+static void set_screen_wh( GLsizei w, GLsizei h )
+{
+ width = w;
+ height = h;
+}
+
+typedef void (GLAPIENTRY *callback_t)();
+
+static void tesse( void )
+{
+ GLUtesselator *tobj;
+ GLdouble data[3];
+ GLuint i, j, point_cnt;
+
+ list_start = glGenLists( 2 );
+
+ tobj = gluNewTess();
+
+ if ( tobj != NULL ) {
+ gluTessNormal( tobj, 0.0, 0.0, 1.0 );
+ gluTessCallback( tobj, GLU_TESS_BEGIN, (callback_t) glBegin );
+ gluTessCallback( tobj, GLU_TESS_VERTEX, (callback_t) glVertex2fv );
+ gluTessCallback( tobj, GLU_TESS_END, (callback_t) glEnd );
+ gluTessCallback( tobj, GLU_TESS_ERROR, (callback_t) error_callback );
+ gluTessCallback( tobj, GLU_TESS_COMBINE, (callback_t) combine_callback );
+
+ 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] );
+ data[1] = (GLdouble)( contours[j].p[i][1] );
+ data[2] = 0.0;
+ gluTessVertex( tobj, data, contours[j].p[i] );
+ }
+ }
+
+ gluEndPolygon( tobj );
+ glEndList();
+
+ gluTessCallback( tobj, GLU_TESS_BEGIN, (callback_t) begin_callback );
+ gluTessCallback( tobj, GLU_TESS_VERTEX, (callback_t) vertex_callback );
+ gluTessCallback( tobj, GLU_TESS_END, (callback_t) end_callback );
+ gluTessCallback( tobj, GLU_TESS_EDGE_FLAG, (callback_t) 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] );
+ data[1] = (GLdouble)( contours[j].p[i][1] );
+ data[2] = 0.0;
+ gluTessVertex( tobj, data, contours[j].p[i] );
+ }
+ }
+
+ gluEndPolygon( tobj );
+ glEndList();
+
+ gluDeleteTess( tobj );
+
+ glutMouseFunc( NULL );
+ mode = TESSELATED;
+ }
+}
+
+static void left_down( int x1, int y1 )
+{
+ GLfloat P[2];
+ 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 ) {
+ glVertex2fv( contours[contour_cnt].p[point_cnt-1] );
+ glVertex2fv( P );
+ } else {
+ glVertex2fv( P );
+ glVertex2fv( P );
+ }
+
+ glEnd();
+ glFinish();
+
+ contours[contour_cnt].point_cnt++;
+}
+
+static void middle_down( int x1, int y1 )
+{
+ GLuint point_cnt;
+ (void) x1;
+ (void) y1;
+
+ point_cnt = contours[contour_cnt].point_cnt;
+
+ if ( point_cnt > 2 ) {
+ glBegin( GL_LINES );
+
+ glVertex2fv( contours[contour_cnt].p[0] );
+ glVertex2fv( 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;
+ }
+}
+
+static 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 ) {
+ left_down( x, y );
+ }
+ break;
+ case GLUT_MIDDLE_BUTTON:
+ if ( state == GLUT_DOWN ) {
+ middle_down( x, y );
+ }
+ break;
+ }
+}
+
+static void display( void )
+{
+ GLuint i,j;
+ GLsizei ii, jj;
+ 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 ( ii = 0 ; ii < width ; ii += 10 ) {
+ for ( jj = 0 ; jj < height ; jj += 10 ) {
+ glVertex2i( 0, jj );
+ glVertex2i( width, jj );
+ glVertex2i( ii, height );
+ glVertex2i( ii, 0 );
+ }
+ }
+
+ glEnd();
+
+ 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:
+ break;
+ case 1:
+ glVertex2fv( contours[i].p[0] );
+ glVertex2fv( contours[i].p[0] );
+ break;
+ case 2:
+ glVertex2fv( contours[i].p[0] );
+ glVertex2fv( contours[i].p[1] );
+ break;
+ default:
+ --point_cnt;
+ for ( j = 0 ; j < point_cnt ; j++ ) {
+ glVertex2fv( contours[i].p[j] );
+ glVertex2fv( contours[i].p[j+1] );
+ }
+ if ( contours[i].p[j+1][0] == -1 ) {
+ glVertex2fv( contours[i].p[0] );
+ glVertex2fv( contours[i].p[j] );
+ }
+ break;
+ }
+
+ glEnd();
+ }
+
+ glFinish();
+ break;
+
+ case TESSELATED:
+ /* draw triangles */
+ glColor3f( 0.7, 0.7, 0.0 );
+ glCallList( list_start );
+
+ glLineWidth( 2.0 );
+ glCallList( list_start + 1 );
+ glLineWidth( 1.0 );
+
+ glFlush();
+ break;
+ }
+
+ glColor3f( 1.0, 1.0, 0.0 );
+}
+
+static void clear( void )
+{
+ contour_cnt = 0;
+ contours[0].point_cnt = 0;
+ triangle_cnt = 0;
+
+ glutMouseFunc( mouse_clicked );
+
+ mode = DEFINE;
+
+ glDeleteLists( list_start, 2 );
+ list_start = 0;
+}
+
+static void quit( void )
+{
+ exit( 0 );
+}
+
+static void menu_selected( int entry )
+{
+ switch ( entry ) {
+ case CLEAR:
+ clear();
+ break;
+ case TESSELATE:
+ tesse();
+ break;
+ case QUIT:
+ quit();
+ break;
+ }
+
+ glutPostRedisplay();
+}
+
+static 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();
+ break;
+ case 27:
+ case 'q':
+ case 'Q':
+ quit();
+ break;
+ }
+
+ glutPostRedisplay();
+}
+
+static 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;
+ 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 );
+}
+
+#endif
+
+
+static void usage( void )
+{
+ printf( "Use left mouse button to place vertices.\n" );
+ printf( "Press middle mouse button when done.\n" );
+ printf( "Select tesselate from the pop-up menu.\n" );
+}
+
+
+int main( int argc, char **argv )
+{
+ const char *version = (const char *) gluGetString( GLU_VERSION );
+ printf( "GLU version string: %s\n", version );
+ if ( strstr( version, "1.0" ) || strstr( version, "1.1" ) ) {
+ fprintf( stderr, "Sorry, this demo reqiures GLU 1.2 or later.\n" );
+ exit( 1 );
+ }
+
+ usage();
+
+ glutInit( &argc, argv );
+ glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
+ glutInitWindowPosition(0, 0);
+ glutInitWindowSize( 400, 400 );
+ glutCreateWindow( argv[0] );
+
+ /* GH: Bit of a hack...
+ */
+#ifdef GLU_VERSION_1_2
+ myinit();
+
+ glutDisplayFunc( display );
+ glutReshapeFunc( reshape );
+
+ glutMainLoop();
+#endif
+
+ return 0;
+}
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