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+/* $Id: tessdemo.c,v 1.1 1999/08/19 00:55:40 jtg Exp $ */
+
+/*
+ * A demo of the GLU polygon tesselation functions written by Bogdan Sikorski.
+ * This demo isn't built by the Makefile because it needs GLUT. After you've
+ * installed GLUT you can try this demo.
+ * Here's the command for IRIX, for example:
+ 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
+ */
+
+
+/*
+ * $Log: tessdemo.c,v $
+ * Revision 1.1 1999/08/19 00:55:40 jtg
+ * Initial revision
+ *
+ * Revision 3.5 1999/03/28 18:24:37 brianp
+ * minor clean-up
+ *
+ * Revision 3.4 1999/02/14 03:37:07 brianp
+ * fixed callback problem
+ *
+ * Revision 3.3 1998/07/26 01:25:26 brianp
+ * removed include of gl.h and glu.h
+ *
+ * Revision 3.2 1998/06/29 02:37:30 brianp
+ * minor changes for Windows (Ted Jump)
+ *
+ * Revision 3.1 1998/06/09 01:53:49 brianp
+ * main() should return an int
+ *
+ * Revision 3.0 1998/02/14 18:42:29 brianp
+ * initial rev
+ *
+ */
+
+
+#include <GL/glut.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAX_POINTS 200
+#define MAX_CONTOURS 50
+
+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
+#define GLCALLBACK CALLBACK
+#else
+#define GLCALLBACK
+#endif
+#endif
+
+
+void GLCALLBACK my_error(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]);
+}
+
+void GLCALLBACK begin_callback(GLenum mode)
+{
+ triangle.no=0;
+}
+
+void GLCALLBACK edge_callback(GLenum flag)
+{
+ if(flag==GL_TRUE)
+ {
+ triangle.color[0]=1.0;
+ triangle.color[1]=1.0;
+ triangle.color[2]=0.5;
+ }
+ else
+ {
+ triangle.color[0]=1.0;
+ triangle.color[1]=0.0;
+ triangle.color[2]=0.0;
+ }
+}
+
+void GLCALLBACK end_callback()
+{
+ glBegin(GL_LINES);
+ glColor3f(triangle.p_color[0][0],triangle.p_color[0][1],
+ triangle.p_color[0][2]);
+ glVertex2i(triangle.p[0][0],triangle.p[0][1]);
+ glVertex2i(triangle.p[1][0],triangle.p[1][1]);
+ glColor3f(triangle.p_color[1][0],triangle.p_color[1][1],
+ triangle.p_color[1][2]);
+ glVertex2i(triangle.p[1][0],triangle.p[1][1]);
+ glVertex2i(triangle.p[2][0],triangle.p[2][1]);
+ glColor3f(triangle.p_color[2][0],triangle.p_color[2][1],
+ triangle.p_color[2][2]);
+ glVertex2i(triangle.p[2][0],triangle.p[2][1]);
+ glVertex2i(triangle.p[0][0],triangle.p[0][1]);
+ glEnd();
+}
+
+void GLCALLBACK vertex_callback(void *data)
+{
+ GLsizei no;
+ GLint *p;
+
+ p=(GLint *)data;
+ no=triangle.no;
+ triangle.p[no][0]=p[0];
+ triangle.p[no][1]=p[1];
+ triangle.p_color[no][0]=triangle.color[0];
+ triangle.p_color[no][1]=triangle.color[1];
+ triangle.p_color[no][2]=triangle.color[2];
+ ++(triangle.no);
+}
+
+void set_screen_wh(GLsizei w, GLsizei h)
+{
+ width=w;
+ height=h;
+}
+
+void tesse(void)
+{
+ GLUtriangulatorObj *tobj;
+ GLdouble data[3];
+ GLuint i,j,point_cnt;
+
+ 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_END,glEnd);
+ gluTessCallback(tobj,GLU_ERROR,my_error);
+ gluTessCallback(tobj,GLU_VERTEX,glVertex2iv);
+ 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);
+ glLineWidth(2.0);
+ gluTessCallback(tobj,GLU_BEGIN,begin_callback);
+ gluTessCallback(tobj,GLU_END,end_callback);
+ gluTessCallback(tobj,GLU_VERTEX,vertex_callback);
+ gluTessCallback(tobj,GLU_EDGE_FLAG,edge_callback);
+ 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);
+ gluDeleteTess(tobj);
+ glutMouseFunc(NULL);
+ glColor3f (1.0, 1.0, 0.0);
+ glLineWidth(1.0);
+ mode=TESSELATED;
+ }
+}
+
+void left_down(int x1,int y1)
+{
+ GLint 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)
+ {
+ glVertex2iv(contours[contour_cnt].p[point_cnt-1]);
+ glVertex2iv(P);
+ }
+ else
+ {
+ glVertex2iv(P);
+ glVertex2iv(P);
+ }
+ glEnd();
+ glFinish();
+ ++(contours[contour_cnt].point_cnt);
+}
+
+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);
+ 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;
+ }
+}
+
+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;
+ }
+}
+
+void display(void)
+{
+ GLuint i,j;
+ 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);
+ glVertex2i(width,j);
+ 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:
+ break;
+ case 1:
+ glVertex2iv(contours[i].p[0]);
+ glVertex2iv(contours[i].p[0]);
+ break;
+ case 2:
+ glVertex2iv(contours[i].p[0]);
+ glVertex2iv(contours[i].p[1]);
+ break;
+ default:
+ --point_cnt;
+ for(j=0;j<point_cnt;j++)
+ {
+ glVertex2iv(contours[i].p[j]);
+ glVertex2iv(contours[i].p[j+1]);
+ }
+ if(contours[i].p[j+1][0]== -1)
+ {
+ glVertex2iv(contours[i].p[0]);
+ glVertex2iv(contours[i].p[j]);
+ }
+ break;
+ }
+ glEnd();
+ }
+ glFinish();
+ break;
+ case TESSELATED:
+ /* draw lines */
+ tesse();
+ break;
+ }
+
+ glColor3f (1.0, 1.0, 0.0);
+}
+
+void clear( void )
+{
+ contour_cnt=0;
+ contours[0].point_cnt=0;
+ glutMouseFunc(mouse_clicked);
+ mode=DEFINE;
+ display();
+}
+
+void quit( void )
+{
+ exit(0);
+}
+
+void menu_selected(int entry)
+{
+ switch(entry)
+ {
+ case CLEAR:
+ clear();
+ break;
+ case TESSELATE:
+ tesse();
+ break;
+ case QUIT:
+ quit();
+ break;
+ }
+}
+
+void key_pressed(unsigned char key,int x,int y)
+{
+ (void) x;
+ (void) y;
+ switch(key)
+ {
+ case 't':
+ case 'T':
+ tesse();
+ glFinish();
+ break;
+ case 'q':
+ case 'Q':
+ quit();
+ break;
+ case 'c':
+ case 'C':
+ clear();
+ break;
+ }
+}
+
+void myinit (void)
+{
+/* clear background to gray */
+ glClearColor (0.4, 0.4, 0.4, 0.0);
+ glShadeModel (GL_FLAT);
+
+ 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);
+}
+
+
+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");
+}
+
+
+/* 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;
+}
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