423 lines
8.3 KiB
C
423 lines
8.3 KiB
C
/* $Id: tessdemo.c,v 1.8 2000/07/11 14:11:58 brianp Exp $ */
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/*
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* A demo of the GLU polygon tesselation functions written by Bogdan Sikorski.
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*/
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#include <GL/glut.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define MAX_POINTS 200
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#define MAX_CONTOURS 50
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static int menu;
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typedef enum
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{ QUIT, TESSELATE, CLEAR }
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menu_entries;
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typedef enum
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{ DEFINE, TESSELATED }
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mode_type;
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struct
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{
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GLint p[MAX_POINTS][2];
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GLuint point_cnt;
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}
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contours[MAX_CONTOURS];
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static GLuint contour_cnt;
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static GLsizei width, height;
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static mode_type mode;
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struct
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{
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GLsizei no;
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GLfloat color[3];
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GLint p[3][2];
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GLclampf p_color[3][3];
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}
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triangle;
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static void GLCALLBACK
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my_error(GLenum err)
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{
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int len, i;
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char const *str;
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glColor3f(0.9, 0.9, 0.9);
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glRasterPos2i(5, 5);
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str = (const char *) gluErrorString(err);
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len = strlen(str);
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for (i = 0; i < len; i++)
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glutBitmapCharacter(GLUT_BITMAP_9_BY_15, str[i]);
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}
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static void GLCALLBACK
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begin_callback(GLenum mode)
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{
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triangle.no = 0;
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}
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static void GLCALLBACK
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edge_callback(GLenum flag)
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{
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if (flag == GL_TRUE) {
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triangle.color[0] = 1.0;
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triangle.color[1] = 1.0;
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triangle.color[2] = 0.5;
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}
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else {
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triangle.color[0] = 1.0;
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triangle.color[1] = 0.0;
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triangle.color[2] = 0.0;
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}
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}
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static void GLCALLBACK
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end_callback()
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{
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glBegin(GL_LINES);
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glColor3f(triangle.p_color[0][0], triangle.p_color[0][1],
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triangle.p_color[0][2]);
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glVertex2i(triangle.p[0][0], triangle.p[0][1]);
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glVertex2i(triangle.p[1][0], triangle.p[1][1]);
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glColor3f(triangle.p_color[1][0], triangle.p_color[1][1],
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triangle.p_color[1][2]);
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glVertex2i(triangle.p[1][0], triangle.p[1][1]);
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glVertex2i(triangle.p[2][0], triangle.p[2][1]);
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glColor3f(triangle.p_color[2][0], triangle.p_color[2][1],
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triangle.p_color[2][2]);
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glVertex2i(triangle.p[2][0], triangle.p[2][1]);
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glVertex2i(triangle.p[0][0], triangle.p[0][1]);
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glEnd();
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}
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static void GLCALLBACK
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vertex_callback(void *data)
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{
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GLsizei no;
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GLint *p;
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p = (GLint *) data;
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no = triangle.no;
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triangle.p[no][0] = p[0];
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triangle.p[no][1] = p[1];
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triangle.p_color[no][0] = triangle.color[0];
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triangle.p_color[no][1] = triangle.color[1];
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triangle.p_color[no][2] = triangle.color[2];
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++(triangle.no);
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}
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static void
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set_screen_wh(GLsizei w, GLsizei h)
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{
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width = w;
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height = h;
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}
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static void
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tesse(void)
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{
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GLUtriangulatorObj *tobj;
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GLdouble data[3];
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GLuint i, j, point_cnt;
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tobj = gluNewTess();
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if (tobj != NULL) {
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glClear(GL_COLOR_BUFFER_BIT);
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glColor3f(0.7, 0.7, 0.0);
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gluTessCallback(tobj, GLU_BEGIN, glBegin);
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gluTessCallback(tobj, GLU_END, glEnd);
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gluTessCallback(tobj, GLU_ERROR, my_error);
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gluTessCallback(tobj, GLU_VERTEX, glVertex2iv);
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gluBeginPolygon(tobj);
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for (j = 0; j <= contour_cnt; j++) {
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point_cnt = contours[j].point_cnt;
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gluNextContour(tobj, GLU_UNKNOWN);
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for (i = 0; i < point_cnt; i++) {
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data[0] = (GLdouble) (contours[j].p[i][0]);
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data[1] = (GLdouble) (contours[j].p[i][1]);
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data[2] = 0.0;
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gluTessVertex(tobj, data, contours[j].p[i]);
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}
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}
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gluEndPolygon(tobj);
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glLineWidth(2.0);
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gluTessCallback(tobj, GLU_BEGIN, begin_callback);
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gluTessCallback(tobj, GLU_END, end_callback);
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gluTessCallback(tobj, GLU_VERTEX, vertex_callback);
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gluTessCallback(tobj, GLU_EDGE_FLAG, edge_callback);
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gluBeginPolygon(tobj);
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for (j = 0; j <= contour_cnt; j++) {
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point_cnt = contours[j].point_cnt;
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gluNextContour(tobj, GLU_UNKNOWN);
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for (i = 0; i < point_cnt; i++) {
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data[0] = (GLdouble) (contours[j].p[i][0]);
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data[1] = (GLdouble) (contours[j].p[i][1]);
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data[2] = 0.0;
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gluTessVertex(tobj, data, contours[j].p[i]);
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}
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}
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gluEndPolygon(tobj);
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gluDeleteTess(tobj);
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glutMouseFunc(NULL);
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glColor3f(1.0, 1.0, 0.0);
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glLineWidth(1.0);
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mode = TESSELATED;
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}
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}
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static void
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left_down(int x1, int y1)
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{
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GLint P[2];
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GLuint point_cnt;
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/* translate GLUT into GL coordinates */
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P[0] = x1;
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P[1] = height - y1;
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point_cnt = contours[contour_cnt].point_cnt;
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contours[contour_cnt].p[point_cnt][0] = P[0];
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contours[contour_cnt].p[point_cnt][1] = P[1];
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glBegin(GL_LINES);
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if (point_cnt) {
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glVertex2iv(contours[contour_cnt].p[point_cnt - 1]);
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glVertex2iv(P);
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}
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else {
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glVertex2iv(P);
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glVertex2iv(P);
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}
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glEnd();
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glFinish();
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++(contours[contour_cnt].point_cnt);
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}
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static void
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middle_down(int x1, int y1)
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{
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GLuint point_cnt;
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point_cnt = contours[contour_cnt].point_cnt;
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if (point_cnt > 2) {
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glBegin(GL_LINES);
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glVertex2iv(contours[contour_cnt].p[0]);
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glVertex2iv(contours[contour_cnt].p[point_cnt - 1]);
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contours[contour_cnt].p[point_cnt][0] = -1;
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glEnd();
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glFinish();
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contour_cnt++;
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contours[contour_cnt].point_cnt = 0;
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}
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}
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static void
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mouse_clicked(int button, int state, int x, int y)
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{
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x -= x % 10;
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y -= y % 10;
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switch (button) {
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case GLUT_LEFT_BUTTON:
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if (state == GLUT_DOWN)
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left_down(x, y);
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break;
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case GLUT_MIDDLE_BUTTON:
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if (state == GLUT_DOWN)
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middle_down(x, y);
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break;
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}
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}
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static void
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display(void)
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{
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GLuint i, j;
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GLuint point_cnt;
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glClear(GL_COLOR_BUFFER_BIT);
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switch (mode) {
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case DEFINE:
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/* draw grid */
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glColor3f(0.6, 0.5, 0.5);
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glBegin(GL_LINES);
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for (i = 0; i < width; i += 10)
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for (j = 0; j < height; j += 10) {
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glVertex2i(0, j);
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glVertex2i(width, j);
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glVertex2i(i, height);
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glVertex2i(i, 0);
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}
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glEnd();
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glColor3f(1.0, 1.0, 0.0);
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for (i = 0; i <= contour_cnt; i++) {
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point_cnt = contours[i].point_cnt;
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glBegin(GL_LINES);
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switch (point_cnt) {
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case 0:
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break;
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case 1:
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glVertex2iv(contours[i].p[0]);
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glVertex2iv(contours[i].p[0]);
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break;
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case 2:
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glVertex2iv(contours[i].p[0]);
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glVertex2iv(contours[i].p[1]);
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break;
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default:
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--point_cnt;
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for (j = 0; j < point_cnt; j++) {
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glVertex2iv(contours[i].p[j]);
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glVertex2iv(contours[i].p[j + 1]);
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}
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if (contours[i].p[j + 1][0] == -1) {
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glVertex2iv(contours[i].p[0]);
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glVertex2iv(contours[i].p[j]);
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}
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break;
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}
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glEnd();
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}
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glFinish();
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break;
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case TESSELATED:
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/* draw lines */
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tesse();
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break;
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}
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glColor3f(1.0, 1.0, 0.0);
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}
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static void
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clear(void)
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{
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contour_cnt = 0;
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contours[0].point_cnt = 0;
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glutMouseFunc(mouse_clicked);
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mode = DEFINE;
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display();
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}
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static void
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quit(void)
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{
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exit(0);
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}
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static void
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menu_selected(int entry)
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{
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switch (entry) {
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case CLEAR:
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clear();
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break;
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case TESSELATE:
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tesse();
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break;
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case QUIT:
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quit();
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break;
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}
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}
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static void
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key_pressed(unsigned char key, int x, int y)
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{
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switch (key) {
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case 't':
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case 'T':
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tesse();
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glFinish();
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break;
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case 'q':
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case 'Q':
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quit();
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break;
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case 'c':
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case 'C':
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clear();
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break;
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}
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}
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static void
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myinit(void)
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{
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/* clear background to gray */
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glClearColor(0.4, 0.4, 0.4, 0.0);
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glShadeModel(GL_FLAT);
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menu = glutCreateMenu(menu_selected);
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glutAddMenuEntry("clear", CLEAR);
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glutAddMenuEntry("tesselate", TESSELATE);
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glutAddMenuEntry("quit", QUIT);
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glutAttachMenu(GLUT_RIGHT_BUTTON);
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glutMouseFunc(mouse_clicked);
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glutKeyboardFunc(key_pressed);
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contour_cnt = 0;
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glPolygonMode(GL_FRONT, GL_FILL);
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mode = DEFINE;
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}
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static void
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reshape(GLsizei w, GLsizei h)
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{
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glViewport(0, 0, w, h);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrtho(0.0, (GLdouble) w, 0.0, (GLdouble) h, -1.0, 1.0);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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set_screen_wh(w, h);
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}
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static void
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usage(void)
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{
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printf("Use left mouse button to place vertices.\n");
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printf("Press middle mouse button when done.\n");
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printf("Select tesselate from the pop-up menu.\n");
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}
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/* Main Loop
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* Open window with initial window size, title bar,
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* RGBA display mode, and handle input events.
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*/
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int
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main(int argc, char **argv)
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{
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usage();
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glutInit(&argc, argv);
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glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
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glutInitWindowSize(400, 400);
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glutCreateWindow(argv[0]);
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myinit();
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glutDisplayFunc(display);
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glutReshapeFunc(reshape);
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glutMainLoop();
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return 0;
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}
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