交互式计算机图形学——基于openGL的自顶向下方法山东大学数字媒体技术专业课本教材附录程序第四版A.1 Sierpinski镂垫程序/* two-dimensional Sierpinski gasket *//* generated using randomly selected vertices *//* and bisection */#include <GL/glut.h>/*you may have to change the include to<glut.h> orelsewhere depending on where it is stored on your system *//* glut.h usually has included for gl.h and glu.h */void myinit(void){/* attributes */glClearColor(1.0, 1.0, 1.0, 1.0); /* white background */glColor3f(1.0, 0.0, 0.0); /* draw in red *//* set up viewing *//* 50.0 × 50.0 camera coordinate window with origin lower left */glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0.0, 50.0, 0.0, 50.0);glMatrixMode(GL_MODELVIEW);}void display(void){/* A triangle */GLfloat vertices[3][2]={{0.0,0.0},{25.0,50.0},{50.0,0.0}};int i, j, k;int rand(); /* standard random number generator */GLfloat p[2] ={7.5,5.0}; /* an arbitrary initial point inside traingle */ glClear(GL_COLOR_BUFFER_BIT); /* clear the window */glBegin(GL_POINTS);/* compute and plots 5000 new points */586交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)for( k=0; k<5000; k++){j=rand()%3; /* pick a vertex at random *//* Compute point halfway between selected vertex and old point */p[0] = (p[0]+vertices[j][0])/2.0;p[1] = (p[1]+vertices[j][1])/2.0;/* plot new point */glVertex2fv(p);}glEnd();glFlush(); /* clear buffers */}void main(int argc, char** argv){/* Standard GLUT initialization */glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); /* default, not needed */glutInitWindowSize(500,500); /* 500 × 500 pixel window */glutInitWindowPosition(0,0); /* place window top left on display */glutCreateWindow("Sierpinski Gasket"); /* window title */glutDisplayFunc(display);/* display callback invoked when window opened */myinit(); /* set attributes */glutMainLoop(); /* enter event loop */}A.2 生成Sierpinski镂垫的递归程序/* Recursive subdivision of triangle to form Sierpinski gasket *//* number of recursive steps given on command line */#include <GL/glut.h>#include<stdlib.h>/* initial triangle */GLfloat v[3][2]={{-1.0, -0.58}, {1.0, -0.58}, {0.0, 1.15}};int n;void triangle( GLfloat *a, GLfloat *b, GLfloat *c)/* display one triangle */附录A 实例程序587{glVertex2fv(a);glVertex2fv(b);glVertex2fv(c);}void divide_triangle(GLfloat *a, GLfloat *b, GLfloat *c, int m){/* triangle subdivision using vertex numbers */GLfloat v0[2], v1[2], v2[2];int j;if(m>0){for(j=0; j<2; j++) v0[j]=(a[j]+b[j])/2;for(j=0; j<2; j++) v1[j]=(a[j]+c[j])/2;for(j=0; j<2; j++) v2[j]=(b[j]+c[j])/2;divide_triangle(a, v0, v1, m-1);divide_triangle(c, v1, v2, m-1);divide_triangle(b, v2, v0, m-1);}else triangle(a,b,c); /* draw triangle at end of recursion */}void display(void){glClear(GL_COLOR_BUFFER_BIT);glBegin(GL_TRIANGLES);divide_triangle(v[0], v[1], v[2], n);glEnd();glFlush();}void myinit(){glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(-2.0, 2.0, -2.0, 2.0);glMatrixMode(GL_MODELVIEW);glClearColor(1.0, 1.0, 1.0, 1.0);glColor3f(0.0,0.0,0.0);}void main(int argc, char **argv){n=atoi(argv[1]); /* or set number of subdivision steps here */glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowSize(500, 500);glutCreateWindow("Sierpinski Gasket");588交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)glutDisplayFunc(display);myinit();glutMainLoop();}A.3 三维Sierpinski镂垫的递归程序/* Recursive subdivision of a tetrahedron to form 3D Sierpinski gasket *//* number of recursive steps given on command line */#include <stdlib.h>#include <GL/glut.h>/* initial tetrahedron */GLfloat v[4][3]={{0.0, 0.0, 1.0},{0.0, 0.942809, -0.33333},{-0.816497, -0.471405, -0.333333},{0.816497, -0.471405, -0.333333}};GLfloat colors[4][3]={{1.0,0.0,0.0},{0.0,1.0,0.0},{0.0,0.0,1.0},{0.0,0.0,0.0}};int n;void triangle( GLfloat *va, GLfloat *vb, GLfloat *vc){glVertex3fv(va);glVertex3fv(vb);glVertex3fv(vc);}void tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d){glColor3fv(colors[0]);triangle(a,b,c);glColor3fv(colors[1]);triangle(a,c,d);glColor3fv(colors[2]);triangle(a,d,b);glColor3fv(colors[3]);triangle(b,d,c);}void divide_tetra(GLfloat *a, GLfloat *b, GLfloat *c, GLfloat *d, int m){GLfloat mid[6][3];int j;if(m>0){/* compute six midpoints */附录A 实例程序589for(j=0; j<3; j++) mid[0][j]=(a[j]+b[j])/2;for(j=0; j<3; j++) mid[1][j]=(a[j]+c[j])/2;for(j=0; j<3; j++) mid[2][j]=(a[j]+d[j])/2;for(j=0; j<3; j++) mid[3][j]=(b[j]+c[j])/2;for(j=0; j<3; j++) mid[4][j]=(c[j]+d[j])/2;for(j=0; j<3; j++) mid[5][j]=(b[j]+d[j])/2;/* create 4 tetrahedrons by subdivision */divide_tetra(a,mid[0],mid[1],mid[2], m-1);divide_tetra(mid[0],b,mid[3],mid[5], m-1);divide_tetra(mid[1],mid[3],c,mid[4], m-1);divide_tetra(mid[2],mid[4],d,mid[5], m-1);}else tetra(a,b,c,d); /* draw tetrahedron at end of recursion */}void display(void){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glBegin(GL_TRIANGLES);divide_tetra(v[0],v[1],v[2],v[3],n);glEnd();glFlush();}void myReshape(int w, int h){glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();if (w <= h)glOrtho(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,2.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);elseglOrtho(-2.0 * (GLfloat) w / (GLfloat) h,2.0 * (GLfloat) w / (GLfloat) h, -2.0, 2.0, -10.0, 10.0);glMatrixMode(GL_MODELVIEW);glutPostRedisplay();}void main(int argc, char **argv){n=atoi(argv[1]); /* or enter number of subdivision steps here */glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);glutInitWindowSize(500, 500);glutCreateWindow("3D Gasket");590交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)glutReshapeFunc(myReshape);glutDisplayFunc(display);glEnable(GL_DEPTH_TEST);glClearColor (1.0, 1.0, 1.0, 1.0);glutMainLoop();}A.4 Marching-Square程序/* generates contours using marching squares *//* region size */#define X_MAX 1.0#define Y_MAX 1.0#define X_MIN -1.0#define Y_MIN -1.0/* number of cells */#define N_X 50#define N_Y 50/* contour value */#define THRESHOLD 0.0#include<gl/glut.h>void display(){double f(double,double);int cell(double,double,double,double);void lines(int,int,int,double,double,double,double);double data[N_X][N_Y];int i,j;int c;glClear(GL_COLOR_BUFFER_BIT);/* form data array from function */for(i=0;i<N_X;i++)for(j=0;j<N_Y;j++)data[i][j]=f(X_MIN+i*(X_MAX-X_MIN) /(N_X-1.0),Y_MIN+j*(Y_MAX-Y_MIN)/(N_Y-1.0));/* process each cell */附录A 实例程序591for(i=0;i<N_X;i++)for(j=0;j<N_Y;j++){c=cell(data[i][j],data[i+1][j],data[i+1][j+1],data[i][j+1]);lines(c,i,j,data[i][j],data[i+1][j],data[i+1][j+1],data[i][j+1]);}glFlush();}/* define function f(x,y) */double f(double x, double y){double a=0.49, b=0.5;/* ovals of Cassini */return (x*x+y*y+a*a)*(x*x+y*y+a*a)-4*a*a*x*x-b*b*b*b;}/* define cell vertices */int cell(double a,double b,double c, double d){int n=0;if(a>THRESHOLD) n+=1;if(b>THRESHOLD) n+=8;if(c>THRESHOLD) n+=4;if(d>THRESHOLD) n+=2;return n ;}/* draw line segments for each case */void lines(int num,int i,int j,double a ,double b,double c,double d){void draw_one(int,int,int,double,double,double,double);void draw_adjacent(int,int,int, double,double,double,double);void draw_opposite(int,int,int,double,double,double,double);switch(num){case 1 : case 2: case 4 : case 7: case 8: case 11: case 13: case 14:draw_one(num,i,j,a,b,c,d);break;case 3: case 6: case 9: case 12:592交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)draw_adjacent(num,i,j,a,b,c,d);break;case 5: case 10:draw_opposite(num,i,j,a,b,c,d);break;case 0: case 15:break;}}void draw_one(int num,int i,int j,double a,double b,double c,double d){double x1,y1,x2,y2;double ox,oy;double dx,dy;dx=(X_MAX-X_MIN)/(N_X-1.0);dy=(Y_MAX-Y_MIN)/(N_Y-1.0);ox=X_MIN+i*(X_MAX-X_MIN)/(N_X-1.0);oy=Y_MIN+j*(Y_MAX-Y_MIN)/(N_Y-1.0);s witch(num){c ase 1 : case 14:x1=ox;y1=oy+dy*(THRESHOLD-a)/(d-a);x2=ox+dx*(THRESHOLD-a)/(b-a);y2=oy;break;c ase 2: case 13:x1=ox;y1=oy+dy*(THRESHOLD-a)/(d-a);x2=ox+dx*(THRESHOLD-d)/(c-d);y2=oy+dy;break;c ase 4: case 11:x1=ox+dx*(THRESHOLD-d)/(c-d);y1=oy+dy;x2=ox+dx;y2=oy+dy*(THRESHOLD-b)/(c-b);break;c ase 7: case 8:x1=ox+dx*(THRESHOLD-a)/(b-a);y1=oy;x2=ox+dx;y2=oy+dy*(THRESHOLD-b)/(c-b);break;}glBegin(GL_LINES);glVertex2d(x1,y1);附录A 实例程序593glVertex2d(x2,y2);glEnd();}void draw_adjacent(int num,int i,int j,double a,double b,double c ,double d){double x1,y1,x2,y2;double ox,oy;double dx,dy;dx=(X_MAX-X_MIN)/(N_X-1.0);dy=(Y_MAX-Y_MIN)/(N_Y-1.0);ox=X_MIN+i*(X_MAX-X_MIN)/(N_X-1.0);oy=Y_MIN+j*(Y_MAX-Y_MIN)/(N_Y-1.0);switch(num){case 3 : case 12:x1=ox+dx*(THRESHOLD-a)/(b-a);y1=oy;x2=ox+dx*(THRESHOLD-d)/(c-d);y2=oy+dy;break;case 6: case 9:x1=ox;y1=oy+dy*(THRESHOLD-a)/(d-a);x2=ox+dx;y2=oy+dy*(THRESHOLD-b)/(c-b);break;}glBegin(GL_LINES);glVertex2d(x1,y1);glVertex2d(x2,y2);glEnd();}void draw_opposite(int num,int i,int j,double a,double b,double c ,double d){double x1,y1,x2,y2,x3,y3,x4,y4;double ox,oy;double dx,dy;dx=(X_MAX-X_MIN)/(N_X-1.0);dy=(Y_MAX-Y_MIN)/(N_Y-1.0);ox=X_MIN+i*(X_MAX-X_MIN)/(N_X-1.0);oy=Y_MIN+j*(Y_MAX-Y_MIN)/(N_Y-1.0);switch(num){case 5 :x1=ox;y1=oy+dy*(THRESHOLD-a)/(d-a);x2=ox+dx*(THRESHOLD-a)/(b-a);594交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)y2=oy;x3=ox+dx*(THRESHOLD-d)/(c-d);y3=oy+dy;x4=ox+dx;y4=oy+dy*(THRESHOLD-b)/(c-b);break;case 10:x1=ox;y1=oy+dy*(THRESHOLD-a)/(d-a);x2=ox+dx*(THRESHOLD-d)/(c-d);y2=oy+dy;x3=ox+dx*(THRESHOLD-d)/(c-d);y3=oy;x4=ox+dx;y4=oy+dy*(THRESHOLD-b)/(c-b);break;}glBegin(GL_LINES);glVertex2d(x1,y1);glVertex2d(x2,y2);glVertex2d(x3,y3);glVertex2d(x4,y4);glEnd();}void myReshape(int w, int h){glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();if (w <= h)gluOrtho2D(X_MIN, X_MAX, Y_MIN * (GLfloat) h / (GLfloat) w,Y_MAX * (GLfloat) h / (GLfloat) w);elsegluOrtho2D(X_MIN * (GLfloat) w / (GLfloat) h,X_MAX * (GLfloat) w / (GLfloat) h, Y_MIN, Y_MAX);glMatrixMode(GL_MODELVIEW);}void main(int argc, char **argv){glutInit(&argc, argv);glutInitWindowSize(500, 500);glutCreateWindow("contour plot");glutReshapeFunc(myReshape);glutDisplayFunc(display);glClearColor(0.0, 0.0, 0.0, 1.0);glColor3f(1.0,1.0,1.0);附录A 实例程序595glutMainLoop();}A.5 生成正方形的程序/* This program illustrates the use of the GLUT library forinterfacing with a Window System *//* The program opens a window, clears it to black,then draws a box at the location of the mouse each time theleft button is clicked. The right button exits the program.The program also reacts correctly when the window ismoved or resized by clearing the new window to black. */#include <GL/glut.h>#include <stdlib.h>/* globals */GLsizei wh = 500, ww = 500; /* initial window size */GLfloat size = 3.0; /* half side length of square */void drawSquare(int x, int y){y=wh-y;glColor3ub( (char) rand()%256, (char) rand()%256, (char) rand()%256);glBegin(GL_POLYGON);glVertex2f(x+size, y+size);glVertex2f(x-size, y+size);glVertex2f(x-size, y-size);glVertex2f(x+size, y-size);glEnd();glFlush();}/* reshaping routine called whenever window is resizedor moved */void myReshape(GLsizei w, GLsizei h){/* adjust clipping box */glMatrixMode(GL_PROJECTION);glLoadIdentity();596交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();/* adjust viewport and clear */glViewport(0,0,w,h);glClear(GL_COLOR_BUFFER_BIT);glFlush();/* set global size for use by drawing routine */ww = w;wh = h;}void myinit(void){glViewport(0,0,ww,wh);/* Pick 2D clipping window to match size of screen window.This choice avoids having to scale object coordinateseach time window is resized. */glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(0.0, (GLdouble) ww, 0.0, (GLdouble) wh, -1.0, 1.0);/* set clear color to black and clear window */glClearColor (0.0, 0.0, 0.0, 1.0);glClear(GL_COLOR_BUFFER_BIT);glFlush();}void mouse(int btn,int state,int x,int y){if(btn==GLUT_RIGHT_BUTTON &&state==GLUT_DOWN) exit(0);}/* display callback required by GLUT*/void display();int main(int argc,char** argv){glutInit(&argc,argv);glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);glutCreateWindow("square");myinit();glutReshapeFunc (myReshape);glutMouseFunc (mouse);附录A 实例程序597glutMotionFunc (drawSquare);glutDisplayFunc (display);glutMainLoop();}A.6 画图程序/* simple painting program with text, lines, triangles,rectangles,and points */#define NULL 0#define LINE 1#define RECTANGLE 2#define TRIANGLE 3#define POINTS 4#define TEXT 5#include <stdlib.h>#include <GL/glut.h>void mouse(int, int, int, int);void key(unsigned char, int, int);void display(void);void drawSquare(int, int);void myReshape(GLsizei, GLsizei);void myinit(void);void screen_box(int, int, int);void right_menu(int);void middle_menu(int);void color_menu(int);void pixel_menu(int);void fill_menu(int);int pick(int, int);/* globals */GLsizei wh = 500, ww = 500; /* initial window size */GLfloat size = 3.0; /* half side length of square */int draw_mode = 0; /* drawing mode */int rx, ry; /* raster position */GLfloat r = 1.0, g = 1.0, b = 1.0; /* drawing color */int fill = 0; /* fill flag */void drawSquare(int x, int y){598交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)y=wh-y;glColor3ub( (char) rand()%256, (char) rand()%256, (char) rand()%256);glBegin(GL_POLYGON);glVertex2f(x+size, y+size);glVertex2f(x-size, y+size);glVertex2f(x-size, y-size);glVertex2f(x+size, y-size);glEnd();}/* rehaping routine called whenever window is resizedor moved */void myReshape(GLsizei w, GLsizei h){/* adjust clipping box */glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();/* adjust viewport and clear */glViewport(0,0,w,h);glClearColor (0.8, 0.8, 0.8, 1.0);glClear(GL_COLOR_BUFFER_BIT);display();glFlush();/* set global size for use by drawing routine */ww = w;wh = h;}void myinit(void){glViewport(0,0,ww,wh);/* Pick 2D clipping window to match size of X window.This choice avoids having to scale object coordinateseach time window is resized.*/glMatrixMode(GL_PROJECTION);附录A 实例程序599glLoadIdentity();glOrtho(0.0, (GLdouble) ww , 0.0, (GLdouble) wh , -1.0, 1.0);/* set clear color to black and clear window */glClearColor (0.8, 0.8, 0.8, 1.0);glClear(GL_COLOR_BUFFER_BIT);glFlush();}void mouse(int btn, int state, int x, int y){static int count;int where;static int xp[2],yp[2];if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN){glPushAttrib(GL_ALL_ATTRIB_BITS);where = pick(x,y);glColor3f(r, g, b);if(where != 0){count = 0;draw_mode = where;}else switch(draw_mode){case(LINE):if(count==0){count++;xp[0] = x;yp[0] = y;}else{glBegin(GL_LINES);glVertex2i(x,wh-y);glVertex2i(xp[0],wh-yp[0]);glEnd();draw_mode=0;count=0;}break;case(RECTANGLE):if(count == 0){count++;xp[0] = x;yp[0] = y;600交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)}else{if(fill) glBegin(GL_POLYGON);else glBegin(GL_LINE_LOOP);glVertex2i(x,wh-y);glVertex2i(x,wh-yp[0]);glVertex2i(xp[0],wh-yp[0]);glVertex2i(xp[0],wh-y);glEnd();draw_mode=0;count=0;}break;case (TRIANGLE):switch(count){case(0):count++;xp[0] = x;yp[0] = y;break;case(1):count++;xp[1] = x;yp[1] = y;break;case(2):if(fill) glBegin(GL_POLYGON);else glBegin(GL_LINE_LOOP);glVertex2i(xp[0],wh-yp[0]);glVertex2i(xp[1],wh-yp[1]);glVertex2i(x,wh-y);glEnd();draw_mode=0;count=0;}break;case(POINTS):{drawSquare(x,y);count++;}break;case(TEXT):{rx=x;ry=wh-y;glRasterPos2i(rx,ry);count=0;附录A 实例程序601}}glPopAttrib();glFlush();}}int pick(int x, int y){y = wh - y;if(y < wh-ww/10) return 0;else if(x < ww/10) return LINE;else if(x < ww/5) return RECTANGLE;else if(x < 3*ww/10) return TRIANGLE;else if(x < 2*ww/5) return POINTS;else if(x < ww/2) return TEXT;else return 0;}void screen_box(int x, int y, int s ){glBegin(GL_QUADS);glVertex2i(x, y);glVertex2i(x+s, y);glVertex2i(x+s, y+s);glVertex2i(x, y+s);glEnd();}void right_menu(int id){if(id == 1) exit(0);else display();}void middle_menu(int id){}void color_menu(int id){if(id == 1) {r = 1.0; g = 0.0; b = 0.0;}else if(id == 2) {r = 0.0; g = 1.0; b = 0.0;}else if(id == 3) {r = 0.0; g = 0.0; b = 1.0;}else if(id == 4) {r = 0.0; g = 1.0; b = 1.0;}else if(id == 5) {r = 1.0; g = 0.0; b = 1.0;}else if(id == 6) {r = 1.0; g = 1.0; b = 0.0;}else if(id == 7) {r = 1.0; g = 1.0; b = 1.0;}602交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)else if(id == 8) {r = 0.0; g = 0.0; b = 0.0;}}void pixel_menu(int id){if (id == 1) size = 2 * size;else if (size > 1) size = size/2;}void fill_menu(int id){if (id == 1) fill = 1;else fill = 0;}void key(unsigned char k, int xx, int yy){if(draw_mode!=TEXT) return;glColor3f(0.0,0.0,0.0);glRasterPos2i(rx,ry);glutBitmapCharacter(GLUT_BITMAP_9_BY_15, k);/* glutStrokeCharacter(GLUT_STROKE_ROMAN,i); */rx+=glutBitmapWidth(GLUT_BITMAP_9_BY_15,k);}void display(void){int shift=0;glPushAttrib(GL_ALL_ATTRIB_BITS);glClearColor (0.8, 0.8, 0.8, 1.0);glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0, 1.0, 1.0);screen_box(0,wh-ww/10,ww/10);glColor3f(1.0, 0.0, 0.0);screen_box(ww/10,wh-ww/10,ww/10);glColor3f(0.0, 1.0, 0.0);screen_box(ww/5,wh-ww/10,ww/10);glColor3f(0.0, 0.0, 1.0);screen_box(3*ww/10,wh-ww/10,ww/10);glColor3f(1.0, 1.0, 0.0);screen_box(2*ww/5,wh-ww/10,ww/10);glColor3f(0.0, 0.0, 0.0);screen_box(ww/10+ww/40,wh-ww/10+ww/40,ww/20);glBegin(GL_LINES);glVertex2i(wh/40,wh-ww/20);glVertex2i(wh/40+ww/20,wh-ww/20);glEnd();附录A 实例程序603glBegin(GL_TRIANGLES);glVertex2i(ww/5+ww/40,wh-ww/10+ww/40);glVertex2i(ww/5+ww/20,wh-ww/40);glVertex2i(ww/5+3*ww/40,wh-ww/10+ww/40);glEnd();glPointSize(3.0);glBegin(GL_POINTS);glVertex2i(3*ww/10+ww/20, wh-ww/20);glEnd();glRasterPos2i(2*ww/5,wh-ww/20);glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'A');shift=glutBitmapWidth(GLUT_BITMAP_9_BY_15, 'A');glRasterPos2i(2*ww/5+shift,wh-ww/20);glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'B');shift+=glutBitmapWidth(GLUT_BITMAP_9_BY_15, 'B');glRasterPos2i(2*ww/5+shift,wh-ww/20);glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'C');glFlush();glPopAttrib();}int main(int argc, char** argv){int c_menu, p_menu, f_menu;glutInit(&argc,argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowSize(500, 500);glutCreateWindow("square");glutDisplayFunc(display);c_menu = glutCreateMenu(color_menu);glutAddMenuEntry("Red",1);glutAddMenuEntry("Green",2);glutAddMenuEntry("Blue",3);glutAddMenuEntry("Cyan",4);glutAddMenuEntry("Magenta",5);glutAddMenuEntry("Yellow",6);glutAddMenuEntry("White",7);glutAddMenuEntry("Black",8);p_menu = glutCreateMenu(pixel_menu);glutAddMenuEntry("increase pixel size", 1);glutAddMenuEntry("decrease pixel size", 2);f_menu = glutCreateMenu(fill_menu);glutAddMenuEntry("fill on", 1);glutAddMenuEntry("fill off", 2);glutCreateMenu(right_menu);glutAddMenuEntry("quit",1);glutAddMenuEntry("clear",2);glutAttachMenu(GLUT_RIGHT_BUTTON);604交互式计算机图形学——基于OpenGL的自顶向下方法(第4版)glutCreateMenu(middle_menu);glutAddSubMenu("Colors", c_menu);glutAddSubMenu("Pixel Size", p_menu);glutAddSubMenu("Fill", f_menu);glutAttachMenu(GLUT_MIDDLE_BUTTON);myinit ();glutReshapeFunc (myReshape);glutKeyboardFunc(key);glutMouseFunc (mouse);glutMainLoop();}A.7 使用双缓存的程序/** double.c* This program demonstrates double buffering for* flicker-free animation. The left and middle mouse* buttons start and stop the spinning motion of the square.*/#include <GL/glut.h>#include <stdlib.h>#include <math.h>#define DEGREES_TO_RADIANS 3.14159/180.0static GLfloat spin = 0.0;GLfloat x,y;int singleb, doubleb;void square(){glBegin(GL_QUADS);glVertex2f(x,y);glVertex2f(-y,x);glVertex2f(-x,-y);glVertex2f(y,-x);glEnd();}void displayd(void){glClear(GL_COLOR_BUFFER_BIT);square();glutSwapBuffers();}void displays(void){glClear(GL_COLOR_BUFFER_BIT);square();glFlush();}void spinDisplay(void){spin = spin + 2.0;if (spin > 360.0) spin = spin - 360.0;x=25.0 * cos(DEGREES_TO_RADIANS*spin);y=25.0 * sin(DEGREES_TO_RADIANS*spin);glutSetWindow(singleb);glutPostRedisplay();glutSetWindow(doubleb);glLoadIdentity();glutPostRedisplay();}void myinit(void){glClearColor(0.0, 0.0, 0.0, 1.0);glColor3f(1.0, 1.0, 1.0);glShadeModel(GL_FLAT);}void mouse(int btn, int state, int x, int y){if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN)glutIdleFunc(spinDisplay);if(btn==GLUT_MIDDLE_BUTTON && state==GLUT_DOWN)glutIdleFunc(NULL);}void myReshape(int w, int h){glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();if (w <= h)glOrtho(-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w,50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);elseglOrtho(-50.0*(GLfloat)w/(GLfloat)h,50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0); glMatrixMode(GL_MODELVIEW);glLoadIdentity();}/* Main Loop* Open window with initial window size, title bar, * RGBA display mode, and handle input events.*/int main(int argc, char** argv){glutInit(&argc,argv);g lutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);s ingleb=glutCreateWindow("single buffered");myinit();g lutDisplayFunc(displays);glutReshapeFunc(myReshape);glutIdleFunc(spinDisplay);glutMouseFunc(mouse);g lutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);d oubleb=glutCreateWindow("double buffered");myinit();g lutDisplayFunc(displayd);glutReshapeFunc(myReshape);glutIdleFunc(spinDisplay);glutMouseFunc(mouse);g lutMainLoop();}A.8 选择模式拾取程序/* demonstrates picking used selection mode */#include <stdlib.h>#include <stdio.h>#include <GL/glut.h>void init(){glClearColor(0.0, 0.0, 0.0, 0.0);}void drawObjects(GLenum mode){if(mode == GL_SELECT) glLoadName(1);glColor3f(1.0, 0.0, 0.0);glRectf(-0.5, -0.5, 1.0, 1.0);if(mode == GL_SELECT) glLoadName(2);glColor3f(0.0, 0.0, 1.0);glRectf(-1.0, -1.0, 0.5, 0.5);}void display(){glClear(GL_COLOR_BUFFER_BIT);drawObjects(GL_RENDER);glFlush();}/* processHits prints out the contents of the* selection array.*/void processHits (GLint hits, GLuint buffer[]){unsigned int i, j;GLuint ii, jj, names, *ptr;printf("hits = %d\n", hits);ptr=(GLuint *) buffer;for (i = 0; i < hits; i++) { /* for each hit */names = *ptr;ptr+=3;for (j = 0; j < names; j++){ /* for each name */if(*ptr==1) printf ("red rectangle\n");else printf ("blue rectangle\n");ptr++;}printf ("\n");}}#define SIZE 512void mouse(int button, int state, int x, int y){GLuint selectBuf[SIZE];GLint hits;GLint viewport[4];if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {glGetIntegerv(GL_VIEWPORT, viewport);glSelectBuffer (SIZE, selectBuf);glRenderMode(GL_SELECT);glInitNames();glPushName(0);glMatrixMode(GL_PROJECTION);glPushMatrix();glLoadIdentity();/* create 5×5 pixel picking region near cursor location */gluPickMatrix((GLdouble) x, (GLdouble) (viewport[3] - y), 5.0, 5.0, viewport);gluOrtho2D(-2.0, 2.0, -2.0, 2.0);drawObjects(GL_SELECT);glMatrixMode(GL_PROJECTION);glPopMatrix();glFlush();hits = glRenderMode(GL_RENDER);processHits(hits, selectBuf);glutPostRedisplay();}}void reshape(int w, int h){glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D (-2.0, 2.0, -2.0, 2.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}void keyboard(unsigned char key, int x, int y){switch (key){case 27:exit(0);break;}}/* Main Loop */int main(int argc, char** argv){glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowSize(500, 500);glutInitWindowPosition(100, 100);glutCreateWindow(argv[0]);init();glutReshapeFunc(reshape);glutDisplayFunc(display);glutMouseFunc(mouse);glutKeyboardFunc(keyboard);glutMainLoop();return 0;}A.9 立方体旋转程序/* Rotating cube with color interpolation *//* Demonstration of use of homogeneous coordinatetransformations and simple data structure for representing cube from Chapter 4 *//* Colors are assigned to the vertices *//* cube is centered at orign*/#include <stdlib.h>#include <GL/glut.h>GLfloat vertices[][3] = {{-1.0,-1.0,-1.0},{1.0,-1.0,-1.0}, {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, {-1.0,-1.0,1.0},{1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}};GLfloat colors[][3] = {{0.0,0.0,0.0},{1.0,0.0,0.0},{1.0,1.0,0.0}, {0.0,1.0,0.0}, {0.0,0.0,1.0},{1.0,0.0,1.0}, {1.0,1.0,1.0}, {0.0,1.0,1.0}};void polygon(int a, int b, int c, int d){/* draw a polygon via list of vertices */glBegin(GL_POLYGON);glColor3fv(colors[a]);glVertex3fv(vertices[a]);glColor3fv(colors[b]);glVertex3fv(vertices[b]);glColor3fv(colors[c]);glVertex3fv(vertices[c]);glColor3fv(colors[d]);glVertex3fv(vertices[d]);glEnd();}。
