//A.13 球体的细分逼近程序/* Recursive subdivision of tetrahedron (Chapter 6). Three displaymodes: wire frame, constant, and interpolative shading *//* Program also illustrates defining materials and light sourcesint init() *//* mode 0 = wire frame, mode 1 = constant shading,mode 3 = interpolative shading */ #include <stdlib.h>#include<math.h>#include <GL/glut.h>typedef float point[3];/* initial tetrahedron */point v[]={{0.0, 0.0, 1.0}, {0.0, 0.942809, -0.33333},{-0.816497, -0.471405, -0.333333}, {0.816497, -0.471405, -0.333333}};static GLfloat theta[] = {0.0,0.0,0.0};int n;int mode;void triangle( point a, point b, point c)/* display one triangle using a line loop for wire frame, a singlenormal for constant shading, or three normals for interpolative shading */{if (mode==0) glBegin(GL_LINE_LOOP);else glBegin(GL_POLYGON);if(mode==1) glNormal3fv(a);if(mode==2) glNormal3fv(a);glVertex3fv(a);if(mode==2) glNormal3fv(b);glVertex3fv(b);if(mode==2) glNormal3fv(c);glVertex3fv(c);glEnd();}void normal(point p){ /* normalize a vector */float d =0.0;int i;for(i=0; i<3; i++) d+=p[i]*p[i];d=sqrt(d);if(d>0.0) for(i=0; i<3; i++) p[i]/=d;}void divide_triangle(point a, point b, point c, int m){/* triangle subdivision using vertex numbersrighthand rule applied to create outward pointing faces */point v1, v2, v3;int j;if(m>0){for(j=0; j<3; j++) v1[j]=a[j]+b[j];normal(v1);for(j=0; j<3; j++) v2[j]=a[j]+c[j];normal(v2);for(j=0; j<3; j++) v3[j]=b[j]+c[j];normal(v3);divide_triangle(a, v1, v2, m-1);divide_triangle(c, v2, v3, m-1);divide_triangle(b, v3, v1, m-1);divide_triangle(v1, v3, v2, m-1);}else(triangle(a,b,c)); /* draw triangle at end of recursion */}void tetrahedron(int m){/* apply triangle subdivision to faces of tetrahedron */ divide_triangle(v[0], v[1], v[2], m);divide_triangle(v[3], v[2], v[1], m);divide_triangle(v[0], v[3], v[1], m);divide_triangle(v[0], v[2], v[3], m);}void display(void){/* Displays all three modes, side by side */glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity();mode=0;tetrahedron(n);mode=1;glTranslatef(-2.0, 0.0,0.0);tetrahedron(n);mode=2;glTranslatef(4.0, 0.0,0.0);tetrahedron(n);glFlush();}void myReshape(int w, int h){glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();if (w <= h)glOrtho(-4.0, 4.0, -4.0 * (GLfloat) h / (GLfloat) w,4.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);elseglOrtho(-4.0 * (GLfloat) w / (GLfloat) h,4.0 * (GLfloat) w / (GLfloat) h, -4.0, 4.0, -10.0, 10.0);glMatrixMode(GL_MODELVIEW);display(); }void myinit(){GLfloat mat_specular[]={1.0, 1.0, 1.0, 1.0};GLfloat mat_diffuse[]={1.0, 1.0, 1.0, 1.0};GLfloat mat_ambient[]={1.0, 1.0, 1.0, 1.0};GLfloat mat_shininess={100.0};GLfloat light_ambient[]={0.0, 0.0, 0.0, 1.0};GLfloat light_diffuse[]={1.0, 1.0, 1.0, 1.0};GLfloat light_specular[]={1.0, 1.0, 1.0, 1.0};/* set up ambient, diffuse, and specular components for light 0 */glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);/* define material proerties for front face of all polygons */glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);glMaterialf(GL_FRONT, GL_SHININESS, mat_shininess);glShadeModel(GL_SMOOTH); /* enable smooth shading */glEnable(GL_LIGHTING); /* enable lighting */glEnable(GL_LIGHT0); /* enable light 0 */glEnable(GL_DEPTH_TEST); /* enable z buffer */glClearColor (1.0, 1.0, 1.0, 1.0);glColor3f (0.0, 0.0, 0.0);}void main(int argc, char **argv){n=3;//n=1,2,3,4,5,6……//n=atoi(argv[1]);//直接运行会出错，具体参照BookCode的此处源码处理方案glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);glutInitWindowSize(500, 500);glutCreateWindow("sphere");myinit();glutReshapeFunc(myReshape);glutDisplayFunc(display);glutMainLoop();}
