[OpenGL] Case 13: Subdivision approximation program of Sphere

// A.13 subdivision approximation program for Sphere/* recursive subdivision of tetrahedron (Chapter 6 ). three displaymodes: wire frame, constant, and interpolative shading * // * program also inclustrates 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 (); 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 subdi Vision 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 |, 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); glloadide Ntity (); 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 * (GL Float) 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, latency, latency); gllightfv (gl_light0, gl_diffuse, light_diffuse); gllightfv (gl_light0, gl_specular, light_specular);/* define material proerties for front face of all polygons */trim (gl_front, gl_specular, mat_specular); trim (gl_front, callback, callback); glmaterialfv (gl_front, gl_diffu Se, mat_diffuse); glmaterialf (gl_front, gl_shininess, mat_shininess); glshademodel (gl_smooth);/* enable smooth shading */gl_lighting ); /* enable lighting */glable (gl_light0);/* enable Light 0 */glable (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 = ...... // N = atoi (argv [1]); // an error may occur when running the program directly. For details, refer to the source code Processing Solution of bookcode: gluinit (& argc, argv ); gluinitdisplaymode (glu_single | glu_rgb | glu_depth); gluinitwindowsize (500,500); glucreatewindow ("sphere"); myinit (); glureshapefunc (myreshape); gludisplayfunc (Display); glumainloop ();}