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/* tess.c - by David Blythe, SGI */
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
static GLfloat spin = 0;
static int level = 4;
static int model = 0;
static GLfloat rotx, roty;
static int ox = -1, oy = -1;
static int mot;
#define PAN 1
#define ROT 2
void
movelight(int x, int y) {
spin += (y-oy);
ox = x; oy = y;
if (spin > 360.) spin -= 360.;
if (spin < -360.) spin -= -360.;
glutPostRedisplay();
}
void
rotate(int x, int y) {
rotx += x-ox;
if (rotx > 360.) rotx -= 360.;
else if (rotx < -360.) rotx += 360.;
roty += y-oy;
if (roty > 360.) roty -= 360.;
else if (roty < -360.) roty += 360.;
ox = x; oy = y;
glutPostRedisplay();
}
void
motion(int x, int y) {
if (mot == PAN) movelight(x, y);
else if (mot == ROT) rotate(x,y);
}
void
mouse(int button, int state, int x, int y) {
if(state == GLUT_DOWN) {
switch(button) {
case GLUT_LEFT_BUTTON:
mot = PAN;
motion(ox = x, oy = y);
break;
case GLUT_MIDDLE_BUTTON:
mot = ROT;
motion(ox = x, oy = y);
break;
case GLUT_RIGHT_BUTTON:
break;
}
} else if (state == GLUT_UP) {
mot = 0;
}
}
void togglewire(void) {
static int toggle = 0;
toggle ^= 1;
glPolygonMode(GL_FRONT_AND_BACK, toggle ? GL_LINE : GL_FILL);
}
void genmodel(void) {
extern void sphere(int level);
glNewList(1, GL_COMPILE);
if (model) {
GLUquadricObj *q = gluNewQuadric();
gluSphere(q, 1.0, 10*level, 10*level);
gluDeleteQuadric(q);
} else {
sphere(level-1);
}
glEndList();
}
void togglemodel(void) {
model ^= 1;
genmodel();
}
void levelup(void) {
level += 1;
if (level > 7) level = 7;
genmodel();
}
void leveldown(void) {
level -= 1;
if (level <= 0) level = 1;
genmodel();
}
void help(void) {
printf("'h' - help\n");
printf("'t' - tessellation style\n");
printf("'UP' - increase tessellation\n");
printf("'DOWN' - decrease tessellation\n");
printf("left mouse - rotate sphere\n");
printf("middle mouse - move light\n");
}
void init(void) {
GLfloat specular[4] = { 1., 1., 1., 1. };
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
genmodel();
glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, specular);
glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 30);
}
void display(void) {
GLfloat position[] = { 0.0, 0.0, 3.5, 1.0 };
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glTranslatef(0.0, 0.0, -5.0);
glPushMatrix();
glRotatef(spin, 1.0, 0.0, 0.0);
glRotatef(0.0, 1.0, 0.0, 0.0);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glPopMatrix();
glRotatef(rotx, 0., 1., 0.);
glRotatef(roty, 1., 0., 0.);
glCallList(1);
glPopMatrix();
glutSwapBuffers();
}
void reshape(int w, int h) {
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);
glMatrixMode(GL_MODELVIEW);
}
/* ARGSUSED1 */
void
key(unsigned char key, int x, int y) {
switch(key) {
case 't': togglemodel(); break;
case 'w': togglewire(); break;
case 'h': help(); break;
case '\033': exit(0);
default: break;
}
glutPostRedisplay();
}
/* ARGSUSED1 */
void
special(int key, int x, int y) {
switch(key) {
case GLUT_KEY_UP: levelup(); break;
case GLUT_KEY_DOWN: leveldown(); break;
}
glutPostRedisplay();
}
void
menu(int value)
{
if(value<0)
special(-value,0,0);
else
key((unsigned char) value,0,0);
}
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitWindowSize(512, 512);
glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
(void)glutCreateWindow("Quality of sphere tesselation");
init();
glutDisplayFunc(display);
glutKeyboardFunc(key);
glutSpecialFunc(special);
glutReshapeFunc(reshape);
glutMouseFunc(mouse);
glutMotionFunc(motion);
glutCreateMenu(menu);
glutAddMenuEntry("Toggle sphere model", 't');
glutAddMenuEntry("Toggle solid/wireframe", 'w');
glutAddMenuEntry("Increase tessellation", -GLUT_KEY_UP);
glutAddMenuEntry("Decrease tessellation", -GLUT_KEY_DOWN);
glutAddMenuEntry("Print help message", 'h');
glutAddMenuEntry("Quit", '\033');
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutMainLoop();
return 0; /* ANSI C requires main to return int. */
}
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