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#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
/* Some <math.h> files do not define M_PI... */
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
#ifndef __sgi
#define trunc(x) ((double)((int)(x)))
#endif
#ifdef _WIN32
#define random() ((long)rand() + (rand() << 15) + (rand() << 30))
#endif
GLUquadricObj *cone, *base, *qsphere;
void create_stipple_pattern(GLuint *pat, GLfloat opacity)
{
int x, y;
long threshold = (float)0x7fffffff * (1. - opacity);
for (y = 0; y < 32; y++) {
pat[y] = 0;
for (x = 0; x < 32; x++) {
if (random() > threshold) pat[y] |= (1 << x);
}
}
}
void init(void)
{
static GLfloat lightpos[] = {.5, .75, 1.5, 1};
GLuint spherePattern[32];
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_POSITION, lightpos);
cone = gluNewQuadric();
base = gluNewQuadric();
qsphere = gluNewQuadric();
gluQuadricOrientation(base, GLU_INSIDE);
create_stipple_pattern(spherePattern, .5);
glPolygonStipple((GLubyte *)spherePattern);
}
void reshape(GLsizei w, GLsizei h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60, 1, .01, 10);
gluLookAt(0, 0, 2.577, 0, 0, -5, 0, 1, 0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void draw_room(void)
{
/* material for the walls, floor, ceiling */
static GLfloat wall_mat[] = {1.f, 1.f, 1.f, 1.f};
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, wall_mat);
glBegin(GL_QUADS);
/* floor */
glNormal3f(0, 1, 0);
glVertex3f(-1, -1, 1);
glVertex3f(1, -1, 1);
glVertex3f(1, -1, -1);
glVertex3f(-1, -1, -1);
/* ceiling */
glNormal3f(0, -1, 0);
glVertex3f(-1, 1, -1);
glVertex3f(1, 1, -1);
glVertex3f(1, 1, 1);
glVertex3f(-1, 1, 1);
/* left wall */
glNormal3f(1, 0, 0);
glVertex3f(-1, -1, -1);
glVertex3f(-1, -1, 1);
glVertex3f(-1, 1, 1);
glVertex3f(-1, 1, -1);
/* right wall */
glNormal3f(-1, 0, 0);
glVertex3f(1, 1, -1);
glVertex3f(1, 1, 1);
glVertex3f(1, -1, 1);
glVertex3f(1, -1, -1);
/* far wall */
glNormal3f(0, 0, 1);
glVertex3f(-1, -1, -1);
glVertex3f(1, -1, -1);
glVertex3f(1, 1, -1);
glVertex3f(-1, 1, -1);
glEnd();
}
void draw_cone(void)
{
static GLfloat cone_mat[] = {0.f, .5f, 1.f, 1.f};
glPushMatrix();
glTranslatef(0, -1, 0);
glRotatef(-90, 1, 0, 0);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, cone_mat);
gluCylinder(cone, .3, 0, 1.25, 20, 1);
gluDisk(base, 0., .3, 20, 1);
glPopMatrix();
}
void draw_sphere(GLdouble angle)
{
static GLfloat sphere_mat[] = {1.f, .5f, 0.f, 1.f};
glPushMatrix();
glTranslatef(0, -.3, 0);
glRotatef(angle, 0, 1, 0);
glTranslatef(0, 0, .6);
glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, sphere_mat);
gluSphere(qsphere, .3, 20, 20);
glPopMatrix();
}
GLdouble get_secs(void)
{
return glutGet(GLUT_ELAPSED_TIME) / 1000.0;
}
void draw(void)
{
GLenum err;
GLdouble secs;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
draw_room();
draw_cone();
secs = get_secs();
/* draw the transparent object... */
glEnable(GL_POLYGON_STIPPLE);
draw_sphere(secs * 360. / 10.);
glDisable(GL_POLYGON_STIPPLE);
err = glGetError();
if (err != GL_NO_ERROR) printf("Error: %s\n", gluErrorString(err));
glutSwapBuffers();
}
/* ARGSUSED1 */
void key(unsigned char key, int x, int y)
{
if (key == 27) exit(0);
}
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowSize(256, 256);
glutInitWindowPosition(0, 0);
glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
glutCreateWindow(argv[0]);
glutDisplayFunc(draw);
glutIdleFunc(draw);
glutKeyboardFunc(key);
glutReshapeFunc(reshape);
init();
glutMainLoop();
return 0;
}
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