particle.c

嵌入式GUI OpenGL源代码。OpenGL是嵌入式开发中常用的一种GUI系统。

	    if (particles[i].alive == 0)
		continue;
	    c = particles[i].position[1]/2.1*255;
	    glColor3ub(c, 128+c*0.5, 255);
	    glVertex3fv(particles[i].position);
	}
	glEnd();
    } else {
	glBegin(GL_LINES);
	for (i = 0; i < num_particles; i++) {
	    if (particles[i].alive == 0)
		continue;
	    c = particles[i].previous[1]/2.1*255;
	    glColor4ub(c, 128+c*0.5, 255, 32);
	    glVertex3fv(particles[i].previous);
	    c = particles[i].position[1]/2.1*255;
	    glColor4ub(c, 128+c*0.5, 255, 196);
	    glVertex3fv(particles[i].position);
	}
	glEnd();
    }

    /* spit out frame rate. */
    if (frame_rate) {
	frames++;
	if (frames > 7) {
	    sprintf(s, "%g fps", (float)7/frame_time);
	    frame_time = 0;
	    frames = 0;
	}
	text(5, 5, s);
    }

    glPopMatrix();
    glutSwapBuffers();
}

void
idle(void)
{
    static int i, j;
    static int living = 0;		/* index to end of live particles */
    static float dt;
    static float last = 0;

    dt = timedelta();
    frame_time += dt;

#if 1
    /* slow the simulation if we can't keep the frame rate up around
       10 fps */
    if (dt > 0.1) {
	slow_down = 1.0/(100*dt);
    } else if (dt < 0.1) {
	slow_down = 1;
    }
#endif

    dt *= slow_down;

    /* resurrect a few particles */
    for (i = 0; i < flow*dt; i++) {
	psNewParticle(&particles[living], dt);
	living++;
	if (living >= num_particles)
	    living = 0;
    }

    for (i = 0; i < num_particles; i++) {
	psTimeStep(&particles[i], dt);

	/* collision with sphere? */
	if (draw_spheres) {
	    for (j = 0; j < draw_spheres; j++) {
		psCollideSphere(&particles[i], &spheres[j]);
	    }
	}

	/* collision with ground? */
	if (particles[i].position[1] <= 0) {
	    psBounce(&particles[i], dt);
	}

	/* dead particle? */
	if (particles[i].position[1] < 0.1 && 
	    fequal(particles[i].velocity[1], 0)) {
	    particles[i].alive = 0;
	}
    }

    glutPostRedisplay();
}

void
visible(int state)
{
    if (state == GLUT_VISIBLE)
	glutIdleFunc(idle);
    else
	glutIdleFunc(NULL);
}

void
bail(int code)
{
    free(particles);
    exit(code);
}

#ifdef SCREEN_SAVER_MODE
void
ss_keyboard(char key, int x, int y)
{
    bail(0);
}

void
ss_mouse(int button, int state, int x, int y)
{
    bail(0);
}

void
ss_passive(int x, int y)
{
    static int been_here = 0;

    /* for some reason, GLUT sends an initial passive motion callback
       when a window is initialized, so this would immediately
       terminate the program.  to get around this, see if we've been
       here before. (actually if we've been here twice.) */

    if (been_here > 1)
	bail(0);
    been_here++;
}

#else

void
keyboard(unsigned char key, int x, int y)
{
    static int fullscreen = 0;
    static int old_x = 50;
    static int old_y = 50;
    static int old_width = 512;
    static int old_height = 512;
    static int s = 0;

    switch (key) {
    case 27:
        bail(0);
	break;

    case 't':
	if (type == PS_WATERFALL)
	    type = PS_FOUNTAIN;
	else if (type == PS_FOUNTAIN)
	    type = PS_WATERFALL;
	break;

    case 's':
	draw_spheres++;
	if (draw_spheres > NUM_SPHERES)
	    draw_spheres = 0;
	break;

    case 'S':
	printf("PSsphere spheres[NUM_SPHERES] = {/* position of spheres */\n");
	for (s = 0; s < NUM_SPHERES; s++) {
	    printf("  { %g, %g, %g, %g },\n", 
		   spheres[s].x, spheres[s].y,
		   spheres[s].z, spheres[s].radius);
	}
	printf("};\n");
	break;

    case 'l':
	points = !points;
	break;

    case 'P':
	point_size++;
	glPointSize(point_size);
	break;
	
    case 'p':
	point_size--;
	if (point_size < 1)
	    point_size = 1;
	glPointSize(point_size);
	break;
	
    case '+':
	flow += 100;
	if (flow > num_particles)
	    flow = num_particles;
	printf("%g particles/second\n", flow);
	break;

    case '-':
	flow -= 100;
	if (flow < 0)
	    flow = 0;
	printf("%g particles/second\n", flow);
	break;

    case '#':
	frame_rate = !frame_rate;
	break;

    case '~':
	fullscreen = !fullscreen;
	if (fullscreen) {
	    old_x = glutGet(GLUT_WINDOW_X);
	    old_y = glutGet(GLUT_WINDOW_Y);
	    old_width = glutGet(GLUT_WINDOW_WIDTH);
	    old_height = glutGet(GLUT_WINDOW_HEIGHT);
	    glutFullScreen();
	} else {
	    glutReshapeWindow(old_width, old_height);
	    glutPositionWindow(old_x, old_y);
	}
	break;

    case '!':
	s++;
	if (s >= NUM_SPHERES)
	    s = 0;
	break;

    case '4':
	spheres[s].x -= 0.05;
	break;

    case '6':
	spheres[s].x += 0.05;
	break;

    case '2':
	spheres[s].y -= 0.05;
	break;

    case '8':
	spheres[s].y += 0.05;
	break;

    case '7':
	spheres[s].z -= 0.05;
	break;

    case '3':
	spheres[s].z += 0.05;
	break;

    case '9':
	spheres[s].radius += 0.05;
	break;

    case '1':
	spheres[s].radius -= 0.05;
	break;

    }
}

void
menu(int item)
{
    keyboard((unsigned char)item, 0, 0);
}

void
menustate(int state)
{
    /* hook up a fake time delta to avoid jumping when menu comes up */
    if (state == GLUT_MENU_NOT_IN_USE)
	timedelta();
}
#endif

int old_x, old_y;

void
mouse(int button, int state, int x, int y)
{
    old_x = x;
    old_y = y;

    glutPostRedisplay();
}

void
motion(int x, int y)
{
    spin_x = x - old_x;
    spin_y = y - old_y;

    glutPostRedisplay();
}

int
main(int argc, char** argv)
{
    glutInitDisplayMode(GLUT_RGB|GLUT_DEPTH|GLUT_DOUBLE);
    glutInitWindowPosition(0, 0);
    glutInitWindowSize(640, 480);
    glutInit(&argc, argv);

    glutCreateWindow("Particles");
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
#ifdef SCREEN_SAVER_MODE
    glutPassiveMotionFunc(ss_passive);
    glutKeyboardFunc(ss_keyboard);
    glutMouseFunc(ss_mouse);
    glutSetCursor(GLUT_CURSOR_NONE);
    glutFullScreen(); 
#else
    glutMotionFunc(motion);
    glutMouseFunc(mouse);
    glutKeyboardFunc(keyboard);
#endif

    glutMenuStateFunc(menustate);
    glutCreateMenu(menu);
    glutAddMenuEntry("Particle", 0);
    glutAddMenuEntry("", 0);
    glutAddMenuEntry("[f]   Fog on/off", 'f');
    glutAddMenuEntry("[t]   Spray type", 't');
    glutAddMenuEntry("[s]   Collision spheres", 's');
    glutAddMenuEntry("[-]   Less flow", '-');
    glutAddMenuEntry("[+]   More flow", '+');
    glutAddMenuEntry("[p]   Smaller points", 'p');
    glutAddMenuEntry("[P]   Larger points", 'P');
    glutAddMenuEntry("[l]   Toggle points/lines", 'l');
    glutAddMenuEntry("[#]   Toggle framerate on/off", '#');
    glutAddMenuEntry("[~]   Toggle fullscreen on/off", '~');
    glutAddMenuEntry("", 0);
    glutAddMenuEntry("Use the numeric keypad to move the spheres", 0);
    glutAddMenuEntry("[!]   Change active sphere", 0);
    glutAddMenuEntry("", 0);
    glutAddMenuEntry("[Esc] Quit", 27);
    glutAttachMenu(GLUT_RIGHT_BUTTON);

    if (argc > 1) {
	if (strcmp(argv[1], "-h") == 0) {
	    fprintf(stderr, "%s [particles] [flow] [speed%]\n", argv[0]);
	    exit(0);
	}
	sscanf(argv[1], "%d", &num_particles);
	if (argc > 2)
	    sscanf(argv[2], "%f", &flow);
	if (argc > 3)
	    sscanf(argv[3], "%f", &slow_down);
    }      

    particles = (PSparticle*)malloc(sizeof(PSparticle) * num_particles);

    glutVisibilityFunc(visible);
    glutMainLoop();
    return 0;
}