demo.c

计算机图形学～想必是很多人需要的～在此共享一下

	glNormal3fv(fnormals[face]);
        glBegin(GL_POLYGON);
  	glColor3fv(colors[a]);
  	/* glNormal3fv(normals[a]); */
  	glTexCoord2f(0.0,0.0);
  	glVertex3fv(vertices[a]);
  	glColor3fv(colors[b]);
  	/* glNormal3fv(normals[b]); */
  	glTexCoord2f(0.0,1.0);
  	glVertex3fv(vertices[b]);
  	glColor3fv(colors[c]);
  	/* glNormal3fv(normals[c]); */
  	glTexCoord2f(1.0,1.0);
  	glVertex3fv(vertices[c]);
  	glColor3fv(colors[d]);
  	/* glNormal3fv(normals[d]); */
  	glTexCoord2f(1.0,0.0);
  	glVertex3fv(vertices[d]);
        glEnd();
    }
}

void colorcube(void)
{

    /* map vertices to faces */

    polygon(1,0,3,2,0);
    polygon(3,7,6,2,1);
    polygon(7,3,0,4,2);
    polygon(2,6,5,1,3);
    polygon(4,5,6,7,4);
    polygon(5,4,0,1,5);
}

/*----------------------------------------------------------------------*/
/* 
** These functions implement a simple trackball-like motion control.
*/

float lastPos[3] = {0.0F, 0.0F, 0.0F};
int curx, cury;
int startX, startY;

void
trackball_ptov(int x, int y, int width, int height, float v[3])
{
    float d, a;

    /* project x,y onto a hemi-sphere centered within width, height */
    v[0] = (2.0F*x - width) / width;
    v[1] = (height - 2.0F*y) / height;
    d = (float) sqrt(v[0]*v[0] + v[1]*v[1]);
    v[2] = (float) cos((M_PI/2.0F) * ((d < 1.0F) ? d : 1.0F));
    a = 1.0F / (float) sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
    v[0] *= a;
    v[1] *= a;
    v[2] *= a;
}


void
mouseMotion(int x, int y)
{
    float curPos[3], dx, dy, dz;

    trackball_ptov(x, y, winWidth, winHeight, curPos);

    dx = curPos[0] - lastPos[0];
    dy = curPos[1] - lastPos[1];
    dz = curPos[2] - lastPos[2];

    if (dx || dy || dz) {
	angle = 90.0F * sqrt(dx*dx + dy*dy + dz*dz);

	axis[0] = lastPos[1]*curPos[2] - lastPos[2]*curPos[1];
	axis[1] = lastPos[2]*curPos[0] - lastPos[0]*curPos[2];
	axis[2] = lastPos[0]*curPos[1] - lastPos[1]*curPos[0];

	lastPos[0] = curPos[0];
	lastPos[1] = curPos[1];
	lastPos[2] = curPos[2];
    }

    glutPostRedisplay();
}

void
startMotion(long time, int button, int x, int y)
{
    if (!trackballEnabled) return;

    trackingMouse = true;
    redrawContinue = false;
    startX = x; startY = y;
    curx = x; cury = y;
    trackball_ptov(x, y, winWidth, winHeight, lastPos);
    trackballMove = true;
}

void
stopMotion(long time, int button, int x, int y)
{
    if (!trackballEnabled) return;

    trackingMouse = false;

    if (startX != x || startY != y) {
	redrawContinue = true;
    } else {
	angle = 0.0F;
	redrawContinue = false;
	trackballMove = false;
    }
}

/*----------------------------------------------------------------------*/

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

    /* view transform */
    glLoadIdentity();
    glTranslatef(0.0,0.0,viewxform_z);

    if (trackballMove) {
	glPushMatrix();
	    glLoadIdentity();
	    glRotatef(angle, axis[0], axis[1], axis[2]);
	    glMultMatrixf((GLfloat *) trackballXform);
	    glGetFloatv(GL_MODELVIEW_MATRIX, trackballXform);
	glPopMatrix();

    }
    glPushMatrix();
	glMultMatrixf((GLfloat*)lightXform);
	setLightPos();
    glPopMatrix();
    glPushMatrix();
	glMultMatrixf((GLfloat *) objectXform);
	colorcube();
    glPopMatrix();

    glFlush();
    glutSwapBuffers();
}

/*----------------------------------------------------------------------*/

void mouseButton(int button, int state, int x, int y)
{
    switch (button) {
      case GLUT_LEFT_BUTTON:
	 trackballXform = (GLfloat*)objectXform;
	 break;
      case GLUT_MIDDLE_BUTTON:
	 trackballXform = (GLfloat*)lightXform;
	 break;
    }
    switch(state) {
    case GLUT_DOWN:
	startMotion(0,1, x,y);
	break;
    case GLUT_UP:
	stopMotion(0,1, x,y);
	break;
    } 
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    winWidth = w;
    winHeight = h;
}

void spinCube()
{
    if (redrawContinue) glutPostRedisplay();
}


void userEventAction(int key) {
    switch(key) {
    case '0':				/* wire frame/polygon  */
      drawLines = !drawLines;
      break;
    case '1':
      smoothEnabled = !smoothEnabled;
      break;
    case '2':				/* lighting */
      lightingEnabled = !lightingEnabled;
      break;
    case '3':				/* texture */
      texEnabled = !texEnabled;
      break;
    case '4':				/* fog */
      fogEnabled = !fogEnabled;
      break;
    case '5':				/* HSR */
      depthEnabled = !depthEnabled;
      break;
    case '6':				/* line aa */
      lineAAEnabled = !lineAAEnabled;
      break;
    case '7':				/* perpective texture */
      fastTexture = !fastTexture;
      break;
    case 'b':
      currentMaterials = &brassMaterials;
      break;
    case 'c':
      currentMaterials = &colorCubeMaterials;
      break;
    case 'C':
      currentLighting = &colorCubeLighting;
      break;
    case 'i':
      idleSpin = !idleSpin;
      break;
    case 'm':				/* mipmapped texture */
      mipmapEnabled = !mipmapEnabled;
      break;
    case 'p':				/* perspective/ortho */
      perspectiveXform = !perspectiveXform;
      break;
    case 'r':
      currentMaterials = &redPlasticMaterials;
      break;
    case 'w':
      currentLighting = &whiteLighting;
      break;
    case 27:
      exit(0);
    default:
      break;
    }
    userSettings();
    glutPostRedisplay();
}

void keyboard(unsigned char key, int x, int y)
{
    userEventAction(key);
}

/*----------------------------------------------------------------------*/

typedef struct menuEntryStruct {
    char *label;
    char key;
} menuEntryStruct;

static menuEntryStruct mainMenu[] = {
    "lines/polygons", 		'0',
    "flat/smooth", 		'1',
    "lighting", 		'2',
    "texture", 			'3',
    "fog", 			'4',
    "HSR", 			'5',
    "line smooth", 		'6',
    "motion", 			'i',
    "ortho/perspective", 	'p',
    "quit", 			27,
};
int mainMenuEntries = sizeof(mainMenu)/sizeof(menuEntryStruct);

void selectMain(int choice)
{
    userEventAction(mainMenu[choice].key);
}

static menuEntryStruct materialsMenu[] = {
    "brass", 		'b',
    "white",		'c',
    "red plastic", 	'r',
};
int materialsMenuEntries = sizeof(materialsMenu)/sizeof(menuEntryStruct);

void selectMaterials(int choice)
{
    userEventAction(materialsMenu[choice].key);
}


static menuEntryStruct lightingMenu[] = {
    "white", 		'w',
    "color",		'C',
};
int lightingMenuEntries = sizeof(lightingMenu)/sizeof(menuEntryStruct);

void selectLighting(int choice)
{
    userEventAction(lightingMenu[choice].key);
}

void setMenuEntries(bool init)
{
    int i, sub1, sub2;

    if (init) {
	sub1 = glutCreateMenu(selectMaterials);
	for (i=0; i < materialsMenuEntries; i++) {
	    glutAddMenuEntry(materialsMenu[i].label, i);
	}
	sub2 = glutCreateMenu(selectLighting);
	for (i=0; i < lightingMenuEntries; i++) {
	    glutAddMenuEntry(lightingMenu[i].label, i);
	}
	glutCreateMenu(selectMain);
	for (i=0; i < mainMenuEntries; i++) {
	    glutAddMenuEntry(mainMenu[i].label, i);
	}
	glutAddSubMenu("materials", sub1);
	glutAddSubMenu("lighting", sub2);
	glutAttachMenu(GLUT_RIGHT_BUTTON);
    } else {
    }
}

/*----------------------------------------------------------------------*/

void
main(int argc, char **argv)
{
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutCreateWindow("colorcube");
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
    glutIdleFunc(spinCube);
    glutMouseFunc(mouseButton);
    glutMotionFunc(mouseMotion);
    glutKeyboardFunc(keyboard);
    initSettings();
    userSettings();
    glutMainLoop();
}