[译]GLUT教程

Lighthouse3d.com >> GLUT Tutorial >> Extras >> The Code So Far VII

以下是子窗体的最终版本代码.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

// angle of rotation for the camera direction
float angle = 0.0f;

// actual vector representing the camera's direction
float lx=0.0f,lz=-1.0f, ly = 0.0f;

// XZ position of the camera
float x=0.0f, z=5.0f, y = 1.75f;

// the key states. These variables will be zero
//when no key is being presses
float deltaAngle = 0.0f;
float deltaMove = 0;
int xOrigin = -1;

// width and height of the window
int h,w;

// variables to compute frames per second
int frame;
long time, timebase;
char s[50];

// variables to hold window identifiers
int mainWindow, subWindow1,subWindow2,subWindow3;
//border between subwindows
int border = 6;

void setProjection(int w1, int h1)
{
    float ratio;
    // Prevent a divide by zero, when window is too short
    // (you cant make a window of zero width).
    ratio = 1.0f * w1 / h1;
    // Reset the coordinate system before modifying
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    // Set the viewport to be the entire window
        glViewport(0, 0, w1, h1);

    // Set the clipping volume
    gluPerspective(45,ratio,0.1,1000);
    glMatrixMode(GL_MODELVIEW);
}

void changeSize(int w1,int h1) {

    if(h1 == 0)
        h1 = 1;

    // we're keeping these values cause we'll need them latter
    w = w1;
    h = h1;

    // set subwindow 1 as the active window
    glutSetWindow(subWindow1);
    // resize and reposition the sub window
    glutPositionWindow(border,border);
    glutReshapeWindow(w-2*border, h/2 - border*3/2);
    setProjection(w-2*border, h/2 - border*3/2);

    // set subwindow 2 as the active window
    glutSetWindow(subWindow2);
    // resize and reposition the sub window
    glutPositionWindow(border,(h+border)/2);
    glutReshapeWindow(w/2-border*3/2, h/2 - border*3/2);
    setProjection(w/2-border*3/2,h/2 - border*3/2);

    // set subwindow 3 as the active window
    glutSetWindow(subWindow3);
    // resize and reposition the sub window
    glutPositionWindow((w+border)/2,(h+border)/2);
    glutReshapeWindow(w/2-border*3/2,h/2 - border*3/2);
    setProjection(w/2-border*3/2,h/2 - border*3/2);
}

void drawSnowMan() {

    glColor3f(1.0f, 1.0f, 1.0f);

// Draw Body
    glTranslatef(0.0f ,0.75f, 0.0f);
    glutSolidSphere(0.75f,20,20);

// Draw Head
    glTranslatef(0.0f, 1.0f, 0.0f);
    glutSolidSphere(0.25f,20,20);

// Draw Eyes
    glPushMatrix();
    glColor3f(0.0f,0.0f,0.0f);
    glTranslatef(0.05f, 0.10f, 0.18f);
    glutSolidSphere(0.05f,10,10);
    glTranslatef(-0.1f, 0.0f, 0.0f);
    glutSolidSphere(0.05f,10,10);
    glPopMatrix();

// Draw Nose
    glColor3f(1.0f, 0.5f, 0.5f);
    glRotatef(0.0f,1.0f, 0.0f, 0.0f);
    glutSolidCone(0.08f,0.5f,10,2);

    glColor3f(1.0f, 1.0f, 1.0f);

}

void renderBitmapString(
        float x,
        float y,
        float z,
        void *font,
        char *string) {

    char *c;
    glRasterPos3f(x, y,z);
    for (c=string; *c != ''; c++) {
        glutBitmapCharacter(font, *c);
    }
}

void restorePerspectiveProjection() {

    glMatrixMode(GL_PROJECTION);
    // restore previous projection matrix
    glPopMatrix();

    // get back to modelview mode
    glMatrixMode(GL_MODELVIEW);
}

void setOrthographicProjection() {

    // switch to projection mode
    glMatrixMode(GL_PROJECTION);

    // save previous matrix which contains the
    //settings for the perspective projection
    glPushMatrix();

    // reset matrix
    glLoadIdentity();

    // set a 2D orthographic projection
    gluOrtho2D(0, w, h, 0);

    // switch back to modelview mode
    glMatrixMode(GL_MODELVIEW);
}

void computePos(float deltaMove) {

    x += deltaMove * lx * 0.1f;
    z += deltaMove * lz * 0.1f;
}

// Common Render Items for all subwindows
void renderScene2() {

// Draw ground

    glColor3f(0.9f, 0.9f, 0.9f);
    glBegin(GL_QUADS);
        glVertex3f(-100.0f, 0.0f, -100.0f);
        glVertex3f(-100.0f, 0.0f,  100.0f);
        glVertex3f( 100.0f, 0.0f,  100.0f);
        glVertex3f( 100.0f, 0.0f, -100.0f);
    glEnd();

// Draw 36 SnowMen
    for(int i = -3; i < 3; i++)
        for(int j=-3; j < 3; j++){
             glPushMatrix();
            glTranslatef(i*10.0f, 0.0f, j * 10.0f);
            drawSnowMan();
            glPopMatrix();
        }
}

// Display func for main window
void renderScene() {
    glutSetWindow(mainWindow);
    glClear(GL_COLOR_BUFFER_BIT);
    glutSwapBuffers();
}

// Display func for sub window 1
void renderScenesw1() {

    glutSetWindow(subWindow1);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();
    gluLookAt(x, y, z,
              x + lx,y + ly,z + lz,
              0.0f,1.0f,0.0f);

    renderScene2();

    // display fps in the top window
     frame++;

    time=glutGet(GLUT_ELAPSED_TIME);
    if (time - timebase > 1000) {
        sprintf(s,"Lighthouse3D - FPS:%4.2f",
            frame*1000.0/(time-timebase));
        timebase = time;
        frame = 0;
    }

    setOrthographicProjection();

    glPushMatrix();
    glLoadIdentity();
    renderBitmapString(5,30,0,GLUT_BITMAP_HELVETICA_12,s);
    glPopMatrix();

    restorePerspectiveProjection();

    glutSwapBuffers();
}

// Display func for sub window 2
void renderScenesw2() {

    glutSetWindow(subWindow2);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();
    gluLookAt(x, y+15, z,
              x ,y - 1,z,
              lx,0,lz);

    // Draw red cone at the location of the main camera
    glPushMatrix();
    glColor3f(1.0,0.0,0.0);
    glTranslatef(x,y,z);
    glRotatef(180-(angle+deltaAngle)*180.0/3.14,0.0,1.0,0.0);
    glutSolidCone(0.2,0.8f,4,4);
    glPopMatrix();

    renderScene2();

    glutSwapBuffers();
}

// Display func for sub window 3
void renderScenesw3() {

    glutSetWindow(subWindow3);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();
    gluLookAt(x-lz*10 , y, z+lx*10,
              x ,y ,z ,
              0.0f,1.0f,0.0f);

    // Draw red cone at the location of the main camera
    glPushMatrix();
    glColor3f(1.0,0.0,0.0);
    glTranslatef(x,y,z);
    glRotatef(180-(angle+deltaAngle)*180.0/3.14,0.0,1.0,0.0);
    glutSolidCone(0.2,0.8f,4,4);
    glPopMatrix();

    renderScene2();

    glutSwapBuffers();
}

// Global idle func
void renderSceneAll() {

    // check for keyboard movement
    if (deltaMove)
        computePos(deltaMove);

    renderScenesw1();
    renderScenesw2();
    renderScenesw3();
}

// -----------------------------------
//             KEYBOARD
// -----------------------------------

void processNormalKeys(unsigned char key, int xx, int yy) {

    if (key == 27) {
        glutDestroyWindow(subWindow1);
        glutDestroyWindow(subWindow2);
        glutDestroyWindow(subWindow3);
        glutDestroyWindow(mainWindow);
        exit(0);
    }
}

void pressKey(int key, int xx, int yy) {

    switch (key) {
        case GLUT_KEY_UP : deltaMove = 0.5f; break;
        case GLUT_KEY_DOWN : deltaMove = -0.5f; break;
    }
}

void releaseKey(int key, int x, int y) {

    switch (key) {
        case GLUT_KEY_UP :
        case GLUT_KEY_DOWN : deltaMove = 0;break;
    }
}

// -----------------------------------
//             MOUSE
// -----------------------------------

void mouseMove(int x, int y) {

    // this will only be true when the left button is down
    if (xOrigin >= 0) {

        // update deltaAngle
        deltaAngle = (x - xOrigin) * 0.001f;

        // update camera's direction
        lx = sin(angle + deltaAngle);
        lz = -cos(angle + deltaAngle);
    }
}

void mouseButton(int button, int state, int x, int y) {

    // only start motion if the left button is pressed
    if (button == GLUT_LEFT_BUTTON) {

        // when the button is released
        if (state == GLUT_UP) {
            angle += deltaAngle;
            deltaAngle = 0.0f;
            xOrigin = -1;
        }
        else  {// state = GLUT_DOWN
            xOrigin = x;

        }
    }
}

// -----------------------------------
//             MAIN and INIT
// -----------------------------------

void init() {

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);

    // register callbacks
    glutIgnoreKeyRepeat(1);
    glutKeyboardFunc(processNormalKeys);
    glutSpecialFunc(pressKey);
    glutSpecialUpFunc(releaseKey);
    glutMouseFunc(mouseButton);
    glutMotionFunc(mouseMove);
}

int main(int argc, char **argv) {

    // init GLUT and create main window
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(800,800);
    mainWindow = glutCreateWindow("Lighthouse3D - GLUT Tutorial");

    // callbacks for main window
    glutDisplayFunc(renderScene);
    glutReshapeFunc(changeSize);
    glutIdleFunc(renderSceneAll);
    init();

    // sub windows
    subWindow1 = glutCreateSubWindow(mainWindow, border,border,w-2*border, h/2 - border*3/2);
    glutDisplayFunc(renderScenesw1);
    init();

    subWindow2 = glutCreateSubWindow(mainWindow, border,(h+border)/2,w/2-border*3/2, h/2 - border*3/2);
    glutDisplayFunc(renderScenesw2);
    init();

    subWindow3 = glutCreateSubWindow(mainWindow, (w+border)/2,(h+border)/2,w/2-border*3/2,h/2 - border*3/2);
    glutDisplayFunc(renderScenesw3);
    init();

    // enter GLUT event processing cycle
    glutMainLoop();

    return 1;
}