GLUT Tutorials 8: GLUT高级键盘控制

博客转自：https://www.cnblogs.com/yangxi/archive/2011/09/16/2178497.html

这一节里，我们再来看看上次的例子，这次我们讲使用高级的键盘控制。在初始化那部分，我们有两个变量：deltaAngle和deltaMode。这些变量控制旋转和移动照相机。当为非0时，照相机执行一些动作，当为0时，照相机就不动，这两个变量的初始值是0，也就是说，照相机初始状态是不动的。

#include <math.h>
#include <GL/glut.h>
 
float angle=0.0,deltaAngle = 0.0,ratio;
float x=0.0f,y=1.75f,z=5.0f;
float lx=0.0f,ly=0.0f,lz=-1.0f;
GLint snowman_display_list;
int deltaMove = 0;
 
 
void reShape(int w, int h)
         {
         // Prevent a divide by zero, when window is too short
         // (you cant make a window of zero width).
         if(h == 0)
                 h = 1;
 
         ratio = 1.0f * w / h;
         // 重置投影矩阵
         glMatrixMode(GL_PROJECTION);
         glLoadIdentity();
         
         // 设置视口大小。
         glViewport(0, 0, w, h);
 
         // 设置可视空间
         gluPerspective(45,ratio,1,1000);
         glMatrixMode(GL_MODELVIEW);
         glLoadIdentity();
         gluLookAt(x, y, z, 
                       x + lx,y + ly,z + lz,
                           0.0f,1.0f,0.0f);
 
 
         }
 
 
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);
}
 
GLuint createDL() {                          //返回一个显示列表
         GLuint snowManDL;
 
         // Create the id for the list
         snowManDL = glGenLists(1);
 
         // start list
         glNewList(snowManDL,GL_COMPILE);
 
         // call the function that contains 
         // the rendering commands
                 drawSnowMan();
 
         // endList
         glEndList();
 
         return(snowManDL);
}
 
void initScene() {
 
         glEnable(GL_DEPTH_TEST);
         snowman_display_list = createDL();
 
}
 
void orientMe(float ang) {
         lx = sin(ang);
         lz = -cos(ang);
         glLoadIdentity();
         gluLookAt(x, y, z, 
                       x + lx,y + ly,z + lz,
                           0.0f,1.0f,0.0f);
}
 
void moveMeFlat(int i) {
         x = x + i*(lx)*0.1;
         z = z + i*(lz)*0.1;
         glLoadIdentity();
         gluLookAt(x, y, z, 
                       x + lx,y + ly,z + lz,
                           0.0f,1.0f,0.0f);
}

下面的代码和以前的有些不同了。下面这个函数最开始，检查我们定义的那两个变量是否为0，如果不为0就调用相应的函数，来控制照相机的移动，和旋转。

void renderScene(void) {
 
         if (deltaMove)
                 moveMeFlat(deltaMove);
         if (deltaAngle) {
                 angle += deltaAngle;
                 orientMe(angle);
         }
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// 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*10.0,0,j * 10.0);
                          glCallList(snowman_display_list);;
                          glPopMatrix();
                 }
         glutSwapBuffers();
}

下面的函数，分别是我们注册的特殊键控制的回调函数，和键的释放（键的松开）。

Main函数里，有三行新的代码行。

glutIgnoreKeyRepeat函数，传递了一个非0值告诉GLUT不发送keyborad repeat消息，然后，glutSpecialUpFunc和glutKeyboardUpFunc调用注册的回调函数。

int main(int argc, char **argv)
{
         glutInit(&argc, argv);
         glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
         glutInitWindowPosition(100,100);
         glutInitWindowSize(640,360);
         glutCreateWindow("SnowMen from 3D-Tech");
 
         initScene();
 
         glutIgnoreKeyRepeat(1);
         glutSpecialFunc(pressKey);
         glutSpecialUpFunc(releaseKey);
 
         glutDisplayFunc(renderScene);
         glutIdleFunc(renderScene);
 
         glutReshapeFunc(changeSize);
 
         glutMainLoop();
 
         return(0);
}

完整代码如下

#include <math.h>
#include <stdlib.h>
#include <gl/glut.h>

static float angle = 0.0, deltaAngle = 0.0,ratio;
static float x = 0.0f, y = 1.75f, z = 5.0f;
static float lx = 0.0f, ly = 0.0f, lz = -1.0f;
static GLint snowman_display_list;
int deltaMove = 0;

void reShape(int width, int height)
{
    // 防止被0除.
    if (height == 0)
        height = 1;

    ratio = 1.0f * width / height;
    //Reset the coordinate system before modifying
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    //设置视口为整个窗口大小
    glViewport(0, 0, width, height);

    //设置可视空间
    gluPerspective(45, ratio, 1, 1000);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(x, y, z,x + lx, y + ly, z + lz,    0.0f, 1.0f, 0.0f);
}

void drawSnowMan() 
{
    glColor3f(1.0f, 1.0f, 1.0f);

    //画身体
    glTranslatef(0.0f, 0.75f, 0.0f);
    glutSolidSphere(0.75f, 20, 20);

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

    // 画眼睛
    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();

    // 画鼻子
    glColor3f(1.0f, 0.5f, 0.5f);
    glRotatef(0.0f, 1.0f, 0.0f, 0.0f);
    glutSolidCone(0.08f, 0.5f, 10, 2);
}

GLuint createDL() 
{
    GLuint snowManDL;

    //生成一个显示列表号
    snowManDL = glGenLists(1);

    // 开始显示列表
    glNewList(snowManDL, GL_COMPILE);

    // call the function that contains 
    // the rendering commands
    drawSnowMan();

    // endList
    glEndList();

    return(snowManDL);
}

void initScene()
{
    glEnable(GL_DEPTH_TEST);
    snowman_display_list = createDL();
}

void moveMeFlat(int direction)
{
    x = x + direction*(lx)*0.1;
    z = z + direction*(lz)*0.1;
    glLoadIdentity();
    gluLookAt(x, y, z, x + lx, y + ly, z + lz, 0.0f, 1.0f, 0.0f);
}

void orientMe(float ang)
{
    lx = sin(ang);
    lz = -cos(ang);
    glLoadIdentity();
    gluLookAt(x, y, z, x + lx, y + ly, z + lz, 0.0f, 1.0f, 0.0f);
}

void renderScene(void)
{
    if (deltaMove)
        moveMeFlat(deltaMove);

    if (deltaAngle)
    {
        angle += deltaAngle;
        orientMe(angle);
    }

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    //画了一个地面
    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();

    //画了36个雪人
    for (int i = -3; i < 3; i++)
    {
        for (int j = -3; j < 3; j++)
        {
            glPushMatrix();
            glTranslatef(i*10.0, 0, j * 10.0);
            glCallList(snowman_display_list);
            glPopMatrix();
        }
    }

    glutSwapBuffers();
}

void inputKey(int key, int x, int y)
{
    switch (key)
    {
    case GLUT_KEY_LEFT:
        angle -= 0.01f;
        orientMe(angle); break;
    case GLUT_KEY_RIGHT:
        angle += 0.01f;
        orientMe(angle); break;
    case GLUT_KEY_UP:
        moveMeFlat(1); break;
    case GLUT_KEY_DOWN:
        moveMeFlat(-1); break;
    }
}

void pressKey(int key, int x, int y)
{
    switch (key) 
    {
    case GLUT_KEY_LEFT:
        deltaAngle = -0.01f; break;
    case GLUT_KEY_RIGHT:
        deltaAngle = 0.01f; break;
    case GLUT_KEY_UP:
        deltaMove = 1; break;
    case GLUT_KEY_DOWN:
        deltaMove = -1; break;
    }
}

void releaseKey(int key, int x, int y) 
{
    switch (key) 
    {
        case GLUT_KEY_LEFT:
        case GLUT_KEY_RIGHT:
            deltaAngle = 0.0f; break;
        case GLUT_KEY_UP:
        case GLUT_KEY_DOWN:
            deltaMove = 0; break;
    }
}

int  main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_RGBA | GLUT_DOUBLE);
    glutInitWindowPosition(100,100);
    glutInitWindowSize(640,360);
    glutCreateWindow("GLUT Tutorials Scene Rovering");

    initScene();

    //glutSpecialFunc(inputKey);

    glutIgnoreKeyRepeat(1);
    glutSpecialFunc(pressKey);
    glutSpecialUpFunc(releaseKey);

    glutDisplayFunc(renderScene);
    glutIdleFunc(renderScene);
    glutReshapeFunc(reShape);

    glutMainLoop();

    return 0;
}

显示效果如下