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
#include
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 changeSize(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）。
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; }
}
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);
}
还可以自己改下照相机设置的函数。 （原文地址：
）
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