在opengl中旋转对象 [英] rotating objects in opengl

问题描述

当我按下一个键时，我需要在一个轴上旋转场景。这是我实现它的方式

  int rotateFlag; 
 
 void rotateScene（int x）{
 if（x）//在x轴上旋转45度
 glRotatef（45,1,0,0）; 
 else // roatate y轴45度
 glRotatef（45,0,1,0）; 
} 
 
 //这是我在glutDisplayFunc中调用的函数
 void drawScene（void）{
 glClear（GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT）; 
 glMatrixMode（GL_MODELVIEW）; 
 glLoadIdentity（）; 
 
 //我正在看原点（场景的中心）
 gluLookAt（x，y，z，0,0,0，0.0，1.0，0.0）; 
 
 rotateScene（rotateFlag）; 
 
 drawObjects（）; //绘制场景中的对象
 
} 
  

当我按左键或向上键时，将值赋给rotateFlag。它只旋转场景一次，因为我的函数rotateScene always 将glRotatef应用于我应该避免的场景的原始布局。有人知道我如何保存旋转的场景，这样我就可以对其应用我的功能（旋转的场景），并且每次按下箭头键时旋转场景？我希望自己清楚了。

我尝试了另一种解决方案，在按下键的同时增加了X和Y的角度

 如果按键左键
 angleX + = 45; 
如果按键按下
 angleY + = 45; 
  

并将我的rotateScene调整为

  void rotateScene（）{
 glRotatef（angleX，1,0,0）; 
 glRotatef（angleY，0,1,0）; 
 
 $ / code> 

当我在单个轴上执行旋转时，一切正常，但是，当我首先在Y上旋转，然后在X上执行旋转，场景的旋转不正确。也许这是因为opengl在Y上旋转之前首先执行旋转，因为函数调用中的顺序。我无法正确使用这个函数，因为在我的应用程序中，旋转场景的顺序非常重要。 使用 glPushMatrix（）将矩阵推送到矩阵堆栈，然后 glPopMatrix（）将其返回。

I need to rotate the scene in an axis when I press a key. Here's how I implemented it

    int rotateFlag;

    void rotateScene(int x){
         if(x)//rotate 45 deg on x axis
             glRotatef(45,1,0,0);
         else // roatate 45 deg on y axis
             glRotatef(45,0,1,0); 
    }

    //this is the function I call in  glutDisplayFunc
    void drawScene(void){
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         glMatrixMode(GL_MODELVIEW); 
         glLoadIdentity();

         //I'm looking at the origin (center of my scene)
         gluLookAt (x, y, z, 0,0,0, 0.0, 1.0, 0.0); 

         rotateScene(rotateFlag);

         drawObjects();//draw Objects in Scene 

    }

I assign value to rotateFlag when i press left key or up key. It rotates the scene once only since my function rotateScene always applies glRotatef on the original arrangement of the scene which I should avoid. Does somebody knows how I can save the rotated scene so I can apply my function on it(the rotated scene) and rotate the scene everytime I press an arrow key? I hope I made myself clear.

I tried another solution by incrementing the angle in X and Y as I press the key

    If keypress left 
         angleX+=45;
    else if keypress up
         angleY+=45;

and adjust my rotateScene to

    void rotateScene(){
        glRotatef(angleX,1,0,0);
        glRotatef(angleY,0,1,0);
    }

Everything is going right when i performed rotation on individual axis, however, when I do Rotate on Y first then I perform rotate on X, the rotation of the scene is incorrect. Maybe this is because opengl executed rotate on X first before rotate on Y because of the ordering in the function call. I can't use this function properly since order in rotating the scene is important in my application.

解决方案

Use glPushMatrix() to push a matrix to the matrix-stack and glPopMatrix() to retreive it back.

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