OpenGL中的光照和键盘控制

这一篇基本上是从Nehe的第7课改编而来的，我将他的Win32代码改写为MFC框架下来实现。
第一个遇到的问题就是MFC窗口中如何响应键盘消息，搜索了下资料，发现只需要重载PreTranslateMessage函数就可以让窗口监听按键消息了。


BOOL COpenGLDemoView::PreTranslateMessage(MSG* pMsg)






{


// TODO: Add your specialized code here and/or call the base class


if(pMsg->message == WM_KEYDOWN)






{


SendMessage(pMsg->message, pMsg->wParam, pMsg->lParam);


return true;


}


else






{


return CView::PreTranslateMessage(pMsg);


}


}





为了监视按键的情况，增设了下面几个变量来负责按键的控制：


GLboolean bLighting;//是否启用光照


bool lPressed;//’L’键是否按下


bool fPressed;//’F’键是否按下



目的是防止用户长时间按住一个键不动（例如‘L’不动，从而导致光照持续地开关）这种情况。


GLfloat xspeed; // X 旋转速度


GLfloat yspeed; // Y 旋转速度


GLfloat z; // 深入屏幕的距离



这几个变量是让用户用来增减旋转速度和Z轴深度用的。


void COpenGLDemoView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)






{


// TODO: Add your message handler code here and/or call default


switch(nChar)






{


case VK_LEFT:






{//左键


yspeed-=0.01f;


break;


}


case VK_RIGHT:






{//右键


yspeed+=0.01f;


break;


}


case VK_NEXT:






{//Page_Down键按下


z+=0.05f;


break;


}


case VK_PRIOR:






{//Page_Up键按下


z-=0.05f;


break;


}


case VK_UP:






{//Page_Up键按下


xspeed-=0.01f;


break;


}


case VK_DOWN:






{//Page_Up键按下


xspeed+=0.01f;


break;


}


case 'F':






{


fPressed = TRUE ;


break;


}


case 'L':






{


lPressed = TRUE;


break;


}





default:


break;


}




CView::OnKeyDown(nChar, nRepCnt, nFlags);


}




void COpenGLDemoView::OnKeyUp(UINT nChar, UINT nRepCnt, UINT nFlags)






{


// TODO: Add your message handler code here and/or call default


switch(nChar)






{


case 'F':






{


if(fPressed == TRUE)






{


filter=(filter+1)%3;


}


fPressed = FALSE;


break;


}


case 'L':






{


if(lPressed==TRUE)






{//防止长时间按着'L'键而导致光照持续变化


bLighting = !bLighting;


if(bLighting)






{


glEnable(GL_LIGHTING);


}


else






{


glDisable(GL_LIGHTING);


}


}


lPressed = FALSE;


break;


}


default:


break;


}


CView::OnKeyUp(nChar, nRepCnt, nFlags);


}



具体的绘制代码如下：


int COpenGLDemoView::DrawGLScene()






{// Here's Where We Do All The Drawing


glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer


glPushAttrib(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_CURRENT_BIT);


glPushMatrix();


glLoadIdentity();


glTranslatef(0.0f,0.0f,z);


glRotatef(xrot,1.0f,0.0f,0.0f);


glRotatef(yrot,0.0f,1.0f,0.0f);


//纹理模式切换，这里提供三种纹理模式


glBindTexture(GL_TEXTURE_2D, texture[this->filter]);//绑定到选定的纹理上


glBegin(GL_QUADS); // 绘制正方形


// Front Face


glNormal3f( 0.0f, 0.0f, 1.0f); // 法线指向观察者


glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);


glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);


glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);


glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);


// Back Face


glNormal3f( 0.0f, 0.0f,-1.0f); // 法线背向观察者


glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);


glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);


glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);


glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);


// Top Face


glNormal3f( 0.0f, 1.0f, 0.0f); // 法线向上


glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);


glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f);


glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f);


glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);


// Bottom Face


glNormal3f( 0.0f,-1.0f, 0.0f); // 法线朝下


glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);


glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);


glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);


glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);


// Right face


glNormal3f( 1.0f, 0.0f, 0.0f); // 法线朝右


glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);


glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);


glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);


glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);


// Left Face


glNormal3f(-1.0f, 0.0f, 0.0f); // 法线朝左


glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);


glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);


glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);


glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);


glEnd(); // 正方形绘制结束


glPopMatrix();


glPopAttrib();


glFlush();


xrot+=xspeed;


yrot+=yspeed;


return TRUE; // Everything Went OK


}



最后效果图如下：