的在opengl下從鼠標座標轉換到三維座標的方法

一般用來拾取物體：

fPoint CMy3D_SurfaceView::Get_3D_pos(CPoint Tpoint)
{
    CMy3D_SurfaceDoc *pDoc=(CMy3D_SurfaceDoc*)GetDocument();

    fPoint Rp;
    GLint viewport[4];
    GLdouble modelview[16];
    GLdouble projection[16];
    GLfloat winX,winY,winZ;
    GLdouble posX,posY,posZ;

    glPushMatrix();
    glTranslatef(TransVect[0],TransVect[1],TransVect[2]);
    if(pDoc->Init)roty=0.0f;
    glRotatef(roty+20.0f,0.0f,1.0f,0.0f);
    glScalef(scalx,scaly,scalz);

    glGetIntegerv(GL_VIEWPORT,viewport);
    glGetDoublev(GL_MODELVIEW_MATRIX,modelview);
    glGetDoublev(GL_PROJECTION_MATRIX,projection);
    glPopMatrix();

    winX=(float)Tpoint.x;
    winY=viewport[3]-(float)Tpoint.y;

    glReadPixels((int)winX,(int)winY,1,1,GL_DEPTH_COMPONENT,GL_FLOAT,&winZ);//獲取鼠標屏幕座標處像素的深度Z
    gluUnProject(winX,winY,winZ,modelview,projection,viewport,&posX,&posY,&posZ);
    
    Rp.x=posX;
    Rp.y=posY;
    Rp.z=posZ;

    return Rp;

}