请问glPushMatrix(); glPopMatrix();都怎么用呀？！

Question

知道来吱一声。

Answer 1

这两句类似堆栈的push和pop操作。
使用之前需要设定当前矩阵堆栈类型：modelview_matrix，或者project_matrix，还可以是纹理矩阵。

Answer 2

glPushMatrix(); glPopMatrix(); 最直观的例子
draw_wheel_and_bolts()
{
   long i;   draw_wheel();
   for(i=0;i<5;i++){
      glPushMatrix();
         glRotatef(72.0*i,0.0,0.0,1.0);
         glTranslatef(3.0,0.0,0.0);
         draw_bolt();
      glPopMatrix();
   }
}draw_body_and_wheel_and_bolts()
{
   draw_car_body();
   glPushMatrix();
      glTranslatef(40,0,30);                     /*move to first wheel position*/
      draw_wheel_and_bolts();
   glPopMatrix();
   glPushMatrix();
      glTranslatef(40,0,-30);                     /*move to 2nd wheel position*/
      draw_wheel_and_bolts();
   glPopMatrix();
   ...                  /*draw last two wheels similarly*/
}