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OpenGL第三节:Viewport视口

LOpengGL.h://不变

LUtil.h  //添加枚举

enum ViewPortMode
{
  VIEWPORT_MODE_FULL,  //全屏
  VIEWPORT_MODE_HALF_CENTER, //中间
  VIEWPORT_MODE_HALF_TOP,//中间上
  VIEWPORT_MODE_QUAD,//四个小方块
  VIEWPORT_MODE_RADAR//雷达
};

LUtil.cpp:
#include "LUtil.h"
bool initGL()
{
  glViewport( 0.f, 0.f, SCREEN_WIDTH, SCREEN_HEIGHT );//设置视口为全屏,参数分别为x,y,w,h
  ......//其他的不变
}


void render()//freeglut的坐标是这样的:(0,0)在左下角,也就是x向右变大,y向上变大。不同的库实现时的坐标系统不同,不能一概而论。而OpenGL本身的坐标系统是(0,0)在左上角。

{
  glClear( GL_COLOR_BUFFER_BIT );
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();//重置模型矩阵为单位矩阵
  glTranslatef( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f, 0.f );//移动到屏幕中心,参数分别为x,y,z
  if( gViewportMode == VIEWPORT_MODE_FULL )//全屏
  {
    glViewport( 0.f, 0.f, SCREEN_WIDTH, SCREEN_HEIGHT );
    glBegin( GL_QUADS );
      glColor3f( 1.f, 0.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
    glEnd();
  }
  else if( gViewportMode == VIEWPORT_MODE_HALF_CENTER )//中心
  {
    glViewport( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
    glBegin( GL_QUADS );
      glColor3f( 0.f, 1.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
    glEnd();
  }
  else if( gViewportMode == VIEWPORT_MODE_HALF_TOP )
  {
    glViewport( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 2.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//上边
    glBegin( GL_QUADS );
      glColor3f( 0.f, 0.f, 1.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, -SCREEN_HEIGHT / 2.f );
      glVertex2f( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
      glVertex2f( -SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );
    glEnd();
  }
  else if( gViewportMode == VIEWPORT_MODE_QUAD )//四个小方块
  {
    glViewport( 0.f, 0.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//左下
    glBegin( GL_QUADS );
      glColor3f( 1.f, 0.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
    glEnd();
    glViewport( SCREEN_WIDTH / 2.f, 0.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//右下
    glBegin( GL_QUADS );
      glColor3f( 0.f, 1.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
    glEnd();
    glViewport( 0.f, SCREEN_HEIGHT / 2.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//左上
    glBegin( GL_QUADS );
      glColor3f( 0.f, 0.f, 1.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
    glEnd();
    glViewport( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//右上
    glBegin( GL_QUADS );
      glColor3f( 1.f, 1.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, -SCREEN_HEIGHT / 4.f );
      glVertex2f( SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
      glVertex2f( -SCREEN_WIDTH / 4.f, SCREEN_HEIGHT / 4.f );
    glEnd();
  }
  else if( gViewportMode == VIEWPORT_MODE_RADAR )//雷达
  {
    glViewport( 0.f, 0.f, SCREEN_WIDTH, SCREEN_HEIGHT );//大的
    glBegin( GL_QUADS );
      glColor3f( 1.f, 1.f, 1.f );
      glVertex2f( -SCREEN_WIDTH / 8.f, -SCREEN_HEIGHT / 8.f );
      glVertex2f( SCREEN_WIDTH / 8.f, -SCREEN_HEIGHT / 8.f );
      glVertex2f( SCREEN_WIDTH / 8.f, SCREEN_HEIGHT / 8.f );
      glVertex2f( -SCREEN_WIDTH / 8.f, SCREEN_HEIGHT / 8.f );
      glColor3f( 0.f, 0.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 16.f, -SCREEN_HEIGHT / 16.f );
      glVertex2f( SCREEN_WIDTH / 16.f, -SCREEN_HEIGHT / 16.f );
      glVertex2f( SCREEN_WIDTH / 16.f, SCREEN_HEIGHT / 16.f );
      glVertex2f( -SCREEN_WIDTH / 16.f, SCREEN_HEIGHT / 16.f );
    glEnd();
    glViewport( SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f, SCREEN_WIDTH / 2.f, SCREEN_HEIGHT / 2.f );//小的
    glBegin( GL_QUADS );
      glColor3f( 1.f, 1.f, 1.f );
      glVertex2f( -SCREEN_WIDTH / 8.f, -SCREEN_HEIGHT / 8.f );
      glVertex2f( SCREEN_WIDTH / 8.f, -SCREEN_HEIGHT / 8.f );
      glVertex2f( SCREEN_WIDTH / 8.f, SCREEN_HEIGHT / 8.f );
      glVertex2f( -SCREEN_WIDTH / 8.f, SCREEN_HEIGHT / 8.f );
      glColor3f( 0.f, 0.f, 0.f );
      glVertex2f( -SCREEN_WIDTH / 16.f, -SCREEN_HEIGHT / 16.f );
      glVertex2f( SCREEN_WIDTH / 16.f, -SCREEN_HEIGHT / 16.f );
      glVertex2f( SCREEN_WIDTH / 16.f, SCREEN_HEIGHT / 16.f );
      glVertex2f( -SCREEN_WIDTH / 16.f, SCREEN_HEIGHT / 16.f );
    glEnd();
  }
  glutSwapBuffers();//刷新屏幕
}
void handleKeys( unsigned char key, int x, int y )
{
if( key == 'q' )//按下q键
{
  gViewportMode++;//枚举默认值是0,1,2.。。。
  if( gViewportMode > VIEWPORT_MODE_RADAR )
  {
    gViewportMode = VIEWPORT_MODE_FULL;
  }
  }
}

...其他文件内容不变





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