[NEHE Couse] 02.My first polygon

     这节比较简单但却很重要，因为几乎所有复杂的物体都是有基本的图形面片组成的(这点会随着你对图形学的深入而变的明显起来)，我在教程原来的基础上，画了一个三角面片，长方体面片和一条直线，都是OpenGL里简单却基础的知识，注意下glPushMatrix()和glPopMatrix()的使用。
代码如下：

  1/**//*
  2Introduction:Written by krisdy,finished at 2009.1.9
  3Apply to:NEHE Couse 02:My First Polygon
  4*/
  5#include <gl/glut.h>
  6#include <stdlib.h>
  7
  8#define WinWidth 500        //the width of the window
  9#define WinHeight 500        //the height of the window
 10
 11static GLint t;
 12
 13void init(void)
 14{
 15    glShadeModel(GL_SMOOTH);
 16    glClearColor(0.0f,0.0f,0.0f,0.0f);
 17    glClearDepth(1.0f);
 18    glEnable(GL_DEPTH_TEST);
 19    glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);
 20}
 21void display(void)
 22{
 23    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
 24    glColor3f(1.0f,0.0f,0.0f);
 25    glMatrixMode(GL_MODELVIEW);
 26    glLoadIdentity();
 27    glPushMatrix();
 28    glTranslatef(1.0f,1.0f,0.0f);
 29    //draw a triangle
 30    glBegin(GL_TRIANGLES);
 31        glVertex3f(0.0f,0.0f,0.0f);
 32        glVertex3f(3.0f,0.0f,0.0f);
 33        glVertex3f(1.5f,4.0f,0.0f);
 34    glEnd();
 35    //draw a line
 36    glLineWidth(3.0);
 37    glBegin(GL_LINES);
 38        glVertex3f(1.5f,7.0f,0.0f);
 39        glVertex3f(8.0f,7.0f,0.0f);
 40    glEnd();
 41    glPopMatrix();
 42    glPushMatrix();
 43    glTranslatef(6.0f,1.0f,0.0f);
 44    //draw a rectangle,without the help of glBegin&&glEnd
 45    glRectf(0.0f,0.0f,3.0f,3.0f);
 46    glPopMatrix();
 47    glFlush();
 48}
 49void reshape(int w,int h)
 50{
 51    GLfloat range = 10.0f;
 52    if(h == 0)
 53        h = 1;
 54    glViewport(0,0,w,h);
 55    glMatrixMode(GL_PROJECTION);
 56    glLoadIdentity();
 57    if(w < h)
 58        glOrtho(0.0f,range,0.0f,GLfloat(range*h/w),-1.0f,1.0f);
 59    else
 60        glOrtho(0.0f,GLfloat(range*w/h),0.0f,range,-1.0f,1.0f);
 61    glMatrixMode(GL_MODELVIEW);
 62    glLoadIdentity();
 63}
 64void keyboard(unsigned char key,int x,int y)
 65{
 66    switch(key)
 67    {
 68        //use the space key to decide whether the window will be full-screen displayed.
 69    case 32:                                            
 70        if(t%2 == 0)
 71                        //requests that the current window be made full screen
 72            glutFullScreen();                            
 73        else
 74                        //requests a change to the size of the current window
 75            glutReshapeWindow(WinWidth,WinHeight);        
 76        t++;
 77        break;
 78        //use the Esc key to quit the application
 79    case 27:                                            
 80        exit(0);
 81        break;
 82    default:
 83        break;
 84    }
 85}
 86int main(int argc,char *argv[])
 87{
 88    glutInit(&argc,argv);
 89    glutInitDisplayMode(GLUT_DEPTH|GLUT_RGB|GLUT_SINGLE);
 90    glutInitWindowSize(WinWidth,WinHeight);
 91    glutInitWindowPosition(100,100);
 92    glutCreateWindow("Lesson 02");
 93
 94    init();
 95    glutDisplayFunc(display);
 96    glutReshapeFunc(reshape);
 97    glutKeyboardFunc(keyboard);
 98    glutMainLoop();
 99    return 0;
}

 

程序效果如下：