几何变换源代码

#include "stdafx.h"
#include "windows.h"
#include <gl.h>
#include <glu.h>
#include <glaux.h>
void myinit(void);
void draw_triangle(void);
void CALLBACK display(void);
void CALLBACK myReshape(GLsizei w, GLsizei h);
void draw_triangle(void)
{
    glBegin(GL_LINE_LOOP);
    glVertex2f(0.0, 25.0);
    glVertex2f(25.0, -25.0);
    glVertex2f(-25.0, -25.0);
    glEnd();
}
void CALLBACK display(void)
{
    glClearColor (0.0, 0.0, 0.0, 1.0);
    glClear (GL_COLOR_BUFFER_BIT);
/* draw an original triangle */
    glLoadIdentity ();
    glColor3f (1.0, 1.0, 1.0);         /* white */
    draw_triangle ();
/* translating a triangle along X_axis  */
    glLoadIdentity ();
    glTranslatef (-20.0, 0.0, 0.0);
    glColor3f(1.0,0.0,0.0);           /* red */
    draw_triangle ();
/* scaling a triangle along X_axis by 1.5 and along Y_axis by 0.5  */
    glLoadIdentity();
    glScalef (1.5, 0.5, 1.0);
    glColor3f(0.0,1.0,0.0);           /* green */
    draw_triangle ();
/* rotating a triangle in a counterclockwise direction about Z_axis */
    glLoadIdentity ();
    glRotatef (35.0, 0.0, 0.0, -1.0);
    glColor3f(0.0,0.0,1.0);          /* blue */
    draw_triangle ();
/*  scaling a triangle along Y_axis and reflecting it about Y_axis  */
    glLoadIdentity();
    glScalef (1.0, -0.5, 1.0);
    glColor3f(1.0,1.0,0.0);          /* yellow */
    draw_triangle ();
    glFlush();
}
void myinit (void)
{
    glShadeModel (GL_FLAT);
}
void CALLBACK myReshape(GLsizei w, GLsizei h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
    glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w,
        50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);
    else
    glOrtho (-50.0*(GLfloat)w/(GLfloat)h,
        50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
}
void main(void)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGBA);
    auxInitPosition (0, 0, 500, 500);
    auxInitWindow ("三角形变换");
    myinit ();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
}