glutSwapBuffers和glutPostRedisplay
双缓存用SwapBuffer，单缓存用glFlush()
/*
* Copyright (c) 1993-2003, Silicon Graphics, Inc.
* All Rights Reserved
*
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* and that the name of Silicon Graphics, Inc. not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission.
*
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF
* PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD
* PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN ADVISED OF
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* OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor clauses
* in the FAR or the DOD or NASA FAR Supplement. Unpublished - rights
* reserved under the copyright laws of the United States.
*
* Contractor/manufacturer is:
* Silicon Graphics, Inc.
* 1500 Crittenden Lane
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*
* OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
*/
/*
* double.c
* This is a simple double buffered program.
* Pressing the left mouse button rotates the rectangle.
* Pressing the middle mouse button stops the rotation.
*/
#include <GL/freeglut.h>
//#include <stdlib.h>
static GLfloat spin = 0.0;
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(spin, 0.0, 0.0, 1.0);
glColor3f(1.0, 1.0, 0.0);
glRectf(-25.0, -25.0, 25.0, 25.0);
//glutSolidCube(5.0f);
glPopMatrix();
// 双缓存用SwapBuffer，单缓存用glFlush()
glutSwapBuffers();
}
void spinDisplay(void)
{
spin = spin + 2.0;
if (spin > 360.0)
spin = spin - 360.0;
// 改变了参数需要重新调用绘制刷新，这里是display函数
// 这里实现空闲时候调用spinDisplay，再调用display函数
glutPostRedisplay();
}
void init(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_SMOOTH);
}
void reshape(int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// 只是定义min(left, bottom, znear), max(right, top, zfar)两个点
glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void mouse(int button, int state, int x, int y)
{
switch (button) {
// 鼠标事件捕获，进行交互
case GLUT_LEFT_BUTTON:
if (state == GLUT_DOWN)
glutIdleFunc(spinDisplay);
break;
case GLUT_MIDDLE_BUTTON:
case GLUT_RIGHT_BUTTON:
if (state == GLUT_DOWN)
glutIdleFunc(NULL);
break;
default:
break;
}
}
/*
* Request double buffer display mode.
* Register mouse input callback functions
*/
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize (250, 250);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
init ();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMouseFunc(mouse);
glutMainLoop();
return 0; /* ANSI C requires main to return int. */
}