[计算机图形学 with OpenGL] Chapter9 三维空间几何变换-栈处理函数与矩阵管理函数的区别

 1 #include <GLUT/GLUT.h>
 2 #include <iostream>
 3 #include <ctime>
 4 
 5 void init (void)
 6 {
 7     glClearColor(1.0, 1.0, 1.0, 0.0);
 8     glMatrixMode(GL_PROJECTION);
 9     glLoadIdentity();
10     gluOrtho2D(-225.0, 225.0, -225.0, 225.0);
11 }
12 
13 void displayFcn (void)
14 {
15     glClear(GL_COLOR_BUFFER_BIT);
16     glMatrixMode(GL_MODELVIEW);
17     
18     time_t nowtime = time(NULL);
19     for(int i = 0; i < 9999999; i++)
20     {
21         glColor3f(0.0, 1.0, 0.0);
22         glRotatef(90.0, 0.0, 0.0, 1.0);
23         glRecti(50, 100, 200, 150);
24         glLoadIdentity();
25     }
26     time_t nowtime1 = time(NULL);
27     std::cout << "original: " << nowtime1 - nowtime << std::endl; // 60sec
28 
29     
30     time_t nowtime2 = time(NULL);
31     for(int i = 0; i < 9999999; i++)
32     {
33         glPushMatrix();
34         glColor3f(0.0, 1.0, 0.0);
35         glRotatef(90.0, 0.0, 0.0, 1.0);
36         glRecti(50, 100, 200, 150);
37         glPopMatrix();
38     }
39     time_t nowtime3 = time(NULL);
40     std::cout << "optimized: " << nowtime3 - nowtime2 << std::endl; //61sec
41     
42     glFlush();
43 }
44 
45 int main(int argc, char * argv[])
46 {
47     glutInit(&argc, argv);
48     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
49     glutInitWindowPosition(50, 50);
50     glutInitWindowSize(600.0, 600.0);
51     glutCreateWindow("Geometric Transformation Compare with Stack");
52     
53     init();
54     glutDisplayFunc(displayFcn);
55 
56     glutMainLoop();
57     
58     return 0;
59 }