1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/**
* Test frustum/user clipping w/ glPolygonMode LINE/POINT.
*
* The bottom/left and bottom/right verts are outside the frustum and clipped.
* The top vertex is clipped by a user clipping plane.
*
* A filled gray reference triangle is shown underneath the points/lines.
*/
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
static int win;
static void
ColorTri(void)
{
glBegin(GL_TRIANGLES);
glColor3f(1, 0, 0); glVertex3f(-1.5, -0.8, 0.0);
glColor3f(0, 1, 0); glVertex3f( 1.5, -0.8, 0.0);
glColor3f(0, 0, 1); glVertex3f( 0.0, 0.9, 0.0);
glEnd();
}
static void
GrayTri(void)
{
glColor3f(0.3, 0.3, 0.3);
glBegin(GL_TRIANGLES);
glVertex3f(-1.5, -0.8, 0.0);
glVertex3f( 1.5, -0.8, 0.0);
glVertex3f( 0.0, 0.9, 0.0);
glEnd();
}
static void
Draw(void)
{
static const GLdouble plane[4] = { 0, -1.0, 0, 0.5 };
glClear(GL_COLOR_BUFFER_BIT);
glPointSize(13.0);
glLineWidth(5.0);
glClipPlane(GL_CLIP_PLANE0, plane);
glEnable(GL_CLIP_PLANE0);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
GrayTri();
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
ColorTri();
glPolygonMode(GL_FRONT_AND_BACK, GL_POINT);
ColorTri();
glutSwapBuffers();
}
static void Reshape(int width, int height)
{
glViewport(0, 0, (GLint)width, (GLint)height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
}
static void
Key(unsigned char key, int x, int y)
{
if (key == 27) {
glutDestroyWindow(win);
exit(0);
}
else {
glutPostRedisplay();
}
}
static void
Init(void)
{
fprintf(stderr, "GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
fprintf(stderr, "GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
fprintf(stderr, "GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
fflush(stderr);
}
int
main(int argc, char **argv)
{
glutInitWindowSize(300, 300);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH);
win = glutCreateWindow(*argv);
if (!win) {
return 1;
}
Init();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
glutMainLoop();
return 0;
}
|
