1/*
2 * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
3 *
4 * Permission to use, copy, modify, distribute, and sell this software and
5 * its documentation for any purpose is hereby granted without fee, provided
6 * that (i) the above copyright notices and this permission notice appear in
7 * all copies of the software and related documentation, and (ii) the name of
8 * Silicon Graphics may not be used in any advertising or
9 * publicity relating to the software without the specific, prior written
10 * permission of Silicon Graphics.
11 *
12 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
13 * ANY KIND,
14 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
15 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
16 *
17 * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
18 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
19 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
20 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
21 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
22 * OF THIS SOFTWARE.
23 */
24
25#include <GL/glew.h>
26#include <math.h>
27#include <stdio.h>
28#include <string.h>
29#include <stdlib.h>
30#include "glut_wrap.h"
31
32
33
34GLenum doubleBuffer;
35
36static void Init(void)
37{
38   fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
39   fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
40   fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
41   fflush(stderr);
42
43   glClearColor(0.0, 0.0, 1.0, 0.0);
44}
45
46static void Reshape(int width, int height)
47{
48    glViewport(0, 0, (GLint)width, (GLint)height);
49
50    glMatrixMode(GL_PROJECTION);
51    glLoadIdentity();
52    glOrtho(-1.0, 1.0, -1.0, 1.0, 0, 100.0);
53    glMatrixMode(GL_MODELVIEW);
54}
55
56static void Key(unsigned char key, int x, int y)
57{
58    switch (key) {
59    case 27:
60	exit(1);
61    default:
62	break;
63    }
64    glutPostRedisplay();
65}
66
67
68static float
69expected(float z, float size, const float atten[3])
70{
71   float dist = fabs(z);
72   const GLfloat q = atten[0] + dist * (atten[1] + dist * atten[2]);
73   const GLfloat a = sqrt(1.0 / q);
74   return size * a;
75}
76
77
78static void Draw(void)
79{
80   static GLfloat atten[3] = { 0.0, 0.1, .01 };
81   float size = 40.0;
82   int i;
83
84   glClear(GL_COLOR_BUFFER_BIT);
85
86   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
87   glPointSize(size);
88   glPointParameterfvARB(GL_POINT_DISTANCE_ATTENUATION_ARB, atten);
89
90   glColor3f(1,0,0);
91
92   printf("Expected point sizes:\n");
93   glBegin(GL_POINTS);
94   for (i = 0; i < 5; i++) {
95      float x = -0.8 + i * 0.4;
96      float z = -i * 20 - 10;
97      glVertex3f( x, 0.0, z);
98      printf(" %f\n", expected(z, size, atten));
99   }
100   glEnd();
101
102   glFlush();
103
104   if (doubleBuffer) {
105      glutSwapBuffers();
106   }
107}
108
109
110static GLenum Args(int argc, char **argv)
111{
112    GLint i;
113
114    doubleBuffer = GL_FALSE;
115
116    for (i = 1; i < argc; i++) {
117        if (strcmp(argv[i], "-sb") == 0) {
118	    doubleBuffer = GL_FALSE;
119	} else if (strcmp(argv[i], "-db") == 0) {
120	    doubleBuffer = GL_TRUE;
121	} else {
122	    fprintf(stderr, "%s (Bad option).\n", argv[i]);
123	    return GL_FALSE;
124	}
125    }
126    return GL_TRUE;
127}
128
129
130int main(int argc, char **argv)
131{
132    GLenum type;
133
134    glutInit(&argc, argv);
135
136    if (Args(argc, argv) == GL_FALSE) {
137	exit(1);
138    }
139
140    glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
141
142    type = GLUT_RGB | GLUT_ALPHA;
143    type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
144    glutInitDisplayMode(type);
145
146    if (glutCreateWindow(argv[0]) == GL_FALSE) {
147	exit(1);
148    }
149
150    glewInit();
151
152    Init();
153
154    glutReshapeFunc(Reshape);
155    glutKeyboardFunc(Key);
156    glutDisplayFunc(Draw);
157    glutMainLoop();
158    return 0;
159}
160