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 <stdio.h>
26 #include <string.h>
27 #include <stdlib.h>
28 #include <glad/glad.h>
29 #include "glut_wrap.h"
30
31
32 #define CI_OFFSET_1 16
33 #define CI_OFFSET_2 32
34
35 #define SIZE 16
36 GLenum doubleBuffer;
37 GLint line = 0;
38
MakeImage(void)39 static void MakeImage(void)
40 {
41 GLubyte tex2d[SIZE][SIZE][3];
42 GLint s, t;
43
44 for (s = 0; s < SIZE; s++) {
45 for (t = 0; t < SIZE; t++) {
46 tex2d[t][s][0] = s*255/(SIZE-1);
47 tex2d[t][s][1] = t*255/(SIZE-1);
48 tex2d[t][s][2] = 0*255/(SIZE-1);
49 }
50 }
51
52 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
53 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
54 SIZE, SIZE,
55 0,
56 GL_RGB, GL_UNSIGNED_BYTE, tex2d);
57 glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
58 glEnable(GL_TEXTURE_2D);
59 }
60
UpdateLine(void)61 static void UpdateLine(void)
62 {
63 GLubyte tex[SIZE][3];
64 GLubyte b = 0;
65 GLint s, t;
66
67 t = line % SIZE;
68 if (line % (SIZE * 2) < SIZE)
69 b = 255;
70 else
71 b = 0;
72
73 for (s = 0; s < SIZE; s++) {
74 tex[s][0] = s*255/(SIZE-1);
75 tex[s][1] = t*255/(SIZE-1);
76 tex[s][2] = b;
77 }
78
79 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
80 glTexSubImage2D(GL_TEXTURE_2D, 0,
81 0, t,
82 SIZE, 1,
83 GL_RGB, GL_UNSIGNED_BYTE, tex);
84 glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
85 }
86
Init(void)87 static void Init(void)
88 {
89 fprintf(stderr, "GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
90 fprintf(stderr, "GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
91 fprintf(stderr, "GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
92 fflush(stderr);
93
94 glClearColor(0.0, 0.0, 1.0, 0.0);
95
96 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
97 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
98 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
99 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
100 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
101
102 MakeImage();
103 UpdateLine();
104 line++;
105 }
106
Reshape(int width,int height)107 static void Reshape(int width, int height)
108 {
109
110 glViewport(0, 0, (GLint)width, (GLint)height);
111
112 glMatrixMode(GL_PROJECTION);
113 glLoadIdentity();
114 glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
115 glMatrixMode(GL_MODELVIEW);
116 }
117
Key(unsigned char key,int x,int y)118 static void Key(unsigned char key, int x, int y)
119 {
120
121 switch (key) {
122 case 27:
123 exit(1);
124 default:
125 UpdateLine();
126 line++;
127 break;
128 }
129
130 glutPostRedisplay();
131 }
132
Draw(void)133 static void Draw(void)
134 {
135 glClear(GL_COLOR_BUFFER_BIT);
136
137 glBegin(GL_QUADS);
138 glTexCoord2f(1,0);
139 glVertex3f( 0.9, -0.9, -30.0);
140 glTexCoord2f(1,1);
141 glVertex3f( 0.9, 0.9, -30.0);
142 glTexCoord2f(0,1);
143 glVertex3f(-0.9, 0.9, -30.0);
144 glTexCoord2f(0,0);
145 glVertex3f(-0.9, -0.9, -30.0);
146 glEnd();
147
148 glFlush();
149
150 if (doubleBuffer) {
151 glutSwapBuffers();
152 }
153 }
154
Args(int argc,char ** argv)155 static GLenum Args(int argc, char **argv)
156 {
157 GLint i;
158
159 doubleBuffer = GL_FALSE;
160
161 for (i = 1; i < argc; i++) {
162 if (strcmp(argv[i], "-sb") == 0) {
163 doubleBuffer = GL_FALSE;
164 } else if (strcmp(argv[i], "-db") == 0) {
165 doubleBuffer = GL_TRUE;
166 } else {
167 fprintf(stderr, "%s (Bad option).\n", argv[i]);
168 return GL_FALSE;
169 }
170 }
171 return GL_TRUE;
172 }
173
main(int argc,char ** argv)174 int main(int argc, char **argv)
175 {
176 GLenum type;
177
178 glutInit(&argc, argv);
179
180 if (Args(argc, argv) == GL_FALSE) {
181 exit(1);
182 }
183
184 glutInitWindowPosition(0, 0);
185 glutInitWindowSize(250, 250);
186
187 type = GLUT_RGB | GLUT_ALPHA;
188 type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
189 glutInitDisplayMode(type);
190
191 if (glutCreateWindow(*argv) == GL_FALSE) {
192 exit(1);
193 }
194
195 gladLoadGL();
196
197 Init();
198
199 glutReshapeFunc(Reshape);
200 glutKeyboardFunc(Key);
201 glutDisplayFunc(Draw);
202 glutMainLoop();
203 return 0;
204 }
205