1
2 /* Draw test patterns to help determine correct gamma value for a display.
3 When the intensities of the inner squares nearly match the intensities
4 of their frames (from some distance the borders should disappear) then
5 you've found the right gamma value.
6
7 You can set Mesa's gamma values (for red, green and blue) with the
8 MESA_GAMMA environment variable. But only on X windows!
9 For example:
10 setenv MESA_GAMMA 1.5 1.6 1.4
11 Sets the red gamma value to 1.5, green to 1.6 and blue to 1.4.
12 See the main README file for more information.
13
14 For more info about gamma correction see:
15 http://www.inforamp.net/~poynton/notes/colour_and_gamma/GammaFAQ.html
16
17 This program is in the public domain
18
19 Brian Paul 19 Oct 1995
20 Kai Schuetz 05 Jun 1999 */
21
22 /* Conversion to GLUT by Mark J. Kilgard */
23
24
25 #include <stdio.h>
26 #include <string.h>
27 #include <stdlib.h>
28 #include "glut_wrap.h"
29
30 static void
Reshape(int width,int height)31 Reshape(int width, int height)
32 {
33 glViewport(0, 0, (GLint) width, (GLint) height);
34
35 glMatrixMode(GL_PROJECTION);
36 glLoadIdentity();
37 glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
38 glMatrixMode(GL_MODELVIEW);
39 glShadeModel(GL_FLAT);
40 }
41
42 /* ARGSUSED1 */
43 static void
key_esc(unsigned char key,int x,int y)44 key_esc(unsigned char key, int x, int y)
45 {
46 if(key == 27) exit(0); /* Exit on Escape */
47 }
48
49 static GLubyte p25[] = {
50 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
51 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
52 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
53 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
54 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
55 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
56 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
57 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
58 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
59 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
60 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
61 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
62 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
63 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
64 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
65 0xaa, 0xaa, 0xaa, 0xaa, 0x00, 0x00, 0x00, 0x00,
66 };
67
68 static GLubyte p50[] = {
69 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
70 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
71 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
72 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
73 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
74 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
75 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
76 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
77 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
78 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
79 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
80 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
81 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
82 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
83 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
84 0xaa, 0xaa, 0xaa, 0xaa, 0x55, 0x55, 0x55, 0x55,
85 };
86
87 static GLubyte p75[] = {
88 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
89 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
90 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
91 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
92 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
93 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
94 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
95 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
96 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
97 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
98 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
99 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
100 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
101 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
102 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
103 0xaa, 0xaa, 0xaa, 0xaa, 0xff, 0xff, 0xff, 0xff,
104 };
105
106 static GLubyte *stippletab[4] = {NULL, p25, p50, p75};
107
108 static void
gamma_ramp(GLfloat yoffs,GLfloat r,GLfloat g,GLfloat b)109 gamma_ramp(GLfloat yoffs, GLfloat r, GLfloat g, GLfloat b)
110 {
111 GLint d;
112
113 glColor3f(0.0, 0.0, 0.0); /* solid black, no stipple */
114 glRectf(-1.0, yoffs, -0.6, yoffs + 0.5);
115
116 for(d = 1; d < 4; d++) { /* increasing density from 25% to 75% */
117 GLfloat xcoord = (-1.0 + d*0.4);
118 GLfloat t = d * 0.25;
119
120 glColor3f(r*t, g*t, b*t); /* draw outer rect */
121 glRectf(xcoord, yoffs, xcoord+0.4, yoffs + 0.5);
122
123 glColor3f(0.0, 0.0, 0.0); /* "clear" inner rect */
124 glRectf(xcoord + 0.1, yoffs + 0.125, xcoord + 0.3, yoffs + 0.375);
125
126 glColor3f(r, g, b); /* draw stippled inner rect */
127 glEnable(GL_POLYGON_STIPPLE);
128 glPolygonStipple(stippletab[d]);
129 glRectf(xcoord + 0.1, yoffs + 0.125, xcoord + 0.3, yoffs + 0.375);
130 glDisable(GL_POLYGON_STIPPLE);
131 }
132 glColor3f(r, g, b); /* solid color, no stipple */
133 glRectf(0.6, yoffs, 1.0, yoffs + 0.5);
134 }
135
136 static void
display(void)137 display(void)
138 {
139 gamma_ramp( 0.5, 1.0, 1.0, 1.0); /* white ramp */
140 gamma_ramp( 0.0, 1.0, 0.0, 0.0); /* red ramp */
141 gamma_ramp(-0.5, 0.0, 1.0, 0.0); /* green ramp */
142 gamma_ramp(-1.0, 0.0, 0.0, 1.0); /* blue ramp */
143 glFlush();
144 }
145
146 int
main(int argc,char ** argv)147 main(int argc, char **argv)
148 {
149 glutInitWindowSize(500, 400);
150 glutInit(&argc, argv);
151 glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
152 glutCreateWindow("gamma test patterns");
153 glutReshapeFunc(Reshape);
154 glutDisplayFunc(display);
155 glutKeyboardFunc(key_esc);
156
157 glutMainLoop();
158 return 0; /* ANSI C requires main to return int. */
159 }
160