1 /* Test GL_TEXTURE_BASE_LEVEL and GL_TEXTURE_MAX_LEVEL
2 * Brian Paul
3 * 10 May 2006
4 */
5
6
7 /* Copyright (c) Mark J. Kilgard, 1994. */
8
9 /*
10 * (c) Copyright 1993, Silicon Graphics, Inc.
11 * ALL RIGHTS RESERVED
12 * Permission to use, copy, modify, and distribute this software for
13 * any purpose and without fee is hereby granted, provided that the above
14 * copyright notice appear in all copies and that both the copyright notice
15 * and this permission notice appear in supporting documentation, and that
16 * the name of Silicon Graphics, Inc. not be used in advertising
17 * or publicity pertaining to distribution of the software without specific,
18 * written prior permission.
19 *
20 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
21 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
22 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
23 * FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
24 * GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
25 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
26 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
27 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
28 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
29 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
30 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
31 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
32 *
33 * US Government Users Restricted Rights
34 * Use, duplication, or disclosure by the Government is subject to
35 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
36 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
37 * clause at DFARS 252.227-7013 and/or in similar or successor
38 * clauses in the FAR or the DOD or NASA FAR Supplement.
39 * Unpublished-- rights reserved under the copyright laws of the
40 * United States. Contractor/manufacturer is Silicon Graphics,
41 * Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
42 *
43 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
44 */
45
46 #include <stdlib.h>
47 #include <stdio.h>
48 #include <glad/glad.h>
49 #include "glut_wrap.h"
50
51
52 static GLfloat LodBias = 6.0; /* make smallest miplevel visible */
53 static GLuint texImage;
54
55 #define WIDTH 2
56 #define HEIGHT 2
57
58 static void
InitValues(void)59 InitValues(void)
60 {
61 LodBias = 6.0; /* make smallest miplevel visible */
62 }
63
64
MakeImage(void)65 static void MakeImage(void)
66 {
67 const GLubyte color0[4] = { 0xff, 0x80, 0x20, 0xff };
68 const GLubyte color1[4] = { 0x10, 0x20, 0x40, 0xff };
69
70 GLubyte img[WIDTH*HEIGHT*3];
71 int i, j;
72 for (i = 0; i < HEIGHT; i++) {
73 for (j = 0; j < WIDTH; j++) {
74 int k = (i * WIDTH + j) * 3;
75 int p = ((i+j)%2);
76 if (p == 0) {
77 img[k + 0] = color0[0];
78 img[k + 1] = color0[1];
79 img[k + 2] = color0[2];
80 }
81 else {
82 img[k + 0] = color1[0];
83 img[k + 1] = color1[1];
84 img[k + 2] = color1[2];
85 }
86 }
87 }
88
89 glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE);
90 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WIDTH, HEIGHT, 0,
91 GL_RGB, GL_UNSIGNED_BYTE, img);
92 glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_FALSE);
93 }
94
95
96
myinit(void)97 static void myinit(void)
98 {
99 InitValues();
100
101 glShadeModel(GL_FLAT);
102
103 glTranslatef(0.0, 0.0, -3.6);
104
105 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
106 glGenTextures(1, &texImage);
107 glBindTexture(GL_TEXTURE_2D, texImage);
108 MakeImage();
109
110 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
111 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
112 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
113 glEnable(GL_TEXTURE_2D);
114
115 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
116 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1);
117
118 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_LOD, -1);
119 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 1);
120
121 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
122 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
123 GL_NEAREST_MIPMAP_NEAREST);
124 }
125
126
127
display(void)128 static void display(void)
129 {
130 GLfloat tcm = 1.0;
131 glBindTexture(GL_TEXTURE_2D, texImage);
132
133 printf("Bias=%.2g\n", LodBias);
134 fflush(stdout);
135
136 glTexEnvf(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, LodBias);
137
138 glClear(GL_COLOR_BUFFER_BIT);
139 glBegin(GL_QUADS);
140 glTexCoord2f(0.0, 0.0); glVertex3f(-2.0, -1.0, 0.0);
141 glTexCoord2f(0.0, tcm); glVertex3f(-2.0, 1.0, 0.0);
142 glTexCoord2f(tcm * 3000.0, tcm); glVertex3f(3000.0, 1.0, -6000.0);
143 glTexCoord2f(tcm * 3000.0, 0.0); glVertex3f(3000.0, -1.0, -6000.0);
144 glEnd();
145 glFlush();
146 }
147
myReshape(int w,int h)148 static void myReshape(int w, int h)
149 {
150 glViewport(0, 0, w, h);
151 glMatrixMode(GL_PROJECTION);
152 glLoadIdentity();
153 gluPerspective(60.0, 1.0*(GLfloat)w/(GLfloat)h, 1.0, 30000.0);
154 glMatrixMode(GL_MODELVIEW);
155 glLoadIdentity();
156 }
157
158 static void
key(unsigned char k,int x,int y)159 key(unsigned char k, int x, int y)
160 {
161 (void) x;
162 (void) y;
163 switch (k) {
164 case 'l':
165 LodBias -= 0.25;
166 break;
167 case 'L':
168 LodBias += 0.25;
169 break;
170 case ' ':
171 InitValues();
172 break;
173 case 27: /* Escape */
174 exit(0);
175 break;
176 default:
177 return;
178 }
179 glutPostRedisplay();
180 }
181
182
usage(void)183 static void usage(void)
184 {
185 printf("usage:\n");
186 printf(" l/L decrease/increase GL_TEXTURE_LOD_BIAS\n");
187 printf(" SPACE reset values\n");
188 }
189
190
main(int argc,char ** argv)191 int main(int argc, char** argv)
192 {
193 glutInit(&argc, argv);
194 glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB );
195 glutInitWindowSize (600, 600);
196 glutCreateWindow (argv[0]);
197 gladLoadGL();
198 myinit();
199 glutReshapeFunc (myReshape);
200 glutDisplayFunc(display);
201 glutKeyboardFunc(key);
202 usage();
203 glutMainLoop();
204 return 0; /* ANSI C requires main to return int. */
205 }
206