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sky-raven
08-25-2002, 01:37 PM
Hello ,
I have recently tried one of your exercises called mutitex.c. This I tried on a Suse 7.2 linux running Glu version 1.1 with Mesa 3.4.1 with OpenGL 1.2 version under X Windows. The number of texturing units available were 2 from running
glGetIntegerv(GL_MAX_TEXTURE_UNITS_ARB,)
Also extensions available with this implementation were found out by running
glGetString(GL_EXTENSIONS)
And gave the following listing of

GL_ARB_multitexture
GL_ARB_texture_cube_map
GL_ARB_tranpose_matrix
GL_EXT_abgr
GL_EXT_blend_color
GL_EXT_blend_func_separate
GL_EXT_blend_logic_op
GL_EXT_blend_minmax
GL_EXT_blend_subtract
GL_EXT_clip_volume_hint
GL_EXT_compiled_vertex_array
GL_EXT_histogram
GL_EXT_packed_pixels
GL_EXT_paletted_texture
GL_EXT_point_parameters
GL_EXT_polygon_offset
GL_EXT_rescale_normal
GL_EXT_shared_texture_palette
GL_EXT_stencil_wrap
GL_EXT_texture3D
GL_EXT_texture_env_add
GL_EXT_texture_env_combine
GL_EXT_texture_env_dot3
GL_EXT_texture_object
GL_EXT_texture_lod_bias
GL_EXT_vertex_array
GL_HP_occlusion_test
GL_INGR_blend_func_separate
GL_MESA_window_pos
GL_MESA_resize_buffers
GL_NV_texgen_reflection
GL_PGI_misc_hints
GL_SGI_color_matrix
GL_SGI_color_table
GL_SGIS_pixel_texture
GL_SGIS_texture_edge_clamp
GL_SGIX_pixel_texture

You will notice that GL_ARB_imaging is not included. When I compiled and ran multitex.c, (see below), I only got a black screen. Why is this? Have I done something wrong?

I look forward to your reply.


David Olivieri

multitex.c programme was taken from Redbook OpenGL Programming Guide 1.2.
See below :-
/*
* Copyright (c) 1993-1999, Silicon Graphics, Inc.
* ALL RIGHTS RESERVED
* Permission to use, copy, modify, and distribute this software for
* any purpose and without fee is hereby granted, provided that the above
* copyright notice appear in all copies and that both the copyright notice
* and this permission notice appear in supporting documentation, and that
* the name of Silicon Graphics, Inc. not be used in advertising
* or publicity pertaining to distribution of the software without specific,
* written prior permission.
*
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor
* clauses in the FAR or the DOD or NASA FAR Supplement.
* Unpublished-- rights reserved under the copyright laws of the
* United States. Contractor/manufacturer is Silicon Graphics,
* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
*
* OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
*/

/* multitex.c
*/
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>

#ifdef GL_VERSION_1_2

static GLubyte texels0[32][32][4];
static GLubyte texels1[16][16][4];

void makeCheckImages(void)
{
int i, j;

for (i = 0; i < 32; i++) {
for (j = 0; j < 32; j++) {
texels0[i][j][0] = (GLubyte) i;
texels0[i][j][1] = (GLubyte) j;
texels0[i][j][2] = (GLubyte) (i*j)/255;
texels0[i][j][3] = (GLubyte) 255;
}
}

for (i = 0; i < 16; i++) {
for (j = 0; j < 16; j++) {
texels1[i][j][0] = (GLubyte) 255;
texels1[i][j][1] = (GLubyte) i;
texels1[i][j][2] = (GLubyte) j;
texels1[i][j][3] = (GLubyte) 255;
}
}
}

void init(void)
{
GLuint texNames[2];

glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);

makeCheckImages();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

glGenTextures(2, texNames);
glBindTexture(GL_TEXTURE_2D, texNames[0]);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA,
GL_UNSIGNED_BYTE, texels0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

glBindTexture(GL_TEXTURE_2D, texNames[1]);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA,
GL_UNSIGNED_BYTE, texels1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
/* Use the two texture objects to define two texture units
* for use in multitexturing */
glActiveTextureARB (GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texNames[0]);
glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glMatrixMode (GL_TEXTURE);
glLoadIdentity();
glTranslatef(0.5f, 0.5f, 0.0f);
glRotatef(45.0f, 0.0f, 0.0f, 1.0f);
glTranslatef(-0.5f, -0.5f, 0.0f);
glMatrixMode (GL_MODELVIEW);
glActiveTextureARB (GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texNames[1]);
glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
}

void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_TRIANGLES);
glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 0.0, 0.0);
glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 1.0, 0.0);
glVertex2f(0.0, 0.0);
glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 0.5, 1.0);
glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 0.5, 0.0);
glVertex2f(50.0, 100.0);
glMultiTexCoord2fARB (GL_TEXTURE0_ARB, 1.0, 0.0);
glMultiTexCoord2fARB (GL_TEXTURE1_ARB, 1.0, 1.0);
glVertex2f(100.0, 0.0);
glEnd();
glFlush();
}

void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w <= h)
gluOrtho2D(0.0, 100.0, 0.0, 100.0 * (GLdouble)h/(GLdouble)w);
else
gluOrtho2D(0.0, 100.0 * (GLdouble)w/(GLdouble)h, 0.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
}
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(250, 250);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutReshapeFunc(reshape);
glutDisplayFunc(display);
glutKeyboardFunc (keyboard);
glutMainLoop();
return 0;
}
#else
int main(int argc, char** argv)
{
fprintf (stderr, "This program demonstrates a feature which is not in OpenGL Version 1.0 or 1.1.\n");
fprintf (stderr, "If your implementation of OpenGL Version 1.0 has the right extensions,\n");
fprintf (stderr, "you may be able to modify this program to make it run.\n");
return 0;
}
#endif

08-26-2002, 04:59 AM
The problem could simply be that your monitor is too dark. If you temporary change the gamma correction with something like "xgamma -gamma 9" and then runs the program will you perhaps see something. In your XF86Config-4 file can you have some constant gamma adjustment. It can be impossible to set a good gamma correction for some monitors.

sky-raven
08-28-2002, 11:09 AM
How do you change the gamma corection? I had a look at the config file could not find any statement with this in it. Where do I go from here?


Originally posted by Zico:
The problem could simply be that your monitor is too dark. If you temporary change the gamma correction with something like "xgamma -gamma 9" and then runs the program will you perhaps see something. In your XF86Config-4 file can you have some constant gamma adjustment. It can be impossible to set a good gamma correction for some monitors.

08-28-2002, 03:46 PM
First do some tests with xgamma to get the best possible gamma correction values. After that put the values in the Monitor section of the XF86Config-4 file. It should look something like this:

Section "Monitor"
Gamma gR gG gB
...
EndSection

gR, gG and gB is the floating point values that you tested with xgamma. I do not think it works with all cards but if xgamma worked should this also be OK.

sky-raven
08-30-2002, 12:10 PM
First of all how do you do xgamma test with this programme? Is it a command line command? Would putting the adjustments upset my screen
and cause me to either damage my monitor or loose Xwindows ?
Below is an extract of my XF86Config file. Where should the above comments in my config file?

Section "Monitor"
HorizSync 29-64
Identifier "Monitor[0]"
ModelName "AutoDetected"
VendorName "AutoDetected"
VertRefresh 47-68
UseModes "Modes[0]"
EndSection

Section "Modes"
Identifier "Modes[0]"
Modeline "640x480" 27.96 640 656 720 864 480 480 485 501
Modeline "800x600" 42.43 800 880 992 1072 600 600 610 626
EndSection

Section "Screen"
DefaultDepth 16
SubSection "Display"
Depth 16
Modes "800x600" "640x480"
EndSubSection
Device "Device[0]"
Identifier "Screen[0]"
Monitor "Monitor[0]"
EndSection

Section "Device"
BoardName "AutoDetected"
Driver "sis"
Identifier "Device[0]"
Option "dpms"
VendorName "AutoDetected"
EndSection

Originally posted by Zico:
First do some tests with xgamma to get the best possible gamma correction values. After that put the values in the Monitor section of the XF86Config-4 file. It should look something like this:

Section "Monitor"
Gamma gR gG gB
...
EndSection

gR, gG and gB is the floating point values that you tested with xgamma. I do not think it works with all cards but if xgamma worked should this also be OK.

08-31-2002, 07:09 PM
I do not know what to say. I have already answered your questions. If you are feeling nervous could you take it in steps. First "xgamma -gamma 1.0000001" and then increase. http://www.opengl.org/discussion_boards/ubb/smile.gif

Can anything you do in software damage the hardware?

sky-raven
09-04-2002, 11:43 AM
Recently I tried the xgamma shell command but notice that the gamma values did change from a command line point of view but no noticable effect from visual point of view was noticed. Would changing the config file be worth it? Values tried with
xgamma were from 0.1 to 10.0.

09-04-2002, 06:30 PM
No, I do not think it is any idea to change the config file. Your only option is to use the controls on the monitor.

sky-raven
10-14-2002, 02:37 AM
No luck with you suggestion

Originally posted by Zico:
No, I do not think it is any idea to change the config file. Your only option is to use the controls on the monitor.