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| Computers Forum Index » Computer - Graphics - API (Opengl) » RedBook, Chapter 8, examples... |
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| Georg Fuss... |
 Posted: Thu Sep 10, 2009 11:38 pm |
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Guest
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The funktion readImage(), used in some example in the chapter 8, does
not work.
This functions reads the file .../data/leeds.bin. The first things read
from the file are sizes of the window, but for me the function reads
impossible values.
readImage(): width = 1459748864 height = -1862205440
These values make no sense as dimensions for a window.
I am working on a 64-Bit linux-system.
The most example are easy to compile and to run.
The file ..../data/leeds.bin I get from
http://www.opengl-redbook.com/source/OpenGL-1.4.tgz |
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| fungus... |
| Posted: Thu Sep 10, 2009 11:38 pm |
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Guest
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On Sep 10, 9:38 pm, Georg Fuss <f... at (no spam) math.TU-Berlin.DE> wrote:
Quote: The first things read
from the file are sizes of the window, but for me the function reads
impossible values.
readImage(): width = 1459748864 height = -1862205440
These values make no sense as dimensions for a window.
I am working on a 64-Bit linux-system.
The most example are easy to compile and to run.
Maybe there's a bug in the loader so it reads 64-bit
ints instead of 32 bits.
--
<\___/>
/ O O \
\_____/ FTB.
http://www.topaz3d.com/ |
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| jbwest... |
| Posted: Fri Sep 11, 2009 4:41 am |
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"Georg Fuss" <fuss at (no spam) math.TU-Berlin.DE> wrote in message
news:7gt2t7F2qp10hU1 at (no spam) mid.dfncis.de...
Quote: The funktion readImage(), used in some example in the chapter 8, does
not work.
This functions reads the file .../data/leeds.bin. The first things read
from the file are sizes of the window, but for me the function reads
impossible values.
readImage(): width = 1459748864 height = -1862205440
These values make no sense as dimensions for a window.
I am working on a 64-Bit linux-system.
The most example are easy to compile and to run.
The file ..../data/leeds.bin I get from
http://www.opengl-redbook.com/source/OpenGL-1.4.tgz
probably an endian-ness or 64-bit-ness error in the code.
jbw |
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| Paul at (no spam) Tcl3D... |
| Posted: Fri Sep 11, 2009 9:37 pm |
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Guest
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Hi Georg,
The RedBook examples were written on and for SGI computers, so the
header data of the images is stored in big-endian format.
The code to read the width and height does not account for little-endianess.
Something like the following will help:
static unsigned int byteToUInt32 (const unsigned char buf[4])
{
return (buf[3] & 0x000000ff) |
((buf[2] <<  & 0x0000ff00) |
((buf[1] << 16) & 0x00ff0000) |
(buf[0] << 24);
}
In function readImage:
....
unsigned char bufWidth[4], bufHeight[4];
FILE* infile = fopen( filename, "rb" );
if ( !infile ) {
fprintf( stderr, "Unable to open file '%s'\n", filename );
return NULL;
}
fread( bufWidth, sizeof( GLsizei ), 1, infile );
fread( bufHeight, sizeof( GLsizei ), 1, infile );
*width = byteToUInt32 (bufWidth);
*height = byteToUInt32 (bufHeight);
....
Paul
Georg Fuss wrote:
Quote: The funktion readImage(), used in some example in the chapter 8, does
not work.
This functions reads the file .../data/leeds.bin. The first things read
from the file are sizes of the window, but for me the function reads
impossible values.
readImage(): width = 1459748864 height = -1862205440
These values make no sense as dimensions for a window.
I am working on a 64-Bit linux-system.
The most example are easy to compile and to run.
The file ..../data/leeds.bin I get from
http://www.opengl-redbook.com/source/OpenGL-1.4.tgz |
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