408 lines
12 KiB
C
408 lines
12 KiB
C
//========================================================================
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// GLFW - An OpenGL framework
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// File: tga.c
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// Platform: Any
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// API version: 2.6
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// WWW: http://glfw.sourceforge.net
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//------------------------------------------------------------------------
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// Copyright (c) 2002-2006 Camilla Berglund
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//
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// This software is provided 'as-is', without any express or implied
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// warranty. In no event will the authors be held liable for any damages
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// arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it
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// freely, subject to the following restrictions:
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//
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// 1. The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software. If you use this software
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// in a product, an acknowledgment in the product documentation would
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// be appreciated but is not required.
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//
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// 2. Altered source versions must be plainly marked as such, and must not
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// be misrepresented as being the original software.
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//
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// 3. This notice may not be removed or altered from any source
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// distribution.
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//
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//------------------------------------------------------------------------
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// $Id: tga.c,v 1.6 2007/03/15 03:20:19 elmindreda Exp $
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//========================================================================
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//========================================================================
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// Description:
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//
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// TGA format image file loader. This module supports version 1 Targa
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// images, with these restrictions:
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// - Pixel format may only be 8, 24 or 32 bits
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// - Colormaps must be no longer than 256 entries
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//
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//========================================================================
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#include "internal.h"
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//************************************************************************
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//**** GLFW internal functions & declarations ****
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//************************************************************************
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//========================================================================
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// TGA file header information
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//========================================================================
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typedef struct {
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int idlen; // 1 byte
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int cmaptype; // 1 byte
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int imagetype; // 1 byte
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int cmapfirstidx; // 2 bytes
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int cmaplen; // 2 bytes
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int cmapentrysize; // 1 byte
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int xorigin; // 2 bytes
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int yorigin; // 2 bytes
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int width; // 2 bytes
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int height; // 2 bytes
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int bitsperpixel; // 1 byte
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int imageinfo; // 1 byte
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int _alphabits; // (derived from imageinfo)
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int _origin; // (derived from imageinfo)
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} _tga_header_t;
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#define _TGA_CMAPTYPE_NONE 0
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#define _TGA_CMAPTYPE_PRESENT 1
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#define _TGA_IMAGETYPE_NONE 0
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#define _TGA_IMAGETYPE_CMAP 1
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#define _TGA_IMAGETYPE_TC 2
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#define _TGA_IMAGETYPE_GRAY 3
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#define _TGA_IMAGETYPE_CMAP_RLE 9
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#define _TGA_IMAGETYPE_TC_RLE 10
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#define _TGA_IMAGETYPE_GRAY_RLE 11
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#define _TGA_IMAGEINFO_ALPHA_MASK 0x0f
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#define _TGA_IMAGEINFO_ALPHA_SHIFT 0
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#define _TGA_IMAGEINFO_ORIGIN_MASK 0x30
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#define _TGA_IMAGEINFO_ORIGIN_SHIFT 4
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#define _TGA_ORIGIN_BL 0
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#define _TGA_ORIGIN_BR 1
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#define _TGA_ORIGIN_UL 2
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#define _TGA_ORIGIN_UR 3
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//========================================================================
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// _glfwReadTGAHeader() - Read TGA file header (and check that it is
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// valid)
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//========================================================================
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static int _glfwReadTGAHeader( _GLFWstream *s, _tga_header_t *h )
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{
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unsigned char buf[ 18 ];
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int pos;
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// Read TGA file header from file
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pos = _glfwTellStream( s );
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_glfwReadStream( s, buf, 18 );
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// Interpret header (endian independent parsing)
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h->idlen = (int) buf[0];
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h->cmaptype = (int) buf[1];
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h->imagetype = (int) buf[2];
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h->cmapfirstidx = (int) buf[3] | (((int) buf[4]) << 8);
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h->cmaplen = (int) buf[5] | (((int) buf[6]) << 8);
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h->cmapentrysize = (int) buf[7];
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h->xorigin = (int) buf[8] | (((int) buf[9]) << 8);
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h->yorigin = (int) buf[10] | (((int) buf[11]) << 8);
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h->width = (int) buf[12] | (((int) buf[13]) << 8);
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h->height = (int) buf[14] | (((int) buf[15]) << 8);
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h->bitsperpixel = (int) buf[16];
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h->imageinfo = (int) buf[17];
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// Extract alphabits and origin information
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h->_alphabits = (int) (h->imageinfo & _TGA_IMAGEINFO_ALPHA_MASK) >>
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_TGA_IMAGEINFO_ALPHA_SHIFT;
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h->_origin = (int) (h->imageinfo & _TGA_IMAGEINFO_ORIGIN_MASK) >>
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_TGA_IMAGEINFO_ORIGIN_SHIFT;
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// Validate TGA header (is this a TGA file?)
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if( (h->cmaptype == 0 || h->cmaptype == 1) &&
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((h->imagetype >= 1 && h->imagetype <= 3) ||
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(h->imagetype >= 9 && h->imagetype <= 11)) &&
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(h->bitsperpixel == 8 || h->bitsperpixel == 24 ||
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h->bitsperpixel == 32) )
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{
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// Skip the ID field
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_glfwSeekStream( s, h->idlen, SEEK_CUR );
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// Indicate that the TGA header was valid
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return GL_TRUE;
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}
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else
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{
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// Restore file position
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_glfwSeekStream( s, pos, SEEK_SET );
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// Indicate that the TGA header was invalid
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return GL_FALSE;
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}
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}
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//========================================================================
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// _glfwReadTGA_RLE() - Read Run-Length Encoded data
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//========================================================================
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static void _glfwReadTGA_RLE( unsigned char *buf, int size, int bpp,
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_GLFWstream *s )
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{
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int repcount, bytes, k, n;
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unsigned char pixel[ 4 ];
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char c;
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// Dummy check
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if( bpp > 4 )
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{
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return;
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}
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while( size > 0 )
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{
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// Get repetition count
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_glfwReadStream( s, &c, 1 );
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repcount = (unsigned int) c;
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bytes = ((repcount & 127) + 1) * bpp;
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if( size < bytes )
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{
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bytes = size;
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}
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// Run-Length packet?
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if( repcount & 128 )
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{
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_glfwReadStream( s, pixel, bpp );
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for( n = 0; n < (repcount & 127) + 1; n ++ )
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{
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for( k = 0; k < bpp; k ++ )
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{
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*buf ++ = pixel[ k ];
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}
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}
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}
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else
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{
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// It's a Raw packet
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_glfwReadStream( s, buf, bytes );
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buf += bytes;
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}
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size -= bytes;
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}
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}
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//========================================================================
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// _glfwReadTGA() - Read a TGA image from a file
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//========================================================================
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int _glfwReadTGA( _GLFWstream *s, GLFWimage *img, int flags )
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{
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_tga_header_t h;
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unsigned char *cmap, *pix, tmp, *src, *dst;
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int cmapsize, pixsize, pixsize2;
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int bpp, bpp2, k, m, n, swapx, swapy;
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// Read TGA header
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if( !_glfwReadTGAHeader( s, &h ) )
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{
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return 0;
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}
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// Is there a colormap?
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cmapsize = (h.cmaptype == _TGA_CMAPTYPE_PRESENT ? 1 : 0) * h.cmaplen *
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((h.cmapentrysize+7) / 8);
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if( cmapsize > 0 )
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{
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// Is it a colormap that we can handle?
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if( (h.cmapentrysize != 24 && h.cmapentrysize != 32) ||
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h.cmaplen == 0 || h.cmaplen > 256 )
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{
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return 0;
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}
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// Allocate memory for colormap
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cmap = (unsigned char *) malloc( cmapsize );
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if( cmap == NULL )
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{
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return 0;
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}
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// Read colormap from file
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_glfwReadStream( s, cmap, cmapsize );
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}
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else
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{
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cmap = NULL;
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}
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// Size of pixel data
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pixsize = h.width * h.height * ((h.bitsperpixel + 7) / 8);
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// Bytes per pixel (pixel data - unexpanded)
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bpp = (h.bitsperpixel + 7) / 8;
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// Bytes per pixel (expanded pixels - not colormap indeces)
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if( cmap )
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{
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bpp2 = (h.cmapentrysize + 7) / 8;
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}
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else
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{
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bpp2 = bpp;
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}
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// For colormaped images, the RGB/RGBA image data may use more memory
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// than the stored pixel data
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pixsize2 = h.width * h.height * bpp2;
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// Allocate memory for pixel data
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pix = (unsigned char *) malloc( pixsize2 );
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if( pix == NULL )
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{
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if( cmap )
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{
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free( cmap );
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}
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return 0;
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}
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// Read pixel data from file
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if( h.imagetype >= _TGA_IMAGETYPE_CMAP_RLE )
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{
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_glfwReadTGA_RLE( pix, pixsize, bpp, s );
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}
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else
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{
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_glfwReadStream( s, pix, pixsize );
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}
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// If the image origin is not what we want, re-arrange the pixels
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switch( h._origin )
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{
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default:
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case _TGA_ORIGIN_UL:
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swapx = 0;
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swapy = 1;
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break;
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case _TGA_ORIGIN_BL:
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swapx = 0;
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swapy = 0;
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break;
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case _TGA_ORIGIN_UR:
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swapx = 1;
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swapy = 1;
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break;
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case _TGA_ORIGIN_BR:
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swapx = 1;
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swapy = 0;
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break;
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}
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if( (swapy && !(flags & GLFW_ORIGIN_UL_BIT)) ||
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(!swapy && (flags & GLFW_ORIGIN_UL_BIT)) )
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{
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src = pix;
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dst = &pix[ (h.height-1)*h.width*bpp ];
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for( n = 0; n < h.height/2; n ++ )
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{
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for( m = 0; m < h.width ; m ++ )
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{
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for( k = 0; k < bpp; k ++ )
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{
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tmp = *src;
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*src ++ = *dst;
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*dst ++ = tmp;
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}
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}
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dst -= 2*h.width*bpp;
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}
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}
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if( swapx )
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{
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src = pix;
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dst = &pix[ (h.width-1)*bpp ];
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for( n = 0; n < h.height; n ++ )
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{
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for( m = 0; m < h.width/2 ; m ++ )
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{
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for( k = 0; k < bpp; k ++ )
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{
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tmp = *src;
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*src ++ = *dst;
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*dst ++ = tmp;
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}
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dst -= 2*bpp;
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}
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src += ((h.width+1)/2)*bpp;
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dst += ((3*h.width+1)/2)*bpp;
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}
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}
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// Convert BGR/BGRA to RGB/RGBA, and optionally colormap indeces to
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// RGB/RGBA values
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if( cmap )
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{
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// Convert colormap pixel format (BGR -> RGB or BGRA -> RGBA)
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if( bpp2 == 3 || bpp2 == 4 )
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{
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for( n = 0; n < h.cmaplen; n ++ )
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{
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tmp = cmap[ n*bpp2 ];
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cmap[ n*bpp2 ] = cmap[ n*bpp2 + 2 ];
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cmap[ n*bpp2 + 2 ] = tmp;
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}
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}
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// Convert pixel data to RGB/RGBA data
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for( m = h.width * h.height - 1; m >= 0; m -- )
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{
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n = pix[ m ];
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for( k = 0; k < bpp2; k ++ )
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{
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pix[ m*bpp2 + k ] = cmap[ n*bpp2 + k ];
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}
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}
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// Free memory for colormap (it's not needed anymore)
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free( cmap );
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}
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else
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{
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// Convert image pixel format (BGR -> RGB or BGRA -> RGBA)
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if( bpp2 == 3 || bpp2 == 4 )
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{
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src = pix;
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dst = &pix[ 2 ];
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for( n = 0; n < h.height * h.width; n ++ )
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{
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tmp = *src;
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*src = *dst;
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*dst = tmp;
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src += bpp2;
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dst += bpp2;
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}
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}
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}
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// Fill out GLFWimage struct (the Format field will be set by
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// glfwReadImage)
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img->Width = h.width;
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img->Height = h.height;
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img->BytesPerPixel = bpp2;
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img->Data = pix;
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return 1;
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}
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