630 lines
17 KiB
C
630 lines
17 KiB
C
//========================================================================
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// GLFW - An OpenGL framework
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// File: image.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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//========================================================================
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// Description:
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//
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// This module acts as an interface for different image file formats (the
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// image file format is detected automatically).
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//
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// By default the loaded image is rescaled (using bilinear interpolation)
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// to the next higher 2^N x 2^M resolution, unless it has a valid
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// 2^N x 2^M resolution. The interpolation is quite slow, even if the
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// routine has been optimized for speed (a 200x200 RGB image is scaled to
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// 256x256 in ~30 ms on a P3-500).
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//
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// Paletted images are converted to RGB/RGBA images.
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//
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// A convenience function is also included (glfwLoadTexture2D), which
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// loads a texture image from a file directly to OpenGL texture memory,
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// with an option to generate all mipmap levels. GL_SGIS_generate_mipmap
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// is used whenever available, which should give an optimal mipmap
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// generation speed (possibly performed in hardware). A software fallback
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// method is included when GL_SGIS_generate_mipmap is not supported (it
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// generates all mipmaps of a 256x256 RGB texture in ~3 ms on a P3-500).
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//
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//========================================================================
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#include "internal.h"
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// We want to support automatic mipmap generation
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#ifndef GL_SGIS_generate_mipmap
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#define GL_GENERATE_MIPMAP_SGIS 0x8191
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#define GL_GENERATE_MIPMAP_HINT_SGIS 0x8192
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#define GL_SGIS_generate_mipmap 1
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#endif // GL_SGIS_generate_mipmap
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//************************************************************************
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//**** GLFW internal functions ****
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//************************************************************************
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//========================================================================
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// _glfwUpsampleImage() - Upsample image, from size w1 x h1 to w2 x h2
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//========================================================================
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static void _glfwUpsampleImage( unsigned char *src, unsigned char *dst,
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int w1, int h1, int w2, int h2, int bpp )
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{
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int m, n, k, x, y, col8;
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float dx, dy, xstep, ystep, col, col1, col2;
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unsigned char *src1, *src2, *src3, *src4;
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// Calculate scaling factor
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xstep = (float)(w1-1) / (float)(w2-1);
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ystep = (float)(h1-1) / (float)(h2-1);
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// Copy source data to destination data with bilinear interpolation
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// Note: The rather strange look of this routine is a direct result of
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// my attempts at optimizing it. Improvements are welcome!
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dy = 0.0f;
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y = 0;
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for( n = 0; n < h2; n ++ )
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{
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dx = 0.0f;
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src1 = &src[ y*w1*bpp ];
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src3 = y < (h1-1) ? src1 + w1*bpp : src1;
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src2 = src1 + bpp;
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src4 = src3 + bpp;
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x = 0;
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for( m = 0; m < w2; m ++ )
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{
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for( k = 0; k < bpp; k ++ )
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{
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col1 = *src1 ++;
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col2 = *src2 ++;
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col = col1 + (col2 - col1) * dx;
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col1 = *src3 ++;
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col2 = *src4 ++;
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col2 = col1 + (col2 - col1) * dx;
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col += (col2 - col) * dy;
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col8 = (int) (col + 0.5);
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if( col8 >= 256 ) col8 = 255;
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*dst++ = (unsigned char) col8;
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}
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dx += xstep;
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if( dx >= 1.0f )
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{
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x ++;
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dx -= 1.0f;
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if( x >= (w1-1) )
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{
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src2 = src1;
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src4 = src3;
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}
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}
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else
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{
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src1 -= bpp;
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src2 -= bpp;
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src3 -= bpp;
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src4 -= bpp;
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}
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}
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dy += ystep;
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if( dy >= 1.0f )
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{
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y ++;
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dy -= 1.0f;
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}
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}
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}
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//========================================================================
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// _glfwHalveImage() - Build the next mip-map level
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//========================================================================
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static int _glfwHalveImage( GLubyte *src, int *width, int *height,
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int components )
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{
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int halfwidth, halfheight, m, n, k, idx1, idx2;
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GLubyte *dst;
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// Last level?
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if( *width <= 1 && *height <= 1 )
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{
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return GL_FALSE;
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}
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// Calculate new width and height (handle 1D case)
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halfwidth = *width > 1 ? *width / 2 : 1;
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halfheight = *height > 1 ? *height / 2 : 1;
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// Downsample image with a simple box-filter
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dst = src;
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if( *width == 1 || *height == 1 )
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{
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// 1D case
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for( m = 0; m < halfwidth+halfheight-1; m ++ )
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{
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for( k = 0; k < components; k ++ )
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{
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*dst ++ = (GLubyte) (((int)*src +
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(int)src[components] + 1) >> 1);
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src ++;
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}
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src += components;
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}
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}
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else
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{
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// 2D case
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idx1 = *width*components;
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idx2 = (*width+1)*components;
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for( m = 0; m < halfheight; m ++ )
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{
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for( n = 0; n < halfwidth; n ++ )
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{
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for( k = 0; k < components; k ++ )
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{
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*dst ++ = (GLubyte) (((int)*src +
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(int)src[components] +
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(int)src[idx1] +
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(int)src[idx2] + 2) >> 2);
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src ++;
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}
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src += components;
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}
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src += components * (*width);
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}
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}
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// Return new width and height
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*width = halfwidth;
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*height = halfheight;
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return GL_TRUE;
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}
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//========================================================================
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// _glfwRescaleImage() - Rescales an image into power-of-two dimensions
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//========================================================================
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static int _glfwRescaleImage( GLFWimage* image )
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{
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int width, height, log2, newsize;
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unsigned char *data;
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// Calculate next larger 2^N width
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for( log2 = 0, width = image->Width; width > 1; width >>= 1, log2 ++ )
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;
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width = (int) 1 << log2;
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if( width < image->Width )
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{
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width <<= 1;
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}
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// Calculate next larger 2^M height
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for( log2 = 0, height = image->Height; height > 1; height >>= 1, log2 ++ )
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;
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height = (int) 1 << log2;
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if( height < image->Height )
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{
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height <<= 1;
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}
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// Do we really need to rescale?
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if( width != image->Width || height != image->Height )
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{
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// Allocate memory for new (upsampled) image data
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newsize = width * height * image->BytesPerPixel;
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data = (unsigned char *) malloc( newsize );
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if( data == NULL )
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{
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free( image->Data );
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return GL_FALSE;
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}
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// Copy old image data to new image data with interpolation
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_glfwUpsampleImage( image->Data, data, image->Width, image->Height,
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width, height, image->BytesPerPixel );
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// Free memory for old image data (not needed anymore)
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free( image->Data );
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// Set pointer to new image data, and set new image dimensions
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image->Data = data;
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image->Width = width;
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image->Height = height;
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}
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return GL_TRUE;
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}
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//************************************************************************
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//**** GLFW user functions ****
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//************************************************************************
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//========================================================================
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// glfwReadImage() - Read an image from a named file
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//========================================================================
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GLFWAPI int GLFWAPIENTRY glfwReadImage( const char *name, GLFWimage *img,
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int flags )
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{
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_GLFWstream stream;
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// Is GLFW initialized?
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if( !_glfwInitialized )
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{
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return GL_FALSE;
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}
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// Start with an empty image descriptor
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img->Width = 0;
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img->Height = 0;
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img->BytesPerPixel = 0;
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img->Data = NULL;
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// Open file
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if( !_glfwOpenFileStream( &stream, name, "rb" ) )
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{
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return GL_FALSE;
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}
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// We only support TGA files at the moment
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if( !_glfwReadTGA( &stream, img, flags ) )
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{
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_glfwCloseStream( &stream );
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return GL_FALSE;
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}
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// Close stream
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_glfwCloseStream( &stream );
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// Should we rescale the image to closest 2^N x 2^M resolution?
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if( !(flags & GLFW_NO_RESCALE_BIT) )
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{
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if( !_glfwRescaleImage( img ) )
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{
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return GL_FALSE;
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}
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}
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// Interpret BytesPerPixel as an OpenGL format
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switch( img->BytesPerPixel )
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{
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default:
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case 1:
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if( flags & GLFW_ALPHA_MAP_BIT )
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{
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img->Format = GL_ALPHA;
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}
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else
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{
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img->Format = GL_LUMINANCE;
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}
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break;
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case 3:
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img->Format = GL_RGB;
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break;
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case 4:
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img->Format = GL_RGBA;
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break;
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}
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return GL_TRUE;
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}
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//========================================================================
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// glfwReadMemoryImage() - Read an image file from a memory buffer
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//========================================================================
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GLFWAPI int GLFWAPIENTRY glfwReadMemoryImage( const void *data, long size, GLFWimage *img, int flags )
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{
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_GLFWstream stream;
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// Is GLFW initialized?
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if( !_glfwInitialized )
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{
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return GL_FALSE;
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}
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// Start with an empty image descriptor
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img->Width = 0;
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img->Height = 0;
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img->BytesPerPixel = 0;
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img->Data = NULL;
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// Open buffer
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if( !_glfwOpenBufferStream( &stream, (void*) data, size ) )
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{
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return GL_FALSE;
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}
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// We only support TGA files at the moment
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if( !_glfwReadTGA( &stream, img, flags ) )
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{
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_glfwCloseStream( &stream );
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return GL_FALSE;
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}
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// Close stream
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_glfwCloseStream( &stream );
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// Should we rescale the image to closest 2^N x 2^M resolution?
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if( !(flags & GLFW_NO_RESCALE_BIT) )
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{
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if( !_glfwRescaleImage( img ) )
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{
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return GL_FALSE;
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}
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}
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// Interpret BytesPerPixel as an OpenGL format
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switch( img->BytesPerPixel )
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{
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default:
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case 1:
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if( flags & GLFW_ALPHA_MAP_BIT )
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{
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img->Format = GL_ALPHA;
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}
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else
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{
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img->Format = GL_LUMINANCE;
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}
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break;
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case 3:
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img->Format = GL_RGB;
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break;
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case 4:
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img->Format = GL_RGBA;
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break;
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}
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return GL_TRUE;
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}
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//========================================================================
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// glfwFreeImage() - Free allocated memory for an image
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//========================================================================
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GLFWAPI void GLFWAPIENTRY glfwFreeImage( GLFWimage *img )
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{
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// Is GLFW initialized?
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if( !_glfwInitialized )
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{
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return;
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}
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// Free memory
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if( img->Data != NULL )
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{
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free( img->Data );
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img->Data = NULL;
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}
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// Clear all fields
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img->Width = 0;
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img->Height = 0;
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img->Format = 0;
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img->BytesPerPixel = 0;
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}
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//========================================================================
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// glfwLoadTexture2D() - Read an image from a file, and upload it to
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// texture memory
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//========================================================================
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GLFWAPI int GLFWAPIENTRY glfwLoadTexture2D( const char *name, int flags )
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{
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GLFWimage img;
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// Is GLFW initialized?
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if( !_glfwInitialized || !_glfwWin.Opened )
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{
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return GL_FALSE;
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}
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// Force rescaling if necessary
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if( !_glfwWin.Has_GL_ARB_texture_non_power_of_two )
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{
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flags &= (~GLFW_NO_RESCALE_BIT);
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}
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// Read image from file
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if( !glfwReadImage( name, &img, flags ) )
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{
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return GL_FALSE;
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}
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if( !glfwLoadTextureImage2D( &img, flags ) )
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{
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return GL_FALSE;
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}
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// Data buffer is not needed anymore
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glfwFreeImage( &img );
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return GL_TRUE;
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}
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//========================================================================
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// glfwLoadMemoryTexture2D() - Read an image from a buffer, and upload it to
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// texture memory
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//========================================================================
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GLFWAPI int GLFWAPIENTRY glfwLoadMemoryTexture2D( const void *data, long size, int flags )
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{
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GLFWimage img;
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// Is GLFW initialized?
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if( !_glfwInitialized || !_glfwWin.Opened )
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{
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return GL_FALSE;
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}
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// Force rescaling if necessary
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if( !_glfwWin.Has_GL_ARB_texture_non_power_of_two )
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{
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flags &= (~GLFW_NO_RESCALE_BIT);
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}
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// Read image from file
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if( !glfwReadMemoryImage( data, size, &img, flags ) )
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{
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return GL_FALSE;
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}
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if( !glfwLoadTextureImage2D( &img, flags ) )
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{
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return GL_FALSE;
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}
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// Data buffer is not needed anymore
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glfwFreeImage( &img );
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return GL_TRUE;
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}
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//========================================================================
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// glfwLoadTextureImage2D() - Upload an image object to texture memory
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//========================================================================
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GLFWAPI int GLFWAPIENTRY glfwLoadTextureImage2D( GLFWimage *img, int flags )
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{
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GLint UnpackAlignment, GenMipMap;
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int level, format, AutoGen, newsize, n;
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unsigned char *data, *dataptr;
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// Is GLFW initialized?
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if( !_glfwInitialized || !_glfwWin.Opened )
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{
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return GL_FALSE;
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}
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// TODO: Use GL_MAX_TEXTURE_SIZE or GL_PROXY_TEXTURE_2D to determine
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// whether the image size is valid.
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// NOTE: May require box filter downsampling routine.
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// Do we need to convert the alpha map to RGBA format (OpenGL 1.0)?
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if( (_glfwWin.GLVerMajor == 1) && (_glfwWin.GLVerMinor == 0) &&
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(img->Format == GL_ALPHA) )
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{
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// We go to RGBA representation instead
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img->BytesPerPixel = 4;
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// Allocate memory for new RGBA image data
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newsize = img->Width * img->Height * img->BytesPerPixel;
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data = (unsigned char *) malloc( newsize );
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if( data == NULL )
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{
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free( img->Data );
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return GL_FALSE;
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}
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// Convert Alpha map to RGBA
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dataptr = data;
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for( n = 0; n < (img->Width*img->Height); ++ n )
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{
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*dataptr ++ = 255;
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*dataptr ++ = 255;
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*dataptr ++ = 255;
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*dataptr ++ = img->Data[n];
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}
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// Free memory for old image data (not needed anymore)
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free( img->Data );
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// Set pointer to new image data
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img->Data = data;
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}
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// Set unpack alignment to one byte
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glGetIntegerv( GL_UNPACK_ALIGNMENT, &UnpackAlignment );
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glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );
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// Should we use automatic mipmap generation?
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AutoGen = ( flags & GLFW_BUILD_MIPMAPS_BIT ) &&
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_glfwWin.Has_GL_SGIS_generate_mipmap;
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// Enable automatic mipmap generation
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if( AutoGen )
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{
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glGetTexParameteriv( GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,
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&GenMipMap );
|
|
glTexParameteri( GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,
|
|
GL_TRUE );
|
|
}
|
|
|
|
// Format specification is different for OpenGL 1.0
|
|
if( _glfwWin.GLVerMajor == 1 && _glfwWin.GLVerMinor == 0 )
|
|
{
|
|
format = img->BytesPerPixel;
|
|
}
|
|
else
|
|
{
|
|
format = img->Format;
|
|
}
|
|
|
|
// Upload to texture memeory
|
|
level = 0;
|
|
do
|
|
{
|
|
// Upload this mipmap level
|
|
glTexImage2D( GL_TEXTURE_2D, level, format,
|
|
img->Width, img->Height, 0, format,
|
|
GL_UNSIGNED_BYTE, (void*) img->Data );
|
|
|
|
// Build next mipmap level manually, if required
|
|
if( ( flags & GLFW_BUILD_MIPMAPS_BIT ) && !AutoGen )
|
|
{
|
|
level = _glfwHalveImage( img->Data, &img->Width,
|
|
&img->Height, img->BytesPerPixel ) ?
|
|
level + 1 : 0;
|
|
}
|
|
}
|
|
while( level != 0 );
|
|
|
|
// Restore old automatic mipmap generation state
|
|
if( AutoGen )
|
|
{
|
|
glTexParameteri( GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS,
|
|
GenMipMap );
|
|
}
|
|
|
|
// Restore old unpack alignment
|
|
glPixelStorei( GL_UNPACK_ALIGNMENT, UnpackAlignment );
|
|
|
|
return GL_TRUE;
|
|
}
|
|
|