TextureLoader.cpp

/*!
 * OpenGL 3.2 Utils - Extension to the Angel library (from the book Interactive Computer Graphics 6th ed
 * https://github.com/mortennobel/OpenGL_3_2_Utils
 *
 * New BSD License
 *
 * Copyright (c) 2011, Morten Nobel-Joergensen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
 * disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "TextureLoader.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>

unsigned char * loadBMPRaw(const char * imagepath, unsigned int& outWidth, unsigned int& outHeight, bool flipY){
	printf("Reading image %s\n", imagepath);
	outWidth = -1;
	outHeight = -1;
	// Data read from the header of the BMP file
	unsigned char header[54];
	unsigned int dataPos;
	unsigned int imageSize;
	// Actual RGB data
	unsigned char * data;

	// Open the file
	FILE * file = fopen(imagepath,"rb");
	if (!file)							    {printf("Image could not be opened\n"); return NULL;}

	// Read the header, i.e. the 54 first bytes

	// If less than 54 byes are read, problem
	if ( fread(header, 1, 54, file)!=54 ){ 
		printf("Not a correct BMP file\n");
		return NULL;
	}
	// A BMP files always begins with "BM"
	if ( header[0]!='B' || header[1]!='M' ){
		printf("Not a correct BMP file\n");
		return NULL;
	}
	// Make sure this is a 24bpp file
	if ( *(int*)&(header[0x1E])!=0  )         {printf("Not a correct BMP file\n");    return NULL;}
	if ( *(int*)&(header[0x1C])!=24 )         {printf("Not a correct BMP file\n");    return NULL;}

	// Read the information about the image
	dataPos    = *(int*)&(header[0x0A]);
	imageSize  = *(int*)&(header[0x22]);
	outWidth      = *(int*)&(header[0x12]);
	outHeight     = *(int*)&(header[0x16]);

	// Some BMP files are misformatted, guess missing information
	if (imageSize==0)    imageSize=outWidth*outHeight*3; // 3 : one byte for each Red, Green and Blue component
	if (dataPos==0)      dataPos=54; // The BMP header is done that way

	// Create a buffer
	data = new unsigned char [imageSize];

	// Read the actual data from the file into the buffer
	fread(data,1,imageSize,file);

	// Everything is in memory now, the file wan be closed
	fclose (file);

	if (flipY){
		// swap y-axis
		unsigned char * tmpBuffer = new unsigned char[outWidth*3];
		int size = outWidth*3;
		for (int i=0;i<outHeight/2;i++){
			// copy row i to tmp
			//memcpy_s(tmpBuffer,size,data+outWidth*3*i,size);
            memcpy(tmpBuffer,data+outWidth*3*i,size);
			// copy row h-i-1 to i
			//memcpy_s(data+outWidth*3*i, size, data+outWidth*3*(outHeight-i-1), size);
            memcpy(data+outWidth*3*i, data+outWidth*3*(outHeight-i-1), size);
			// copy tmp to row h-i-1
			//memcpy_s(data+outWidth*3*(outHeight-i-1), size,tmpBuffer, size);
            memcpy(data+outWidth*3*(outHeight-i-1),tmpBuffer, size);
		}
		delete [] tmpBuffer;
	}

	return data;
}


//return red channel for pixel (i,j) of image data, where (i,j) vary between (0,0) and (width,height)
unsigned char getTextureR(int i, int j, unsigned char * data, int width, int height)
{
   return  data[j*width*3+i*3+2];
}

//return green channel for pixel (i,j) of image data, where (i,j) vary between (0,0) and (width,height)
unsigned char getTextureG(int i, int j, unsigned char * data, int width, int height)
{
   return  data[j*width*3+i*3+1];
}

//return blue channel for pixel (i,j) of image data, where (i,j) vary between (0,0) and (width,height)
unsigned char getTextureB(int i, int j, unsigned char * data, int width, int height)
{
   return  data[j*width*3+i*3];
}

//set red channel for pixel (i,j) of image data to val, where (i,j) vary between (0,0) and (width,height) and val varies between 0 and 255
void setTextureR(int i, int j, unsigned char * data, int width, int height, unsigned char val)
{
   data[j*width*3+i*3+2] = val;
}

//set green channel for pixel (i,j) of image data to val, where (i,j) vary between (0,0) and (width,height) and val varies between 0 and 255
void setTextureG(int i, int j, unsigned char * data, int width, int height, unsigned char val)
{
   data[j*width*3+i*3+1] = val;
}

//set blue channel for pixel (i,j) of image data to val, where (i,j) vary between (0,0) and (width,height) and val varies between 0 and 255
void setTextureB(int i, int j, unsigned char * data, int width, int height, unsigned char val)
{
   data[j*width*3+i*3] = val;
}