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#include<stdio.h>
#include<stdlib.h>
#include"GLheaders.h"


typedef struct{
	char IDsize;
	char colormaptype;
	char imagetype;
	unsigned short colormapstart;
	unsigned short colormaplength;
	unsigned char colormapbits;
	unsigned short xstart;
	unsigned short ystart;
	unsigned short width;
	unsigned short height;
	char bpp;
	char descriptor;
}TGA_HEADER;


GLbyte* LoadTGA(const char *szFileName, GLint *iWidth, GLint *iHeight, GLint *iComponents, GLenum *eFormat){
	
	FILE *data;
	TGA_HEADER header;
	unsigned long imageSize;
	short depth;
	GLbyte *pbits;
	
	//default
	*iWidth = 0;
    *iHeight = 0;
    *eFormat = GL_BGR_EXT;
    *iComponents = GL_RGB8;
	
	data = fopen(szFileName, "rb");
	
	if(data == NULL){
		return NULL;
	}
	
	fread(&header, 18, 1, data);
	
	*iWidth = header.width;
	*iHeight = header.height;
	depth = header.bpp / 8;
	
	if(header.bpp != 8 && header.bpp != 24 && header.bpp != 32){
		return NULL;
	}
	
	imageSize = header.width * header.height * header.bpp;
	
	pbits = (GLbyte*)malloc(imageSize * sizeof(GLbyte));
	
	if(pbits == NULL){
		return NULL;
	}
	
	if(fread(pbits, imageSize, 1, data) != 1)
		{
        free(pbits);
        return NULL;
		}
	
	switch(depth)
		{
        case 3:     // Most likely case
            *eFormat = GL_BGR_EXT;
            *iComponents = GL_RGB8;
            break;
        case 4:
            *eFormat = GL_BGRA_EXT;
            *iComponents = GL_RGBA8;
            break;
        case 1:
            *eFormat = GL_LUMINANCE;
            *iComponents = GL_LUMINANCE8;
            break;
		};
		
		fclose(data);
		
		return pbits;
}