textures.h:


typedef struct {
	unsigned int id;
	int num;
	char **data;
} mipmap;

extern int load_texture(char *data, int level, char *file);

extern int load_mipmap(mipmap *mip, char *basename, int size);

extern void free_mipmap(mipmap *mip);


----------------------------------------------------------------------


textures.c:
#include "main.h"



int load_texture(char *data, int level, char *file) {
	FILE *src=fopen(file,"rb");
	int temp;
	char ctemp;
	int size;
	int bytespp;
	int height;
	int width;
	int bpp;

	
	
	if(!src) {
		fprintf(stderr,"load_texture: Unable to open texture file \"%s\"\n",file);
		return -1;
	}


	fseek(src,12,SEEK_SET);
	
	//get texture width
	temp=fgetc(src);
	width=(fgetc(src)<<8)+temp;
	
	//get texture height
	temp=fgetc(src);
	height=(fgetc(src)<<8)+temp;
	
	bpp=fgetc(src);
	if(bpp!=24 && bpp!=32) {
		fprintf(stderr,"load_texture Texture file must be 24 or 32 bits per pixel\n");
		fclose(src);
		return -1;
	}

	fseek(src,1,SEEK_CUR);
	
	bytespp=bpp/8;

	size=width*height*bytespp;

	data=malloc(size);
	
	if(!data) {
		fprintf(stderr,"load_texture: memory\n");
		fclose(src);
		return -1;
	}
	
	if(fread(data,1,size,src)!=size) {
		fprintf(stderr,"load_texture: Error reading texture file\n");
		free(data);
		fclose(src);
		return -1;
	}

	fclose(src);
	
	
	//convert image data from BGR to RGB
	
	for(temp=0;temp<size;temp+=bytespp) {
		ctemp=data[temp];
		data[temp]=data[temp+2];
		data[temp+2]=ctemp;
	}
	
	
	temp=(bpp==24?GL_RGB:GL_RGBA);
	
	//build the texture
	glTexImage2D(GL_TEXTURE_2D,level,temp,width,height,0,temp,GL_UNSIGNED_BYTE,data);

	return 0;
}


int load_mipmap(mipmap *mip, char *basename, int size) {
	char *buffer=malloc(strlen(basename)+3);
	int i;
	int num=0;

	for(i=size;i;i/=2)
		num++;
	
	mip->data=malloc(num*sizeof(char *));


	
	if(!buffer) {
		fprintf(stderr,"load_mipmap: memory\n");
		return -1;
	}
	if(!mip->data) {
		fprintf(stderr,"load_mipmap: memory\n");
		free(buffer);
		return -1;
	}
	
	mip->num=num;

	
	glGenTextures(1,&mip->id);
	glBindTexture(GL_TEXTURE_2D,mip->id);
	
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
	
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
	

	num=0;

	for(i=size;i;i/=2,num++) {
		sprintf(buffer,basename,i);
		
		if(load_texture(mip->data[num],num,buffer)) {
			fprintf(stderr,"load_mipmap: Unable to load mipmap\n",buffer);
			free(buffer);
			free(mip->data);
			return -1;
		}
		free(mip->data[0]);
return 0;
	}


	free(buffer);
	return 0;
}

void free_mipmap(mipmap *mip) {
	int i=0;
		
	for(;i<mip->num;i++) {
		free(mip->data[i]);
	}
	free(mip->data);

}