#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "constants.h"
#include "funcdefs.h"

int width, linesize;
FILE *fp;

int startpic(char *fname, int y, int x)
{
	int header[2];
	if ((fp = fopen(fname, "w")) == NULL){
		fprintf(stderr, "fopen() failed\n");
		fflush(stderr);
		return -1;
	}
	
	width = x;
	linesize = 3 * width * sizeof(unsigned char);
	header[0] = y;
	header[1] = x;

	fprintf(fp, "P3\n");	
	fprintf(fp, "%d %d\n", y, x);
	fprintf(fp, "255\n");

	return 0;
}

int linepic(double pixels[SCREENWIDTH][3])
{
	unsigned char buffer[SCREENWIDTH][3];
	int i, r, g, b;
	for (i = 0; i < width; i++) {
		r = gammacorrect(pixels[i][0]);
		g = gammacorrect(pixels[i][1]);
		b = gammacorrect(pixels[i][2]);
		buffer[i][0] = r;
		buffer[i][1] = g;
		buffer[i][2] = b;
		fprintf(fp, "%d %d %d\t",
			buffer[i][0], buffer[i][1], buffer[i][2]);
	}
	fprintf(fp, "\n");
	return 0;
}

int endpic()
{
	fclose(fp);
	return 0;
}

int gammacorrect(double intensity)
{
	int ival;
	double dval;

	dval = intensity / 250.0;
	if (dval > 1.0) dval = 1.0;
	if (dval < 0.001) dval = 0.001;
	dval = exp(log(dval) / GAMMA);
	dval *= 255.0;
	ival = (int)(dval + 0.5);
	return ival;
}