#include <math.h>
#include "typedefs.h"
#include "funcdefs.h"
#include "globalvar.h"

#define PI 3.14159261
#define DEGREETORADIAN(x) (x * PI / 180.0)

int viewing(t_3d *scrnx, t_3d *scrny, t_3d *firstray)
{
	t_3d gaze;
	double dist, magnitude;

	gaze.x = firstray->x = lookp.x - eyep.x;
	gaze.y = firstray->y = lookp.y - eyep.y;
	gaze.z = firstray->z = lookp.z - eyep.z;

	dist = normalize(&gaze);
	/* printf("dist = %f\n", dist); exit(0); */

	crossp(scrnx, &gaze, &up);
	normalize(scrnx);
	crossp(scrny, scrnx, &gaze);
	normalize(scrny);

	magnitude = 2.0 * dist * tan(DEGREETORADIAN(hfov / 2.0)) / sizex;
	scrnx->x *= magnitude;
	scrnx->y *= magnitude;
	scrnx->z *= magnitude;

	magnitude = 2.0 * dist * tan(DEGREETORADIAN(vfov / 2.0)) / sizey;
	scrny->x *= magnitude;
	scrny->y *= magnitude;
	scrny->z *= magnitude;

	firstray->x += sizey / 2.0 * scrny->x - sizex / 2.0 * scrnx->x; 
	firstray->y += sizey / 2.0 * scrny->y - sizex / 2.0 * scrnx->y; 
	firstray->z += sizey / 2.0 * scrny->z - sizex / 2.0 * scrnx->z;

	return 0;
}