/*
 * Gcalc.c
 * ~~~~~~~
 * This is the calculation function to figure position
 * of object (x,y) at time (time) it uses externaly 
 * defined structure XY which is passed and def.
 * from main module graph.c
 * © Copyright 1991 Christian E. Hopps
*/


#include <exec/types.h>
#include <libraries/mathffp.h>
#include "link:/graph/constants.h"
float CalcGrav();
extern struct MathBase *MathBase;
extern struct MathTransBase *MathTransBase;
extern struct Clip

{
	short clipx1;
	short clipy1;
	short clipx2;
	short clipy2;
};
extern struct XY
{
	float voy;
	float vox;
	float x;
	float y;
	short xp;
	short yp;
	BOOL clipped;
	int scale;
	struct Clip *clip;
};


void Gcalc(time, xy)

struct XY *xy;
float time;

{
float x,y,g,k;
float vox,voy;
vox = xy->vox;
voy = xy->voy;

k = SPFlt(2);
g = SPDiv(SPFlt(xy->scale),4.9);
x = SPMul(vox,
		time
		);

y = SPSub(
		
		SPMul(
				g,
				SPPow(k,time)
			),
		SPMul(
			voy,
			time
			)  
		);

xy->x = x; 
xy->y = y;
}