#include <neofx/physics.h>
#include <neofx/math.h>
#include <math.h>

static VECTOR gravitation = {0, -9.8, 0};


void SetGravitation(VECTOR v) {
	gravitation = v;
}

void ApplyPhysics(OBJECT o, float delta) {
	VERTEX old_pos = o.pos;
	VECTOR old_move = o.move;
	float e;
	
	e = expf(-o.air_resistance*delta);
	
	o.move = VectorAdd(VectorMul(gravitation, 1/o.air_resistance),
	         VectorMul(VectorSub(old_move, VectorMul(gravitation, 1/o.air_resistance)),
	         e));
	
	o.pos = VectorAdd(old_pos, VectorAdd(VectorMul(gravitation, delta/o.air_resistance),
	        VectorMul(VectorSub(old_move, VectorMul(gravitation, 1/o.air_resistance)),
	        (1-e)/o.air_resistance)));
}