vect2_t d;v2_dir(&ship1->position, &ship2->position, &d);vect2_t dv = ship1->velocity;v2_sub(&dv, &ship2->velocity);// calculating the impulse as a projection of// ship velocities on the line going through their centres// At least this is what I think I''m doingfloat k = v2_dot(&d, &dv);// projecting it backvect2_t r = d;v2_mul(&r, k);// Adding the impulse (mass = 1, so forget it) to the ship velocitiesv2_sub(&ship1->velocity, &r);v2_add(&ship2->velocity, &r);  

  struct ship_t{	vect2_t position;	vect2_t velocity;// and so on};  

  struct vect2_t{	float x;	float y;};  

  // ugly, but simplevoid v2_add(vect2_t *v1, vect2_t *v2){	v1->x += v2->x;	v1->y += v2->y;}void v2_sub(vect2_t *v1, vect2_t *v2){	v1->x -= v2->x;	v1->y -= v2->y;}void v2_mul(vect2_t *v, float a){	v->x *= a;	v->y *= a;}// make unit vector showing the direction from v1 to v2void v2_dir(vect2_t *v1, vect2_t *v2, vect2_t *d){	float dx = v2->x - v1->x;	float dy = v2->y - v1->y;	float l = sqrt(dx * dx + dy * dy);	d->x = dx / l;	d->y = dy / l;}// dot productfloat v2_dot(vect2_t *v1, vect2_t *v2){	return v1->x * v2->x + v1->y * v2->y;}