static void
buzztrack_preprocess (PELEMENT ElementPtr)
{
if (ElementPtr->thrust_wait)
--ElementPtr->thrust_wait;
else
{
COUNT facing = 0;
if (ElementPtr->hTarget == 0
&& TrackShip (ElementPtr, &facing) < 0)
{
ZeroVelocityComponents (&ElementPtr->velocity);
}
else
{
#define ACTIVATE_RANGE 224 /* Originally SPACE_WIDTH */
SIZE delta_x, delta_y;
ELEMENTPTR eptr;
LockElement (ElementPtr->hTarget, &eptr);
delta_x = eptr->current.location.x
- ElementPtr->current.location.x;
delta_y = eptr->current.location.y
- ElementPtr->current.location.y;
UnlockElement (ElementPtr->hTarget);
delta_x = WRAP_DELTA_X (delta_x);
delta_y = WRAP_DELTA_Y (delta_y);
facing = NORMALIZE_FACING (
ANGLE_TO_FACING (ARCTAN (delta_x, delta_y))
);
if (delta_x < 0)
delta_x = -delta_x;
if (delta_y < 0)
delta_y = -delta_y;
delta_x = WORLD_TO_DISPLAY (delta_x);
delta_y = WORLD_TO_DISPLAY (delta_y);
if (delta_x >= ACTIVATE_RANGE
|| delta_y >= ACTIVATE_RANGE
|| (DWORD)((UWORD)delta_x * delta_x)
+ (DWORD)((UWORD)delta_y * delta_y) >=
(DWORD)ACTIVATE_RANGE * ACTIVATE_RANGE)
{
ZeroVelocityComponents (&ElementPtr->velocity);
}
else
{
ElementPtr->thrust_wait = TRACK_WAIT;
SetVelocityVector (&ElementPtr->velocity,
DISPLAY_TO_WORLD (2), facing);
}
}
}
spin_preprocess (ElementPtr);
}
static void
decelerate_preprocess (ELEMENT *ElementPtr)
{
SIZE dx, dy;
GetCurrentVelocityComponents (&ElementPtr->velocity, &dx, &dy);
dx /= 2;
dy /= 2;
SetVelocityComponents (&ElementPtr->velocity, dx, dy);
if (dx == 0 && dy == 0)
{
ElementPtr->preprocess_func = buzztrack_preprocess;
}
spin_preprocess (ElementPtr);
}
