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fixed clutter cos functions; fixed tilt calculations in elliptic path

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This commit is contained in:
Tomas Frydrych
2007-05-29 09:21:18 +00:00
parent 5b845d3940
commit 6e39efb9aa
4 changed files with 37 additions and 25 deletions
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41
clutter/clutter-behaviour-ellipse.c
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@ -111,33 +111,30 @@ clutter_behaviour_ellipse_advance (ClutterBehaviourEllipse * e,
if (e->priv->angle_tilt)
{
/* Problem: sqrti is not giving us sufficient precission here
* and ClutterFixed range is too small to hold x^2+y^2 even for
* reasonable x, y values.
/*
* x2 = r * cos (angle + tilt)
* y2 = r * sin (angle + tilt)
*
* These can be trasformed to the formulas below using properties of
* sin (a + b) and cos (a + b)
*
* We take advantage of sqrt (a * b^2) == sqrt (a) * b,
* and divide repeatedly by 4 until we get it into range, and then
* multiply the result by 2 the same number of times.
*/
ClutterFixed r;
guint q = x*x + y*y;
gint shift = 0;
ClutterFixed x2, y2;
while (q > G_MAXINT16)
{
++shift;
q >>= 2;
}
x2 = x * clutter_cosi (e->priv->angle_tilt) -
y * clutter_sini (e->priv->angle_tilt);
r = clutter_sqrtx (CLUTTER_INT_TO_FIXED (q)) << shift;
x = CFX_INT (CFX_MUL (r, clutter_cosi (angle + e->priv->angle_tilt)));
y = CFX_INT (CFX_MUL (r, clutter_sini (angle + e->priv->angle_tilt)));
y2 = y * clutter_cosi (e->priv->angle_tilt) +
x * clutter_sini (e->priv->angle_tilt);
knot->x = CFX_INT (x2);
knot->y = CFX_INT (y2);
}
else
{
knot->x = x;
knot->y = y;
}
knot->x = x;
knot->y = y;
#if 0
g_debug ("advancing to angle %d [%d, %d] (a: %d, b: %d)",