Commit: fa5508b91eeaa7b7413e142d8f64812e74b665f3
Author: Campbell Barton
Date: Mon May 16 07:35:44 2016 +1000
Branches: compositor-2016
https://developer.blender.org/rBfa5508b91eeaa7b7413e142d8f64812e74b665f3
Curve Fitting: correct circular tangent length calculation
Method for scaling is still not perfect but quite close.
===================================================================
M extern/curve_fit_nd/intern/curve_fit_cubic.c
===================================================================
diff --git a/extern/curve_fit_nd/intern/curve_fit_cubic.c
b/extern/curve_fit_nd/intern/curve_fit_cubic.c
index b977634..473e4ca 100644
--- a/extern/curve_fit_nd/intern/curve_fit_cubic.c
+++ b/extern/curve_fit_nd/intern/curve_fit_cubic.c
@@ -429,14 +429,43 @@ static double points_calc_circumference_factor(
* (tangents that point away from each other).
* We could try support this but will likely cause extreme >1
scales which could cause other issues. */
// assert(angle >= len_tangent);
- double factor = (angle / len_tangent) / (M_PI / 2);
- factor = 1.0 - pow(1.0 - factor, 1.75);
- assert(factor < 1.0 + DBL_EPSILON);
+ double factor = (angle / len_tangent);
+ assert(factor < (M_PI / 2) + DBL_EPSILON);
return factor;
}
else {
/* tangents are exactly aligned (think two opposite sides of a
circle). */
- return 1.0;
+ return (M_PI / 2);
+ }
+}
+
+/**
+ * Return the value which the distance between points will need to be scaled
by,
+ * to define a handle, given both points are on a perfect circle.
+ *
+ * \note the return value will need to be multiplied by 1.3... for correct
results.
+ */
+static double points_calc_circle_tangent_factor(
+ const double tan_l[],
+ const double tan_r[],
+ const uint dims)
+{
+ const double angle_sin = len_vnvn(tan_l, tan_r, dims) / 2.0;
+ if (angle_sin != 0.0) {
+ const double tan_dot = dot_vnvn(tan_l, tan_r, dims);
+ double scale;
+ if (tan_dot > -1.0) {
+ const double angle = acos(tan_dot) / 2.0;
+ const double angle_cos = cos(angle);
+ scale = (1.0 - angle_cos) / (angle_sin * 2.0);
+ }
+ else {
+ scale = 1.0 / 2.0;
+ }
+ return (scale / angle_sin);
+ }
+ else {
+ return (1.0 / 3.0) * 0.75;
}
}
@@ -451,9 +480,20 @@ static double points_calc_cubic_scale(
const double coords_length, uint dims)
{
const double len_direct = len_vnvn(v_l, v_r, dims);
- const double len_circle_factor =
points_calc_circumference_factor(tan_l, tan_r, dims) * 1.75;
- const double len_points = min(coords_length, len_circle_factor *
len_direct);
- return (len_direct + ((len_points - len_direct) * len_circle_factor)) /
3.0;
+ const double len_circle_factor =
points_calc_circle_tangent_factor(tan_l, tan_r, dims);
+
+ /* if this curve is a circle, this value doesn't need modification */
+ const double len_circle_handle = (len_direct * (len_circle_factor /
0.75));
+
+ /* scale by the difference from the circumference distance */
+ const double len_circle = len_direct *
points_calc_circumference_factor(tan_l, tan_r, dims);
+ double scale_handle = (coords_length / len_circle);
+
+ /* Could investigate an accurate calculation here,
+ * though this gives close results */
+ scale_handle = ((scale_handle - 1.0) * 1.75) + 1.0;
+
+ return len_circle_handle * scale_handle;
}
static void cubic_from_points_fallback(
_______________________________________________
Bf-blender-cvs mailing list
[email protected]
https://lists.blender.org/mailman/listinfo/bf-blender-cvs
