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authorStanislaw Halik <sthalik@misaki.pl>2016-10-29 23:09:42 +0200
committerStanislaw Halik <sthalik@misaki.pl>2016-10-29 23:09:42 +0200
commitcea0ec20e60e31b998c08cbae96c4601758f101f (patch)
tree688cd75505e92767087d3de6364e15f6104fb371 /spline-widget/spline.cpp
parent031ef4c3b2ede47b30f69718fb1c0b9c4cfc1bf1 (diff)
spline-widget: don't compute the same thing over and over again
Diffstat (limited to 'spline-widget/spline.cpp')
-rw-r--r--spline-widget/spline.cpp30
1 files changed, 18 insertions, 12 deletions
diff --git a/spline-widget/spline.cpp b/spline-widget/spline.cpp
index 1bd57f89..4742bdc8 100644
--- a/spline-widget/spline.cpp
+++ b/spline-widget/spline.cpp
@@ -188,13 +188,27 @@ void spline::update_interp_data()
for (int i = 0; i < points.size(); i++)
{
const QPointF p0 = ensure_in_bounds(points, i - 1);
- const QPointF p1 = ensure_in_bounds(points, i);
+ const QPointF p1 = ensure_in_bounds(points, i + 0);
const QPointF p2 = ensure_in_bounds(points, i + 1);
const QPointF p3 = ensure_in_bounds(points, i + 2);
-
const double p0_x = p0.x(), p1_x = p1.x(), p2_x = p2.x(), p3_x = p3.x();
const double p0_y = p0.y(), p1_y = p1.y(), p2_y = p2.y(), p3_y = p3.y();
+ const double cx[4] = {
+ 2 * p1_x, // 1
+ -p0_x + p2_x, // t
+ 2 * p0_x - 5 * p1_x + 4 * p2_x - p3_x, // t^2
+ -p0_x + 3 * p1_x - 3 * p2_x + p3_x, // t3
+ };
+
+ const double cy[4] =
+ {
+ 2 * p1_y, // 1
+ -p0_y + p2_y, // t
+ 2 * p0_y - 5 * p1_y + 4 * p2_y - p3_y, // t^2
+ -p0_y + 3 * p1_y - 3 * p2_y + p3_y, // t3
+ };
+
// multiplier helps fill in all the x's needed
const unsigned end = std::min(unsigned(value_count), unsigned(p2_x * mult_));
const unsigned start = std::max(0u, unsigned(p1_x * mult));
@@ -205,16 +219,8 @@ void spline::update_interp_data()
const double t2 = t*t;
const double t3 = t*t*t;
- const int x = int(.5 * ((2 * p1_x) +
- (-p0_x + p2_x) * t +
- (2 * p0_x - 5 * p1_x + 4 * p2_x - p3_x) * t2 +
- (-p0_x + 3 * p1_x - 3 * p2_x + p3_x) * t3)
- * mult);
-
- const float y = float(.5 * ((2 * p1_y) +
- (-p0_y + p2_y) * t +
- (2 * p0_y - 5 * p1_y + 4 * p2_y - p3_y) * t2 +
- (-p0_y + 3 * p1_y - 3 * p2_y + p3_y) * t3));
+ const int x = iround(.5 * mult * (cx[0] + cx[1] * t + cx[2] * t2 + cx[3] * t3));
+ const float y = float(.5 * (cy[0] + cy[1] * t + cy[2] * t2 + cy[3] * t3));
if (x >= 0 && x < value_count)
data[unsigned(x)] = y;