From 918031892a487e02b46755913bdc75fb0c5a1776 Mon Sep 17 00:00:00 2001
From: Seebs <seebs@seebs.net>
Date: Mon, 5 Jun 2017 19:46:16 -0500
Subject: [PATCH] smaller imdraw optimizations
For polyline, don't compute each normal twice; when we're going through a line,
the "next" normal for segment N is always the "previous" normal for segment
N+1, and we can compute fewer of them.
---
imdraw/imdraw.go | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/imdraw/imdraw.go b/imdraw/imdraw.go
index 2fe1fad..0d40452 100644
--- a/imdraw/imdraw.go
+++ b/imdraw/imdraw.go
@@ -543,6 +543,8 @@ func (imd *IMDraw) polyline(thickness float64, closed bool) {
imd.pushPt(points[j].pos.Sub(normal), points[j])
// middle points
+ // compute "previous" normal:
+ ijNormal := points[1].pos.Sub(points[0].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
for i := 0; i < len(points); i++ {
j, k := i+1, i+2
@@ -558,7 +560,6 @@ func (imd *IMDraw) polyline(thickness float64, closed bool) {
k %= len(points)
}
- ijNormal := points[j].pos.Sub(points[i].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
jkNormal := points[k].pos.Sub(points[j].pos).Rotated(math.Pi / 2).Unit().Scaled(thickness / 2)
orientation := 1.0
@@ -589,6 +590,8 @@ func (imd *IMDraw) polyline(thickness float64, closed bool) {
imd.pushPt(points[j].pos.Add(jkNormal), points[j])
imd.pushPt(points[j].pos.Sub(jkNormal), points[j])
}
+ // "next" normal becomes previous normal
+ ijNormal = jkNormal
}
// last point
--
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