From 918031892a487e02b46755913bdc75fb0c5a1776 Mon Sep 17 00:00:00 2001 From: Seebs 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