From a32319d59838ad845b305f3e62d458ad1c229ffa Mon Sep 17 00:00:00 2001
From: Gavin Nishizawa <gavin@terrastruct.com>
Date: Wed, 12 Jul 2023 15:30:41 -0700
Subject: [PATCH] fix dagre_broken_arrowhead

---
 d2graph/layout.go                 | 8 ++++----
 d2layouts/d2dagrelayout/layout.go | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/d2graph/layout.go b/d2graph/layout.go
index 4b53cee12..05ef65fb0 100644
--- a/d2graph/layout.go
+++ b/d2graph/layout.go
@@ -346,7 +346,7 @@ func (edge *Edge) TraceToShape(points []*geo.Point, startIndex, endIndex int) (n
 				points[startIndex] = p
 				startingSegment.End = p
 				// if the segment becomes too short, just merge it with the next segment
-				if startIndex+1 < len(points)-1 && startingSegment.Length() < MIN_SEGMENT_LEN {
+				if startIndex+1 < endIndex && startingSegment.Length() < MIN_SEGMENT_LEN {
 					points[startIndex+1] = points[startIndex]
 					startIndex++
 				}
@@ -359,7 +359,7 @@ func (edge *Edge) TraceToShape(points []*geo.Point, startIndex, endIndex int) (n
 			points[startIndex] = intersections[0]
 			startingSegment.End = intersections[0]
 			// if the segment becomes too short, just merge it with the next segment
-			if startIndex+1 < len(points)-1 && startingSegment.Length() < MIN_SEGMENT_LEN {
+			if startIndex+1 < endIndex && startingSegment.Length() < MIN_SEGMENT_LEN {
 				points[startIndex+1] = points[startIndex]
 				startIndex++
 			}
@@ -391,7 +391,7 @@ func (edge *Edge) TraceToShape(points []*geo.Point, startIndex, endIndex int) (n
 				points[endIndex] = p
 				endingSegment.End = p
 				// if the segment becomes too short, just merge it with the previous segment
-				if endIndex-1 > 0 && endingSegment.Length() < MIN_SEGMENT_LEN {
+				if endIndex-1 > startIndex && endingSegment.Length() < MIN_SEGMENT_LEN {
 					points[endIndex-1] = points[endIndex]
 					endIndex--
 				}
@@ -404,7 +404,7 @@ func (edge *Edge) TraceToShape(points []*geo.Point, startIndex, endIndex int) (n
 			points[endIndex] = intersections[0]
 			endingSegment.End = intersections[0]
 			// if the segment becomes too short, just merge it with the previous segment
-			if endIndex-1 > 0 && endingSegment.Length() < MIN_SEGMENT_LEN {
+			if endIndex-1 > startIndex && endingSegment.Length() < MIN_SEGMENT_LEN {
 				points[endIndex-1] = points[endIndex]
 				endIndex--
 			}
diff --git a/d2layouts/d2dagrelayout/layout.go b/d2layouts/d2dagrelayout/layout.go
index cea99951f..6949f7179 100644
--- a/d2layouts/d2dagrelayout/layout.go
+++ b/d2layouts/d2dagrelayout/layout.go
@@ -273,7 +273,7 @@ func Layout(ctx context.Context, g *d2graph.Graph, opts *ConfigurableOpts) (err
 
 		// arrowheads can appear broken if segments are very short from dagre routing a point just outside the shape
 		// to fix this, we try extending the previous segment into the shape instead of having a very short segment
-		if !start.Equals(points[0]) && startIndex+2 < len(points) {
+		if startIndex+2 < len(points) {
 			newStartingSegment := *geo.NewSegment(start, points[startIndex+1])
 			if newStartingSegment.Length() < d2graph.MIN_SEGMENT_LEN {
 				// we don't want a very short segment right next to the source because it will mess up the arrowhead
@@ -294,7 +294,7 @@ func Layout(ctx context.Context, g *d2graph.Graph, opts *ConfigurableOpts) (err
 				}
 			}
 		}
-		if !end.Equals(points[len(points)-1]) && endIndex-2 >= 0 {
+		if endIndex-2 >= 0 {
 			newEndingSegment := *geo.NewSegment(end, points[endIndex-1])
 			if newEndingSegment.Length() < d2graph.MIN_SEGMENT_LEN {
 				// extend the prev segment into the shape border if possible