From 1630cf0e6c4c278bc4913ecc0ba7503c5ff8eb06 Mon Sep 17 00:00:00 2001
From: Peter Kohaut
Date: Sat, 9 Mar 2019 19:03:18 +0100
Subject: BLADERUNNER: Better fix for bug in pathfinding

Basically just more robust (but slower) fix to the intermittent assert
in pathfinding code when polygons were touching only by a single corner.
---
 engines/bladerunner/obstacles.cpp | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

(limited to 'engines/bladerunner')

diff --git a/engines/bladerunner/obstacles.cpp b/engines/bladerunner/obstacles.cpp
index a0e9d7ab11..66f3f73382 100644
--- a/engines/bladerunner/obstacles.cpp
+++ b/engines/bladerunner/obstacles.cpp
@@ -191,7 +191,6 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
 	bool flagAddVertexToVertexList = true;
 	bool flagDidFindIntersection = false;
 	int vertIndex = 0;
-	int lastIntersectionIndex = -1;
 
 	Polygon *startingPolygon = polyPrimary;
 	int flagDone = false;
@@ -205,7 +204,12 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
 		polyPrimaryType = polyPrimary->vertexType[vertIndex];
 
 		if (flagAddVertexToVertexList) {
-			assert(polyMerged.verticeCount < kPolygonVertexCount);
+			// In some cases polygons will have only one intersection (touching corners) and because of that second SWAP never occure,
+			// algorithm will stop only when the merged polygon is full.
+			if (polyMerged.verticeCount >= kPolygonVertexCount) {
+				flagDidMergePolygons = false;
+				break;
+			}
 			polyMerged.vertices[polyMerged.verticeCount] = polyLine.start;
 			polyMerged.vertexType[polyMerged.verticeCount] = polyPrimaryType;
 			polyMerged.verticeCount++;
@@ -227,15 +231,8 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
 			SWAP(polyPrimary, polySecondary);
 
 			flagDidMergePolygons = true;
-			lastIntersectionIndex = polySecondaryIntersectionIndex;
 		} else {
 			vertIndex = (vertIndex + 1) % polyPrimary->verticeCount;
-			// In some cases polygons will have only one intersection (touching corners) and because of that second SWAP never occure and algorithm will never stop.
-			// This can be avoided by stopping the algorithm after looping over whole polygon. Such polygons will not merge.
-			if (vertIndex == lastIntersectionIndex) {
-				flagDidMergePolygons = false;
-				break;
-			}
 			flagDidFindIntersection = false;
 		}
 		if (polyPrimary->vertices[vertIndex] == startingPolygon->vertices[0]) {
-- 
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