From e4eb093c62044cdce05ada0e0a42011c7e6628cf Mon Sep 17 00:00:00 2001
From: Ferenc Arn <tagcup@yahoo.com>
Date: Sun, 21 May 2017 14:55:21 -0500
Subject: [PATCH] Avoid overestimating the cost in AStar heuristics.

This is a necessary condition for finding optimal solutions.
This is achieved by simply requiring/ensuring that no weights are smaller than 1.

Fixes #8584.
---
 core/math/a_star.cpp | 2 +-
 doc/base/classes.xml | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/core/math/a_star.cpp b/core/math/a_star.cpp
index 7e061359fcf..fa84144271f 100644
--- a/core/math/a_star.cpp
+++ b/core/math/a_star.cpp
@@ -43,6 +43,7 @@ int AStar::get_available_point_id() const {
 
 void AStar::add_point(int p_id, const Vector3 &p_pos, real_t p_weight_scale) {
 	ERR_FAIL_COND(p_id < 0);
+	ERR_FAIL_COND(p_weight_scale < 1);
 	if (!points.has(p_id)) {
 		Point *pt = memnew(Point);
 		pt->id = p_id;
@@ -221,7 +222,6 @@ bool AStar::_solve(Point *begin_point, Point *end_point) {
 
 			real_t cost = p->distance;
 			cost += _estimate_cost(p->id, end_point->id);
-			cost *= p->weight_scale;
 
 			if (cost < least_cost) {
 
diff --git a/doc/base/classes.xml b/doc/base/classes.xml
index a04890d4fde..da614e14d30 100644
--- a/doc/base/classes.xml
+++ b/doc/base/classes.xml
@@ -1991,6 +1991,7 @@
 			<argument index="1" name="pos" type="Vector3">
 			</argument>
 			<argument index="2" name="weight_scale" type="float" default="1">
+				Weight scale has to be 1 or larger.
 			</argument>
 			<description>
 			</description>