From fb59ba45b31bf8507e72134adec67c2740c40b44 Mon Sep 17 00:00:00 2001
From: Harald Csaszar <harald.csaszar@pixelcloudgames.com>
Date: Wed, 5 Apr 2023 15:42:26 +0200
Subject: [PATCH] [csharp] Fix of incorrect bugfix commit f5fb9b5a. Fixed IK
 constraint NaN when a parent bone has zero scale.

---
 spine-csharp/src/IkConstraint.cs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/spine-csharp/src/IkConstraint.cs b/spine-csharp/src/IkConstraint.cs
index 3d3ed93c7..6a6955ce0 100644
--- a/spine-csharp/src/IkConstraint.cs
+++ b/spine-csharp/src/IkConstraint.cs
@@ -182,7 +182,9 @@ namespace Spine {
 			}
 			default: {
 				float x = targetX - p.worldX, y = targetY - p.worldY;
-				float d = Math.Max(0.0001f, pa * pd - pb * pc);
+				float d = pa * pd - pb * pc;
+				if (d > 0) d = Math.Max(0.0001f, d);
+				else d = Math.Min(-0.0001f, d);
 				tx = (x * pd - y * pb) / d - bone.ax;
 				ty = (y * pa - x * pc) / d - bone.ay;
 				break;
@@ -256,7 +258,9 @@ namespace Spine {
 			b = pp.b;
 			c = pp.c;
 			d = pp.d;
-			float id = 1 / Math.Max(0.0001f, a * d - b * c), x = cwx - pp.worldX, y = cwy - pp.worldY;
+			float id = a * d - b * c, x = cwx - pp.worldX, y = cwy - pp.worldY;
+			if (id > 0) id = 1 / Math.Max(0.0001f, id);
+			else id = 1 / Math.Min(-0.0001f, id);
 			float dx = (x * d - y * b) * id - px, dy = (y * a - x * c) * id - py;
 			float l1 = (float)Math.Sqrt(dx * dx + dy * dy), l2 = child.data.length * csx, a1, a2;
 			if (l1 < 0.0001f) {