From 83f0125cf83835235154928e7a0ac6783b9e6f23 Mon Sep 17 00:00:00 2001
From: Steve Streeting <steve@stevestreeting.com>
Date: Wed, 8 Nov 2023 11:34:14 +0000
Subject: [PATCH] Add OverlapConvex utility function

---
 .../Private/StevesMathHelpers.cpp             | 45 +++++++++++++++++++
 .../Public/StevesMathHelpers.h                | 19 ++++++++
 .../StevesUEHelpers/StevesUEHelpers.Build.cs  |  4 +-
 3 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 Source/StevesUEHelpers/Private/StevesMathHelpers.cpp

diff --git a/Source/StevesUEHelpers/Private/StevesMathHelpers.cpp b/Source/StevesUEHelpers/Private/StevesMathHelpers.cpp
new file mode 100644
index 0000000..b1b7338
--- /dev/null
+++ b/Source/StevesUEHelpers/Private/StevesMathHelpers.cpp
@@ -0,0 +1,45 @@
+#include "StevesMathHelpers.h"
+
+#include "Chaos/CastingUtilities.h"
+#include "Chaos/GeometryQueries.h"
+
+bool StevesMathHelpers::OverlapConvex(const FKConvexElem& Convex,
+                                      const FTransform& ConvexTransform,
+                                      const FCollisionShape& Shape,
+                                      const FVector& ShapePos,
+                                      const FQuat& ShapeRot,
+                                      FMTDResult& OutResult)
+{
+	const FPhysicsShapeAdapter ShapeAdapter(ShapeRot, Shape);
+	const TSharedPtr<Chaos::FConvex, ESPMode::ThreadSafe>& ChaosConvex = Convex.GetChaosConvexMesh();
+	if (!ChaosConvex.IsValid())
+		return false;
+
+	const Chaos::FImplicitObject& ShapeGeom = ShapeAdapter.GetGeometry();
+	const FTransform& ShapeGeomTransform = ShapeAdapter.GetGeomPose(ShapePos);
+
+	OutResult.Distance = 0;
+
+	bool bHasOverlap = false;
+
+	Chaos::FMTDInfo MTDInfo;
+	if (Chaos::Utilities::CastHelper(ShapeGeom,
+									 ShapeGeomTransform,
+									 [&](const auto& Downcast, const auto& FullGeomTransform)
+									 {
+										 return Chaos::OverlapQuery(*ChaosConvex.Get(),
+																	ConvexTransform,
+																	Downcast,
+																	FullGeomTransform,
+																	/*Thickness=*/
+																	0,
+																	&MTDInfo);
+									 }))
+	{
+		bHasOverlap = true;
+		OutResult.Distance = MTDInfo.Penetration;
+		OutResult.Direction = MTDInfo.Normal;
+	}
+
+	return bHasOverlap;	
+}
diff --git a/Source/StevesUEHelpers/Public/StevesMathHelpers.h b/Source/StevesUEHelpers/Public/StevesMathHelpers.h
index 0805cfe..791f705 100644
--- a/Source/StevesUEHelpers/Public/StevesMathHelpers.h
+++ b/Source/StevesUEHelpers/Public/StevesMathHelpers.h
@@ -1,5 +1,7 @@
 #pragma once
 
+struct FKConvexElem;
+
 /// Helper maths routines that UE4 is missing, all static
 class STEVESUEHELPERS_API StevesMathHelpers
 {
@@ -79,4 +81,21 @@ public:
 		}
 		return false;
 	}
+
+	/**
+	 * Explicitly test the overlap of any collision shape with a convex element.
+	 * @param Convex The convex element
+	 * @param ConvexTransform The world transform of the convex element
+	 * @param Shape The test shape
+	 * @param ShapePos The test shape world position 
+	 * @param ShapeRot The test shape world rotation
+	 * @param OutResult Details of the result if returning true
+	 * @return Whether this shape overlaps the convex element
+	 */
+	static bool OverlapConvex(const FKConvexElem& Convex,
+					   const FTransform& ConvexTransform,
+					   const FCollisionShape& Shape,
+					   const FVector& ShapePos,
+					   const FQuat& ShapeRot,
+					   FMTDResult& OutResult);
 };
\ No newline at end of file
diff --git a/Source/StevesUEHelpers/StevesUEHelpers.Build.cs b/Source/StevesUEHelpers/StevesUEHelpers.Build.cs
index fd53c74..102a76e 100644
--- a/Source/StevesUEHelpers/StevesUEHelpers.Build.cs
+++ b/Source/StevesUEHelpers/StevesUEHelpers.Build.cs
@@ -37,7 +37,9 @@ public class StevesUEHelpers : ModuleRules
 		PrivateDependencyModuleNames.AddRange(
 			new string[]
 			{
-				"RenderCore"
+				"RenderCore",
+				"PhysicsCore",
+				"Chaos"
 			}
 			);