From 759320b189fe97796baa66c294ca400797f8d94f Mon Sep 17 00:00:00 2001
From: RaveYard <29225776+MrRaveYard@users.noreply.github.com>
Date: Wed, 6 Sep 2023 14:30:57 +0200
Subject: [PATCH] CPU tracelight portal fix

---
 .../rendering/hwrenderer/data/hw_levelmesh.h  | 46 +++++++++++++++++--
 src/rendering/hwrenderer/doom_levelmesh.h     |  8 +---
 .../hwrenderer/scene/hw_spritelight.cpp       |  2 +-
 3 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/src/common/rendering/hwrenderer/data/hw_levelmesh.h b/src/common/rendering/hwrenderer/data/hw_levelmesh.h
index 9a3648c63..bd9b7555c 100644
--- a/src/common/rendering/hwrenderer/data/hw_levelmesh.h
+++ b/src/common/rendering/hwrenderer/data/hw_levelmesh.h
@@ -199,10 +199,50 @@ public:
 	FVector3 SunColor = FVector3(0.0f, 0.0f, 0.0f);
 	uint16_t LightmapSampleDistance = 16;
 
-	bool Trace(const FVector3& start, FVector3 direction, float maxDist)
+	LevelMeshSurface* Trace(const FVector3& start, FVector3 direction, float maxDist)
 	{
-		FVector3 end = start + direction * std::max(maxDist - 10.0f, 0.0f);
-		return !TriangleMeshShape::find_any_hit(Collision.get(), start, end);
+		maxDist = std::max(maxDist - 10.0f, 0.0f);
+
+		FVector3 origin = start;
+		FVector3 end;
+
+		auto collision = Collision.get();
+
+		LevelMeshSurface* hitSurface = nullptr;
+
+		while (true)
+		{
+			end = origin + direction * maxDist;
+
+			auto hit = TriangleMeshShape::find_first_hit(collision, origin, end);
+
+			if (hit.triangle < 0)
+			{
+				return nullptr;
+			}
+
+			hitSurface = GetSurface(MeshSurfaceIndexes[hit.triangle]);
+			auto portal = hitSurface->portalIndex;
+
+			if (!portal)
+			{
+				break;
+			}
+
+			auto& transformation = Portals[portal];
+
+			auto travelDist = hit.fraction * maxDist + 2.0f;
+			if (travelDist >= maxDist)
+			{
+				break;
+			}
+
+			origin = transformation.TransformPosition(origin + direction * travelDist);
+			direction = transformation.TransformRotation(direction);
+			maxDist -= travelDist;
+		}
+
+		return hitSurface; // I hit something
 	}
 
 	void BuildSmoothingGroups()
diff --git a/src/rendering/hwrenderer/doom_levelmesh.h b/src/rendering/hwrenderer/doom_levelmesh.h
index 8205337e2..603a0f240 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.h
+++ b/src/rendering/hwrenderer/doom_levelmesh.h
@@ -31,12 +31,8 @@ public:
 	bool TraceSky(const FVector3& start, FVector3 direction, float dist)
 	{
 		FVector3 end = start + direction * dist;
-		TraceHit hit = TriangleMeshShape::find_first_hit(Collision.get(), start, end);
-		if (hit.fraction == 1.0f)
-			return true;
-
-		int surfaceIndex = MeshSurfaceIndexes[hit.triangle];
-		return Surfaces[surfaceIndex].bSky;
+		auto surface = Trace(start, direction, dist);
+		return surface && surface->bSky;
 	}
 
 	void UpdateLightLists() override;
diff --git a/src/rendering/hwrenderer/scene/hw_spritelight.cpp b/src/rendering/hwrenderer/scene/hw_spritelight.cpp
index c1cfd306f..dc2f3a3b3 100644
--- a/src/rendering/hwrenderer/scene/hw_spritelight.cpp
+++ b/src/rendering/hwrenderer/scene/hw_spritelight.cpp
@@ -74,7 +74,7 @@ public:
 		}
 		else
 		{
-			bool traceResult = level.levelMesh->Trace(FVector3((float)light->Pos.X, (float)light->Pos.Y, (float)light->Pos.Z), FVector3(-L.X, -L.Y, -L.Z), dist);
+			bool traceResult = !level.levelMesh->Trace(FVector3((float)light->Pos.X, (float)light->Pos.Y, (float)light->Pos.Z), FVector3(-L.X, -L.Y, -L.Z), dist);
 			Actor->StaticLightsTraceCache.Bits |= ((uint64_t)traceResult) << CurrentBit;
 			CurrentBit++;
 			return traceResult;