From eb548d13d886d72f89f18241347497a889f93ddb Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Thu, 19 Jan 2023 11:52:30 +0100
Subject: [PATCH] Added plane and center point to face struct, for early
 backface culling.

---
 main.cpp | 23 +++++++++++++++++++++--
 ps1bsp.h |  5 +++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/main.cpp b/main.cpp
index 096dfbe..c34657d 100644
--- a/main.cpp
+++ b/main.cpp
@@ -280,6 +280,16 @@ static SVECTOR convertNormal(vec3_t normal)
 	return outNormal;
 }
 
+static SVECTOR convertPoint(vec3_t point)
+{
+	SVECTOR outPoint;
+	outPoint.vx = (short)(point.x * 4);
+	outPoint.vy = (short)(point.y * 4);
+	outPoint.vz = (short)(point.z * 4);
+	outPoint.pad = 1;
+	return outPoint;
+}
+
 int process_faces(const world_t* world)
 {
 	// Write some data to a file
@@ -324,8 +334,12 @@ int process_faces(const world_t* world)
 		face_t* face = &world->faces[faceIdx];
 
 		ps1bsp_face_t outFace = { 0 };
+		outFace.planeId = face->plane_id;
+		outFace.side = face->side;
 		outFace.firstFaceVertex = (unsigned short)outFaceVertices.size();
 
+		Vec3 vertexSum;
+
 		// Traverse the list of face edges to collect all of the face's vertices
 		BoundBox bounds;
 		for (int edgeListIdx = 0; edgeListIdx < face->ledge_num; ++edgeListIdx)
@@ -343,10 +357,14 @@ int process_faces(const world_t* world)
 
 			// Calculate bounding box of this face
 			const vertex_t* vertex = &world->vertices[vertIndex];
+			Vec3 vertexPoint = vertex->toVec();
 			if (edgeListIdx == 0)
-				bounds.init(vertex->toVec());
+				bounds.init(vertexPoint);
 			else
-				bounds.includePoint(vertex->toVec());
+				bounds.includePoint(vertexPoint);
+
+			// Sum all vertices to calculate an average center point
+			vertexSum = vertexSum + vertexPoint;
 		}
 
 		// Sample lightmap contribution of this face on each vertex
@@ -369,6 +387,7 @@ int process_faces(const world_t* world)
 		//	export_lightmap(world, face, bounds, faceIdx);
 
 		outFace.numFaceVertices = (unsigned short)(outFaceVertices.size() - outFace.firstFaceVertex);
+		outFace.centerPoint = convertPoint(vertexSum / outFace.numFaceVertices);
 		outFaces.push_back(outFace);
 	}
 
diff --git a/ps1bsp.h b/ps1bsp.h
index 1fbf7e3..f840c67 100644
--- a/ps1bsp.h
+++ b/ps1bsp.h
@@ -71,9 +71,14 @@ typedef struct
 
 typedef struct
 {
+	unsigned short planeId;
+	unsigned short side;
+
 	unsigned short firstFaceVertex;
 	unsigned short numFaceVertices;
 
+	SVECTOR centerPoint;
+
 	u_long drawFrame;	// Which frame was this face last drawn on? Used to check if this face should be drawn.
 } ps1bsp_face_t;