Create a reusable texture space transform matrix per face, and use it to build up the texture boundaries.

lighting.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "bsp.h"
+#include "matrix.h"
 
 struct EdgeData
 {
@@ -18,15 +19,12 @@ struct Surface
 struct FaceBound
 {
 	BoundBox worldBounds;
-	double minS = DBL_MAX, minT = DBL_MAX;
-	double maxS = DBL_MIN, maxT = DBL_MIN;
+	Matrix4x4 textureTransform;
+	BoundBox textureBounds;
 
 	void addTexturePoint(double s, double t)
 	{
-		if (s < minS) minS = s;
-		if (s > maxS) maxS = s;
-		if (t < minT) minT = t;
-		if (t > maxT) maxT = t;
+		textureBounds.includePoint(Vec3(s, t, 0.0));
 	}
 };
 

main.cpp

@@ -111,11 +111,11 @@ int process_faces(const world_t* world, const TextureList& textures)
 		outFace.firstFaceVertex = (unsigned short)outFaceVertices.size();
 		outFace.textureId = (unsigned char)texinfo->texture_id;
 
-		Matrix4x4 textureTrsf = tesselator.buildTextureSpaceTransform(texinfo, miptex, plane);
+		FaceBound bounds;
+		bounds.textureTransform = tesselator.buildTextureSpaceTransform(texinfo, miptex, plane);
 
 		// Traverse the list of face edges to collect all of the face's vertices
 		Vec3 vertexSum;
-		FaceBound bounds;
 		for (int edgeListIdx = 0; edgeListIdx < face->ledge_num; ++edgeListIdx)
 		{
 			int edgeIdx = world->edgeList[face->ledge_id + edgeListIdx];
@@ -133,7 +133,7 @@ int process_faces(const world_t* world, const TextureList& textures)
 			else
 				bounds.worldBounds.includePoint(vertexPoint);
 
-			Vec3 texturePoint = textureTrsf.TransformPoint(vertexPoint);
+			Vec3 texturePoint = bounds.textureTransform.TransformPoint(vertexPoint);
 			bounds.addTexturePoint(texturePoint.x, texturePoint.y);
 
 			// Sum all vertices to calculate an average center point

matrix.h

@@ -39,7 +39,7 @@ public:
 		m[14] = value.z;
 	}
 
-	Vec3 TransformPoint(const Vec3& point)
+	Vec3 TransformPoint(const Vec3& point) const
 	{
 		return Vec3(
 			(double)point.x * m[0] +
@@ -58,7 +58,7 @@ public:
 			m[14]);
 	}
 
-	Vec3 TransformDirection(const Vec3& dir)
+	Vec3 TransformDirection(const Vec3& dir) const
 	{
 		return Vec3(
 			(double)dir.x * m[0] +