Apply uv offsets only on non-repeating textures, to avoid overflow errors on textures near the texture page edges. Fixes wonky textures on maps like E1M1 and E1M8.

tesselate.cpp

@@ -42,8 +42,8 @@ std::vector<Tesselator::Polygon> Tesselator::tesselateFace(const face_t* face)
 
 		// Transform the vertex to texture space and calculate the texture UV bounds
 		Vec3 st = textureTrsf.TransformPoint(vertexPoint);
-		if (st.x > maxS) maxS = ceil(st.x); if (st.x < minS) minS = floor(st.x);
-		if (st.y > maxT) maxT = ceil(st.y); if (st.y < minT) minT = floor(st.y);
+		if (st.x > maxS) maxS = st.x; if (st.x < minS) minS = st.x;
+		if (st.y > maxT) maxT = st.y; if (st.y < minT) minT = st.y;
 
 		contour.vertex[edgeListIdx] = gpc_vertex{ st.x, st.y };
 	}
@@ -68,9 +68,9 @@ std::vector<Tesselator::Polygon> Tesselator::tesselateFace(const face_t* face)
 		minT = floor(minT / cellHeight) * cellHeight;
 	}
 
-	for (double y = minT; y < maxT; y += cellHeight)
+	for (double y = floor(minT); y < ceil(maxT); y += cellHeight)
 	{
-		for (double x = minS; x < maxS; x += cellWidth)
+		for (double x = floor(minS); x < ceil(maxS); x += cellWidth)
 		{
 			// Create a square polygon that covers the entire cell
 			gpc_polygon cell = { 0 };

texture.cpp

@@ -351,9 +351,14 @@ bool process_textures(const world_t* world, TextureList& outTextures)
 				tex.uoffs = (u_char)((x % 64) << (2 - outTim.format));
 				tex.voffs = (u_char)(y & 0xFF);
 				if (texture_isRepeatable(miptex))
-					tex.ps1tex.twin = getTexWindow(tex.uoffs, tex.voffs, tex.w, tex.h);	// TODO: figure out the right offsets that are multiples of w and h; NOTE: if uoffs has to >> 1, then w probably has to as well
+				{
+					tex.ps1tex.twin = getTexWindow(tex.uoffs, tex.voffs, tex.w, tex.h);
+					tex.uoffs = tex.voffs = 0;	// Apply offset only through the texture window, otherwise we can get overflowing UV values
+				}
 				else
+				{
 					tex.ps1tex.twin = getTexWindow(0, 0, 0, 0);
+				}
 			}
 		}