#5717: LWO2 exporter preserves mesh vertex colours

radiantcore/model/export/Lwo2Exporter.cpp

@@ -137,18 +137,28 @@ void Lwo2Exporter::exportToStream(std::ostream& stream)
 	Lwo2Chunk::Ptr pols = fileChunk.addChunk("POLS");
 	Lwo2Chunk::Ptr ptag = fileChunk.addChunk("PTAG");
 	Lwo2Chunk::Ptr vmap = fileChunk.addChunk("VMAP");
+	Lwo2Chunk::Ptr colourVmap = fileChunk.addChunk("VMAP");
 
 	// We only ever export FACE polygons
 	pols->stream.write("FACE", 4);
 	ptag->stream.write("SURF", 4); // we tag the surfaces
 
+	// Texture UV Coordinates go into one VMAP
 	// VMAP { type[ID4], dimension[U2], name[S0], ...) }
 	vmap->stream.write("TXUV", 4);		// "TXUV"
-	stream::writeBigEndian<uint16_t>(vmap->stream, 2); // dimension
+	stream::writeBigEndian<uint16_t>(vmap->stream, 2); // dimension (2 vector components)
 
 	std::string uvmapName = "UVMap";
 	stream::writeString(vmap->stream, uvmapName);
 
+	// Vertex Colours go into another VMAP
+	// VMAP { type[ID4], dimension[U2], name[S0], ...) }
+	colourVmap->stream.write("RGBA", 4); // type [ID4] == "RGBA"
+	stream::writeBigEndian<uint16_t>(colourVmap->stream, 4); // dimension (4 colour components)
+
+	std::string vertColourMapName = "VertexColourMap";
+	stream::writeString(colourVmap->stream, vertColourMapName); // map name [S0]
+
 	std::size_t vertexIdxStart = 0;
 	std::size_t polyNum = 0; // poly index is used across all surfaces
 
@@ -175,6 +185,13 @@ void Lwo2Exporter::exportToStream(std::ostream& stream)
 			stream::writeBigEndian<float>(vmap->stream, static_cast<float>(vertex.texcoord.x()));
 			stream::writeBigEndian<float>(vmap->stream, 1.0f - static_cast<float>(vertex.texcoord.y()));
 
+			// Write the vertex colour data
+			stream::writeVariableIndex(colourVmap->stream, vertNum);
+			stream::writeBigEndian<float>(colourVmap->stream, static_cast<float>(vertex.colour.x()));
+			stream::writeBigEndian<float>(colourVmap->stream, static_cast<float>(vertex.colour.y()));
+			stream::writeBigEndian<float>(colourVmap->stream, static_cast<float>(vertex.colour.z()));
+			stream::writeBigEndian<float>(colourVmap->stream, 1.0f);
+
 			// Accumulate the BBOX
 			bounds.includePoint(vertex.vertex);
 		}
@@ -215,6 +232,13 @@ void Lwo2Exporter::exportToStream(std::ostream& stream)
 		stream::writeBigEndian<float>(colr->stream, 1.0f);
 		stream::writeVariableIndex(colr->stream, 0);
 
+		// Reference the name of the vertex colour map
+		Lwo2Chunk::Ptr vcol = surf->addSubChunk("VCOL");
+		stream::writeBigEndian<float>(vcol->stream, 1.0f); // intensity [F4]
+		stream::writeVariableIndex(vcol->stream, 0); // [VX]
+		vcol->stream.write("RGBA", 4); // vmap-type [ID4]
+		stream::writeString(vcol->stream, vertColourMapName); // name [S0]
+
 		// Smoothing angle
 		Lwo2Chunk::Ptr sman = surf->addSubChunk("SMAN");
 		stream::writeBigEndian<float>(sman->stream, static_cast<float>(degrees_to_radians(95.0f))); // 95 degrees smoothing angle

radiantcore/model/export/ModelExporterBase.h

@@ -65,12 +65,13 @@ class ModelExporterBase :
 			for (const auto& meshVertex : vertices)
 			{
 				// Copy-construct based on the incoming meshVertex, transform the vertex.
-				// Transform the normal using the inverse transpose
-				// We discard the tangent and bitangent vectors here, none of the exporters is using them.
-				surface.vertices.emplace_back(
-					localToWorld.transformPoint(meshVertex.vertex),
-					invTranspTransform.transformPoint(meshVertex.normal).getNormalised(),
-					meshVertex.texcoord);
+                // Transform the normal using the inverse transpose
+                // We discard the tangent and bitangent vectors here, none of the exporters is using them.
+                surface.vertices.emplace_back(
+                    localToWorld.transformPoint(meshVertex.vertex),
+                    invTranspTransform.transformPoint(meshVertex.normal).getNormalised(),
+                    meshVertex.texcoord,
+                    meshVertex.colour);
 			}
 
 			surface.indices.reserve(surface.indices.size() + indices.size());