diff -r c93e4a1eaadb -r 232e7634cc8a src/gl/compiler.cpp
--- a/src/gl/compiler.cpp	Thu Jun 09 11:51:42 2022 +0300
+++ b/src/gl/compiler.cpp	Thu Jun 09 13:32:55 2022 +0300
@@ -196,20 +196,14 @@
 	}
 }
 
-static gl::ArrayClass classifyPolygon(const gl::Polygon& polygon)
+static constexpr gl::ArrayClass classifyPolygon(const PolygonElement& element)
 {
-	switch (polygon.type)
-	{
-	case gl::Polygon::EdgeLine:
-		return gl::ArrayClass::Lines;
-	case gl::Polygon::Triangle:
-		return gl::ArrayClass::Triangles;
-	case gl::Polygon::Quadrilateral:
-		return gl::ArrayClass::Quads;
-	case gl::Polygon::ConditionalEdge:
-		return gl::ArrayClass::ConditionalLines;
-	}
-	return gl::ArrayClass::Lines;
+	return visitPolygon<gl::ArrayClass>(
+		[](const LineSegment&) { return gl::ArrayClass::Lines; },
+		[](const Triangle&) { return gl::ArrayClass::Triangles; },
+		[](const Quadrilateral&) { return gl::ArrayClass::Quads; },
+		[](const ConditionalEdge&) { return gl::ArrayClass::ConditionalLines; },
+		element);
 }
 
 template<typename Fn>
@@ -221,7 +215,7 @@
 		PolygonCache* cache = context->getPolygonCacheForModel(modelId.value());
 		if (cache != nullptr)
 		{
-			for (const gl::Polygon& polygon : getCachedPolygons(cache, model, context))
+			for (const WithId<PolygonElement>& polygon : getCachedPolygons(cache, model, context))
 			{
 				fn(polygon);
 			}
@@ -230,7 +224,7 @@
 }
 
 static QColor getColorForPolygon(
-	const gl::Polygon& polygon,
+	const PolygonElement& polygon,
 	const gl::RenderPreferences& preferences,
 	const ColorTable& colorTable)
 {
@@ -259,12 +253,11 @@
 BoundingBox gl::boundingBoxForModel(Model* model, DocumentManager* context)
 {
 	BoundingBox result = emptyBoundingBox;
-	iterateModelPolygons(model, context, [&](const gl::Polygon& polygon)
+	iterateModelPolygons(model, context, [&](const PolygonElement& polygon)
 	{
-		for (unsigned int i = 0; i < polygon.numPolygonVertices(); i += 1)
-		{
-			addPointToBox(result, polygon.vertices[i]);
-		}
+		visitPoints(
+			[&result](const glm::vec3& p) { addPointToBox(result, p); },
+			polygon);
 	});
 	return result;
 }
@@ -282,7 +275,7 @@
 	for (gl::ModelShaders::ShaderObject& shader : shaders->shaderObjects) {
 		shader.cachedData.clear();
 	}
-	iterateModelPolygons(model, context, [&](const Polygon& polygon)
+	iterateModelPolygons(model, context, [&](const PolygonElement& polygon)
 	{
 		const int index = static_cast<int>(classifyPolygon(polygon));
 		std::vector<gl::ModelShaders::Vertex>& vertexBuffer = shaders->shaderObjects[index].cachedData;