diff -r 180072db4a83 -r a39f454a3d7f src/gl/partrenderer.h
--- a/src/gl/partrenderer.h	Sun Jul 03 15:59:22 2022 +0300
+++ b/src/gl/partrenderer.h	Sun Jul 03 20:18:34 2022 +0300
@@ -72,3 +72,48 @@
 	void renderVao(const gl::ArrayClass arrayClass);
 	void checkForGLErrors();
 };
+
+inline QVector<QPointF> convertWorldPointsToScreenPoints(
+	const std::vector<glm::vec3> &worldPoints,
+	const PartRenderer* renderer)
+{
+	QVector<QPointF> points2d;
+	points2d.reserve(static_cast<int>(worldPoints.size()));
+	for (const glm::vec3& point : worldPoints)
+	{
+		points2d.push_back(renderer->modelToScreenCoordinates(point));
+	}
+	return points2d;
+}
+
+inline Winding worldPolygonWinding(
+	const std::vector<glm::vec3> &points,
+	const PartRenderer* renderer)
+{
+	return winding(QPolygonF{convertWorldPointsToScreenPoints(points, renderer)});
+}
+
+inline void drawWorldPoint(
+	QPainter* painter,
+	const glm::vec3& worldPoint,
+	const PartRenderer* renderer)
+{
+	const QPointF center = renderer->modelToScreenCoordinates(worldPoint);
+	painter->drawEllipse(inscribe(CircleF{center, 5}));
+}
+
+inline void drawWorldPolyline(
+	QPainter *painter,
+	const std::vector<glm::vec3> &points,
+	const PartRenderer* renderer)
+{
+	painter->drawPolyline(QPolygonF{convertWorldPointsToScreenPoints(points, renderer)});
+}
+
+inline void drawWorldPolygon(
+	QPainter* painter,
+	const std::vector<glm::vec3> &points,
+	const PartRenderer* renderer)
+{
+	painter->drawPolygon(QPolygonF{convertWorldPointsToScreenPoints(points, renderer)});
+}