diff -r 87c906545fc3 -r 77c819262b7a src/gl/partrenderer.h
--- a/src/gl/partrenderer.h	Sat Feb 29 23:51:03 2020 +0200
+++ b/src/gl/partrenderer.h	Mon Mar 02 11:08:13 2020 +0200
@@ -34,9 +34,10 @@
 	const ldraw::ColorTable& colorTable;
 	gl::Compiler* const compiler;
 	ldraw::Id highlighted = ldraw::NULL_ID;
-	std::optional<glm::vec3> screenToModelCoordinates(const QPoint& point, const geom::Plane& plane);
-	QPointF modelToScreenCoordinates(const glm::vec3& point);
-	glm::vec3 unproject(const glm::vec3& win);
+	std::optional<glm::vec3> screenToModelCoordinates(const QPoint& point, const geom::Plane& plane) const;
+	QPointF modelToScreenCoordinates(const glm::vec3& point) const;
+	geom::Line cameraLine(const QPoint& point) const;
+	glm::vec3 unproject(const glm::vec3& win) const;
 	glm::mat4 projectionMatrix;
 	glm::mat4 viewMatrix;
 	glm::mat4 modelMatrix;