diff -r 2bdc3ac5e77c -r 55a55a9ec2c2 src/objecttypes/polygon.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/objecttypes/polygon.cpp	Sun Sep 22 11:51:41 2019 +0300
@@ -0,0 +1,97 @@
+#include "polygon.h"
+
+modelobjects::Triangle::Triangle(
+	const Vertex& point_1,
+	const Vertex& point_2,
+	const Vertex& point_3,
+	Color color_index) :
+	ColoredBaseObject{color_index},
+	points{point_1, point_2, point_3}
+{
+}
+
+QVariant modelobjects::Triangle::getProperty(const Property id) const
+{
+	switch (id)
+	{
+	case Property::Point1:
+		return points[0];
+	case Property::Point2:
+		return points[1];
+	case Property::Point3:
+		return points[2];
+	default:
+		return ColoredBaseObject::getProperty(id);
+	}
+}
+
+auto modelobjects::Triangle::setProperty(Property id, const QVariant& value)
+	-> SetPropertyResult
+{
+	switch (id)
+	{
+	case Property::Point1:
+		points[0] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	case Property::Point2:
+		points[1] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	case Property::Point3:
+		points[2] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	default:
+		return ColoredBaseObject::setProperty(id, value);
+	}
+}
+
+modelobjects::Quadrilateral::Quadrilateral(
+	const Vertex& point_1,
+	const Vertex& point_2,
+	const Vertex& point_3,
+	const Vertex& point_4,
+	Color color_index) :
+	ColoredBaseObject{color_index},
+	points{point_1, point_2, point_3, point_4}
+{
+}
+
+QVariant modelobjects::Quadrilateral::getProperty(const Property id) const
+{
+	switch (id)
+	{
+	case Property::Point1:
+		return points[0];
+	case Property::Point2:
+		return points[1];
+	case Property::Point3:
+		return points[2];
+	case Property::Point4:
+		return points[3];
+	default:
+		return ColoredBaseObject::getProperty(id);
+	}
+}
+
+auto modelobjects::Quadrilateral::setProperty(
+	const Property id,
+	const QVariant& value)
+	-> SetPropertyResult
+{
+	switch (id)
+	{
+	case Property::Point1:
+		points[0] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	case Property::Point2:
+		points[1] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	case Property::Point3:
+		points[2] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	case Property::Point4:
+		points[3] = value.value<Vertex>();
+		return SetPropertyResult::Success;
+	default:
+		return ColoredBaseObject::setProperty(id, value);
+	}
+}