diff -r c7241f504117 -r 6d95c1a41e6e src/gl/partrenderer.cpp
--- a/src/gl/partrenderer.cpp	Mon Jun 13 02:18:25 2022 +0300
+++ b/src/gl/partrenderer.cpp	Tue Jun 14 17:55:50 2022 +0300
@@ -18,6 +18,7 @@
 
 #include <glm/ext/matrix_transform.hpp>
 #include <glm/ext/matrix_clip_space.hpp>
+#include <QPainter>
 #include <GL/glu.h>
 #include <QMouseEvent>
 #include <QMessageBox>
@@ -132,6 +133,10 @@
 	for (RenderLayer* layer : this->activeRenderLayers) {
 		layer->paintGL();
 	}
+	QPainter painter{this};
+	for (RenderLayer* layer : this->activeRenderLayers) {
+		layer->overpaint(&painter);
+	}
 }
 
 void PartRenderer::renderScene()
@@ -292,6 +297,7 @@
 {
 	const bool left = event->buttons() & Qt::LeftButton;
 	const QPoint move = event->pos() - this->lastMousePosition;
+	this->totalMouseMove += move.manhattanLength();
 	if (left and not move.isNull())
 	{
 		// q_x is the rotation of the brick along the vertical y-axis, because turning the
@@ -306,6 +312,27 @@
 		this->updateModelMatrix();
 	}
 	this->lastMousePosition = event->pos();
+	for (RenderLayer* layer : this->activeRenderLayers) {
+		layer->mouseMoved(event);
+	}
+	this->update();
+}
+
+void PartRenderer::mousePressEvent(QMouseEvent* event)
+{
+	this->totalMouseMove = 0;
+	this->lastMousePosition = event->pos();
+}
+
+void PartRenderer::mouseReleaseEvent(QMouseEvent* event)
+{
+	if (this->totalMouseMove < (2.0 / sqrt(2)) * 5.0)
+	{
+		for (RenderLayer* layer : this->activeRenderLayers) {
+			layer->mouseClick(event);
+		}
+		this->update();
+	}
 }
 
 void PartRenderer::wheelEvent(QWheelEvent* event)
@@ -320,6 +347,7 @@
 void PartRenderer::addRenderLayer(RenderLayer* layer)
 {
 	this->activeRenderLayers.push_back(layer);
+	layer->setRendererPointer(this);
 	this->update();
 }
 
@@ -364,12 +392,17 @@
 {
 	const glm::vec3 projected = glm::project(
 		point,
-		this->viewMatrix * glm::mat4_cast(this->modelQuaternion),
+		this->viewMatrix * this->modelMatrix,
 		this->projectionMatrix,
 		this->viewportVector);
 	return toQPointF(glm::vec2{projected.x, this->height() - projected.y});
 }
 
+bool PartRenderer::isDark() const
+{
+	return luma(this->renderPreferences.backgroundColor) < 0.25;
+}
+
 Line<3> PartRenderer::cameraLine(const QPointF& point) const
 {
 	const glm::vec3 p1 = this->unproject({point.x(), point.y(), 0});
@@ -386,7 +419,7 @@
 {
 	return glm::unProject(
 		glm::vec3{win.x, this->height() - win.y, win.z},
-		this->viewMatrix * glm::mat4_cast(this->modelQuaternion),
+		this->viewMatrix * this->modelMatrix,
 		this->projectionMatrix,
 		viewportVector);
 }
@@ -445,3 +478,10 @@
 {
 	return this->highlighted;
 }
+
+void PartRenderer::setSelection(const QSet<ModelId>& selection)
+{
+	Q_ASSERT(not selection.contains({0}));
+	gl::setModelShaderSelectedObjects(&this->shaders, selection);
+	this->update();
+}