diff -r a5111f4e6412 -r 918b6c0f8b5b src/gl/partrenderer.cpp
--- a/src/gl/partrenderer.cpp	Fri Dec 13 15:55:56 2019 +0200
+++ b/src/gl/partrenderer.cpp	Fri Dec 13 21:35:59 2019 +0200
@@ -21,15 +21,6 @@
 	this->rotation *= QQuaternion::fromAxisAndAngle({0, 1, 0}, 330);
 }
 
-// https://stackoverflow.com/a/12943456
-static void perspectiveGL(GLdouble fovY, GLdouble aspect, GLdouble zNear, GLdouble zFar)
-{
-	//fH = tan( (fovY / 2) / 180 * pi ) * zNear;
-	const GLdouble fH = std::tan(fovY / 360 * pi) * zNear;
-	const GLdouble fW = fH * aspect;
-	glFrustum(-fW, fW, -fH, fH, zNear, zFar);
-}
-
 /*
  * Pads a 3×3 matrix into a 4×4 one by adding cells from the identity matrix.
  */
@@ -63,17 +54,27 @@
 void PartRenderer::resizeGL(int width, int height)
 {
 	constexpr GLfloat near = 1.0f;
-	constexpr GLfloat far = 1.0e+05f;
+	constexpr GLfloat far = 1e+05f;
 	glViewport (0, 0, width, height);
 	glMatrixMode(GL_PROJECTION);
 	glLoadIdentity();
-	::perspectiveGL(45.0f, static_cast<double>(width) / static_cast<double>(height), near, far);
+	gluPerspective(45.0f, static_cast<double>(width) / static_cast<double>(height), near, far);
 	glMatrixMode(GL_MODELVIEW);
 }
 
 // https://www.codemiles.com/c-opengl-examples/drawing-teapot-using-opengl-t9010.html?mobile=on
 void PartRenderer::paintGL()
 {
+	switch (this->renderStyle)
+	{
+	case gl::RenderStyle::Normal:
+	case gl::RenderStyle::BfcRedGreen:
+	case gl::RenderStyle::RandomColors:
+		break;
+	case gl::RenderStyle::Wireframe:
+		glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+		break;
+	}
 	glMatrixMode(GL_MODELVIEW);
 	// clear the drawing buffer.
 	glClear(GL_COLOR_BUFFER_BIT);
@@ -116,3 +117,10 @@
 	}
 	this->lastMousePosition = pointToPointF(event->pos());
 }
+
+void PartRenderer::setRenderStyle(const gl::RenderStyle newStyle)
+{
+	this->renderStyle = newStyle;
+	this->update();
+}
+