perforated screens

Question

Hi, 
 I'm trying to create a circular perforation into an square shape (or any shape like in an ellipse). Does anyone know how to do this? 
 Do you have to turn the square shape into a solid? Is it possible to make cuts into a shape? 
 I've attached a picture, to show what i mean. 
 Thanks.

Mueller · Accepted Answer

Hi Ivana, 
 
Cutting holes in a square or other polygon requires an intermediate step: use the Polygon to create a BSplineSurface.FromClosedCurve, then use that BSplineSurface as input for another BSplineSurface.TrimByProjectedCurve. The curves (Circle nodes) are then the input to TrimCurve, which requires a list as input. In case of the circles, if they are more-dimensional lists (e.g. replicated), use MyCircles.Flatten() to make sure they are in a one-dimensional list. SelectorPoint could be any one of the Polygon's Vertices. 
 
Wishing you good success, 
 
 Volker

Marc Thomas · Answer

I'm curious what is behind the question. Do you need to model all of the perforations in such a screen for production documentation/fabrication purposes or do you simply wish to create a visual representation? 
 The reason that I ask is that modelling such detailed geometry and (I'm assuming) adding multiple instances into a model will create a heavy load for the application to manipulate and display (not just Bentley's, but other vendor's applications too). Control of level of detail is important in large models. 
 If you simply need a visual representation our visualisation tools include the Displacement Mapping feature that will render simple plane geometry into complex/repetitive 3D visuals, a brief description is here: Luxology - Displacement Maps 
 The steps Volker describes are equally applicable to creating geometry from which displacement maps can be created.