We learned so far that IFC is all about objects, relationships and properties. But we know that this is not enough. For many use cases you need more detailed graphical information than any description can ever deliver. Special patten for tiles, starting point for laying them etc. Hatches are commonly used in tools like AutoCAD, Revit, Archicad and the like. Do we have to do without this when using native IFC?
It never gets boring to answer such kind of questions with “no, you don’t!”. IFC has all the bolts and nuts to add hatches and tilings to your elements.
The schema contains a class called “IfcFillAreaStyle” where you can define this. It is not intended to be used for renderings (I’ll cover textures etc. in a future post) but for a “plan view” styling.
You have a few options here, and you can use combinations of those based on your design intent.
- IfcColour allows you to add a solid color, either alone ore as a background color for additional hatches
- IfcFillAreaStyleHatching is a vector based hatch definition. Line styles and their directions (parallel or crossing) make it possible to create all the standard pattern you are already used to. While not forbidden it is not recommended to use more than two defining lines.
- IfcFillAreaStyleTiles is a bit more advanced but allows for even more complex patterns. You basically define a “styled item” (let’s simplify it by saying “draw a few lines”) and define how the pattern is distributed in two directions (U and V, not necessarily perpendicular).
- These patterns can even be stored in a different place and be referenced as IfcExternallyDefinedHatchStyle. ISO standard hatching anyone? Company standards? Sure!
- Similar to Revit, there is an “toggle” to choose whether the pattern is used for “model” or “draughting”. The first selection means that the hatch uses real world measures like tile or parquet sizes. The second tells that it is meant for plans, so no scaling is applied.
Simple, but flexible enough to cover most hatching needs I think. Unfortunately support by major BIM programs is not so good (yet). Maybe in a distant future?