[Radiance-general] Creating a void in a wall

[Lars O. Grobe]

Hi Ehsan,

nothing is impossible with Radiance ;) You can get a hole into your wall without modifying the underlying geometry of the wall polygon. One way is to cut out the opening with a box of material antimatter. Everything within that box will become invisible. This means that you can also not place window frame and glass inside. The second option is to apply a mixfunc modifier to your wall. At locations defined by a simple function, the material will be "air" (e.g. void, or trans with pure specular transmission), everything else will be your wall material.

But: you likely introduce later problems when modeling that way. Once that you have overlaps of your invisible, but still existing wall polygon with other geometry (window pane, bsdf or illum, ..) you will get strang results which are hard to debug. I would not recommend this for a simple wall. There are cases where this may make sense, though - e.g. if you want to cut a hole into a sphere, you can either use antimatter or mixfunc into a sphere primitive with few lines of Radiance scene description, or you have to mesh the hole sphere object... possibly leading to a megabyte of triangles...

Cheers, Lars.

> Dear All,
> 
> Is it possible to create a void in a wall instead of creating polygons around a void?
> 
> For instance:
> for creating a window we can generate polygons surrounding the window and then a polygon which refers to glass. now I want to know instead of doing that is it possible to define a wall as a polygon and create a window on the wall without manipulating the wall's polygon.
> 
> It might have a simple solution.
> 
> Best Regards,
> 
> Ehsan
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