Urgent.. section cut and shadow

krit.ja

I'm doing light and shadow analysis for 3-storey shophouse and i need to know if there's any solution that would make the part that was cut out by section-cut still casts shadow?

Tobobo

Separate the two halves of the section and group them. Then you can hide one and that might solve your problem.

do you have a picture that can better explain the issue?

Gaieus

Use TIG's SectionCutFace plugin. It will add a 2D group to the section plane (moved back a bit so the plane does not hide it) and fills the "voids" (based on guessing by front and back faces of thick walls and such) but will leave the empty spaces (like a room) unfilled.

Now you can edit this group just like any other geometry; trace an edge of an empty area ("room" with the line tool to fill it.

The use a completely transparent png image material (for our convenience, attached below) to paint this fill. SU cannot handle png transparency with its shadow engine and will cast shadow where you can simply see through.

Also see an example attached below.

(and there is no bug here so I moved the topic to the main SU discussion topic)

Dummy.skm

SectionCut.skp

nickdk

Gaieus,

I have been trying to do what you describe but no matter what I do maxwell renders the transparent roof as solid white and also if I use your sample files.

I have tried via SU7 + 8 with maxwell 2.5

I have tried to use the hide to camera option on the group too but it's still rendered as solid white, do you have any idea?

It's a great method you're describing if only I could make it work!

Gaieus

Well, as I do not use Maxwell, I cannot really tell what's going on. The above example is mainly for native SketchUp as SU does not render image transparency when it comes to shadows.
Maybe Maxwell cannot render alpha transparency either and would need clipmaps when rendering.

But in any case, if renderers can use image transparency for clipping, the above solution only works if they can either render double sided materials (or what) like in V-ray or they can ad shadow to a completely transparent material (like Thea).