Transparent behind transparent.

[Magnus Forsberg]

I thought I should fix the missing inside surface structure in 11439p01-p04.
A dual mould of a transparent core, inside a transparent part. 

I had a look into similar parts, the Stein cup and the Ant, to see how it should be made. The cup is made with the coloured content after a BFC Noclip, but the Ant doesn't use the BFC Noclip.  Hm.

I made 2 files using the BFC Noclip, red and black, but didn't add it to the blue version.
But when I looked at the result it became strange.

In LDView it looks like this:
   
The transparent surfaces behind another transparent surface is rendered, independent of a BFC Noclip, or not.

In LDCad it looks like this:
   
The transparent surface behind another transparent surface is NOT rendered, independant of the BFC Noclip. Only the solid coloured surfaces are rendered correct.

Is the rendering in LDCad dependant of some setting I have missed, or can't it show trans surfaces behind another trans surface?

[Rene Rechthaler]

I guess thats dependant of the render, there are some edge cases to check:
- placing two differently shaded windows slightly shifted on each other, do they mix?
- do lenses work? (light and view)
- what about these marbled / blended parts like 51874 (there are more like that, even with two transparent parts) instead of dual mold
- is transparency related to thickness or number of parts (for example one 1LDU wall, one 100 LDU wall or 100 1LDU walls), because normally even transparent parts shade a bit
- is it possible to have luminous parts? is this light from there paintable or mixable?

guess its also matters if it is just a preview or the final hi-res render...

[Roland Melkert]

Is the rendering in LDCad dependant of some setting I have missed, or can't it show trans surfaces behind another trans surface?

LDCad groups parts into single meshes (as it is optimal for model editing), so the whole part is rendered dual sided or not.

If noclip is encountered or any subpart is missing winding info the whole part will be rendered dual sided.

You can check this in the logs.

You can also force all transparent parts to always render dual sided (prefs/ldraw/two sided transparency)

But it can still look wrong resulting from the draw order as LDCad only does partlevel z-sorting for transparent parts.

LDView does polygon sorting so it usually does a better job at rendering models with lots of transparent parts.

[Travis Cobbs]

But it can still look wrong resulting from the draw order as LDCad only does partlevel z-sorting for transparent parts.

LDView does polygon sorting so it usually does a better job at rendering models with lots of transparent parts.

Based on this, you might get improved results in LDCad if you make sure the interior geometry comes first in the part. (However, I'm not positive about that.)

[Magnus Forsberg]

Based on this, you might get improved results in LDCad if you make sure the interior geometry comes first in the part. (However, I'm not positive about that.)

Tried it, and it seems to work fine. I changed the green cup and the blue flame.