[Neil Lowe]

Does IL2 use double sided polys, a poly whose texture is visible from both sides?

Cheers, Neil

[RAF_Magpie]

Kind of...

There is a material assignment, that will make it 'dual' sided, but apparently applies extra load on your machine when applied...

From Il2 Modelling Bible;

07. Gloss2_D2o
All as 02-04 above, but with 2-sided ON. This is the only difference.

The two-sided materials can be used for certain undamaged parts, but they are most useful for damage effects. Let's take an example, say, WingRMid_D2_00, which is the center section of the right wing in the D2 state. Imagine your airplane is attacked in the game, and it is struck in the wing by heavy cannon fire. The D0 piece is instantly replaced with the D2 piece, which has large holes blown through the wing via the alpha channel... But if you didn't build it with the two-sided material, then you will be able to see completely through the wing section, no matter what the angle. At a low enough angle you will see through things that just shouldn't be transparent... As if the whole underside of the wing didn't exist. This is obviously visually "wrong". To get around this you use the 2-Sided material for the D2 part. Now when you have a large alpha hole in the wing, you can see the opposing surface of the wing interior, basically just showing the texture on both sides of the surface.

There are two problems with this though. First, there is a performance hit for this (when rendering in 3DS MAX, and in the game as well), so use it only when appropriate. The other catch is, if you have a light undersurface color (as most camouflaged airplanes do), when the Material is two-sided, if a hole in the upper surface is larger than a corresponding adjacent hole in the lower surface, the lower surface may show bright camouflage color.

For example, let's say that you've modeled the effects of a cannon shell entering the wing from below, making a small hole, and then exploding against the inside of the upper wing surface, making a LARGE hole in the upper wing. Then there will be a light-colored undersurface, double-sided and plainly visible from above through the large hole. The I-16's wing, when heavily damaged, is a good in-game example of this phenomenon, which is especially apparent on VVS aircraft with their bright sky-blue bellies. Theoretically you could build an interior surface for the wing and map it separately to a dark color, but then modeling ragged-edged holes would require a large number of polygons. Using a material with the 2-sided option is the most effective compromise. A suggestion for getting around the undersurface color show-through is to try and model the holes in the upper surfaces to be smaller than the holes in the lower surfaces, or offset them somewhat (assume that a cannon shell has come in at a shallow angle).

[Neil Lowe]

Thanx for the reply Maggie

Cheers, Neil

[canonuk]

What I do is make and texture a poly, clone it, flip the normals of the clone, and attach it to the original object.