3D Sleepers on 2D ballast

[sumitsingh]

Hello,
I need a small assistance for my ballast texture.
I am aware that there is always much noise when ever we use a sleeper as a middle geometry. So I decided to use a track texture with sleepers.
Can any one explain me this statement?

On most track, such as Scale Rails, the ties are alpha'd onto a plane that floats above the ballast. Shadows are drawn on the ballast to make it look '3D'

Thanks.

[TrabantDeLuxe]

It means that the sleepers (ties) are simple 2D flat rectangles. The underlying track bed texture has a shadow baked/painted onto it. This is a trick to save on polygons, and looks rather convincing.The shadows baked onto the ballast help 'blend in' the 2D sleepers.


Something like this, as a quick mockup. The sleepers either be middle geometry, or a continuous plane floating over the ballast with the ties alpha'd out.

[AndiS]

When Scale Rail introduced this technique long ago, it was noted that the spacing of the repeated geometry does not take the gradient into account. So the sleepers got out of sync with their shade (or the 2D image of the chairs or whatever). Anyone knows whether this still is the case?

[TrabantDeLuxe]

Came to think of that over a beer just now. I think what actually happens is the sleepers not being middle geometry, instead a part of the loft using an alpha texture for translucency.

[AndiS]

I guess someone who owns them is needed. Otherwise too many theories escape my mind. Like two loft on top of each other, the bottom one just the ballast and the shade, the top one for the sleepers and rails, with the empty space transparent parts of the plane that shows the sleeper tops.

I never made any track myself, so I cannot say if that would work. All the cross-sections I dissected were simple single-layer things. But since the vertices have normals, you could have a dual-layer loft that has just one cross-section. Like I said, too much theory and too little practice ...
(My excuse is that without a chance to construct your own pointwork, I lost interest.)

[sumitsingh]

On looking very carefully, I finally figured out it. That is the game of shadows to make them 3D like.