Curved Patterned Part/Sticker Question

[Greg Takacs]

My question pertains to patterned parts/stickers. Once you add pattern to the curved part, even if the original curvature of the sticker could have been represented with a primitive the new, color specific elements simply cannot.

At what angular resolution should the resulting sticker/part be exported at using nothing but a poly-mesh of triangles?

Also, for curved stickers/patterns is the preferred method to create ldraw mesh for them or is it better to use the PNG map instead?

Next question: what should be the smallest triangle face length on a patterned part or is there a general guideline as to the number of vertexes a part should have?

Last question:
How do you handle a part with sides that are curved primitives (semi circles) but the patterned curved side being defined using only triangles? 22.5 degree seems rather low for the curved part but leaving the sides as primitives is more ideal, however the rendered curved patterned part (see the Sian brake calipers) must match up to it and if it's done at a higher resolution things look weird in LDCad bit if it's rendered at only 22.5 degree faces it looks poor when rendered in Stud.io.

I have created a few patterned pieces already but I want to make sure they're matching guideline standards before I even make an attempt at submitting them.

   

[Philippe Hurbain]

Hi Greg,

Maybe you could post the parts you've done, we could then have a look? anyway they seem great!!!

[Massimo Maso]

My question pertains to patterned parts/stickers. Once you add pattern to the curved part, even if the original curvature of the sticker could have been represented with a primitive the new, color specific elements simply cannot.

At what angular resolution should the resulting sticker/part be exported at using nothing but a poly-mesh of triangles?

Also, for curved stickers/patterns is the preferred method to create ldraw mesh for them or is it better to use the PNG map instead?

Next question: what should be the smallest triangle face length on a patterned part or is there a general guideline as to the number of vertexes a part should have?

Last question:
How do you handle a part with sides that are curved primitives (semi circles) but the patterned curved side being defined using only triangles? 22.5 degree seems rather low for the curved part but leaving the sides as primitives is more ideal, however the rendered curved patterned part (see the Sian brake calipers) must match up to it and if it's done at a higher resolution things look weird in LDCad bit if it's rendered at only 22.5 degree faces it looks poor when rendered in Stud.io.

I have created a few patterned pieces already but I want to make sure they're matching guideline standards before I even make an attempt at submitting them.

Hi Greg, you can take a look at what we did in 6255869 and 6142622.
When the angle to be covered is small, both methods work well (as in 11477), when the angle is wider making the faces flat there is some interference (as in 93606).

if you want, some time ago, I made some subparts with Lamborghini logos (named logolamb ...).

[Roland Melkert]

My question pertains to patterned parts/stickers. Once you add pattern to the curved part, even if the original curvature of the sticker could have been represented with a primitive the new, color specific elements simply cannot.

I'm not a part author, but rendering wise these kind of parts are known to cause normal interpolation problems.

This because the surface of triangles does not match the same portion of the part's curve.

I think you could prevent it by adding extra triangles so the pattern 'rests' on a evenly curved grid.

Or it might be better to use textures for non flat stickers.

[N. W. Perry]

I would certainly include this in a list of not-quite-solved issues in LDraw, as there is always some degree of conflict between curved parts that are smoothed in some way by the rendering software (i.e., by primitive substitution or surface shading), and those that aren't or cannot be. The classic example of this is the seams that appear on a minifig head, where the unpatterned part of the head is nicely represented by various curved primitives, but the face itself is rendered on just a pair of incompatible flat quads.

As for whether to use textures vs. geometry for curved patterned surfaces—I wonder if it's possible to actually combine these two ideas? That is, instead of taking a bitmap/raster image and mapping it onto an already-curved surface, could the pattern be stored as vector data (whether LDraw code, SVG or whatever), and then map that onto a surface, after any smoothing or substitution is applied by the renderer so that the pattern benefits from that process?