Texture Mapping extension

RE: Texture Mapping extension
(2018-01-26, 20:23)Leonardo Zide Wrote: The picture is nice but it's missing the location of point 3, which I think should be defined in the standard. Without it it's unclear if one should do (p3-p1)x(p2-p1) or (p2-p1)x(p3-p1) to calculate the horizontal plane normal. If the plane normal isn't defined then some implementations could "flip" the textures and draw them upside down.
fyi: I used (p2-p1)x(p3-p1)  in LDCad, don't remember the reasoning, could be as simple as the default 'find normal of triangle' function I've used does that.

(2018-01-26, 20:23)Leonardo Zide Wrote: That led me to think, it might be better to define the sphere similar to how the cylinder is defined: p1 = center, p2 = front and p3 = top. This way part authors could have an ellipsoid to define the projection and different scale values for u and v. Even if the different scales are not useful, having the up direction defined would be better IMO.
I think using it as a CW or CCW triangle might be clearer we just need to state if it's CW or CCW Smile

(2018-01-26, 20:23)Leonardo Zide Wrote: Also, I think the spec should state that planar projected textures are clamped (it's implied given that it says uvs go from 0 to 1). Maybe adding an extra parameter to allow uvs to wrap would be useful so that we can have tiled textures, but I can't think of any parts right now that could use it besides a few checkerboard patterns.
I would be open to that.
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Messages In This Thread
Re: Texture Mapping extension - by Tim Gould - 2012-04-14, 22:08
Re: Texture Mapping extension - by Tim Gould - 2012-11-15, 22:51
RE: Texture Mapping extension - by Roland Melkert - 2018-01-26, 21:20
Re: Texture Mapping extension - by Tim Gould - 2012-11-30, 21:55

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