Mirror imaging

Questions and answers about the how and why of making maps.
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The Purple Panzer
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Mirror imaging

Post by The Purple Panzer » Thu May 04, 2017 3:20 pm

If I have an object that's defined, e.g.

define BuildingWing
meshbox...
...
enddef

Is there any straightforward way of producing it's mirror image? I don't think it's doable just with spins, though I may just be rusty with my mathematics of symmetries. I may test out using a negative scale, which might do a reflection through the origin.

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JeffM
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Re: Mirror imaging

Post by JeffM » Thu May 04, 2017 3:32 pm

No, a mirror requires two things, a negative scale in an axis, and then the reversal of the mesh order. We have the first as a map transform, but not the second. You will need to use a modeler to mirror the mesh.

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The Purple Panzer
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Re: Mirror imaging

Post by The Purple Panzer » Sun May 07, 2017 1:34 am

The only quibble I have with your comment is that I'm not talking about custom meshes, just "meshbox"s and meshpyramids, and other basic V2 map primitives. For my purposes the internals of those things don't need to be mirrored, just their overall positions (reflecting a meshbox with a texture is, as far as I can see, the same meshbox with the same texture, with x => -x, y => -y, or both). The objects themselves don't need to change internally.

Maybe you misunderstood my question as more general, that it involved more general meshes, and I can see that as more complicated. Maybe I don't understand your phrase "we have the first as a map transform" - I tried it, scaling negatively in x, y, and both, and nothing seemed quite right, so I don't mean to argue your larger point.

No need to respond - I was hoping there was an easy answer for simple objects, and empirically I don't think there is. If I need it I'll just keep track of the objects I'm generating and apply the symmetry operation(s) I need.

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