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Reflections on Pyramid


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mmmh.. the distorded reflection is typically the problem encountered with computeNormals() on vertices belonging to exacly 3 coplanar faces : http://www.babylonjs-playground.com/#TPE3U#4


However the new cylinder re-implementation doesn't use computeNormal() any longer but dedicated computed normals from the cylinder geometry itself.

I tested it, there were no artifact, even with many subdivisions (I didn't test tessellation = 4 ...) .

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Ok, got it : http://www.babylonjs-playground.com/#TPE3U#5


Well, it's rightly the same problem than encountered with computeNormals() about 2 coplanar facets having vertices with different normals due to their but ... without computeNormals() !

Because there is only a quad per face and many subdivisions, we create here this specific case : 2 coplanar triangles, but different normalson each, so the quad plane has no 4 similar normals => visual artifact.


I'm afraid, in this very case, the solutions are to set the subdivisions to 1 OR to set your normals afterwards with a computation dedicated to the specific geometry.



NOTE : this means computeNormals() is not magic, but dedicated computed computed are neither

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If you really need to keep many cylinder subdivisions (instead of 1 to avoid the artifact), you could convert your mesh to a flat shaded one : http://www.babylonjs-playground.com/#TPE3U#6


Each mesh face will then have its own normals not depending from the other side vertices. This is a really simple way to deal with artifacts on meshes which have edge angles lower than 120°

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gotcha : https://github.com/BabylonJS/Babylon.js/blob/master/src/Mesh/babylon.mesh.vertexData.ts#L790


JS lazy evaluation :

diameterTop = diameterTop || options.diameterTop || 1;

if diameterTop is falsy then options.diameterTop else 1 ...

But 0 is falsy in JS !

I'm fixing this right now.



@DK : I think we've got the same problem on each sideOrientation evaluation :

sideOrientation = sideOrientation || options.sideOrientation || Mesh.DEFAULTSIDE;

This will work only as long as the constant DEFAULTSIDE is set to zero.

If we change it some day, the lazy evaluation might come to strange results.

ex : if DEFAULT is set to 1 and we call the method by requesting sideOrientation: FRONTSIDE, what is zero => we'll get DEFAULT (== 1) instead


Maybe something like this would be better :

            if (sideOrientation === 0 || options.sideOrientation === 0) {                sideOrientation = 0;            } else {                sideOrientation = sideOrientation || options.sideOrientation || Mesh.DEFAULTSIDE;            }
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