Default opengl shader misrepresents polymeshes with no N prim var

[bentoogood]

If an object of type:MeshPrimitive and interpolation:linear has no 'N' primvar (normals data) the default 3d Viewer shader doesn't function correctly.

Meshes set to interpolation:catmullClark don't suffer from this problem.

[bentoogood]

Sample torus used to demonstrate problem (save as .obj file):

# This file uses centimeters as units for non-parametric coordinates.

v 1.500000 -0.000000 0.000001
v 1.213526 -0.000000 -0.881677
v 0.463526 -0.000000 -1.426585
v -0.463526 -0.000000 -1.426585
v -1.213525 -0.000000 -0.881678
v -1.500000 -0.000000 -0.000000
v -1.213526 -0.000000 0.881678
v -0.463526 -0.000000 1.426585
v 0.463525 -0.000000 1.426585
v 1.213526 -0.000000 0.881678
v 1.404508 -0.293893 0.000001
v 1.136272 -0.293893 -0.825549
v 0.434017 -0.293893 -1.335767
v -0.434017 -0.293893 -1.335767
v -1.136271 -0.293893 -0.825550
v -1.404508 -0.293893 -0.000000
v -1.136271 -0.293893 0.825549
v -0.434017 -0.293893 1.335767
v 0.434017 -0.293893 1.335767
v 1.136271 -0.293893 0.825549
v 1.154509 -0.475528 0.000001
v 0.934017 -0.475528 -0.678603
v 0.356763 -0.475528 -1.098003
v -0.356763 -0.475528 -1.098003
v -0.934017 -0.475528 -0.678603
v -1.154509 -0.475528 -0.000000
v -0.934017 -0.475528 0.678603
v -0.356763 -0.475528 1.098003
v 0.356763 -0.475528 1.098003
v 0.934017 -0.475528 0.678603
v 0.845491 -0.475528 0.000001
v 0.684017 -0.475528 -0.496967
v 0.261271 -0.475528 -0.804110
v -0.261271 -0.475528 -0.804110
v -0.684017 -0.475528 -0.496967
v -0.845491 -0.475528 -0.000000
v -0.684017 -0.475528 0.496967
v -0.261271 -0.475528 0.804110
v 0.261271 -0.475528 0.804110
v 0.684017 -0.475528 0.496967
v 0.595491 -0.293892 0.000000
v 0.481763 -0.293892 -0.350021
v 0.184017 -0.293892 -0.566346
v -0.184017 -0.293892 -0.566346
v -0.481763 -0.293892 -0.350021
v -0.595491 -0.293892 -0.000000
v -0.481763 -0.293892 0.350021
v -0.184017 -0.293892 0.566346
v 0.184017 -0.293892 0.566346
v 0.481763 -0.293892 0.350021
v 0.500000 0.000000 0.000000
v 0.404509 0.000000 -0.293892
v 0.154509 0.000000 -0.475528
v -0.154509 0.000000 -0.475528
v -0.404508 0.000000 -0.293893
v -0.500000 0.000000 -0.000000
v -0.404509 0.000000 0.293893
v -0.154509 0.000000 0.475528
v 0.154508 0.000000 0.475528
v 0.404509 0.000000 0.293893
v 0.595492 0.293893 0.000000
v 0.481763 0.293893 -0.350021
v 0.184017 0.293893 -0.566346
v -0.184017 0.293893 -0.566346
v -0.481763 0.293893 -0.350021
v -0.595492 0.293893 -0.000000
v -0.481763 0.293893 0.350021
v -0.184017 0.293893 0.566346
v 0.184017 0.293893 0.566346
v 0.481763 0.293893 0.350021
v 0.845492 0.475528 0.000001
v 0.684018 0.475528 -0.496967
v 0.261272 0.475528 -0.804111
v -0.261272 0.475528 -0.804111
v -0.684017 0.475528 -0.496968
v -0.845492 0.475528 -0.000000
v -0.684017 0.475528 0.496968
v -0.261271 0.475528 0.804111
v 0.261271 0.475528 0.804111
v 0.684017 0.475528 0.496968
v 1.154509 0.475528 0.000001
v 0.934018 0.475528 -0.678603
v 0.356763 0.475528 -1.098003
v -0.356763 0.475528 -1.098003
v -0.934017 0.475528 -0.678604
v -1.154509 0.475528 -0.000000
v -0.934018 0.475528 0.678603
v -0.356763 0.475528 1.098003
v 0.356763 0.475528 1.098004
v 0.934018 0.475528 0.678603
v 1.404509 0.293892 0.000001
v 1.136272 0.293892 -0.825549
v 0.434017 0.293892 -1.335767
v -0.434017 0.293892 -1.335767
v -1.136271 0.293892 -0.825550
v -1.404509 0.293892 -0.000000
v -1.136272 0.293892 0.825550
v -0.434017 0.293892 1.335767
v 0.434017 0.293892 1.335767
v 1.136272 0.293892 0.825550
f 1 11 12 2
f 2 12 13 3
f 3 13 14 4
f 4 14 15 5
f 5 15 16 6
f 6 16 17 7
f 7 17 18 8
f 8 18 19 9
f 9 19 20 10
f 10 20 11 1
f 11 21 22 12
f 12 22 23 13
f 13 23 24 14
f 14 24 25 15
f 15 25 26 16
f 16 26 27 17
f 17 27 28 18
f 18 28 29 19
f 19 29 30 20
f 20 30 21 11
f 21 31 32 22
f 22 32 33 23
f 23 33 34 24
f 24 34 35 25
f 25 35 36 26
f 26 36 37 27
f 27 37 38 28
f 28 38 39 29
f 29 39 40 30
f 30 40 31 21
f 31 41 42 32
f 32 42 43 33
f 33 43 44 34
f 34 44 45 35
f 35 45 46 36
f 36 46 47 37
f 37 47 48 38
f 38 48 49 39
f 39 49 50 40
f 40 50 41 31
f 41 51 52 42
f 42 52 53 43
f 43 53 54 44
f 44 54 55 45
f 45 55 56 46
f 46 56 57 47
f 47 57 58 48
f 48 58 59 49
f 49 59 60 50
f 50 60 51 41
f 51 61 62 52
f 52 62 63 53
f 53 63 64 54
f 54 64 65 55
f 55 65 66 56
f 56 66 67 57
f 57 67 68 58
f 58 68 69 59
f 59 69 70 60
f 60 70 61 51
f 61 71 72 62
f 62 72 73 63
f 63 73 74 64
f 64 74 75 65
f 65 75 76 66
f 66 76 77 67
f 67 77 78 68
f 68 78 79 69
f 69 79 80 70
f 70 80 71 61
f 71 81 82 72
f 72 82 83 73
f 73 83 84 74
f 74 84 85 75
f 75 85 86 76
f 76 86 87 77
f 77 87 88 78
f 78 88 89 79
f 79 89 90 80
f 80 90 81 71
f 81 91 92 82
f 82 92 93 83
f 83 93 94 84
f 84 94 95 85
f 85 95 96 86
f 86 96 97 87
f 87 97 98 88
f 88 98 99 89
f 89 99 100 90
f 90 100 91 81
f 91 1 2 92
f 92 2 3 93
f 93 3 4 94
f 94 4 5 95
f 95 5 6 96
f 96 6 7 97
f 97 7 8 98
f 98 8 9 99
f 99 9 10 100
f 100 10 1 91

[johnhaddon]

So what we'd be wanting here is to add face-normals so it is shaded in a faceted manner?

[bentoogood]

faceted per face normals sounds fine.

[johnhaddon]

The problem here is actually in IECoreGL in Cortex, so we'll need to deal with it there.

[johnhaddon]

Closing this, as the root cause has been fixed in ImageEngine/cortex#118.