[usdGeom] PrimVar::ComputeFlattened not working for time-sampled faceVarying attributes

[pmolodo]

Description of Issue

If you create a time-sampled faceVarying primvar (ie, uv/st), then when you call ComputeFlattened() on it, it just returns the "raw" samples, not the expanded per-face-vert ones.

ie, if you have:

float2[] primvars:st (
    interpolation = "faceVarying"
    unauthoredValuesIndex = 0
)
float2[] primvars:st.timeSamples = {
    0: [ (50 entries) ],
    1: [ (50 entries) ],
    ...
}
int[] primvars:st:indices.timeSamples = {
    0: [ (200 entries) ],
    1: [ (200 entries) ],
    ...
}

...and you have a primvar for st, ComputeFlattened will return an array with 50 entries, not 200, as you should get.

The reason is that PrimVar::IsIndexed() returns False, where I think it should return True. The culprit is that it's using indexAttr.Get() - ie, using the default time, which for a time-sampled attribute, returns nothing.

A possible (and easy) fix would be to change PrimVar::IsIndexed() to call Get with some arbitrary time (other than the UsdTimeCode::Default()) - 0, or UsdTimeCode::EarliestTime() perhaps.

Steps to Reproduce

1. Create a usd with a faceVarying time-sampled primvar.
2. call ComputeFlattened() on it - it will be the simple, non-indexed version.
3. call IsIndexed() on it - it will return False

[spiffmon]

Ah, nice find, Paul. I suspect we changed from HasAuthoredValue() to Get() when we added attribute blocking (since a block *is* an authored value), and did so a little hastily. EarliestTime() is for just these kinds of queries. Should be able to fix quickly!

…

--SpiffiPhone

On Jul 12, 2017, at 4:33 PM, Paul Molodowitch ***@***.***> wrote: Description of Issue If you create a time-sampled faceVarying primvar (ie, uv/st), then when you call ComputeFlattened() on it, it just returns the "raw" samples, not the expanded per-face-vert ones. ie, if you have: float2[] primvars:st ( interpolation = "faceVarying" unauthoredValuesIndex = 0 ) float2[] primvars:st.timeSamples = { 0: [ (50 entries) ], 1: [ (50 entries) ], ... } int[] primvars:st:indices.timeSamples = { 0: [ (200 entries) ], 1: [ (200 entries) ], ... } ...and you have a primvar for st, ComputeFlattened will return an array with 50 entries, not 200, as you would get if it weren't time sampled. The reason is that PrimVar::IsIndexed() returns False, where I think it should return True. The culprit is that it's using indexAttr.Get() - ie, using the default time, which for a time-sampled attribute, returns nothing. A possible (and easy) fix would be to change PrimVar::IsIndexed() to call Get with some arbitrary time (other than the UsdTimeCode::Default()) - 0, or UsdTimeCode::EarliestTime() perhaps. Steps to Reproduce Create a usd with a faceVarying time-sampled primvar. call ComputeFlattened() on it - it will be the simple, non-indexed version. call IsIndexed() on it - it will return False — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[jtran56]

Filed as internal issue #148740.

[pmolodo]

Saw that this was addressed (in 2746117) , so I'm closing this issue. Thanks!