[mtoh] Add playblasting support.

[marsupial]

No description provided.

[pmolodo]

So, if I'm reading this correctly - this only changes things when playblasting using a delegate other than HdStorm - ie, generally a non-realtime delegate - in which case, it waits for convergence at each frame of the playblast, correct?

Eventually, we'll probably want some user-controllable settings for this - ie, set a max time to wait for convergence for each frame - but as a first pass, this is definitely an improvement over simply using whatever first super-chunky result we first get back...

[marsupial]

Updated with cancelaltion.

[pmolodo]

Looks good now, thanks!

[kxl-adsk]

Please fix the compilation with USD versions prior to 20.05. Here is an error we are getting on Windows with USD 20.02 and USD 19.11

maya-usd_pr\lib\mayaUsd\render\mayaToHydra\renderOverride.cpp(405): error C2672: 'std::dynamic_pointer_cast': no matching overloaded function found
maya-usd_pr\lib\mayaUsd\render\mayaToHydra\renderOverride.cpp(405): error C2784: 'std::shared_ptr<_Other> std::dynamic_pointer_cast(const std::shared_ptr<_Ty0> &) noexcept': could not deduce template argument for 'const std::shared_ptr<_Ty0> &' from '_Ty'
        with
        [
            _Ty=pxrInternal_v0_20__pxrReserved__::HdTaskSharedPtr
        ]
C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VC\Tools\MSVC\14.16.27023\include\memory(1756): note: see declaration of 'std::dynamic_pointer_cast'
maya-usd_pr\lib\mayaUsd\render\mayaToHydra\renderOverride.cpp(407): error C2440: 'initializing': cannot convert from 'initializer list' to 'std::vector<pxrInternal_v0_20__pxrReserved__::HdTaskSharedPtr,std::allocator<_Ty>>'
        with
        [
            _Ty=pxrInternal_v0_20__pxrReserved__::HdTaskSharedPtr
        ]

[kxl-adsk]

@marsupial Do you have any update on this PR? Would be great to fix compilation error with older USD versions and get it in.

[marsupial]

Moving to 20.08, so I am updating it, but not sure how much it's in the cards for support < 20.05 here though...you might be on your own with that.

[kxl-adsk]

We won't be able to accept the PR if it doesn't build with supported USD versions.

[marsupial]

Understand, but there isn't much need (or resources) to support these old versions on our side.
Hopefully the latest alleviates the issues going back to 20.02

[kxl-adsk]

Looks good now, thank you.