ID 548479 - Transform nodes, like Transform and Crop, don't cache the Viewer image when using the Viewer transform handles when the knobs being transformed are moved through pre-existing cached values

Problem summary
Transform nodes, like Transform and Crop, don't cache the Viewer image when using the Viewer transform handles when the knobs being transformed are moved through pre-existing cached values
 
This means even though you can see the final result in the Viewer, if you change frame and change back, the Viewer is re-rendered
 
Customer reported version
nuke.14.0v5
 
Customer reported platform
 
Steps to reproduce
 
1) Open Nuke

2) Create a ColorBars node, attach a Transform node and View the Transform node

3) In the Viewer, rotate the image 90 degrees
 
4) In the Script Editor, run the following code to check the the Viewer has been cached, it should print True:
 

print(nuke.activeViewer().node().frameCached(nuke.frame()))

 
5) In the Viewer, rotate the image again, up to around 100 degrees and while still holding the rotate control, rotate back to 90 degrees, then after a couple of seconds rotate to about 70 degrees
 
6) Again in the Viewer, rotate the image up to 90 degrees and still holding the rotate control,  after a couple of seconds rotate to about 100 degrees
 
6) In the Script Editor, run the following code to check the the Viewer has been cached, it should now print False:
 

print(nuke.activeViewer().node().frameCached(nuke.frame()))

 

 
*It may take a couple of attempts to see this. It does also happen then scale and translate controls, though it is easier to reproduce with rotation. With the Crop node, dragging any of the horizontal or vertical controls in the Viewer will result in a similar result:
 

 
Expected behaviour
For the image in the Viewer to be cached
 
Actual behaviour
The image is not cached, meaning it has to be rendered when changing frames
 
Workaround
Use the knobs on the node to control the Transform nodes, that seems to always cache the Viewer
 
Reproduced by support
This bug has been reproduced in:
Nuke 14.0v5 - Windows 10, CentOS 7, macOS Monterey
Nuke 10.0v1 - Windows 10
 
Earliest version tested
Nuke 10.0v1 - This issue appears to be in all tested versions of the product