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Bug: Modifiers -> Time -> Time Scale -> negative

PostPosted: Wed Oct 06, 2021 10:59 am
by TheBloke
Confirmed in: Fusion Studio 17.3.1 and Resolve Studio 17.3.1
On: macOS 11.5.2

Bug: The Time Scale control in the Calculation and Offset modifiers appears not to work with a negative value in scale, as it should do. For example a value of -1 for "First Operand Time Scale" + a suitable offset in "First Operand Time Offset" should result in a parameter playing backwards in time, but instead either results in a static value, or glitches between correct and incorrect values.

Reading the manual, I tried to recreate the Calculation modifier example given in Chapter 61, p1476-7, of the Fusion Studio v17 manual and Chapter 122, page 2475-6 in the Resolve v17 reference manual.

"Example: The following example uses a calculation to apply blur to a Text node in inverse proportion to the size of the text."

Following the steps given does not produce the desired result. Instead the modified parameter shows as locked on a specific value, never changing despite the example saying "Return to the Tools tab at the top of the Inspector and press Play (Spacebar) to watch how the value of the Blur Size relates to the value of the Text Size."

It will also sometimes glitch: the viewed node suddenly jerks between different states, as if experiencing some cache problem.

When it glitches I think it's glitching between the broken state (never updating the parameter) and the correct state. So sometimes you see glimpses of it doing the desired effect (applying the parameter backwards in time), but it seemingly only works on a few frames, and never reliably.

I then tested the Offset Distance modifier, which has the same Time controls, and experienced the same problem.

Demonstration video showing broken Time controls on Calculation and Offset Distance modifiers. The first setup shown, Text -> Blur, is an exact recreation of the tutorial in the Fusion Studio/Resolve Studio manuals.

Attached: example Fusion Studio composition to demonstrate the issue with both modifiers:

Re: Bug: Modifiers -> Time -> Time Scale -> negative

PostPosted: Fri Oct 08, 2021 7:12 am
by TheBloke
Also occurs in 17.3.2.

Re: Bug: Modifiers -> Time -> Time Scale -> negative

PostPosted: Fri Oct 22, 2021 12:20 pm
by TheBloke
Looks like this has been fixed in 17.4, thank you.