Animate Parameter from External Data for Every Frame?

Hi,

Is there a way to animate the parameter from external data for every frame?
For instance, with this LUA data ("sample_data.txt")

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{
   1= 10,
   2= 30,
   3= 40,
}


Assuming to affect size of a transform node, the expected result is to have
the size at 10 in Frame 10,
the size at 30 in Frame 2, and so forth.

On Sourcing External Data
I guess this is the code:

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assert(io.open(comp:MapPath("D:/sample_data.txt"), "r")):read("*all")


My problem is I don't know how to 1) assign it to a variable for accessing and eventually 2) fetch a corresponding number

In Python, this can be done like:

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# Assigning it in the variable
import json
with open("D:\sample_data.json", "r") as read_file:
    data = json.load(read_file)

transform_node = get_transform_node()
frame_number = get_frame_number()

# Fetching it and using it
transform_node.size = data[frame_number]



On Executing Every Frame
I guess this can be done through the Frame Render Script?

Is there a solution for this?
Any inputs are appreciated.

Thanks

P.S. If this can be done entirely done in Python, that is most preferred.

As a general point, for more advanced scripting stuff I'd recommend browsing the Fusion 8 Scripting Guide if you haven't already.

I've heard that it might be possible to execute Python code in Frame Render Scripts, but I was unable to do so in my own testing. I know you can do either of:

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comp:Execute("!Py: print('Hello from Python')")
comp:RunScript("/path/to/pythonscript.py")


But I'm not sure if it's possible to write Python code directly in a Frame Render Script, and thus have the same scope as the Lua script would. Unfortunately it didn't work to prepend the Frame Render script with !Py:

Just for fun I did some playing about with JSON in Lua. Firstly I saved the following JSON file:

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[
  [1,10 ],
  [2,30 ],
  [3,40 ]
]

Then I downloaded the Lua module jsonrocks from its Github repository and installed it in the Modules/Lua directory of Fusion Studio. On macOS that's:

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Fusion Studio:
/Library/Application Support/Blackmagic Design/Fusion/Modules/Lua
DaVinci Resolve:
/Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/Modules/Lua

You'll need to Google for Windows, but it's probably something along the lines of:

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%APPDATA%\Blackmagic Design\DaVinci Resolve\Fusion\Modules\Lua

I put the file and directory I linked above in that folder:

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lunajson.lua
lunajson/


And then I ran the following code in a Background node's Frame Render Script:

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lunajson = require 'lunajson'
file = io.open("/Users/tomj/sample_data.json", "r"):read("*all")
jsonparse = lunajson.decode ( file )
for k, v in ipairs(jsonparse) do
  if v[1] == comp.CurrentTime then TopLeftAlpha = v[2] end
end

And it worked as expected.

Just a quick hack/demo, probably much better ways to do it. But that did function OK.

I should add that for a far more comprehensive and knowledgeable look at reading and writing data from Render scripts, check out Andrew Hazelden's excellent recent post on We Suck Less, describing a pair of scripts that read and write node data:

Node Editing

For this experiment, I started using a CSV (comma-separated value) exporting technique then decided I should make the export more intelligent by naming each channel of data. The end result is a pair of intool scripts that read and write out Lua table structures, which are a bit like a JSON file but are friendlier for use inside of Fusion's expressions and intool scripting fields.

I'm sure you can take portions of these scripts and do everything you need with minimal effort, and without needing to install any Lua libraries.

Hi @TheBloke

I'm terrible sorry for the late response. I totally missed your response (no excuse).

That said, I can confirm after re-performing your detailed write up, it works as expected.

Just some notes:
1) JSON format seems to be different with LUA and Python.
2) The feedback on reading the external file is live through the viewer but the UI (the slider doesn't update). It somehow stays at the value it was initially set.

I haven't tried the CSV method you linked above, but the JSON workflow works so far for my use case.

Thanks for the response and have a great day ahead!