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Wojciech Czub

Nov. 5, 2021 09:48:19

Hello,
I suspect it may be my lack of understanding of the USD..

I have a situation like on the screenshot. I am trying to "animate" the parameters to turn the light on / off using a Switch with a simple expression.

When I render inside Solaris (HYDRA_RENDER_CHECK node in my example) the light turns on and off like I wanted. After saving to USD, this modification is not saved and it looks as if only the state of the first frame was saved in USD (despite Frame Range set to all frames).

Wojciech Czub

Nov. 5, 2021 11:40:01

I analyzed the usda file I get on the output and compared it with what it should look like based on this example:

Your text to link here... [graphics.pixar.com]

And as I expected - the parameter override is saved, but without the time sample. It looks like this:

            over "red_light"
            {
                float inputs:intensity = 0
            }

I can manually write the code like that below and it works when I've load it! But USD ROP save the file without this time samples.

            over "red_light"
            {
                float inputs:intensity.timeSamples = {
                    1:0,
                    102:450,
                }
            }

jsmack

Nov. 5, 2021 12:05:06

In solaris the nodes that perform the edits create layers. A switch changes the layer stack, however the layer stack cannot be animated with USD. One way to add animation is by keyframing the parameters of the nodes performing edits.

Wojciech Czub

Nov. 5, 2021 12:11:28

Yes, I assumed that this (SOP-style) construction with a switch could be problematic. Thank you jsmack! It explains everything.