feat: make options for appendAnimation and detachAnimation optional

[Frank3K]

Description

This PR makes all parameters of AppendAnimationOptions and DetachAnimationOptions optional.

Such that the following is possible:

// Example: Only specify repetitions
appendAnimation('some-animation', { repetitions: 5 });

// Example: Only specify fade for detach
detachAnimation('some-animation', { fade: 200 });

Previously, you had to pass all options, or no options at all (in case the default was used). Current code in master:

model-viewer/packages/model-viewer/src/features/animation.ts

Lines 33 to 41 in 4efaf8e

	interface AppendAnimationOptions {
	pingpong: boolean, repetitions: number|null, weight: number,
	timeScale: number, fade: boolean|number, warp: boolean|number,
	relativeWarp: boolean, time: number|null
	}
	interface DetachAnimationOptions {
	fade: boolean|number
	}

@mohammadbaghaei Would you be so kind to do the review? I tried to use appendAnimation, but then I was a bit surprised I needed to pass all parameters. I have no real experience with these methods, so it would be nice if you can take a look and functionally test.

Reference Issue

[Frank3K]

@mohammadbaghaei I am particularly not 100% sure about this line.

[diegoteran]

Thanks for requesting these changes, I'll need to test them before submitting

[diegoteran]

I believe these are all optional already.

If you look at the example in https://modelviewer.dev/examples/animation/index.html#appendAnimation

Do you mind checking again @Frank3K ? In case this change is not necessary.

[Frank3K]

Do you mind checking again @Frank3K ? In case this change is not necessary.

Thanks for reviewing!

You're right that the options parameter is optional - but the properties inside the object are not. In master, AppendAnimationOptions declares all fields as required, so passing { weight: 0.5 } is a TypeScript type error.

More importantly, it's also a runtime bug. Default parameter values only apply when the argument is undefined (omitted entirely). If you pass { weight: 0.5 }, DEFAULT_APPEND_OPTIONS is never used, and options.timeScale, options.fade, options.warp, etc. all become undefined. The docs example silently produces incorrect behavior on master.

This PR fixes both issues by making the properties optional and merging with defaults inside the function {...DEFAULT_APPEND_OPTIONS, ...options}.

I've updated with master and fixed conflicts.

[diegoteran]

Thanks for the explanation and changes. I'm trying to figure out fi the broken tests are flaky