Impossible to set sprite filters as an empty array to then add multiple filters about pixijs

[bigtimebuddy]

Here's the code reference for v8 filters assignment:

pixijs/src/scene/container/container-mixins/effectsMixin.ts

Line 137 in c3c8d0e

set filters(value: Filter | Filter[] | null | undefined)

Because assigning filters to [] means that internally hasFilters is false in that function. So this is called:

this.removeEffect(this._filters.effect);
returnFilterEffect(this._filters.effect);
this._filters.effect = null;

Then when you obj.filters.push(filter) later, the effect is never getting set.

@GoodBoyDigital thoughts? Should the filters array be a Proxy object instead?

[GoodBoyDigital]

this is a bit of a tricky one as generally! We want to not have to cause filters to break batching, so we check at the time of assignment if there are actually any filters. this is done to not have to check the whole scene graph for filter changes each frame.

this means currently the following:

container.filters = [] // no filters - s oskipped
container.filters.push(filter) // this is not watched, so still thinks there are no filters

this best way is to always assign the filters directly:

container.filters = [] // no filters
container.filters = [filter] // will add a filter

i know its a bit weird but, perf wise i know devs use this container.filters = [] syntax to null out filters.

[GoodBoyDigital]

to add to that :)

container.filters = [filter] // will add a filter
container.filters.pop() // will not render filters, but still break the batches

[bigtimebuddy]

Two ideas how we could enforce this:

• Have filters getter type as readonly Filters[] type
• Do Object.freeze on the setter input to keep users from manipulating the array at runtime