Havok `EventType` TypeScript issue

Questions
1

In the function

HP_Body_SetEventMask(bodyId : HP_BodyId, eventMask : number): Result;

eventMask is a number. An acceptable value for eventMask is EventType.COLLISION_STARTED.value. However, we cannot use .value in TypeScript unless we use // @ts-ignore

Is there a way we can use HP_Body_SetEventMask() in TypeScript without // @ts-ignore? Thanks!

ts issue
ts issue1823×559 32 KB

GitHub Source demonstrating the TypeScript issue

1 Like
2

You don’t have to use .value. You can pass directly the enum member.

EventType is a number enum:

declare enum EventType {
    COLLISION_STARTED,
    COLLISION_CONTINUED,
    COLLISION_FINISHED,
    TRIGGER_ENTERED,
    TRIGGER_EXITED
}
3

Unfortunately, we do have to use .value

The .d.ts types file suggests that EventType.__ is an enum/number. However, on the JS side after loading Havok, EventType.__ is actually an object of type { value: number }

Here’s the line in the Babylon.js source code that uses .value for EventType:

const collideEvents = this._hknp.EventType.COLLISION_STARTED.value | this._hknp.EventType.COLLISION_CONTINUED.value | this._hknp.EventType.COLLISION_FINISHED.value;

You can also open the Dev Console in the Playground and run the following code to see this:

EventType
EventType2560×1440 145 KB

4

But your project is in Typescript. You can use enums as is.

image
image2938×846 275 KB

No errors.

5

It’s true that you will get no TypeScript errors by omitting .value. However, collision callbacks will not fire if .value is omitted. This is why the Babylon.js source code uses .value

6

Try defining your own enum:

enum HKEventType {
    COLLISION_STARTED = 0,
    COLLISION_CONTINUED = 1,
    COLLISION_FINISHED = 2,
    TRIGGER_ENTERED = 3,
    TRIGGER_EXITED = 4
}

and use this enum

OR:

const COLLISION_STARTED = HK.EventType["COLLISION_STARTED" as keyof typeof HK.EventType]

OR:

(<{value: number}><unknown>HK.EventType.COLLISION_CONTINUED).value - you can create your own type too

OR:

cast to any and surpress warnings

7

@roland Thank you for taking the time to look into this and sharing these workarounds :slight_smile:

Respectfully, if we must use a workaround, I’m fine with just using // @ts-ignore with .value as the Babylon.js source code does.

I hope that the Babylon.js team could consider a change so that we don’t need to use a workaround. @RaananW @Cedric I’m curious to hear your thoughts on this when you have time. It seems like there are 2 approaches for a solution:

  1. On the JS side: Make EventType.COLLISION_STARTED a number instead of an object of type { value: number }
  2. On the TS .d.ts side: Expose .value on EventType somehow
3 Likes
8

The workaround seems to work:

import type { HavokPhysicsWithBindings } from '@babylonjs/havok';

declare global {
	const HK: HavokPhysicsWithBindings & {
		EventType: {
			COLLISION_STARTED: { value: number };
			COLLISION_CONTINUED: { value: number };
			COLLISION_FINISHED: { value: number };
		};
	};
}

const flags = HK.EventType.COLLISION_STARTED.value | HK.EventType.COLLISION_CONTINUED.value;
9

Maybe @eoin will have some thoughts.

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