The code example for test raycast query is not working for collideWith == 3

Bugs
1

Hi Team Babylon,

I was trying the raycast query playground code and found the collideWith == 3 option is not working as expected. Or is it that I am mistaking the feature.

Attached an image for reference to show the issue.

image
image962Ă—847 16.9 KB

3

Sure, it’s in the official list of examples in the babylon website under the name Raycast Filtering Example.

I modified the box transparency to check whether the intersecting sphere are inside the box and attached the image.

4

cc @Cedric and @eoin

5

This is actually working as expected. The filter checks are performed using a bit mask:

  • The blue box has a membership of “1”, or, in binary, “0001”
  • The green box has a membership of “2”, or, in binary, “0010”
  • When the ray tests for “3” (binary “0011”), it should hit both, and it happens to hit the blue one first.

You can learn some more about bit masks here: Mask (computing) - Wikipedia

1 Like
6

@eoin Okay, thanks for answering, so is there a way we can get the list of object a ray hits in it’s length sorted with the hit distance.

7

Oh sorry, I missed your follow-up question.
By default, the raycast query interface just returns the closest hit.

However, there is support for collecting multiple hits; take a look at how havokPlugin.ts does raycasts.

First, the plugin creates a “query collector” with a capacity of 1: Babylon.js/packages/dev/core/src/Physics/v2/Plugins/havokPlugin.ts at master · BabylonJS/Babylon.js · GitHub - you could make yourself a collector with a higher capacity, say 100:

this._queryCollector = this._hknp.HP_QueryCollector_Create(100)[1];

Then, look at the raycast function (Babylon.js/packages/dev/core/src/Physics/v2/Plugins/havokPlugin.ts at master · BabylonJS/Babylon.js · GitHub) it currently checks if the collector has any hits, and populates from the 0th hit:

if (this._hknp.HP_QueryCollector_GetNumHits(this._queryCollector)[1] > 0) {
            const [, hitData] = this._hknp.HP_QueryCollector_GetCastRayResult(this._queryCollector, 0)[1];

So you could write a for loop to iterate over the number of hits to access each one from your expanded collector.

8

Cool, thanks for the solution. :+1: