Havoc, ThinInstances & CollisionCallback

aWeirdo · April 28, 2023, 12:38am

Hi team,
Adding additional ThinInstances after creating the physics body,
calling body.updateBodyInstances() fails to update some internal properties used for collisions callback / observable, causes a crash.

Edit; Updated to avoid confusion

Press any key to move the capsule & model into the sphere in front of it.
See error in console.
Un-Comment line #45 fixes the error.

aWeirdo · April 29, 2023, 2:16pm

Traced the error to HavocPlugin._bodies not being updated when instances are being updated rather than created/initiated, assumably when removing instances the map wont be updated either

github.com

BabylonJS/Babylon.js/blob/412c3d1172f6e7b34deed53f96132fd89bf324a9/packages/dev/core/src/Physics/v2/Plugins/havokPlugin.ts#L387


      
           * world.

           */

          public initBodyInstances(body: PhysicsBody, motionType: PhysicsMotionType, mesh: Mesh): void {

              const instancesCount = mesh._thinInstanceDataStorage?.instancesCount ?? 0;

              const matrixData = mesh._thinInstanceDataStorage.matrixData;

              if (!matrixData) {

                  return; // TODO: error handling

              }

              this._createOrUpdateBodyInstances(body, motionType, matrixData, 0, instancesCount, false);

              body._pluginDataInstances.forEach((bodyId, index) => {

                  this._bodies.set(bodyId.hpBodyId[0], { body: body, index: index });

              });

          }

          

          private _createOrUpdateBodyInstances(body: PhysicsBody, motionType: PhysicsMotionType, matrixData: Float32Array, startIndex: number, endIndex: number, update: boolean): void {

              const rotation = TmpVectors.Quaternion[0];

              const rotationMatrix = Matrix.Identity();

              for (let i = startIndex; i < endIndex; i++) {

                  const position = [matrixData[i * 16 + 12], matrixData[i * 16 + 13], matrixData[i * 16 + 14]];

                  let hkbody;

                  if (!update) {

aWeirdo · April 30, 2023, 2:19pm

PR Ref: Update havokPlugin.ts by aWeirdo · Pull Request #13783 · BabylonJS/Babylon.js · GitHub

bghgary · May 1, 2023, 6:50pm

@Cedric @RaananW

Cedric · May 2, 2023, 7:30am

Good catch! Adding @carolhmj

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Havoc, ThinInstances & CollisionCallback

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