Methods to avoid slowDownRadius when requestMoveTarget.

[rob-myers]

When an agent approaches a requestMoveTarget position, it slows down a bit (arrival) due to the following line of code:

https://github.com/recastnavigation/recastnavigation/blob/455a019e7aef99354ac3020f04c1fe3541aa4d19/DetourCrowd/Source/DetourCrowd.cpp#L1204

const float slowDownRadius = ag->params.radius*2;	

It doesn't slow down particularly quickly.

Ideally we should be able to force this, relying upon e.g. AnimationAction.fadeIn
for a smooth animated transition. I've tried two methods:

• When close to the target switch to requestMoveVelocity, then stop when really close.
• When close to the target requestMoveTarget again, overshooting a bit, then stop a bit early so you end up at the original target.

---

The first seems preferable, but I'd prefer to specify a parameter somewhere.

Could we alter the underlying C++ code e.g. somehow provide a new agent parameter?

[isaac-mason]

Hey @rob-myers!

If it's just a matter of changing wrapper javascript / c++ code here, we can for sure. If you're thinking of swapping between requestMoveVelocity / requestMoveTarget, maybe this could be done using the existing recast-navigation-js APIs? Or if you're imagining new agent slowdown parameters, maybe we could modify recast-navigation-js's Crowd javascript class and add parameters there?

If you think these changes are best made inside recastnavigation though, I think it'd be ideal to try contributing any changes to the upstream repo. You could fork both recast-navigation-js & recastnavigation to test/use your changes in the meantime. You can modify this build script to clone recastnavigation from a different repo / comment it out and link a local folder: https://github.com/isaac-mason/recast-navigation-js/blob/main/packages/recast-navigation-wasm/build.sh#L18

[rob-myers]

Hey,

I found a workaround:

when close to the target, we can adjust the maxSpeed to undo the scaling done in recast-detour.

// onTick method
if (distanceToTarget < 2 * agentRadius) {
  this.agent.updateParameters({ maxSpeed: this.getMaxSpeed() * ((2 * agentRadius) / distanceToTarget) });
}

This is preferable because requestMoveTarget will steer the agent, whereas requestMoveVelocity does not. I'd still prefer a parameter, so I guess I'll request one in the underlying repo. Cheers!

[isaac-mason]

Nice, thanks for sharing!