Add WaypointPath trait

[JPonte]

Issue #804

Simply create a path like:

val path = WaypointPath(
    waypoints = List(Vector2(20, 20), Vector2(80, 30), Vector2(120, 100)),
    radius = 0.0,
    loop = true
)

and in either the updateModel or present methods one can get the expected position with:

path.calculatePosition(at = 0.5)

where at is the relative position in the path. So 0.0 is the beginning of the path and 1.0 is the end. If looping is enabled values above 1.0 wrap around and values lower than 0.0 also wrap around but in reverse.

It can be easily integrated in timelines like:

def loopedPathSignalFunction(waypoints: Vector2*): SignalFunction[Double, (Vector2, Radians)] =
  val path = WaypointPath(waypoints.toList, 0.0, true)
  SignalFunction(over => path.calculatePosition(over))

val traverseSimplePath = loopedPathSignalFunction(Vector2(0, 0), Vector2(1, 0), Vector2(1, 1))

val tl: Timeline[Graphic[Material.ImageEffects]] =
  timeline(
    layer(
      animate(2.seconds) { g =>
        lerp >>> traverseSimplePath >>> SignalFunction((v, r) => g.moveTo(v.toPoint).rotateTo(r))
      }
    )
  )

[JPonte]

I'm not sure how useful this is. The idea is that if the waypoints aren't precise locations but general positions and when a character with a large sprite gets close enough to it, it considers it visited.

[davesmith00000]

I don't know how this feels in practice, but generally I think that's a very sensible approach. Waiting for things to land perfectly something is a headache and usually not worth the hassle!

Might be worth making this configurable though? How close is close enough? You have a few 'config' options already, if you add any more, consider creating a config object:

WaypointPathConfig(pathRadius: Radians, loop: Boolean, requiredProximity: Vector2)
object WaypointPathConfig:
  val initial: WaypointPathConfig = WaypointPathConfig(Radians.zero, false, Vector2.one)

requiredProximity is probably a poor name, it could also be a function that lets the user supply a proximity test - but that's proably overkill for the first cut.

[JPonte]

I added an example of it in the sandbox that hopefully illustrates how it works.

[JPonte]

@davesmith00000 not sure this is what you had in mind but added a sandbox example of it working with timelines.

[davesmith00000]

It's great! 🔥

I've peppered it with comments that are mostly about bringing it inline with the rest of Indigo's style. Up to you if you feel like doing the work, I can always merge and refine afterwards.

Either way, the effort is much appreciated. 🙏

[davesmith00000]

I shall forever wonder if this is the right thing to have done, but for consistency, Vector2 should probably be Vertex. They're almost identical, but a vertex is a position on a graph / space where vector2 is an expression of direction. LineSegment uses Vertex, I am open to counter arguments. 😄

indigo/indigo/indigo/src/main/scala/indigo/shared/geometry/LineSegment.scala

Line 5 in 684df20

final case class LineSegment(start: Vertex, end: Vertex) derives CanEqual:

[davesmith00000]

Additionally, can we replace List with Batch? Batch is much faster and used everywhere.

[JPonte]

I'm glad you mention this because I just realised yesterday that there is both Vertex and Vector2 and I wasn't sure what was the difference 😅 I'll change both.

[davesmith00000]

I don't know how this feels in practice, but generally I think that's a very sensible approach. Waiting for things to land perfectly something is a headache and usually not worth the hassle!

Might be worth making this configurable though? How close is close enough? You have a few 'config' options already, if you add any more, consider creating a config object:

WaypointPathConfig(pathRadius: Radians, loop: Boolean, requiredProximity: Vector2)
object WaypointPathConfig:
  val initial: WaypointPathConfig = WaypointPathConfig(Radians.zero, false, Vector2.one)

requiredProximity is probably a poor name, it could also be a function that lets the user supply a proximity test - but that's proably overkill for the first cut.

[davesmith00000]

Glorious. 10/10 demo. 👏

[davesmith00000]

Looks great. I've reviewed the demo - thanks for doing that. 🙏