54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
package observers
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import (
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"github.com/mlange-42/arche/ecs"
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"github.com/mlange-42/arche/ecs/event"
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"github.com/mlange-42/arche/generic"
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"github.com/mlange-42/arche/listener"
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)
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// will be added as an ecs.Resource to the world so we can use it in
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// CollisionSystem to dynamically make it appear or disappear
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type ParticleObserver struct {
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// we only have one particle so far, if we use multiple ones, turn
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// this in to a map, see player_observer.go for an example
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Entity ecs.Entity
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}
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// Create a new resource of type PlayerObserver which will hold all
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// player entities. We also add a Listener which looks for
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// EntityRemoved events and if a player gets removed, we also remove
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// it from the Entity map in our observer.
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func NewParticleObserver(world *ecs.World) {
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observer := &ParticleObserver{}
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resmanger := generic.NewResource[ParticleObserver](world)
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resmanger.Add(observer)
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listen := listener.NewCallback(
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func(world *ecs.World, event ecs.EntityEvent) {
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observerID := ecs.ResourceID[ParticleObserver](world)
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observer := world.Resources().Get(observerID).(*ParticleObserver)
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observer.RemoveEntity(event.Entity)
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},
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event.EntityRemoved,
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)
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world.SetListener(&listen)
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}
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func GetParticleObserver(world *ecs.World) *ParticleObserver {
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observerID := ecs.ResourceID[ParticleObserver](world)
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observer := world.Resources().Get(observerID).(*ParticleObserver)
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return observer
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}
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func (observer *ParticleObserver) AddEntity(entity ecs.Entity) {
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observer.Entity = entity
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}
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func (observer *ParticleObserver) RemoveEntity(entity ecs.Entity) {
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observer.Entity = ecs.Entity{}
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}
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