79 lines
1.9 KiB
Go
79 lines
1.9 KiB
Go
package gohan
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import (
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"time"
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)
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// Entity is an entity identifier.
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type Entity int
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// NewEntity returns a new (or previously removed and cleared) Entity. Because
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// Gohan reuses removed Entity IDs, a previously removed ID may be returned.
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func NewEntity() Entity {
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w.entityMutex.Lock()
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defer w.entityMutex.Unlock()
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if len(w.availableEntities) > 0 {
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id := w.availableEntities[0]
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w.availableEntities = w.availableEntities[1:]
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w.allEntities = append(w.allEntities, id)
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return id
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}
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w.maxEntityID++
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w.allEntities = append(w.allEntities, w.maxEntityID)
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w.components = append(w.components, make([]interface{}, w.maxComponentID+1))
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return w.maxEntityID
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}
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// Remove removes the provided Entity's components, causing it to no
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// longer be handled by any system. Because Gohan reuses removed EntityIDs,
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// applications must also remove any internal references to the removed Entity.
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func (e Entity) Remove() bool {
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w.entityMutex.Lock()
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defer w.entityMutex.Unlock()
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for i, ent := range w.allEntities {
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if ent == e {
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w.allEntities = _removeAt(w.allEntities, i)
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// Remove components.
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for i := range w.components[e] {
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w.components[e][i] = nil
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}
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w.removedEntities = append(w.removedEntities, e)
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return true
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}
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}
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return false
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}
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// AllEntities returns a slice of all active entities. To retrieve only the
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// number of currently active entities, use CurrentEntities.
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func AllEntities() []Entity {
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w.entityMutex.Lock()
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defer w.entityMutex.Unlock()
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allEntities := make([]Entity, len(w.allEntities))
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copy(allEntities, w.allEntities)
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return allEntities
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}
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var numEntities int
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var numEntitiesT time.Time
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// CurrentEntities returns the number of currently active entities.
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func CurrentEntities() int {
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if time.Since(numEntitiesT) >= w.cacheTime {
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numEntities = len(w.allEntities)
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numEntitiesT = time.Now()
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}
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return numEntities
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}
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func _removeAt(v []Entity, i int) []Entity {
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v[i] = v[len(v)-1]
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return v[:len(v)-1]
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}
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