two players fuse now if they collide

systems/player_system.go

@@ -2,9 +2,11 @@ package systems
 
 import (
 	"log/slog"
+	"openquell/components"
 	. "openquell/components"
 	. "openquell/config"
 	"openquell/grid"
+	"openquell/observers"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
@@ -29,6 +31,67 @@ func NewPlayerSystem(world *ecs.World, gridcontainer *grid.GridContainer) System
 }
 
 func (system PlayerSystem) Update() error {
+	var EntitiesToRemove []ecs.Entity
+
+	// check if we need to switch player[s]
+	system.SwitchPlayers()
+
+	// check player movements etc
+	query := system.Selector.Query(system.World)
+	count := query.Count()
+
+	for query.Next() {
+		playerposition, velocity, player, _ := query.Get()
+
+		if !player.IsPrimary {
+			continue
+		}
+
+		// check if the user alters or initiates movement
+		system.CheckMovement(velocity)
+
+		// check if player collides with walls or edges
+		system.CheckGridCollision(playerposition, velocity)
+
+		if count > 1 {
+			// check if player collides with another player, fuse them if any
+			EntitiesToRemove = system.CheckPlayerCollision(playerposition, velocity, query.Entity())
+		}
+	}
+
+	// 2nd pass: move player after obstacle or collectible updates
+	query = system.Selector.Query(system.World)
+	for query.Next() {
+		playerposition, velocity, _, _ := query.Get()
+		playerposition.Move(velocity)
+	}
+
+	// we may have lost players, remove them here
+
+	for _, entity := range EntitiesToRemove {
+		slog.Debug("remove player", "ent", entity.IsZero())
+		system.World.RemoveEntity(entity)
+	}
+
+	return nil
+}
+
+func (system *PlayerSystem) Draw(screen *ebiten.Image) {
+	// write the movable tiles
+	op := &ebiten.DrawImageOptions{}
+	query := system.Selector.Query(system.World)
+
+	for query.Next() {
+		pos, _, _, sprite := query.Get()
+
+		op.GeoM.Reset()
+		op.GeoM.Translate(float64(pos.X), float64(pos.Y))
+
+		screen.DrawImage(sprite.Image, op)
+	}
+}
+
+func (system *PlayerSystem) SwitchPlayers() {
 	// first check if we need to switch player
 	switchable := false
 	query := system.Selector.Query(system.World)
@@ -65,16 +128,9 @@ func (system PlayerSystem) Update() error {
 			}
 		}
 	}
-
-	// check player movements etc
-	query = system.Selector.Query(system.World)
-	for query.Next() {
-		playerposition, velocity, player, _ := query.Get()
-
-		if !player.IsPrimary {
-			continue
 }
 
+func (system *PlayerSystem) CheckMovement(velocity *components.Velocity) {
 	if !velocity.Moving() {
 		switch {
 		case ebiten.IsKeyPressed(ebiten.KeyRight):
@@ -85,27 +141,13 @@ func (system PlayerSystem) Update() error {
 			velocity.Change(South)
 		case ebiten.IsKeyPressed(ebiten.KeyUp):
 			velocity.Change(North)
-			case ebiten.IsKeyPressed(ebiten.Key1):
-				velocity.Speed = 1
-			case ebiten.IsKeyPressed(ebiten.Key2):
-				velocity.Speed = 2
-			case ebiten.IsKeyPressed(ebiten.Key3):
-				velocity.Speed = 3
-			case ebiten.IsKeyPressed(ebiten.Key4):
-				velocity.Speed = 4
-			case ebiten.IsKeyPressed(ebiten.Key5):
-				velocity.Speed = 5
-			case ebiten.IsKeyPressed(ebiten.Key6):
-				velocity.Speed = 6
-			case ebiten.IsKeyPressed(ebiten.Key7):
-				velocity.Speed = 7
-			case ebiten.IsKeyPressed(ebiten.Key8):
-				velocity.Speed = 8
-			case ebiten.IsKeyPressed(ebiten.Key9):
-				velocity.Speed = 9
-				// other keys: <tab>: switch player, etc
 		}
 	}
+}
+
+func (system *PlayerSystem) CheckGridCollision(
+	playerposition *components.Position,
+	velocity *components.Velocity) {
 
 	if velocity.Moving() {
 		ok, newpos := system.GridContainer.Grid.BumpEdge(playerposition, velocity)
@@ -130,27 +172,33 @@ func (system PlayerSystem) Update() error {
 	}
 }
 
-	query = system.Selector.Query(system.World)
+func (system *PlayerSystem) CheckPlayerCollision(
-	for query.Next() {
+	position *components.Position,
-		// move player after obstacle or collectible updates
+	velocity *components.Velocity,
-		playerposition, velocity, _, _ := query.Get()
+	player ecs.Entity) []ecs.Entity {
-		playerposition.Move(velocity)
+
+	observer := observers.GetGameObserver(system.World)
+	posID := ecs.ComponentID[components.Position](system.World)
+	EntitiesToRemove := []ecs.Entity{}
+
+	for _, otherplayer := range observer.GetPlayers() {
+		if !system.World.Alive(otherplayer) {
+			continue
 		}
 
-	return nil
+		if otherplayer == player {
+			continue
 		}
 
-func (system *PlayerSystem) Draw(screen *ebiten.Image) {
+		otherposition := (*Position)(system.World.Get(otherplayer, posID))
-	// write the movable tiles
-	op := &ebiten.DrawImageOptions{}
-	query := system.Selector.Query(system.World)
 
-	for query.Next() {
+		ok, _ := otherposition.Intersects(position, velocity)
-		pos, _, _, sprite := query.Get()
+		if ok {
-
+			// keep displaying it until the two fully intersect
-		op.GeoM.Reset()
+			EntitiesToRemove = append(EntitiesToRemove, otherplayer)
-		op.GeoM.Translate(float64(pos.X), float64(pos.Y))
-
-		screen.DrawImage(sprite.Image, op)
 		}
 	}
+
+	// FIXME: add an animation highlighting the fusion
+	return EntitiesToRemove
+}