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)
@@ -65,92 +128,77 @@ func (system PlayerSystem) Update() error {
 			}
 		}
 	}
+}
 
-	// check player movements etc
+func (system *PlayerSystem) CheckMovement(velocity *components.Velocity) {
-	query = system.Selector.Query(system.World)
+	if !velocity.Moving() {
-	for query.Next() {
+		switch {
-		playerposition, velocity, player, _ := query.Get()
+		case ebiten.IsKeyPressed(ebiten.KeyRight):
-
+			velocity.Change(East)
-		if !player.IsPrimary {
+		case ebiten.IsKeyPressed(ebiten.KeyLeft):
-			continue
+			velocity.Change(West)
+		case ebiten.IsKeyPressed(ebiten.KeyDown):
+			velocity.Change(South)
+		case ebiten.IsKeyPressed(ebiten.KeyUp):
+			velocity.Change(North)
 		}
+	}
+}
 
-		if !velocity.Moving() {
+func (system *PlayerSystem) CheckGridCollision(
-			switch {
+	playerposition *components.Position,
-			case ebiten.IsKeyPressed(ebiten.KeyRight):
+	velocity *components.Velocity) {
-				velocity.Change(East)
-			case ebiten.IsKeyPressed(ebiten.KeyLeft):
-				velocity.Change(West)
-			case ebiten.IsKeyPressed(ebiten.KeyDown):
-				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
-			}
-		}
 
-		if velocity.Moving() {
+	if velocity.Moving() {
-			ok, newpos := system.GridContainer.Grid.BumpEdge(playerposition, velocity)
+		ok, newpos := system.GridContainer.Grid.BumpEdge(playerposition, velocity)
+		if ok {
+			//slog.Debug("falling off the edge", "newpos", newpos)
+			playerposition.Set(newpos)
+		} else {
+			ok, tilepos := system.GridContainer.Grid.GetSolidNeighborPosition(playerposition, velocity, true)
 			if ok {
-				//slog.Debug("falling off the edge", "newpos", newpos)
+				slog.Debug("HaveSolidNeighbor", "ok", ok, "tilepos",
-				playerposition.Set(newpos)
+					tilepos.Point(), "playerpos", playerposition)
-			} else {
+				intersects, newpos := tilepos.Intersects(playerposition, velocity)
-				ok, tilepos := system.GridContainer.Grid.GetSolidNeighborPosition(playerposition, velocity, true)
+				if intersects {
-				if ok {
+					// slog.Debug("collision detected", "tile",
-					slog.Debug("HaveSolidNeighbor", "ok", ok, "tilepos",
+					// 	tilepos, "player", playerposition, "new", newpos)
-						tilepos.Point(), "playerpos", playerposition)
-					intersects, newpos := tilepos.Intersects(playerposition, velocity)
-					if intersects {
-						// slog.Debug("collision detected", "tile",
-						// 	tilepos, "player", playerposition, "new", newpos)
 
-						playerposition.Set(newpos)
+					playerposition.Set(newpos)
-						velocity.Change(Stop)
+					velocity.Change(Stop)
-					}
 				}
 			}
 		}
 	}
-
-	query = system.Selector.Query(system.World)
-	for query.Next() {
-		// move player after obstacle or collectible updates
-		playerposition, velocity, _, _ := query.Get()
-		playerposition.Move(velocity)
-	}
-
-	return nil
 }
 
-func (system *PlayerSystem) Draw(screen *ebiten.Image) {
+func (system *PlayerSystem) CheckPlayerCollision(
-	// write the movable tiles
+	position *components.Position,
-	op := &ebiten.DrawImageOptions{}
+	velocity *components.Velocity,
-	query := system.Selector.Query(system.World)
+	player ecs.Entity) []ecs.Entity {
 
-	for query.Next() {
+	observer := observers.GetGameObserver(system.World)
-		pos, _, _, sprite := query.Get()
+	posID := ecs.ComponentID[components.Position](system.World)
+	EntitiesToRemove := []ecs.Entity{}
 
-		op.GeoM.Reset()
+	for _, otherplayer := range observer.GetPlayers() {
-		op.GeoM.Translate(float64(pos.X), float64(pos.Y))
+		if !system.World.Alive(otherplayer) {
+			continue
+		}
 
-		screen.DrawImage(sprite.Image, op)
+		if otherplayer == player {
+			continue
+		}
+
+		otherposition := (*Position)(system.World.Get(otherplayer, posID))
+
+		ok, _ := otherposition.Intersects(position, velocity)
+		if ok {
+			// keep displaying it until the two fully intersect
+			EntitiesToRemove = append(EntitiesToRemove, otherplayer)
+		}
 	}
+
+	// FIXME: add an animation highlighting the fusion
+	return EntitiesToRemove
 }