openquell/systems/player_system.go

package systems

import (
	"log/slog"
	. "openquell/components"
	. "openquell/config"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/mlange-42/arche/ecs"
	"github.com/mlange-42/arche/generic"
)

type PlayerSystem struct {
	World       *ecs.World
	Selector    *generic.Filter5[Position, Velocity, Player, Renderable, Speed]
	Particle    *ParticleSystem
	Collectible *CollectibleSystem
	Obstacle    *ObstacleSystem
	Grid        *GridSystem
}

func NewPlayerSystem(world *ecs.World, grid *GridSystem) *PlayerSystem {
	system := &PlayerSystem{
		Selector:    generic.NewFilter5[Position, Velocity, Player, Renderable, Speed](),
		Particle:    NewParticleSystem(world, grid.Tilesize),
		Collectible: NewCollectibleSystem(world),
		Obstacle:    NewObstacleSystem(world),
		Grid:        grid,
		World:       world,
	}

	return system
}

func (system PlayerSystem) Update() error {
	query := system.Selector.Query(system.World)

	for query.Next() {
		playerposition, velocity, _, _, speed := query.Get()

		if !velocity.Moving() {
			switch {
			case ebiten.IsKeyPressed(ebiten.KeyRight):
				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)
				// other keys: <tab>: switch player, etc
			}
		}

		if velocity.Moving() {
			ok, newpos := system.Grid.BumpEdge(playerposition, velocity)
			if ok {
				slog.Debug("falling off the edge", "newpos", newpos)
				playerposition.Set(newpos)
			} else {
				ok, tilepos := system.Grid.GetSolidNeighborPosition(playerposition, velocity, true)
				if ok {
					intersects, newpos := tilepos.Intersects(playerposition, velocity)
					if intersects {
						slog.Debug("collision detected", "tile",
							tilepos, "player", playerposition, "new", newpos)

						playerposition.Set(newpos)
						velocity.Change(Stop)
					}
				}
			}
		}

		playerposition.Move(velocity, speed)
	}

	system.Particle.Update()
	system.Obstacle.Update()
	system.Collectible.Update()

	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)
	}

	system.Collectible.Draw(screen)
	system.Particle.Draw(screen)
	system.Obstacle.Draw(screen)
}