openquell/grid/grid.go

package grid

import (
	"fmt"
	"image"
	"log"
	"openquell/assets"
	"openquell/components"
	"openquell/observers"

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

type Grid struct {
	Width    int
	Height   int
	Size     int
	Tilesize int
	Map      map[image.Point]*assets.Tile
}

// FIXME: put component addition into extra callable function, to be called
// by game.go in a level-loop. Also remove components of previous level
func NewGrid(world *ecs.World,
	tilesize, width, height int, mapslice map[image.Point]*assets.Tile) *Grid {

	// we use this to turn  our tiles into iterable entities, used for
	// collision detection, transformation and other things
	playermapper := generic.NewMap4[
		components.Position,
		components.Velocity,
		components.Renderable,
		components.Player](world)

	solidmapper := generic.NewMap4[
		components.Position,
		components.Renderable,
		components.Tilish,
		components.Solid](world)

	emptymapper := generic.NewMap2[components.Position, components.Tilish](world)

	colmapper := generic.NewMap3[
		components.Position,
		components.Renderable,
		components.Collectible](world)

	var pos *components.Position
	var render *components.Renderable

	playerobserver := observers.GetPlayerObserver(world)

	for point, tile := range mapslice {
		switch tile.Renderable {
		case true:
			switch {
			case tile.Solid:
				entity := solidmapper.New()
				pos, render, _, _ = solidmapper.Get(entity)
			case tile.Player:
				entity := playermapper.New()
				pos, _, render, _ = playermapper.Get(entity)
				playerobserver.AddEntity(entity)

				fmt.Printf("player start pos: %d,%d\n", point.X*tilesize, point.Y*tilesize)
			case tile.Collectible:
				entity := colmapper.New()
				pos, render, _ = colmapper.Get(entity)
			default:
				log.Fatalln("unsupported tile type encountered")
			}

			render.Image = tile.Sprite

		default:
			// empty  cell, this is  where the player[s]  move. No
			// sprite required since  every level has a background
			// image.
			entity := emptymapper.New()
			pos, _ = emptymapper.Get(entity)
		}

		// however, every tile has a position
		pos.Update(point.X*tilesize, point.Y*tilesize, tilesize)
	}

	return &Grid{
		Size:     len(mapslice),
		Tilesize: tilesize,
		Width:    width,
		Height:   height,
		Map:      mapslice,
	}
}

// return the tile the moving object would end up on if indeed moving
func (grid *Grid) GetTile(
	position *components.Position,
	velocity *components.Velocity) *assets.Tile {

	newpoint := image.Point{
		int(position.X+velocity.Data.X) / grid.Tilesize,
		int(position.Y+velocity.Data.Y) / grid.Tilesize,
	}

	tile := grid.Map[newpoint]
	return tile
}