added primary and secondary player mode

assets/levels/04-mayhem.lvl

@@ -0,0 +1,17 @@
+Description: use multiple players
+Background: background-lila
+                    
+                    
+                    
+                    
+     ##########     
+    #         v#    
+    #          #    
+    #S        s#    
+    #          #    
+    #^         #    
+     ##########     
+                    
+                    
+                    
+                    

assets/loader-levels.go

@@ -27,6 +27,7 @@ type Tile struct {
 	Class       string
 	Solid       bool
 	Player      bool
+	IsPrimary   bool
 	Renderable  bool
 	Velocity    bool
 	Collectible bool
@@ -38,15 +39,32 @@ type Tile struct {
 	Direction   int // obstacles
 }
 
-func NewTilePlayer() *Tile {
-	return &Tile{
+const (
+	Primary   bool = true
+	Secondary bool = false
+)
+
+func NewTilePlayer(isprimary bool) *Tile {
+	tile := &Tile{
 		Id:         'S',
-		Sprite:     Assets["sphere-blue"],
 		Class:      "sphere",
 		Renderable: true,
 		Player:     true,
 		Velocity:   true,
+		IsPrimary:  isprimary,
 	}
+
+	switch isprimary {
+	case Primary:
+		tile.Sprite = Assets["sphere-blue"]
+	case Secondary:
+		tile.Sprite = Assets["sphere-blue-secondary"]
+		tile.Id = 's'
+	}
+
+	// primary sprite is always the first one
+	tile.Tiles = []*ebiten.Image{Assets["sphere-blue"], Assets["sphere-blue-secondary"]}
+	return tile
 }
 
 func NewTileBlock(class string) *Tile {
@@ -148,7 +166,8 @@ func InitTiles() TileRegistry {
 		' ': {Id: ' ', Class: "floor", Renderable: false},
 		'#': NewTileBlock("block-grey32"),
 		'B': NewTileBlock("block-orange-32"),
-		'S': NewTilePlayer(),
+		'S': NewTilePlayer(Primary),
+		's': NewTilePlayer(Secondary),
 		'o': NewTileCollectible("collectible-orange"),
 		'+': NewTileObstacle("obstacle-star", config.All),
 		'^': NewTileObstacle("obstacle-north", config.North),