fixed slow grid drawing, which also fixed transient tile quirk

systems/grid_system.go

@@ -1,9 +1,6 @@
 package systems
 
 import (
-	"image"
-	"image/draw"
-	"log/slog"
 	. "openquell/components"
 
 	"github.com/hajimehoshi/ebiten/v2"
@@ -40,32 +37,33 @@ func NewGridSystem(world *ecs.World, width, height,
 	return system
 }
 
-func (system *GridSystem) Update() error { return nil }
+func (system *GridSystem) Update() error {
+	return nil
+}
 
 func (system *GridSystem) Draw(screen *ebiten.Image) {
 	op := &ebiten.DrawImageOptions{}
 	query := system.Selector.Query(system.World)
+
 	if !system.UseCache || query.Count() != system.Count {
-		slog.Debug("entity number changes", "old", system.Count, "current", query.Count())
 		// map not cached or cacheable, write it to the cache
-		draw.Draw(system.Cache, system.Background.Bounds(), system.Background, image.ZP, draw.Src)
+		system.Cache.DrawImage(system.Background, op)
 
 		system.Count = query.Count()
-
+		counter := 0
 		for query.Next() {
 			sprite, pos, _ := query.Get()
-
-			//slog.Debug("drawing sprite", "sprite", sprite, "point", pos.Point())
-			draw.Draw(
-				system.Cache,
-				image.Rect(pos.X, pos.Y, pos.X+pos.Cellsize, pos.Y+pos.Cellsize),
-				sprite.Image, image.ZP, draw.Over)
+			counter++
+			op.GeoM.Reset()
+			op.GeoM.Translate(float64(pos.X), float64(pos.Y))
+			system.Cache.DrawImage(sprite.Image, op)
 		}
 
 		op.GeoM.Reset()
 		screen.DrawImage(system.Cache, op)
 
 		system.UseCache = true
+
 	} else {
 		// use the cached map
 		op.GeoM.Reset()

systems/transient_system.go

@@ -1,6 +1,7 @@
 package systems
 
 import (
+	"log/slog"
 	"openquell/assets"
 	"openquell/components"
 	. "openquell/components"
@@ -78,17 +79,19 @@ func (system *TransientSystem) Update() error {
 						Position:  *transientposition,
 						NewSprite: transient.GetNext(),
 					})
-					//slog.Debug("done transient", "transient", transientposition)
+					slog.Debug("transient added to make solid")
 				}
 			}
 		}
 	}
 
 	for _, convertible := range EntitiestoMakeSolid {
+		slog.Debug("transient remove")
 		// remove transient entity
 		system.World.RemoveEntity(convertible.Entity)
 
 		// replace with solid entity
+		slog.Debug("transient add solid")
 		entity := system.SolidMapper.New()
 		pos, render, _, _ := system.SolidMapper.Get(entity)