server/block: Add ProjectileHitter interface

server/block/block.go

@@ -74,6 +74,12 @@ type EntityInsider interface {
 	EntityInside(pos cube.Pos, tx *world.Tx, e world.Entity)
 }
 
+// ProjectileHitter represents a block that handles being hit by a projectile.
+type ProjectileHitter interface {
+	// ProjectileHit is called when a projectile hits the block.
+	ProjectileHit(pos cube.Pos, tx *world.Tx, e world.Entity, face cube.Face)
+}
+
 // Frictional represents a block that may have a custom friction value. Friction is used for entity drag when the
 // entity is on ground. If a block does not implement this interface, it should be assumed that its friction is 0.6.
 type Frictional interface {

server/entity/projectile.go

@@ -175,6 +175,9 @@ func (lt *ProjectileBehaviour) Tick(e *Ent, tx *world.Tx) *Movement {
 		if t, ok := tx.Block(bpos).(block.TNT); ok && e.OnFireDuration() > 0 {
 			t.Ignite(bpos, tx, nil)
 		}
+		if h, ok := tx.Block(bpos).(block.ProjectileHitter); ok {
+			h.ProjectileHit(bpos, tx, e, r.Face())
+		}
 		if lt.conf.SurviveBlockCollision {
 			lt.hitBlockSurviving(e, r, m, tx)
 			return m