From 8466b5c6dcdd084ba001bec89654a8b9b4b3da6b Mon Sep 17 00:00:00 2001
From: karl <karl.bittner@hexaquo.at>
Date: Sun, 21 Nov 2021 12:52:19 +0100
Subject: [PATCH] Improved collision and line removal

---
 GameBoard.gd | 60 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 12 deletions(-)

diff --git a/GameBoard.gd b/GameBoard.gd
index 96c59f9..1223daa 100644
--- a/GameBoard.gd
+++ b/GameBoard.gd
@@ -15,6 +15,9 @@ var active_shape: TetrisShape
 
 const RASTER_SIZE = 64
 const BOTTOM = RASTER_SIZE * 10
+const SPAWN = -RASTER_SIZE * 7
+const LEFT = -RASTER_SIZE * 5
+const RIGHT = RASTER_SIZE * 5
 
 
 func _ready():
@@ -26,6 +29,7 @@ func _ready():
 func get_random_shape():
 	var new_shape = shapes[randi() % shapes.size()].instance()
 	add_child(new_shape)
+	new_shape.position.y = SPAWN
 	return new_shape
 
 
@@ -44,14 +48,32 @@ func move_active_down():
 
 
 func can_active_move_down():
-	if active_shape.position.y >= BOTTOM:
-		return false
-	
+	return _can_active_move_towards(Vector2(0.0, RASTER_SIZE))
+
+
+func can_active_move_left():
+	return _can_active_move_towards(Vector2(-RASTER_SIZE, 0.0))
+
+
+func can_active_move_right():
+	return _can_active_move_towards(Vector2(RASTER_SIZE, 0.0))
+
+
+func _can_active_move_towards(diff: Vector2):
 	for block in active_shape.get_blocks():
-		var down_x = block.global_position.x
-		var down_y = block.global_position.y + RASTER_SIZE
+		var new_x = block.global_position.x + diff.x
+		var new_y = block.global_position.y + diff.y
 		
-		if is_block_at_position(down_x, down_y):
+		var global_bottom = to_global(Vector2(0.0, BOTTOM)).y
+		var global_left = to_global(Vector2(LEFT, 0.0)).x
+		var global_right = to_global(Vector2(RIGHT, 0.0)).x
+		
+		if new_x <= global_left \
+				or new_x >= global_right \
+				or new_y >= global_bottom:
+			return false
+		
+		if is_block_at_position(new_x, new_y):
 			return false
 	
 	return true
@@ -70,11 +92,16 @@ func turn_active_into_static():
 func check_for_full_line():
 	var line_counts = {} # Maps a y position to a count
 	
+	# Count how many blocks we have in each line (with at least 1 block)
 	for block in $StaticBlocks.get_children():
 		if not line_counts.has(block.position.y):
 			line_counts[block.position.y] = 0
 		line_counts[block.position.y] += 1
 	
+	# Remember which blocks we need to move down later (we can't apply this immediately because that
+	# would mess with comparisons to the line_counts
+	var pending_position_diffs = {}
+	
 	for line_count_y in line_counts.keys():
 		if line_counts[line_count_y] == 10:
 			# Free this line
@@ -82,18 +109,27 @@ func check_for_full_line():
 				if line_block.position.y == line_count_y:
 					line_block.free()
 				elif line_block.position.y < line_count_y:
-					# Move higher-up blocks down
-					line_block.position.y += RASTER_SIZE
+					# If this block is above the line currently being freed, remember to move down
+					# by one raster cell
+					if not pending_position_diffs.has(line_block):
+						pending_position_diffs[line_block] = 0
+					pending_position_diffs[line_block] += RASTER_SIZE
+	
+	# Apply the pending downward movements, but only if the block hasn't been freed (because that
+	# line was above, but also full)
+	for block in pending_position_diffs.keys():
+		if is_instance_valid(block):
+			block.position.y += pending_position_diffs[block]
 
 
 func move_left():
-	# TODO: Check for collision
-	active_shape.position.x -= RASTER_SIZE
+	if can_active_move_left():
+		active_shape.position.x -= RASTER_SIZE
 
 
 func move_right():
-	# TODO: Check for collision
-	active_shape.position.x += RASTER_SIZE
+	if can_active_move_right():
+		active_shape.position.x += RASTER_SIZE
 
 
 func rotate_shape():