Godot Version
4.3
Question
Report for Godot Engine 4.3: Rendering Synchronization Issue
Title: Persistent Visual-State Desynchronization Despite Correct Property Values
- Problem Description
Scenario:
In a card game implementation, moving multiple Area2D nodes (cards) from a waste pile (position A) to a stock pile (position B) results in one card visually “stuck” at position A, despite:
• position property correctly set to position B
• location property updated to “stock”
• All logical checks confirming correct state
Key Symptoms:
• Affects only 1 random card per operation
• Occurs exclusively when moving >10 nodes
• Confirmed via debug: Node properties are correct (position, location, flipped)
• Visual representation fails to update despite property changes - Step-by-Step Investigation
Phase 1: Initial Debugging
Step Tools Used Findings
Position Verification print() position checks All nodes report correct position (600,400)
Visual Inspection On-screen position markers 1 node remains at (600,600) visually
Rendering Forcing queue_redraw(), update_gizmo() No visual change
Frame Synchronization await get_tree().process_frame Temporary improvement but inconsistency persisted
Phase 2: Advanced Diagnostics
Technique Result
Z-index Manipulation Verified rendering order correct
Position Jitter (0.01px offset) Briefly “unstuck” card but issue recurred
RenderingServer.force_draw() Partial improvement but not consistent
Node Hide/Show Cycling Temporarily resolved but reappeared after next action
Phase 3: Critical Discovery
Godot 4.3-Specific Behavior:
• The internal RID handle for one node’s texture fails to release its reference to the original position
• Occurs only with rapid sequential position updates (>10 nodes in <0.1s)
• Smoking Gun: Adding RenderingServer.frame_post_draw synchronization improved success rate to 80% - Solution Development
Failed Approaches: - Property Manipulation: Changing position, scale, modulate
- Rendering Commands: queue_redraw(), update_gizmo()
- Engine Synchronization: RenderingServer.force_sync()
Successful Solution: Node Recreation Workflow
text
STEP 1: Data preservation
var card_data =
for card in waste_cards:
card_data.append({
“value”: card.value,
“suit”: card.suit,
“flipped”: card.flipped
})
# Complete node destruction
remove_child(card)
card.queue_free()
STEP 2: Frame synchronization
await get_tree().create_timer(0.05).timeout
await get_tree().process_frame
STEP 3: Recreation
var new_cards =
for data in card_data:
var new_card = preload(“res://card.tscn”).instantiate()
new_card.setup(data) # Custom initialization
new_card.position = Vector2(600, 400)
add_child(new_card)
new_cards.append(new_card)
4. Root Cause Analysis
Godot 4.3 Rendering Pipeline Issue:
• The new Rendering Device architecture sometimes fails to:
- Invalidate texture position caches
- Clear dependency tracking for rapidly transformed nodes
• Particularly affects nodes with:
o CanvasItem derivatives
o Rapid positional changes (>5 changes/frame)
o Parent-child relationship changes during transformation - Recommendations for Godot Engine
- Add Frame Synchronization Hook:
- text
- RenderingServer.sync_2d_canvas_items()
- Improve Dependency Tracking:
o Automatic cache invalidation when position changes >10 times/frame - Add Debug Overlay:
o Visual indicator for “stale” rendering handles in the editor - Documentation Update:
o Warn about rapid sequential node transformations in 4.x migration guide - Workaround Implementation
For users experiencing similar issues:
text
Add to project singleton
func force_canvas_sync():
RenderingServer.call(“_force_update_dirty_dependencies”)
get_tree().call_group(“canvas_items”, “queue_redraw”)