How to Fix Eight-Direction Sprite Animation Bugs When Porting Between Godot and Unity

Eight-direction sprite animation commonly breaks when porting between Godot 4 and Unity 6 because the two engines use opposite Y-axis conventions — Godot treats screen-up as negative Y, while Unity's 2D world treats up as positive Y. This mismatch causes the wrong directional animation to play when vertical input is processed at runtime, even if all animation clips are correctly named. Developers are advised to keep movement vectors analog and only quantize a separate copy for visual direction selection, using dot products to map input to the nearest of eight authored directions. Idle behavior should rely on a stored last-facing direction rather than raw input, and updates should be gated above a dead zone threshold to prevent controller noise from causing animation flicker. Thorough testing should cover sector boundaries at 22.5-degree intervals, low-magnitude input, rapid reversals, and simultaneous opposing key presses to ensure stable transitions.