Why does Godot is_action_just_pressed miss buffered jumps?

is_action_just_pressed returns true only the frame after the press. If the player presses jump just before landing, the just_pressed pulse passes before is_on_floor becomes true. Implement a buffer timer that remembers presses for ~150 ms.

How do I implement input buffering in Godot?

In _input or _process, when is_action_just_pressed for jump, set jump_buffer_until = Time.get_ticks_msec() + 150. In _physics_process, if Time.get_ticks_msec() < jump_buffer_until and is_on_floor(), execute jump and clear the buffer.

Should I read input in _input or _physics_process?

_input is event-driven, fires on each press immediately. _physics_process is fixed-rate. Read just_pressed in _input or _process to capture every event; consume the buffer flag in _physics_process for movement.

Fix: Godot Input Action Buffer Not Firing

Q: Should I read input in _input or _physics_process?

_input is event-driven, fires on each press immediately. _physics_process is fixed-rate. Read just_pressed in _input or _process to capture every event; consume the buffer flag in _physics_process for movement.

Quick answer: Set a 150 ms input buffer when is_action_just_pressed returns true. In _physics_process, if buffer is still valid and conditions allow (e.g., on floor), execute and clear buffer.

Here is how to fix Godot 4 platformer jumps dropped because the player pressed jump a frame before landing. Input buffering forgives mistimed presses.

The Symptom

Player presses jump 1–2 frames before landing. is_on_floor still false; jump check fails. By the next frame, is_action_just_pressed is gone. Player feels unresponsive.

What Causes This

One-frame just_pressed. The pulse exists for one frame; if conditions are not met, it is wasted.

Physics-Update sync. _physics_process runs at fixed step; can miss between-frame events.

The Fix

Step 1: Buffer the press in _input.

extends CharacterBody2D

var jump_buffer := 0.0
var coyote := 0.0

func _input(event):
    if event.is_action_pressed("jump"):
        jump_buffer = 0.15   # 150 ms buffer

Step 2: Consume in _physics_process.

func _physics_process(delta):
    jump_buffer = max(jump_buffer - delta, 0)
    coyote = max(coyote - delta, 0)

    if is_on_floor():
        coyote = 0.12
        velocity.y = 0
    else:
        velocity.y += 980 * delta

    if jump_buffer > 0 and coyote > 0:
        velocity.y = -400
        jump_buffer = 0
        coyote = 0

    move_and_slide()

Buffer + coyote covers both early and late presses.

Step 3: Tune buffer length to feel. 100 ms = strict, 150 ms = forgiving, 200 ms = very forgiving. Test with multiple players.

Step 4: Apply same pattern to other actions. Wall jump, attack cancel, dash — all benefit from buffering.

Step 5: Disable buffer during cutscenes. Buffer triggering after a paused interlude can cause unwanted action; clear on pause.

Understanding the issue

Input bugs are perceptible to players even when the gameplay code is correct. A 16ms delay that the profiler considers fine is the difference between 'responsive' and 'sluggish'. The fix is often in the input pipeline, not the gameplay.

The specific bug described above is the kind that surfaces during integration rather than unit testing. It depends on a combination of factors: the asset configuration, the runtime state, the platform's specific behavior. In isolation, each piece looks correct; in combination, the bug emerges. This is why thorough integration testing - playing the actual game in realistic conditions - catches things that automated tests miss.

Why this happens

Bugs of this class are particularly easy to ship past internal QA because they often depend on specific runtime conditions - hardware combinations, network states, or asset configurations that QA didn't reproduce. Players hit them in the wild, file reports that are hard to repro, and the bug accumulates negative reviews while engineering tries to recreate the failure mode.

At the engine level, the behavior comes from a deliberate design decision in Godot. The engine team chose a particular trade-off - usually performance versus convenience, or generality versus specificity - and that trade-off has consequences when you push against it. Understanding the trade-off is what turns 'this bug is mysterious' into 'this bug is the expected consequence of this design'.

Verifying the fix

After applying the fix, the verification step has three parts: confirm the original repro is resolved, confirm no obvious regressions in adjacent functionality, and (for shipping titles) deploy to a small player cohort first and watch the crash and report rates. Each step catches something the others miss.

Reproducibility is the prerequisite for verification. If you can't reliably reproduce the bug pre-fix, you can't reliably verify it post-fix. Spend time getting a clean reproduction before you write any fix code. The fix is fast once you understand the reproduction; the reproduction is the slow part.

Variations to watch for

Related bug classes often share the same root cause. If you find yourself fixing this issue, look for cousins: similar symptoms in adjacent systems, the same data flow but a different value, or the same fix pattern in another module. The catalog of 'we've seen this before' becomes valuable institutional knowledge.

Adjacent bugs often share a root cause. After fixing the case you've found, spend an hour searching the codebase for similar patterns. What's the same call with different arguments? The same data flow with a different entity type? The same lifecycle issue in a sibling system? Each match is a candidate for the same fix, or a related fix that prevents future bugs of the same class.

In production

Live games surface this bug class at scale. What's a rare edge case in development becomes a daily occurrence once you have a few thousand concurrent players. The class isn't 'this player has a unique setup'; it's 'one in N thousand sessions will trigger this exact combination'.

When triaging a similar issue in production, prioritize gathering data over hypothesizing causes. A player report describes a symptom; what you need is a build SHA, a session timestamp, and ideally a screen recording or session replay. With those, the bug becomes tractable. Without them, you're guessing at hypothetical reproductions that may not match what the player actually hit.

Performance considerations

Performance implications matter when this bug class scales with player count or asset count. A bug that fires once per session is annoying; a bug that fires once per frame compounds. After fixing, profile the affected code path under realistic load. The fix that's correct for one entity may be too slow for ten thousand.

Diagnostic approach

Diagnosing this class of bug benefits from a structured approach: confirm the symptom, isolate the variables, hypothesize the cause, and verify the hypothesis before writing fix code. Skipping the isolation step is the most common mistake; without it, fixes often address symptoms while the underlying cause continues to produce other variations.

For Godot-specific diagnostics, the editor's profiler is the canonical starting point. Capture a representative frame with the symptom present; compare against a frame without the symptom; the diff often points directly at the cause. If the symptom is non-deterministic, capture multiple frames and look for the pattern - the cause is usually a state transition or a specific input value rather than a continuous effect.

Tooling and ecosystem

Third-party plugins often provide better diagnostics for their own behavior than the engine does. If the affected code is in a plugin, check the plugin's documentation for debug modes, verbose logging, or inspector tools - these can save hours of investigation when they exist.

Within Godot, the relevant diagnostic surfaces include the standard frame debugger, memory profiler, and engine-specific debug overlays. Each one shows a different facet of what's happening. The frame debugger reveals draw call ordering and state transitions; the memory profiler shows allocation patterns; the debug overlay reveals per-system state. Bugs that resist one tool usually surrender to another - the trick is knowing which tool to reach for first.

Edge cases and pitfalls

Edge cases for this class of issue often involve specific timing: the first frame after a state change, the last frame before a transition, frames where multiple subsystems update simultaneously. Reproducing these reliably is part of what makes the bug class hard to test.

When writing a regression test for this fix, focus on the boundary conditions that surfaced the original bug. Tests that exercise the happy path catch obvious regressions; tests that exercise the boundary catch the subtler regressions that look like new bugs but are really the original returning. The latter are the tests that earn their keep over the long life of the project.

Team communication

Document the fix and its rationale in the commit message or attached engineering doc. Future engineers will encounter related issues; the rationale tells them whether your fix is reusable or specific to the case at hand. Without rationale, the fix gets reverted or copied incorrectly.

If this fix touches a system several engineers work in, a short writeup in the team's engineering channel helps. Not a full design doc - a paragraph explaining what was wrong, what's fixed, and what to watch for. Future engineers encountering similar symptoms will search for the fix; making it findable is a small investment that pays back later.

“Buffer in _input. Consume in _physics_process. Coyote pairs with buffer. Jumps land.”

Related Issues

For CharacterBody3D velocity, see Velocity Y. For mouse mode, see Mouse Mode.

150ms jump buffer. Coyote 120ms. Both cleared on use. Forgiving controls.