Player movement abilities dash sprint and double jump

When to use

The player already walks and jumps (see third-person-and-platformer-movement or first-person-controls) and now needs an extra move: a dash burst, a sprint that speeds them up while a key is held, or a second jump in the air. The engine has no DashComponent, SprintComponent, or DoubleJumpComponent; each ability is a script layered on the real CharacterMovementComponent motor, and the burst itself is the same ctx.physics.command launch that jump pads use.

The recipe

Prerequisite: the player carries CharacterMovementComponent (enableKcc: true, a maxSpeed, a jumpSpeed, a groundY) and an InputProfileComponent. Add one action per ability (see input-mapping-actions-bindings): a sprint boolean and a dash (or doubleJump) button. Author the behavior with project_apply_script_semantic_patch using the ai_safe op pack.

Sprint (faster while held)

1. addActionHandler { "actionKey":"sprint", "handlerKey":"onSprint" }.
2. In the handler, branch on the InputActionEvent phase: on pressed, ctx.entity.patchComponent the player's CharacterMovementComponent to a higher maxSpeed (for example 11); on released, patch it back to the walk value (for example 7). Read the walk value once with ctx.entity.readComponent and stash it in state if you want it dynamic.
3. Optional stamina: seed a stamina number with writeTypedStateValue, drain it each tick while sprinting with incrementNumericState { "by": -1 }, and force released behavior when it hits 0.

Dash (a burst in the facing direction)

1. addActionHandler { "actionKey":"dash", "handlerKey":"onDash" }.
2. Keep the current facing fresh: addTickHandler { "handlerKey":"onMoveSample" } that, in a replaceScriptFromGessaScript body, reads the move action value (the InputActionEvent value, a vector2d) and, when it is non-zero, writeTypedStateValue a facing vector. This gives the dash a direction even at a standstill (last-moved).
3. In onDash (whole-body GessaScript), read facing, scale it to a dash speed (for example 18), and fire ctx.physics.command(playerId, { type: "launch", velocity: { x: fx*18, y: 0, z: fz*18 } }) where playerId is the entity the handler runs on (ctx.entity is the self-accessor for reads and patches; pass the player's own id to the command). launch SETS the kinematic character's velocity for this step, which is the one sanctioned way to fling a CharacterMovementComponent body; do not patch TransformComponent position to fake the dash.
4. Cooldown: setBooleanState { "field":"dashReady", "value": false } on dash, and flip it back after a delay with a TimerComponent (see timers-countdowns-and-waves). Gate the dash on dashReady so it cannot be spammed.

Double jump (a second jump before landing)

1. Track jumps used: seed jumpsUsed to 0 with writeTypedStateValue.
2. Ground reset: in an addTickHandler body, ctx.entity.readComponent the TransformComponent position.y and the CharacterMovementComponent groundY; when the player is at (or near) groundY, writeTypedStateValue jumpsUsed back to 0. This is the grounded check without a hidden velocity lane.
3. Jump action: addActionHandler { "actionKey":"jump", "handlerKey":"onJump" }. readTypedStateValue jumpsUsed; if it is less than the allowed count (2 for a double jump), ctx.physics.command(playerId, { type:"launch", velocity:{ x:0, y: jumpSpeed, z:0 } }) and incrementNumericState jumpsUsed { "by": 1 }. When jumpsUsed reaches the cap, ignore the press.

Pitfalls

• The launch y for a jump should match the movement jumpSpeed so the double jump feels like the first; read it with ctx.entity.readComponent rather than hardcoding a second number that can drift from the motor.
• launch REPLACES velocity, it does not add to it: a dash issued mid-fall wipes the fall speed for that step. That is usually what you want for a crisp dash; for a momentum-preserving dash, compose the desired resultant yourself.
• Do NOT author a VelocityComponent or ForceComponent to move the character; both are hidden internal runtime lanes. Every burst goes through ctx.physics.command, every speed change through CharacterMovementComponent.maxSpeed.
• Ground the double-jump reset on position vs groundY, not on a landing event you cannot subscribe to; there is no grounded-state flag on the movement component to read.
• Sprint changes maxSpeed; it does not multiply an existing velocity. If sprint feels like it does nothing, confirm you patched the same CharacterMovementComponent the mover reads and that enableKcc is true.

Verify

• engine_get_component_schema on CharacterMovementComponent to confirm maxSpeed/jumpSpeed/groundY before patching.
• project_get_graph_snapshot to confirm the sprint/dash/jump handlers and the ScriptComponent binding exist on the player.
• simulation_run (qa.run.start) to prove sprint raises speed while held, the dash launches in the move direction, and a second jump fires in the air but a third does not.