CameraTween

Class

Source: CameraTween.h

Description

Fixed-capacity camera tween pool with enum-based easing.

Owns a fixed array of N tween slots, each tracking a from → to Vector2 interpolation with an independent duration and easing curve. Every active tween writes its current interpolated position to the camera via Camera2D::setPosition() on each update() call. When multiple tweens are active, last-write-wins on the camera position.

Zero heap allocation — the slot array and all easing math live on the stack or in the object's fixed-size storage. Copy and move are deleted because the pool is its identity.

N Maximum number of simultaneously active tweens (default 4). When N=0, startTween() always returns kInvalidSlotId and activeCount() always returns 0.

Methods

uint8_t startTween(pixelroot32::math::Vector2 from, pixelroot32::math::Vector2 to, uint16_t durationMs, TweenEasing easing)

Description:

Start a new camera tween.

Parameters:

• from: Starting position (world coordinates).
• to: Target position (world coordinates).
• durationMs: Total duration in milliseconds, 1..65535. 0 is treated as an instant no-op (returns kInvalidSlotId without consuming a slot).
• easing: Easing curve for the interpolation.

Returns: Slot id 0..N-1 on success, or kInvalidSlotId (0xFF) if the pool is full, N==0, or durationMs==0.

void update(uint16_t deltaTimeMs, Camera2D* camera)

Description:

Advance all active tweens and write interpolated positions to the camera.

Parameters:

• deltaTimeMs: Milliseconds elapsed since the last frame.
• camera: Target camera (must not be nullptr when tweens are active; safe nullptr when activeCount()==0).

bool isComplete(uint8_t slotId) const

Description:

Check whether a given tween slot has completed.

Parameters:

• slotId: The slot id returned by startTween().

Returns: true if the slot exists, was previously started, and has finished (elapsed ≥ duration); false otherwise, including for invalid/out-of-range slotId.

A cancelled slot is also "complete" — cancel() marks it inactive.

uint8_t activeCount() const

Description:

Number of currently active (running) tweens.

Returns: Count in 0..N.

void cancel(uint8_t slotId)

Description:

Cancel a tween without writing to the camera.

Parameters:

• slotId: The slot id returned by startTween().

static uint32_t applyEasing(TweenEasing easing, uint32_t progressRaw)

Description:

Compute eased progress in Q16.16 raw integer arithmetic.

Parameters:

• easing: One of the four TweenEasing values.
• progressRaw: Normalised progress in Q16.16 (0..ONE_Q16).

Returns: Eased progress in Q16.16 (0..ONE_Q16).

static constexpr uint8_t slotCount()

Description:

Effective slot count (N==0 collapses to 1 dummy slot).