37 lines
2.1 KiB
Markdown
37 lines
2.1 KiB
Markdown
# local-player-presentation-state Specification
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## Purpose
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Define how the local player's presentation layer holds current display state and smoothly interpolates toward the simulation layer's target state each frame.
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## ADDED Requirements
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### Requirement: Presentation layer holds current and target state
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The local player's presentation layer SHALL maintain `_currentPosition` and `_currentRotation` (the actively displayed state) separately from `_targetPosition` and `_targetRotation` (the simulation layer's output).
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#### Scenario: Presentation state initializes from first simulation target
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- **WHEN** the presentation layer is initialized or first receives a simulation target
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- **THEN** `_currentPosition` and `_currentRotation` are set equal to the initial target
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- **THEN** subsequent updates lerp toward the target
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### Requirement: Presentation layer lerps toward target each frame
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The presentation layer SHALL each frame interpolate `_currentPosition` and `_currentRotation` toward `_targetPosition` and `_targetRotation` using linear interpolation, then apply the result to the Rigidbody.
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#### Scenario: Lerp position and rotation toward target
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- **WHEN** the presentation layer updates each frame with interpolation alpha α
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- **THEN** `_currentPosition` is updated to `Vector3.Lerp(_currentPosition, _targetPosition, α)`
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- **THEN** `_currentRotation` is updated to `Quaternion.Slerp(_currentRotation, _targetRotation, α)`
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- **THEN** `_rigid.position` and `_rigid.rotation` are set to `_currentPosition` and `_currentRotation`
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### Requirement: Presentation layer snaps when target error exceeds threshold
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When the distance between `_currentPosition` and `_targetPosition` exceeds the snap threshold, the presentation layer SHALL immediately snap `_currentPosition` to `_targetPosition` without lerping.
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#### Scenario: Snap when error exceeds threshold
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- **WHEN** `Vector3.Distance(_currentPosition, _targetPosition) > SnapThreshold`
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- **THEN** `_currentPosition` is set equal to `_targetPosition`
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- **THEN** `_currentRotation` is set equal to `_targetRotation`
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- **THEN** no lerping occurs in this frame
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