Motion & Animation Foundation v1.0

Status: Accepted for Sprint 1.4

Scope: heroes, enemies, bosses, props, UI, particles, and VFX.

This foundation defines all movement rules for Streetline Heroes. Animation must feel responsive, readable, weighty, and arcade-sharp before it feels smooth.

Core Philosophy

| Principle | Rule |

| --- | --- |

| Gameplay First | Movement must communicate game state and input intent. |

| Readability First | Key poses must read at combat scale. |

| Weight over Smoothness | Fewer strong frames beat many mushy frames. |

| Snappy Controls | Player actions need quick response and clear recovery. |

| Arcade Feel | Impact, contrast, pose holds, and timing exaggeration are expected. |

Modules

1. [Animation Philosophy](animation/01_AnimationPhilosophy.md)

2. [Timing](animation/02_Timing.md)

3. [Spacing](animation/03_Spacing.md)

4. [Weight](animation/04_Weight.md)

5. [Anticipation](animation/05_Anticipation.md)

6. [Follow Through](animation/06_FollowThrough.md)

7. [Arcs](animation/07_Arcs.md)

8. [Smear Frames](animation/08_SmearFrames.md)

9. [Impact Frames](animation/09_ImpactFrames.md)

10. [Animation Readability](animation/10_AnimationReadability.md)

11. [Frame Planning](animation/11_FramePlanning.md)

12. [Animation QA](animation/12_AnimationQA.md)

Frame Counts

| Animation | Standard frames | Notes |

| --- | ---: | --- |

| Idle | 4-8 | Subtle breathing and weight shifts. |

| Walk | 8 | Full readable contact cycle. |

| Run | 8 | Stronger spacing and diagonal lean. |

| Jump | 6 | Anticipation, takeoff, air, peak. |

| Fall | 4 | Clear downward read. |

| Attack Light | 5 | Fast anticipation, impact, recovery. |

| Attack Heavy | 7 | Larger anticipation and hit hold. |

| Block | 3 | Snap into protected silhouette. |

| Hit | 3 | Fast reaction, readable direction. |

| Death | 8 | Collapse and settle. |

| Taunt | 8 | Personality pose. |

| Victory | 8 | Readable celebration loop. |

Motion Types

| Type | Motion rule |

| --- | --- |

| Heroes | Responsive, readable, expressive. |

| Enemies | Faster, cheaper, lower detail, clear threat telegraph. |

| Bosses | Slower, heavier, larger anticipation, longer impact holds. |

| Props | Simple state animation, clear break/hit/move state. |

| UI | Snappy, minimal, no distracting bounce. |

| Particles | Short-lived, directional, clustered. |

| VFX | Cause and result readable in the first frames. |

QA Checklist

□ timing

□ spacing

□ weight

□ arcs

□ anticipation

□ follow through

□ readability

□ events

□ schema

Machine-readable events live in assets/definitions/animation/events.standard.yaml.