Ecsplendid/motion blur

[ecsplendid]

Summary

This PR adds professional-grade motion blur to Revideo using temporal sub-frame accumulation - the same technique used in film and professional video production.

Left: Motion blur ON | Right: Motion blur OFF (per-element control)

Features

Core Capabilities

• Quality presets: low (4), medium (8), high (16), ultra (32) samples
• Shutter curves: box (uniform), triangle (linear falloff), gaussian (bell curve)
• Shutter angle: 0-720° (film standard is 180°)
• Shutter position: center, start, or end alignment
• Per-element control: Enable/disable blur on individual elements

Implementation

Two-pass rendering architecture:

1. Pass 1 (blur): Render blur-enabled elements with sub-frame accumulation

   • Advance scene through sub-frame time offsets
   • Accumulate each render with curve-based weights (box/triangle/gaussian)
   • Normalize accumulated values using high-precision float buffer

2. Pass 2 (static): Render blur-disabled elements on top

   • Single render at frame time, composited over blurred result
   • Keeps text/UI sharp while background animates with blur

Usage

export default makeProject({
  scenes: [scene],
  settings: {
    rendering: {
      motionBlur: {
        enabled: true,
        quality: 'high',
        shutterAngle: 180,
        shutterCurve: 'gaussian',
        shutterPosition: 'center',
      },
    },
  },
});

Per-element control:
<Circle fill="blue" />                          // Will be blurred
<Txt text="UI" motionBlur={{enabled: false}} /> // Stays sharp

Files Changed

| File                                     | Purpose                                           |
|------------------------------------------|---------------------------------------------------|
| packages/core/src/types/MotionBlur.ts    | Config types, quality presets, weight calculation |
| packages/core/src/app/Renderer.ts        | Two-pass rendering, sub-frame loop                |
| packages/core/src/app/Stage.ts           | Float32 accumulation buffer, clearCanvas option   |
| packages/2d/src/lib/components/Node.ts   | Render pass filtering per element                 |
| packages/2d/src/lib/components/View2D.ts | Motion blur subframe signals                      |
| packages/2d/src/lib/scenes/Scene2D.ts    | setMotionBlurSubframe implementation              |

Test Plan

- Motion blur renders correctly at all quality presets
- Shutter curves (box/triangle/gaussian) produce correct weights
- Per-element control works (see demo GIF)
- All existing tests pass (478 tests)
- Documentation in docs/MOTION_BLUR.md

Documentation

Full guide: ./docs/MOTION_BLUR.md

---
🤖 Generated with https://claude.com/claude-code

[ecsplendid]

Examples

transfer-entropy.mp4

translation-rotation-invariance.mp4

nn-vs-ebm-cost.mp4