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FilmGateWeave.md

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Film Gate Weave Node

A ComfyUI node that simulates the characteristic weaving motion of film as it passes through a projector gate. This effect recreates the subtle (or pronounced) horizontal and vertical movement that occurs due to mechanical imperfections in film projection systems.

Presets

The node includes several carefully tuned presets for common film weave patterns:

  • none: No weave effect (stable image)
  • subtle: Minimal movement, suitable for well-maintained projectors
  • moderate: Medium movement, typical of standard projection
  • heavy: Pronounced movement, simulating worn equipment
  • custom: Full control over weave parameters and motion pattern

Parameters

Motion Controls

  • amplitude_x (0.0 - 20.0, default: 3.0)

    • Controls the amount of horizontal movement
    • Higher values create more side-to-side motion
    • Lower values restrict horizontal movement

  • amplitude_y (0.0 - 20.0, default: 1.0)

    • Controls the amount of vertical movement
    • Higher values create more up-and-down motion
    • Typically kept lower than amplitude_x for realism

  • frequency (0.1 - 5.0, default: 1.0)

    • Controls how quickly the weave pattern repeats
    • Higher values create more rapid movement
    • Lower values create slower, more gradual movement

  • phase_shift (0.0 - 2π, default: 0.0)

    • Offsets the starting point of the weave pattern
    • Useful for creating variation between sequences
    • Measured in radians

Custom Animation

  • custom_expression (String, default: "sin(t * 0.1) * 5")
    • Mathematical expression for custom weave patterns
    • Uses 't' as the time variable (0 to 2π)
    • Supports mathematical functions:
      • sin: Sine function
      • cos: Cosine function
      • tan: Tangent function
      • pi: Mathematical constant π

Preset Details

Subtle Preset

  • Minimal horizontal weave (2.0 amplitude)
  • Very slight vertical movement (0.5 amplitude)
  • Slower frequency (0.8)
  • Simple sinusoidal motion
  • Suitable for most vintage film looks

Moderate Preset

  • Medium horizontal weave (4.0 amplitude)
  • Light vertical movement (1.0 amplitude)
  • Standard frequency (1.2)
  • Combined sine/cosine motion
  • Good for typical projection effects

Heavy Preset

  • Strong horizontal weave (8.0 amplitude)
  • Noticeable vertical movement (2.0 amplitude)
  • Faster frequency (1.5)
  • Complex motion pattern
  • Simulates poorly maintained equipment

Technical Details

The node implements sophisticated techniques to create realistic film weave:

  1. Motion Generation

    • Time-based animation system
    • Separate X and Y displacement calculations
    • Smooth interpolation between frames
    • Phase-shifted vertical movement

  2. Image Transformation

    • 2D mesh grid displacement
    • Bilinear interpolation for smooth movement
    • Edge handling to prevent artifacts
    • Proper scaling with image dimensions

  3. Expression Evaluation

    • Safe mathematical expression parsing
    • Support for common trigonometric functions
    • Time normalization for consistent motion
    • Error handling for invalid expressions

Usage Tips

  1. For Modern Film Look:

    • Use "subtle" preset
    • Reduce amplitude_x to 1.0-2.0
    • Keep amplitude_y below 0.5
    • Use slower frequency (0.5-0.8)

  2. For Vintage Projection:

    • Start with "moderate" preset
    • Increase amplitude_x slightly
    • Add custom expression for variation
    • Example: "sin(t * 1.2) * 4 + sin(t * 0.4) * 2"

  3. For Damaged Film Effect:

    • Use "heavy" preset
    • Increase both amplitudes
    • Add faster frequency
    • Combine with other film damage effects

  4. For Custom Patterns:

    • Start with basic sinusoidal motion
    • Add complexity gradually
    • Combine multiple frequencies
    • Example expressions:
      • Simple: "sin(t) * 5"
      • Complex: "sin(t * 1.5) * 4 + cos(t * 0.7) * 2"
      • Random: "sin(t) * (3 + sin(t * 2) * 2)"

Common Applications

  1. Film Restoration:

    • Simulate original projection characteristics
    • Add period-appropriate movement
    • Maintain subtle, consistent motion

  2. Vintage Effects:

    • Combine with grain and scratches
    • Use moderate weave settings
    • Match movement to film era

  3. Creative Effects:

    • Experiment with custom expressions
    • Create rhythmic motion patterns
    • Synchronize with audio or scene cuts