SKSL Script

Defines a custom filter effect using a SkiaSharp Shading Language (SKSL) shader. Runs as a per-pixel program through Skia.

Library location

Library → Filter Effect → Script → SKSL Script

Properties

Script

The SKSL shader source.

• Type: string
• Default:

  uniform shader src;
  uniform float progress;  // 0.0 - 1.0
  uniform float duration;  // seconds
  uniform float time;      // seconds
  uniform float width;     // render target width (device px)
  uniform float height;    // render target height (device px)
  // Also available:
  // uniform float2 iResolution;  // (width, height) in device px
  // uniform float  iScale;       // working density (device px per logical px)
  // uniform float  iTime;
  
  half4 main(float2 fragCoord) {
      half4 c = src.eval(fragCoord);
      return c;
  }

• Animatable: No

Usage

Provide a main(float2 coord) → half4 shader. The source layer is provided through src and animatable parameters are passed as uniforms.

For processing only the current pixel’s color, you can also define half4 apply(half4 color), receiving an input color and returning the output color. The existing main(float2) form remains supported.

Resolution scaling

Beutl can render at a working density that differs from the project resolution — for example a downscaled preview or a supersampled export. width / height / iResolution report the complete output’s device-pixel dimensions at that density, and iScale is the working density in device pixels per logical pixel (1.0 when unscaled).

A shader that works in normalized coordinates (for example fragCoord / iResolution) is automatically resolution-independent and needs no changes. If your shader uses absolute pixel literals — a fixed radius, offset, or border width measured in pixels — multiply them by iScale so they keep the same on-screen size at any density. A shader that never reads iScale renders exactly as before at scale 1.0.

Source

src/Beutl.Engine/Graphics/FilterEffects/SKSLScriptEffect.cs