composeAlpha static method

@visibleForTesting double composeAlpha({ required double shadowVisibility, required double occlusion, required double shadowIntensity, required double aoStrength, double radialDistance = 0.0, double fadeStart = 0.0, double fadeEnd = 0.0, })

The catcher's composed straight alpha, the same math the shader runs.

shadowVisibility and occlusion are 1 fully lit/unoccluded to 0 fully dark; radialDistance is the fragment's distance from the mesh origin in local units.

Implementation

@visibleForTesting
static double composeAlpha({
  required double shadowVisibility,
  required double occlusion,
  required double shadowIntensity,
  required double aoStrength,
  double radialDistance = 0.0,
  double fadeStart = 0.0,
  double fadeEnd = 0.0,
}) {
  final shadowTerm = shadowIntensity * (1.0 - shadowVisibility);
  final aoTerm = aoStrength * (1.0 - occlusion);
  var radialFade = 1.0;
  if (fadeEnd > fadeStart) {
    final t = ((radialDistance - fadeStart) / (fadeEnd - fadeStart)).clamp(
      0.0,
      1.0,
    );
    radialFade = 1.0 - t * t * (3.0 - 2.0 * t);
  }
  return (shadowTerm + aoTerm).clamp(0.0, 1.0) * radialFade;
}