// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import type {ShaderPass} from '@luma.gl/shadertools';

const source = /* wgsl */ `\
struct vignetteUniforms {
  radius: f32,
  amount: f32,
};

@group(0) @binding(auto) var<uniform> vignette: vignetteUniforms;

fn vignette_filterColor_ext(color: vec4f, texSize: vec2f, texCoord: vec2f) -> vec4f {
  let dist = distance(texCoord, vec2f(0.5, 0.5));
  let ratio = smoothstep(
    0.8,
    vignette.radius * 0.799,
    dist * (vignette.amount + vignette.radius)
  );
  return color * ratio + vec4f(0.0, 0.0, 0.0, 1.0) * (1.0 - ratio);
}
`;

const fs = /* glsl */ `\
layout(std140) uniform vignetteUniforms {
  float radius;
  float amount;
} vignette;

vec4 vignette_filterColor_ext(vec4 color, vec2 texSize, vec2 texCoord) {
  float dist = distance(texCoord, vec2(0.5, 0.5));
  float ratio = smoothstep(0.8, vignette.radius * 0.799, dist * (vignette.amount + vignette.radius));
  return color.rgba * ratio + (1.0 - ratio)*vec4(0.0, 0.0, 0.0, 1.0);
}
`;

/**
 * Vignette - Adds a simulated lens edge darkening effect.
 */
export type VignetteProps = {
  /** 0 to 1 (0 for center of frame, 1 for edge of frame) */
  radius?: number;
  /** 0 to 1 (0 for no effect, 1 for maximum lens darkening) */
  amount?: number;
};

export type VignetteUniforms = VignetteProps;

/**
 * Vignette -
 * Adds a simulated lens edge darkening effect.
 */
export const vignette = {
  props: {} as VignetteProps,
  uniforms: {} as VignetteUniforms,

  name: 'vignette',
  source,
  fs,

  uniformTypes: {
    radius: 'f32',
    amount: 'f32'
  },
  defaultUniforms: {
    radius: 0.5,
    amount: 0.5
  },
  propTypes: {
    radius: {value: 0.5, min: 0, max: 1},
    amount: {value: 0.5, min: 0, max: 1}
  },

  passes: [{filter: true}]
} as const satisfies ShaderPass<VignetteProps, VignetteProps>;