@luma.gl/effects/src/passes/postprocessing/image-adjust-filters/brightnesscontrast.ts

Post-processing effects for luma.gl

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

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

const source = /* wgsl */ `\
struct brightnessContrastUniforms {
  brightness: f32,
  contrast: f32
};

// Binding 0:1 is reserved for shader passes
@group(0) @binding(1) var<uniform> brightnessContrast : brightnessContrastUniforms;

fn brightnessContrast_filterColor_ext(color: vec4f, texSize: vec2<f32>, texCoords: vec2<f32>) -> vec4f {
  color.rgb += brightnessContrast.brightness;
  if (brightnessContrast.contrast > 0.0) {
    color.rgb = (color.rgb - 0.5) / (1.0 - brightnessContrast.contrast) + 0.5;
  } else {
    color.rgb = (color.rgb - 0.5) * (1.0 + brightnessContrast.contrast) + 0.5;
  }
  return vec4f(1.0, 0.0, 0.0, 1.0);
}
`;

const fs = /* glsl */ `\
uniform brightnessContrastUniforms {
  float brightness;
  float contrast;
} brightnessContrast;

vec4 brightnessContrast_filterColor(vec4 color) {
  color.rgb += brightnessContrast.brightness;
  if (brightnessContrast.contrast > 0.0) {
    color.rgb = (color.rgb - 0.5) / (1.0 - brightnessContrast.contrast) + 0.5;
  } else {
    color.rgb = (color.rgb - 0.5) * (1.0 + brightnessContrast.contrast) + 0.5;
  }
  return color;
}

vec4 brightnessContrast_filterColor_ext(vec4 color, vec2 texSize, vec2 texCoord) {
  return brightnessContrast_filterColor(color);
}
`;

export type BrightnessContrastProps = {
  brightness?: number;
  contrast?: number;
};

export type BrightnessContrastUniforms = BrightnessContrastProps;

/**
 * Brightness / Contrast -
 * Provides additive brightness and multiplicative contrast control.
 * @param brightness -1 to 1 (-1 is solid black, 0 is no change, and 1 is solid white)
 * @param contrast   -1 to 1 (-1 is solid gray, 0 is no change, and 1 is maximum contrast)
 */
export const brightnessContrast = {
  name: 'brightnessContrast',
  source,
  fs,

  props: {} as BrightnessContrastProps,
  uniformTypes: {
    brightness: 'f32',
    contrast: 'f32'
  },
  defaultUniforms: {
    brightness: 0,
    contrast: 0
  },
  propTypes: {
    brightness: {format: 'f32', value: 0, min: -1, max: 1},
    contrast: {format: 'f32', value: 0, min: -1, max: 1}
  },

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