@thi.ng/rasterize/shader.js

Headless 2D shape drawing, filling & rasterization for arbitrary targets/purposes (no canvas required)

import { isFunction } from "@thi.ng/checks/is-function";
import {
  porterDuffP,
  porterDuffPInt,
  SRC_OVER_F,
  SRC_OVER_I
} from "@thi.ng/porter-duff/porter-duff";
import { SYSTEM } from "@thi.ng/random/system";
const defPattern = (pattern) => {
  const [w, h] = pattern.size;
  return (_, x, y) => pattern.getAtUnsafe(x % w, y % h);
};
const defStripes = ({
  dir,
  size,
  sizeA,
  a,
  b
}) => dir === "h" ? (_, x) => x % size < sizeA ? a : b : dir === "v" ? (_, __, y) => y % size < sizeA ? a : b : (_, x, y) => (x + y) % size < sizeA ? a : b;
const defNoise = (opts) => {
  const { probability = 0.5, rnd = SYSTEM, a, b } = opts;
  return () => rnd.probability(probability) ? a : b;
};
const defBlendF = (col, blend = SRC_OVER_F, isPremultiplied = false) => {
  blend = isPremultiplied ? blend : porterDuffP(blend);
  return isFunction(col) ? (buf, x, y) => {
    const dest = buf.getAtUnsafe(x, y);
    return blend(dest, col(buf, x, y), dest);
  } : (buf, x, y) => {
    const dest = buf.getAtUnsafe(x, y);
    return blend(dest, col, dest);
  };
};
const defBlendI = (col, blend = SRC_OVER_I, isPremultiplied = false) => {
  blend = isPremultiplied ? blend : porterDuffPInt(blend);
  return isFunction(col) ? (buf, x, y) => blend(col(buf, x, y), buf.getAtUnsafe(x, y)) : (buf, x, y) => blend(col, buf.getAtUnsafe(x, y));
};
export {
  defBlendF,
  defBlendI,
  defNoise,
  defPattern,
  defStripes
};