ShaderParts.ts

import {BlendFilter} from "./BlendFilter";
import {BLEND_MODES} from "@pixi/constants";

export const NPM_BLEND: string =
    `if (b_src.a == 0.0) {
  gl_FragColor = vec4(0, 0, 0, 0);
  return;
}
vec3 Cb = b_src.rgb / b_src.a, Cs;
if (b_dest.a > 0.0) {
  Cs = b_dest.rgb / b_dest.a;
}
%NPM_BLEND%
b_res.a = b_src.a + b_dest.a * (1.0-b_src.a);
b_res.rgb = (1.0 - b_src.a) * Cs + b_src.a * B;
b_res.rgb *= b_res.a;
`;

//reverse hardlight
export const OVERLAY_PART: string =
    `vec3 multiply = Cb * Cs * 2.0;
vec3 Cb2 = Cb * 2.0 - 1.0;
vec3 screen = Cb2 + Cs - Cb2 * Cs;
vec3 B;
if (Cs.r <= 0.5) {
  B.r = multiply.r;
} else {
  B.r = screen.r;
}
if (Cs.g <= 0.5) {
  B.g = multiply.g;
} else {
  B.g = screen.g;
}
if (Cs.b <= 0.5) {
  B.b = multiply.b;
} else {
  B.b = screen.b;
}
`;

export const HARDLIGHT_PART: string =
    `vec3 multiply = Cb * Cs * 2.0;
vec3 Cs2 = Cs * 2.0 - 1.0;
vec3 screen = Cb + Cs2 - Cb * Cs2;
vec3 B;
if (Cb.r <= 0.5) {
  B.r = multiply.r;
} else {
  B.r = screen.r;
}
if (Cb.g <= 0.5) {
  B.g = multiply.g;
} else {
  B.g = screen.g;
}
if (Cb.b <= 0.5) {
  B.b = multiply.b;
} else {
  B.b = screen.b;
}
`;

export const SOFTLIGHT_PART: string =
    `vec3 first = Cb - (1.0 - 2.0 * Cs) * Cb * (1.0 - Cb);
vec3 B;
vec3 D;
if (Cs.r <= 0.5)
{
  B.r = first.r;
}
else
{
  if (Cb.r <= 0.25)
  {
    D.r = ((16.0 * Cb.r - 12.0) * Cb.r + 4.0) * Cb.r;    
  }
  else
  {
    D.r = sqrt(Cb.r);
  }
  B.r = Cb.r + (2.0 * Cs.r - 1.0) * (D.r - Cb.r);
}
if (Cs.g <= 0.5)
{
  B.g = first.g;
}
else
{
  if (Cb.g <= 0.25)
  {
    D.g = ((16.0 * Cb.g - 12.0) * Cb.g + 4.0) * Cb.g;    
  }
  else
  {
    D.g = sqrt(Cb.g);
  }
  B.g = Cb.g + (2.0 * Cs.g - 1.0) * (D.g - Cb.g);
}
if (Cs.b <= 0.5)
{
  B.b = first.b;
}
else
{
  if (Cb.b <= 0.25)
  {
    D.b = ((16.0 * Cb.b - 12.0) * Cb.b + 4.0) * Cb.b;    
  }
  else
  {
    D.b = sqrt(Cb.b);
  }
  B.b = Cb.b + (2.0 * Cs.b - 1.0) * (D.b - Cb.b);
}
`;

export const MULTIPLY_FULL: string =
    `if (dest.a > 0.0) {
  b_res.rgb = (dest.rgb / dest.a) * ((1.0 - src.a) + src.rgb);
  b_res.a = min(src.a + dest.a - src.a * dest.a, 1.0);
  b_res.rgb *= mult.a;
}
`;
export const OVERLAY_FULL = NPM_BLEND.replace(`%NPM_BLEND%`, OVERLAY_PART);
export const HARDLIGHT_FULL = NPM_BLEND.replace(`%NPM_BLEND%`, HARDLIGHT_PART);
export const SOFTLIGHT_FULL = NPM_BLEND.replace(`%NPM_BLEND%`, SOFTLIGHT_PART);

export const blendFullArray: Array<string> = [];

blendFullArray[BLEND_MODES.MULTIPLY] = MULTIPLY_FULL;
blendFullArray[BLEND_MODES.OVERLAY] = OVERLAY_FULL;
blendFullArray[BLEND_MODES.HARD_LIGHT] = HARDLIGHT_FULL;
blendFullArray[BLEND_MODES.SOFT_LIGHT] = SOFTLIGHT_FULL;

let filterCache: Array<BlendFilter> = [];
let filterCacheArray: Array<Array<BlendFilter>> = [];

export function getBlendFilter(blendMode: BLEND_MODES) {
    if (!blendFullArray[blendMode]) {
        return null;
    }
    if (!filterCache[blendMode]) {
        filterCache[blendMode] = new BlendFilter({blendCode: blendFullArray[blendMode]});
    }
    return filterCache[blendMode];
}

export function getBlendFilterArray(blendMode: BLEND_MODES) {
    if (!blendFullArray[blendMode]) {
        return null;
    }
    if (!filterCacheArray[blendMode]) {
        filterCacheArray[blendMode] = [getBlendFilter(blendMode)];
    }
    return filterCacheArray[blendMode];
}