third_party/skia/resources/particles/writing.json

{
   "MaxCount": 4000,
   "Drawable": {
      "Type": "SkCircleDrawable",
      "Radius": 2
   },
   "Code": [
      "void effectSpawn(inout Effect effect) {",
      "  effect.lifetime = 4;",
      "}",
      "",
      "void effectUpdate(inout Effect effect) {",
      "  effect.color.r = 0;",
      "  effect.color.g = 1 - effect.age;",
      "  effect.color.b = effect.age;",
      "",
      "  effect.rate = effect.age < 0.75 ? 800 : 0;",
      "}",
      "",
      "uniform float2 mouse_pos;",
      "",
      "void spawn(inout Particle p) {",
      "  p.lifetime = 4;",
      "  p.pos = mouse_pos;",
      "  p.frame = effect.age / 0.75 + mix(-0.05, 0.05, rand(p.seed));",
      "}",
      "",
      "void update(inout Particle p) {",
      "  p.pos = mix(p.pos, text(p.frame).xy, 0.05);",
      "}",
      ""
   ],
   "Bindings": [
      {
         "Type": "SkTextBinding",
         "Name": "text",
         "Text": "HELLO WORLD",
         "FontSize": 96
      }
   ]
}