Merge pull request #7 from Briggs-Richardson/feature/briggs-matrix

Add matrix animation

src/animations/briggs-matrix.ts

@@ -0,0 +1,110 @@
+import { runner, Light, colors } from 'christmas-tree';
+
+/**
+ * "Merry Christmas!"
+ *      /\       -------
+ *     /  \      level 0
+ *    /    \     -------
+ *    \    /     level 1
+ *    /    \     -------
+ *   /      \      ...
+ *  /        \
+ *  \        /
+ *   /      \
+ *   \      /
+ *    |    |     --------
+ *      | |      level 9
+ *      ---      --------
+ */
+
+// ---------------------------------- SET-UP ------------------------------
+
+const BOTTOM_LEVEL_NUMBER: number = 9;
+const GLITCH_CHANCE: number = 0.1;
+const DROP_RESTART_CHANCE: number = 0.02;
+
+// Gets the level number the light is located at using its z-coordinate.
+//   The z-coordinate can range from [0, 1]. Levels are subdivided by tenths.
+function getLevelNum(light: Light): number {
+  // Edge case
+  if (light._location.z === 1) {
+    return BOTTOM_LEVEL_NUMBER;
+  }
+  return Math.floor((light._location.z * 10));
+}
+
+// Gets the closest light in the next level with respect to the x-y plane.
+function getClosestLightInNextLevel(light: Light): Light | null {
+  const levelNum = getLevelNum(light);
+  if (levelNum === BOTTOM_LEVEL_NUMBER) {
+    return null;
+  }
+
+  let closest: Light | null = null;
+  let shortestDistance = Infinity;
+  for (const lightAtNextLevel of levels[levelNum + 1]) {
+    const dist = Math.sqrt(
+      Math.pow(light._location.x - lightAtNextLevel._location.x, 2) +
+      Math.pow(light._location.y - lightAtNextLevel._location.y, 2)
+    );
+    if (dist < shortestDistance) {
+      shortestDistance = dist;
+      closest = lightAtNextLevel;
+    }
+  } 
+  return closest;
+}
+
+function isRandomlyGlitched(): boolean {
+  return Math.random() < GLITCH_CHANCE;
+}
+
+// Organize lights into their respective levels.
+const levels = [...Array(10)].map(_ => []);
+for (const light of runner.lights) {
+  levels[getLevelNum(light)].push(light);
+}
+
+// Pre-compute the the drop path from each starting light in the zeroth (top) level.
+//   The path is terminated with a null value.
+const dropPaths = levels[0].map((topLight: Light) => {
+  const path = [topLight];
+  while (path[path.length - 1] != null) {
+    path.push(getClosestLightInNextLevel(path[path.length - 1]));
+  }
+  return path;
+});
+
+const drops = dropPaths.map((path) => {
+  return {
+    path,
+    index: path.length - 1,
+    glitched: isRandomlyGlitched()
+  }
+});
+
+// ---------------------------------- Animation ------------------------------
+
+function fadeTree(): void {
+  for (const light of runner.lights) {
+    light.color = light.color.intensity(0.85);
+  }
+}
+
+for (const light of runner.lights) {
+  light.color = colors.black;
+}
+
+runner.update = (time, delta, iteration) => {
+  fadeTree();
+  for (const drop of drops) {
+    const dropLight = drop.path[drop.index];
+    if (dropLight != null) {
+      dropLight.color = drop.glitched ? colors.green : colors.darkGreen;
+      drop.index += 1;
+    } else if (Math.random() < DROP_RESTART_CHANCE) {
+      drop.index = 0;
+      drop.glitched = isRandomlyGlitched();
+    }
+  }
+};