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+---
+title: >-
+ Ripple: A Game
+description: >-
+ Hop Till You Drop!
+---
+
+<p>
+ <b>Movement:</b> Arrow keys or WASD<br/>
+ <b>Jump:</b> Space<br/>
+ <b>Goal:</b> Jump as many times as possible without touching a ripple!<br/>
+ <br/>
+ <b>Press Jump To Begin!</b>
+</p>
+
+<canvas id="canvas"
+ style="border:1px dashed #AAA"
+ tabindex=0>
+Your browser doesn't support canvas. At this point in the world that's actually
+pretty cool, well done!
+</canvas>
+<button onclick="resetGame()">(R)eset</button>
+<span style="font-size: 2rem; margin-left: 1rem;">Score:
+ <span style="font-weight: bold" id="score">0</span>
+</span>
+
+<script type="text/javascript">
+
+const palette = [
+ "#264653",
+ "#2A9D8F",
+ "#E9C46A",
+ "#F4A261",
+ "#E76F51",
+];
+
+const width = 800;
+const height = 600;
+
+function hypotenuse(w, h) {
+ return Math.sqrt(Math.pow(w, 2) + Math.pow(h, 2));
+}
+
+let canvas = document.getElementById("canvas");
+canvas.width = width;
+canvas.height = height;
+
+let score = document.getElementById("score");
+
+const whitelistedKeys = {
+ "ArrowUp": {},
+ "KeyW": {map: "ArrowUp"},
+ "ArrowLeft": {},
+ "KeyA": {map: "ArrowLeft"},
+ "ArrowRight": {},
+ "KeyD": {map: "ArrowRight"},
+ "ArrowDown": {},
+ "KeyS": {map: "ArrowDown"},
+ "Space": {},
+ "KeyR": {},
+};
+
+let keyboard = {};
+
+canvas.addEventListener('keydown', (event) => {
+ let keyInfo = whitelistedKeys[event.code];
+ if (!keyInfo) return;
+
+ let code = event.code;
+ if (keyInfo.map) code = keyInfo.map;
+
+ event.preventDefault();
+ keyboard[code] = true;
+});
+
+canvas.addEventListener('keyup', (event) => {
+ let keyInfo = whitelistedKeys[event.code];
+ if (!keyInfo) return;
+
+ let code = event.code;
+ if (keyInfo.map) code = keyInfo.map;
+
+ event.preventDefault();
+ delete keyboard[code];
+});
+
+let ctx = canvas.getContext("2d");
+
+let currTick;
+let drops;
+
+class Drop {
+ constructor(x, y, bounces, color) {
+ this.tick = currTick;
+ this.x = x;
+ this.y = y;
+ this.thickness = (bounces+1) * 0.25;
+ this.color = color ? color : palette[Math.floor(Math.random() * palette.length)];
+ this.winner = false;
+
+ this.maxRadius = hypotenuse(x, y);
+ this.maxRadius = Math.max(this.maxRadius, hypotenuse(width-x, y));
+ this.maxRadius = Math.max(this.maxRadius, hypotenuse(x, height-y));
+ this.maxRadius = Math.max(this.maxRadius, hypotenuse(width-x, height-y));
+
+ drops.push(this);
+
+ if (bounces > 0) {
+ new Drop(x, -y, bounces-1, this.color);
+ new Drop(-x, y, bounces-1, this.color);
+ new Drop((2*width)-x, y, bounces-1, this.color);
+ new Drop(x, (2*height)-y, bounces-1, this.color);
+ }
+ }
+
+ radius() { return currTick - this.tick; }
+
+ draw() {
+ ctx.beginPath();
+ ctx.arc(this.x, this.y, this.radius(), 0, Math.PI * 2, false);
+ ctx.closePath();
+ ctx.lineWidth = this.thickness;
+ ctx.strokeStyle = this.winner ? "#FF0000" : this.color;
+ ctx.stroke();
+ }
+
+ canGC() {
+ return this.radius() > this.maxRadius;
+ }
+}
+
+const playerRadius = 10;
+const playerMoveAccel = 0.5;
+const playerMoveDecel = 0.7;
+const playerMaxMoveSpeed = 4;
+const playerJumpSpeed = 0.08;
+const playerMaxHeight = 1;
+const playerGravity = 0.01;
+
+class Player{
+ constructor(x, y, color) {
+ this.x = x;
+ this.y = y;
+ this.z = 0;
+ this.xVelocity = 0;
+ this.yVelocity = 0;
+ this.zVelocity = 0;
+ this.color = color;
+ this.falling = false;
+ this.lastJumpHeight = 0;
+ this.loser = false;
+ }
+
+ act() {
+ if (keyboard["ArrowUp"]) {
+ this.yVelocity = Math.max(-playerMaxMoveSpeed, this.yVelocity - playerMoveAccel);
+ } else if (keyboard["ArrowDown"]) {
+ this.yVelocity = Math.min(playerMaxMoveSpeed, this.yVelocity + playerMoveAccel);
+ } else if (this.yVelocity > 0) {
+ this.yVelocity = Math.max(0, this.yVelocity - playerMoveDecel);
+ } else if (this.yVelocity < 0) {
+ this.yVelocity = Math.min(0, this.yVelocity + playerMoveDecel);
+ }
+
+ this.y += this.yVelocity;
+ this.y = Math.max(0+playerRadius, this.y);
+ this.y = Math.min(height-playerRadius, this.y);
+
+ if (keyboard["ArrowLeft"]) {
+ this.xVelocity = Math.max(-playerMaxMoveSpeed, this.xVelocity - playerMoveAccel);
+ } else if (keyboard["ArrowRight"]) {
+ this.xVelocity = Math.min(playerMaxMoveSpeed, this.xVelocity + playerMoveAccel);
+ } else if (this.xVelocity > 0) {
+ this.xVelocity = Math.max(0, this.xVelocity - playerMoveDecel);
+ } else if (this.xVelocity < 0) {
+ this.xVelocity = Math.min(0, this.xVelocity + playerMoveDecel);
+ }
+
+ this.x += this.xVelocity;
+ this.x = Math.max(0+playerRadius, this.x);
+ this.x = Math.min(width-playerRadius, this.x);
+
+ let jumpHeld = keyboard["Space"];
+
+ if (jumpHeld && !this.falling && this.z < playerMaxHeight) {
+ this.lastJumpHeight = 0;
+ this.zVelocity = playerJumpSpeed;
+ } else {
+ this.zVelocity = Math.max(-playerJumpSpeed, this.zVelocity - playerGravity);
+ this.falling = this.z > 0;
+ }
+
+ let prevZ = this.z;
+ this.z = Math.max(0, this.z + this.zVelocity);
+ this.lastJumpHeight = Math.max(this.z, this.lastJumpHeight);
+ }
+
+ draw() {
+ let y = this.y - (this.z * 40);
+ let radius = playerRadius * (this.z+1)
+
+ // draw main
+ ctx.beginPath();
+ ctx.arc(this.x, y, radius, 0, Math.PI * 2, false);
+ ctx.closePath();
+ ctx.lineWidth = 0;
+ ctx.fillStyle = this.color;
+ ctx.fill();
+ if (this.loser) {
+ ctx.strokeStyle = '#FF0000';
+ ctx.lineWidth = 2;
+ ctx.stroke();
+ }
+
+ // draw shadow, if in the air
+ if (this.z > 0) {
+ let radius = Math.max(0, playerRadius * (1.2 - this.z));
+ ctx.beginPath();
+ ctx.arc(this.x, this.y, radius, 0, Math.PI * 2, false);
+ ctx.closePath();
+ ctx.lineWidth = 0;
+ ctx.fillStyle = this.color+"33";
+ ctx.fill();
+ }
+ }
+}
+
+let player;
+let gameState;
+let numJumps;
+
+function resetGame() {
+ currTick = 0;
+ drops = [];
+ player = new Player(width/2, height/2, palette[0]);
+ gameState = 'play';
+ numJumps = 0;
+ canvas.focus();
+}
+resetGame();
+
+let requestAnimationFrame =
+ window.requestAnimationFrame ||
+ window.mozRequestAnimationFrame ||
+ window.webkitRequestAnimationFrame ||
+ window.msRequestAnimationFrame;
+
+function doTick() {
+ if (keyboard['KeyR']) {
+ resetGame();
+ }
+
+ if (gameState == 'play') {
+ let playerPrevZ = player.z;
+ player.act();
+ if (playerPrevZ > 0 && player.z == 0) {
+ let bounces = Math.floor((player.lastJumpHeight*1.8)+1);
+ console.log("spawning drop with bounces:", bounces);
+ new Drop(player.x, player.y, bounces);
+ } else if (playerPrevZ == 0 && player.z > 0) {
+ numJumps++;
+ }
+ score.innerHTML = numJumps;
+
+ if (player.z == 0) {
+ for (let i in drops) {
+ let drop = drops[i];
+ let dropRadius = drop.radius();
+ if (dropRadius < playerRadius * 1.5) continue;
+ let hs = Math.pow(drop.x-player.x, 2) + Math.pow(drop.y-player.y, 2);
+ if (hs > Math.pow(playerRadius + dropRadius, 2)) {
+ continue;
+ } else if (Math.sqrt(hs) <= Math.abs(dropRadius-playerRadius)) {
+ continue;
+ } else {
+ console.log("game over");
+ drop.winner = true;
+ player.loser = true;
+ gameState = 'gameOver';
+ }
+ }
+ }
+ }
+
+ ctx.clearRect(0, 0, canvas.width, canvas.height);
+ player.draw()
+ drops.forEach(drop => drop.draw());
+ drops = drops.filter(drop => !drop.canGC());
+
+ if (gameState == 'play') currTick++;
+ requestAnimationFrame(doTick);
+}
+requestAnimationFrame(doTick);
+
+</script>
+
+_Do you have the patience to wait<br/>
+till your mud settles and the water is clear?_
+
+## Backstory
+
+This is a game I originally implemented in lua, which you can find [here][orig].
+It's a fun concept that I wanted to show off again, as well as to see if I could
+whip it up in an evening in javascript (I can!)
+
+Send me your high scores! I top out around 17.
+
+[orig]: https://github.com/mediocregopher/ripple

Please direct all issues, questions, and patches to me@mediocregopher.com.

Check mediocregopher.com for periodic updates about projects I'm working on.