From 681c5d8123bfd25e875db68e4a093e802ec474ba Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Tue, 11 May 2021 18:31:32 -0600
Subject: ripple v3

---
 src/_posts/2021-05-11-ripple-v3.md | 442 +++++++++++++++++++++++++++++++++++++
 1 file changed, 442 insertions(+)
 create mode 100644 src/_posts/2021-05-11-ripple-v3.md

(limited to 'src/_posts')

diff --git a/src/_posts/2021-05-11-ripple-v3.md b/src/_posts/2021-05-11-ripple-v3.md
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+---
+title: >-
+    Ripple V3
+description: >-
+    We're getting there!
+tags: tech
+series: ripple
+---
+
+<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>
+
+_Who can make the muddy water clear?<br/>
+Let it be still, and it will gradually become clear._
+
+<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="reset()">(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;
+
+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];
+});
+
+
+const C = 700; // scales the overall speed of the radius
+const T = 500; // on which tick the radius change becomes linear
+
+/*
+    f(x) = sqrt(C*x)                        when x < T
+           (C/(2*sqrt(CT)))(x-T) + sqrt(CT) when x >= T
+
+    radius(x) = f(x) + playerRadius;
+*/
+
+const F1 = (x) => Math.sqrt(C*x);
+const F2C1 = C / (2 * Math.sqrt(C*T));
+const F2C2 = Math.sqrt(C * T);
+const F2 = (x) => (F2C1 * (x - T)) + F2C2;
+const F = (x) => {
+    if (x < T) return F1(x);
+    return F2(x);
+};
+
+class Ripple {
+
+    constructor(id, currTick, x, y, bounces, color) {
+        this.id = id;
+        this.tick = currTick;
+        this.x = x;
+        this.y = y;
+        this.thickness = Math.pow(bounces+1, 1.25);
+        this.color = color;
+        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));
+    }
+
+    radius(currTick) {
+        const x = currTick - this.tick;
+        return F(x) + playerRadius;
+    }
+
+    draw(ctx, currTick) {
+        ctx.beginPath();
+        ctx.arc(this.x, this.y, this.radius(currTick), 0, Math.PI * 2, false);
+        ctx.closePath();
+        ctx.lineWidth = this.thickness;
+        ctx.strokeStyle = this.winner ? "#FF0000" : this.color;
+        ctx.stroke();
+    }
+
+    canGC(currTick) {
+        return this.radius(currTick) > 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;
+        if (this.y < 0) this.y += height;
+        else if (this.y > height) this.y -= height;
+
+        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;
+        if (this.x < 0) this.x += width;
+        else if (this.x > width) this.x -= width;
+
+        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);
+    }
+
+    drawAt(ctx, atX, atY) {
+        const y = atY - (this.z * 40);
+        const radius = playerRadius * (this.z+1)
+
+        // draw main
+        ctx.beginPath();
+        ctx.arc(atX, 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(atX, atY, radius, 0, Math.PI * 2, false);
+            ctx.closePath();
+            ctx.lineWidth = 0;
+            ctx.fillStyle = this.color+"33";
+            ctx.fill();
+        }
+    }
+
+    draw(ctx) {
+        [-1, 0, 1].forEach((wScalar) => {
+            const w = width * wScalar;
+            [-1, 0, 1].forEach((hScalar) => {
+                const h = height * hScalar;
+                this.drawAt(ctx, this.x+w, this.y+h);
+            })
+        })
+    }
+}
+
+class Game {
+
+    constructor(canvas, scoreEl) {
+        this.currTick = 0;
+        this.player = new Player(width/2, height/2, palette[0]);
+        this.state = 'play';
+        this.score = 0;
+        this.scoreEl = scoreEl;
+        this.canvas = canvas;
+        this.ctx = canvas.getContext("2d");
+        this.ripples = [];
+        this.nextRippleID = 0;
+    }
+
+    shouldReset() {
+        return keyboard['KeyR'];
+    }
+
+    newRippleID() {
+        let id = this.nextRippleID;
+        this.nextRippleID++;
+        return id;
+    }
+
+    // newRipple initializes and stores a new ripple at the given coordinates, as
+    // well as all sub-ripples which make up the initial ripple's reflections.
+    newRipple(x, y, bounces, color) {
+        color = color ? color : palette[Math.floor(Math.random() * palette.length)];
+
+        let ripplePos = [];
+        let nextRipples = [];
+
+        let addRipple = (x, y) => {
+            for (let i in ripplePos) {
+                if (ripplePos[i][0] == x && ripplePos[i][1] == y) return;
+            }
+
+            let ripple = new Ripple(this.newRippleID(), this.currTick, x, y, bounces, color);
+            nextRipples.push(ripple);
+            ripplePos.push([x, y]);
+            this.ripples.push(ripple);
+        };
+
+        // add initial ripple, after this we deal with the sub-ripples.
+        addRipple(x, y);
+
+        while (bounces > 0) {
+            bounces--;
+            let prevRipples = nextRipples;
+            nextRipples = [];
+
+            for (let i in prevRipples) {
+                let prevX = prevRipples[i].x;
+                let prevY = prevRipples[i].y;
+
+                [-1, 0, 1].forEach((wScalar) => {
+                    const w = this.canvas.width * wScalar;
+                    [-1, 0, 1].forEach((hScalar) => {
+                        const h = this.canvas.height * hScalar;
+                        addRipple(prevX + w, prevY + h);
+                    })
+                })
+            }
+        }
+    }
+
+    // playerRipplesState returns a mapping of rippleID -> boolean, where each
+    // boolean indicates the ripple's relation to the player at the moment. true
+    // indicates the player is outside the ripple, false indicates the player is
+    // within the ripple.
+    playerRipplesState() {
+        let state = {};
+        for (let i in this.ripples) {
+            let ripple = this.ripples[i];
+            let rippleRadius = ripple.radius(this.currTick);
+            let hs = Math.pow(ripple.x-this.player.x, 2) + Math.pow(ripple.y-this.player.y, 2);
+            state[ripple.id] = hs > Math.pow(rippleRadius + playerRadius, 2);
+        }
+        return state;
+    }
+
+    playerHasJumpedOverRipple(prev, curr) {
+        for (const rippleID in prev) {
+            if (!curr.hasOwnProperty(rippleID)) continue;
+            if (curr[rippleID] != prev[rippleID]) return true;
+        }
+        return false;
+    }
+
+    update() {
+        if (this.state != 'play') return;
+
+        let playerPrevZ = this.player.z;
+        this.player.act();
+
+        if (playerPrevZ == 0 && this.player.z > 0) {
+            // player has jumped
+            this.prevPlayerRipplesState = this.playerRipplesState();
+
+        } else if (playerPrevZ > 0 && this.player.z == 0) {
+
+            // player has landed, don't produce a ripple unless there are no
+            // existing ripples or the player jumped over an existing one.
+            if (
+                this.ripples.length == 0 ||
+                this.playerHasJumpedOverRipple(
+                    this.prevPlayerRipplesState,
+                    this.playerRipplesState()
+                )
+            ) {
+                //let bounces = Math.floor((this.player.lastJumpHeight*1.8)+1);
+                const bounces = 1;
+
+                console.log("spawning ripple with bounces:", bounces);
+                this.newRipple(this.player.x, this.player.y, bounces);
+                this.score += bounces;
+            }
+        }
+
+        if (this.player.z == 0) {
+            for (let i in this.ripples) {
+                let ripple = this.ripples[i];
+                let rippleRadius = ripple.radius(this.currTick);
+                if (rippleRadius < playerRadius * 1.5) continue;
+                let hs = Math.pow(ripple.x-this.player.x, 2) + Math.pow(ripple.y-this.player.y, 2);
+                if (hs > Math.pow(rippleRadius + playerRadius, 2)) {
+                    continue;
+                } else if (hs <= Math.pow(rippleRadius - playerRadius, 2)) {
+                    continue;
+                } else {
+                    console.log("game over", ripple);
+                    ripple.winner = true;
+                    this.player.loser = true;
+                    this.state = 'gameOver';
+                    // deliberately don't break here, in case multiple ripples hit
+                    // the player on the same frame
+                }
+            }
+        }
+
+        this.ripples = this.ripples.filter(ripple => !ripple.canGC(this.currTick));
+
+        this.currTick++;
+    }
+
+    draw() {
+        this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
+        this.ripples.forEach(ripple => ripple.draw(this.ctx, this.currTick));
+        this.player.draw(this.ctx)
+        this.scoreEl.innerHTML = this.score;
+    }
+}
+
+
+const requestAnimationFrame =
+    window.requestAnimationFrame ||
+    window.mozRequestAnimationFrame ||
+    window.webkitRequestAnimationFrame ||
+    window.msRequestAnimationFrame;
+
+let game = new Game(canvas, document.getElementById("score"));
+
+function reset() {
+    game = new Game(canvas, document.getElementById("score"));
+}
+
+function nextFrame() {
+    if (game.shouldReset()) reset();
+
+    game.update()
+    game.draw()
+    requestAnimationFrame(nextFrame);
+}
+requestAnimationFrame(nextFrame);
+
+canvas.focus();
+
+</script>
+
+## Changelog
+
+The previous version was two easy to break, even with the requirement of jumping
+over a ripple to generate a new one and increase your score. This led to the
+following major changes:
+
+* The game now incorporates asteroid/pacman mechanics. Rather than bouncing off
+  walls, the player and ripples will instead come out the opposite wall they
+  travel through.
+
+* Jump height no longer affects score or the "strength" of a ripple.
-- 
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