stuff

js/Level.js

 				if (nSteps > 1) {
 					console.log(
 						"Too long between frames for physics ("+dt.toFixed(2)+"s). "+
-						"Running "+nSteps+" simulations in one frame.");
+						"Running "+nSteps+" simulations ("+physdt.toFixed(2)+"s) in one frame.");
 				}
 
 				for (let i = 0; i < nSteps; ++i)

js/Shaker.js

+import Vec2 from "./Vec2.js";
+
+export default class Shaker {
+	constructor(decay = 7) {
+		this.vec = new Vec2();
+		this.decay = decay;
+		this.shakeX = 0;
+		this.shakeY = 0;
+	}
+
+	shake(x, y = x) {
+		this.shakeX = x;
+		this.shakeY = y;
+	}
+
+	update(dt) {
+		if (this.shakeX > 0.1)
+			this.vec.x = (Math.random() - 0.5) * this.shakeX * dt;
+		if (this.shakeY > 0.1)
+			this.vec.y = (Math.random() - 0.5) * this.shakeY * dt;
+
+		var xRatio = 1 / (1 + (dt * this.decay));
+		this.shakeX *= xRatio;
+		this.shakeY *= xRatio;
+	}
+}

js/assets.js

 		.defineTile("platform", 0, 2)
 		.defineTile("platform-l", 1, 2)
 		.defineTile("platform-r", 2, 2)
-		.defineTile("platform-lr", 3, 2),
+		.defineTile("platform-lr", 3, 2)
+
+		.defineTile("broken-platform", 0, 3)
+		.defineTile("broken-platform-l", 1, 3)
+		.defineTile("broken-platform-r", 2, 3)
+		.defineTile("broken-platform-lr", 3, 3),
 
 	entities: new SpriteSheet("assets/entities.png", 19, 32, 2)
 		.defineTile("player-head", 0, 0),

js/entities/BrokenPlatform.js

+import Entity from "../Entity.js";
+import Texture from "../Texture.js";
+import Tile from "../Tile.js";
+import Shaker from "../Shaker.js";
+import assets from "../assets.js";
+
+import TPlatform from "../traits/TPlatform.js";
+import TCollider from "../traits/TCollider.js";
+import TPhysics from "../traits/TPhysics.js";
+
+export default class BrokenPlatform extends Entity {
+	constructor(level, width = 5) {
+		super(level);
+
+		this.bounds.size.set(width, 0.5);
+		this.addTrait(new TCollider(this));
+		this.addTrait(new TPlatform(this));
+		this.addTrait(new TPhysics(this));
+
+		this.texture = new Texture(assets.tiles,
+			Tile.createLine(this.bounds.size.x, "broken-platform"));
+
+		this.shaker = new Shaker();
+		this.shake = 0;
+		this.shakeAccel = 14;
+		this.shaking = false;
+		this.floating = true;
+		this.reliableTime = 1;
+		this.resetTime = 4;
+	}
+
+	init() {
+		this.initialPos = this.bounds.pos.clone();
+	}
+
+	reset() {
+		this.shake = 0;
+		this.shaking = false;
+		this.floating = true;
+		this.t.physics.velocity.set(0, 0);
+		this.bounds.pos.set(this.initialPos.x, this.initialPos.y);
+	}
+
+	startShake() {
+		this.shake = 0;
+		this.shaking = true
+
+		setTimeout(() => {
+			this.floating = false;
+			this.shaking = false;
+
+			setTimeout(() => {
+				this.reset();
+			}, this.resetTime * 1000);
+		}, this.reliableTime * 1000);
+	}
+
+	update(dt) {
+		if (!this.shaking && !this.falling) {
+			this.t.collider.entities.forEach(e => {
+				if (e.has("physics")) {
+					this.startShake();
+				}
+			});
+		}
+
+		if (this.floating)
+			this.t.physics.velocity.y -= this.t.physics.gravity * dt;
+		if (this.shaking) {
+			this.shaker.shake(this.shake);
+			this.shake += this.shakeAccel * dt;
+		}
+
+		this.shaker.update(dt);
+	}
+
+	draw(ctx) {
+		this.texture.draw(
+			ctx,
+			this.bounds.pos.pixelX + this.shaker.vec.pixelX,
+			this.bounds.pos.pixelY + this.shaker.vec.pixelY);
+	}
+}

js/entities/FallingPlatform.js

 import TCollider from "../traits/TCollider.js";
 import TPhysics from "../traits/TPhysics.js";
 
-export default class Platform extends Entity {
+export default class FallingPlatform extends Entity {
 	constructor(level, width = 5) {
 		super(level);
 

js/entities/FloatingPlatform.js

 import TCollider from "../traits/TCollider.js";
 import TPhysics from "../traits/TPhysics.js";
 
-export default class Platform extends Entity {
+export default class FloatingPlatform extends Entity {
 	constructor(level, width = 5) {
 		super(level);
 
 		this.addTrait(new TPlatform(this));
 		this.addTrait(new TPhysics(this));
 
+		this.texture = new Texture(assets.tiles,
+			Tile.createLine(this.bounds.size.x, "platform"));
+
 		this.targetSpeed = 3;
 		this.accel = 5;
 		this.dir = 1;
-		this.movement = 5;
-
-		this.texture = new Texture(assets.tiles,
-			Tile.createLine(this.bounds.size.x, "platform"));
+		this.distance = 5;
 	}
 
 	init() {
 		this.targetTop = this.bounds.pos.y;
-		this.targetBottom = this.targetTop + this.movement;
+		this.targetBottom = this.targetTop + this.distance;
 
 		this.t.physics.gravity = 0;
 		this.t.physics.velocity.y = 0;

js/main.js

 import Player from "./entities/Player.js";
 import FloatingPlatform from "./entities/FloatingPlatform.js";
 import FallingPlatform from "./entities/FallingPlatform.js";
+import BrokenPlatform from "./entities/BrokenPlatform.js";
 import structures from "./structures.js";
 
 let canvas = document.getElementById("canvas");
 level.spawnEntity(new Player(level), 10, 1);
 level.spawnEntity(new FloatingPlatform(level), 16, 4);
 level.spawnEntity(new FallingPlatform(level), 20, 1);
+level.spawnEntity(new FallingPlatform(level), 20, 0);
+level.spawnEntity(new FallingPlatform(level), 20, -1);
+level.spawnEntity(new FallingPlatform(level), 20, -2);
 level.spawnStructure(structures.floor(8, 6), 4, 4);
 
+level.spawnEntity(new BrokenPlatform(level), 27, 4);
+
 level.start();
 
 // Pause the game when the tab has been out of focus for more than half a second

js/traits/TPhysics.js

 
 		if (this.entity.has("collider")) {
 
+			let jumping =
+				this.groundVelocity &&
+				this.velocity.y < this.groundVelocity.y;
+
 			// Check if we're still on the same ground
 			if (this.onGround) {
 				let stillOnGround =
 					(this.entity.bounds.intersects(this.groundBounds)) &&
-					(this.entity.bounds.intersectSide(this.groundBounds) === "top");
+					(this.entity.bounds.intersectSide(this.groundBounds) === "top") &&
+					!jumping;
 
 				if (stillOnGround) {
 					this.entity.bounds.bottom = this.groundBounds.top;
 			}
 
 			// Collide with new stuff
-			let collider = this.entity.t.collider;
-			collider.entities.forEach(e => {
-				let vel;
-				if (e.has("physics"))
-					vel = e.t.physics.absVelocity;
-				else
-					vel = zeroVector;
-
-				if (e.has("wall"))
-					this.collideWall(e.bounds, vel);
-				else if (e.has("platform"))
-					this.collidePlatform(e.bounds, vel);
-			});
-			collider.structures.forEach((s, i) => {
-				let bounds = collider.structureBounds[i];
-				if (s.attrs.wall)
-					this.collideWall(bounds, zeroVector);
-				else if (s.attrs.platform)
-					this.collidePlatform(bounds, zeroVector);
-			});
+			if (!jumping) {
+				let collider = this.entity.t.collider;
+				collider.entities.forEach(e => {
+					let vel;
+					if (e.has("physics"))
+						vel = e.t.physics.absVelocity;
+					else
+						vel = zeroVector;
+
+					if (e.has("wall"))
+						this.collideWall(e.bounds, vel);
+					else if (e.has("platform"))
+						this.collidePlatform(e.bounds, vel);
+				});
+				collider.structures.forEach((s, i) => {
+					let bounds = collider.structureBounds[i];
+					if (s.attrs.wall)
+						this.collideWall(bounds, zeroVector);
+					else if (s.attrs.platform)
+						this.collidePlatform(bounds, zeroVector);
+				});
+			}
 
 			this.oldGroundBounds = null;
 		}

package-lock.json

       }
     },
     "dev-refresh": {
-      "version": "0.3.0",
-      "resolved": "https://registry.npmjs.org/dev-refresh/-/dev-refresh-0.3.0.tgz",
-      "integrity": "sha512-aSbk/oqQ3MokCkNscC0Evu20ht82YgTIPnV2essHFb1bDHzftM88U/ovETFBAzs/9F45uf3t5qNAgiqwMSD6Og==",
+      "version": "file:../dev-refresh",
       "dev": true,
       "requires": {
         "minimist": "1.2.0",
         "node-watch": "0.5.5",
         "open": "0.0.5",
         "webframe": "0.8.2"
+      },
+      "dependencies": {
+        "minimist": {
+          "version": "1.2.0",
+          "bundled": true,
+          "dev": true
+        },
+        "node-watch": {
+          "version": "0.5.5",
+          "bundled": true,
+          "dev": true
+        },
+        "open": {
+          "version": "0.0.5",
+          "bundled": true,
+          "dev": true
+        },
+        "webframe": {
+          "version": "0.8.2",
+          "bundled": true,
+          "dev": true
+        }
       }
     },
     "diffie-hellman": {
       "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g=",
       "dev": true
     },
-    "node-watch": {
-      "version": "0.5.5",
-      "resolved": "https://registry.npmjs.org/node-watch/-/node-watch-0.5.5.tgz",
-      "integrity": "sha512-z9xN2ibI6P0UylFadN7oMcIMsoTeCENC0rZyRM5MVK9AqzSPx+uGqKG6KMPeC/laOV4wOGZq/GH0PTstRNSqOA==",
-      "dev": true
-    },
     "number-is-nan": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/number-is-nan/-/number-is-nan-1.0.1.tgz",
         "wrappy": "1.0.2"
       }
     },
-    "open": {
-      "version": "0.0.5",
-      "resolved": "https://registry.npmjs.org/open/-/open-0.0.5.tgz",
-      "integrity": "sha1-QsPhjslUZra/DcQvOilFw/DK2Pw=",
-      "dev": true
-    },
     "os-browserify": {
       "version": "0.3.0",
       "resolved": "https://registry.npmjs.org/os-browserify/-/os-browserify-0.3.0.tgz",
         "indexof": "0.0.1"
       }
     },
-    "webframe": {
-      "version": "0.8.2",
-      "resolved": "https://registry.npmjs.org/webframe/-/webframe-0.8.2.tgz",
-      "integrity": "sha512-ohoXTI8ULn/gGJ6lfhXAYn/2qsfApdd7wTJSts0jYcCJyWOW3+VSKLMEddRn9JLOu88/OeuPIiuHlxZ92IHPBA==",
-      "dev": true
-    },
     "wrappy": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",

package.json

     "babel-preset-env": "^1.6.1",
     "babelify": "^8.0.0",
     "browserify": "^14.5.0",
-    "dev-refresh": "^0.3.0"
+    "dev-refresh": "file:../dev-refresh"
   }
 }