Fix angle resolution

js/consts.mjs

@@ -8,6 +8,8 @@
 
 // For fixing floating point rounding errors.
 export const EPSILON = 1e-8;
+// Don't change these.
+export const TAU = Math.PI * 2;
 // Unit length of sector. Only for internal representation.
 export const SECTOR_SIZE = 512;
 // G, G-boy, The big G, Mr. G, g's big brother, G-dog

js/game/events.mjs

@@ -8,15 +8,17 @@ import * as edit from './edit.mjs';
 
 export let shipLanded = false;
 
-let notification;
+let notification = null;
 let notLife = 0;
 
 function notify(message) {
+	if (notification === null) return;
 	notification.text = message;
 	notLife = 60;
 }
 
 export function tick() {
+	if (notification === null) return;
 	if (notLife-- <= 0)
 		notification.text = '';
 }

js/graphics/index.mjs

@@ -6,6 +6,8 @@ import {render as renderBackground} from './background.mjs';
 import * as world from '../world/index.mjs';
 import * as consts from '../consts.mjs';
 
+const TAU = consts.TAU;
+
 export let canvas, context, tempCanvas, tempContext;
 export let perspective;
 export let trace = false;
@@ -30,6 +32,10 @@ export function render() {
 	context.fillStyle = '#000';
 	context.fillRect(0, 0, canvas.width, canvas.height);
 
+	context.beginPath();
+	context.rect(0, 0, canvas.width, canvas.height);
+	context.clip();
+
 	context.save();
 	perspective.tick();
 	perspective.transformRotate();
@@ -118,7 +124,7 @@ class Perspective {
 	}
 
 	get currentRotation() {
-		return this.interpolate(this.targetRotation, this.oldTarget);
+		return this.interpolateAngles(this.targetRotation, this.oldTarget);
 	}
 
 	get currentZoom() {
@@ -131,15 +137,11 @@ class Perspective {
 	}
 
 	interpolateAngles(cur, old, x = this.transition) {
-		let a = cur % (Math.PI * 2);
-		let b = old % (Math.PI * 2);
+		return old + this.angleDifference(old, cur) * (1 - x);
+	}
 
-		let sum = a + b;
-
-		if (sum > (Math.PI * 2) && sum < (Math.PI * 3))
-			sum %= Math.PI;
-
-		return sum / 2;
+	angleDifference(a, b) {
+		return Math.atan2(Math.sin(b - a), Math.cos(b - a));
 	}
 
 	tick() {
@@ -195,7 +197,7 @@ class Perspective {
 	normalize() {
 		this.targetZoom = Math.max(consts.MIN_ZOOM,
 			Math.min(consts.MAX_ZOOM, this.targetZoom));
-		this.targetRotation %= (Math.PI * 2);
+		this.targetRotation %= TAU;
 	}
 
 	transformRotate() {
@@ -218,4 +220,8 @@ class Perspective {
 		context.translate(tx + bw / 2, ty + bh / 2);
 		context.scale(this.zoom, this.zoom);
 	}
+
+	normalizeAngle(a = this.r) {
+		return ((a % TAU) + TAU) % TAU;
+	}
 }

js/world/body.mjs

@@ -1,4 +1,4 @@
-import {GRAVITATIONAL_CONSTANT as G} from '../consts.mjs';
+import {GRAVITATIONAL_CONSTANT as G, TAU} from '../consts.mjs';
 
 export default class Body {
 	constructor(x, y, mass) {
@@ -24,6 +24,14 @@ export default class Body {
 		return Math.sqrt(this.xvel ** 2 + this.yvel ** 2);
 	}
 
+	angleDifference(a, b) {
+		return Math.atan2(Math.sin(a - b), Math.cos(a - b));
+	}
+
+	normalizeAngle(a = this.r) {
+		return ((a % TAU) + TAU) % TAU;
+	}
+
 	getCelestialCollision(celestials) {
 		let result = false;
 		celestials.forEach(c => {
@@ -51,6 +59,7 @@ export default class Body {
 			(y * Math.cos(r) - x * Math.sin(r))];
 	}
 
+	// TODO: Remove and replace uses with `rotateVector`.
 	relativeVector(x, y) {
 		return this.rotateVector(x, y, this.r);
 	}

js/world/ship.mjs

@@ -112,24 +112,27 @@ export default class Ship extends Body {
 	}
 
 	resolveCelestialCollision(pos, cel) {
-		// I don't even know why this works, don't touch it.
-		let theta = this.angleTo(...this.com, ...cel.com);
-		let angleToCom = this.angleTo(...this.com, ...pos);
-		let turnAngle = angleToCom - theta;
-		let checkAngle = theta - this.r - Math.PI / 2;
+		let celToCom = this.angleTo(...this.com, ...cel.com);
+		let celToPoc = this.angleTo(...pos, ...cel.com);
+		let pocToCom = this.angleTo(...this.com, ...pos);
+
+		let turnAngle = this.angleDifference(celToPoc, pocToCom);
+		let checkAngle = this.angleDifference(celToPoc, this.r + Math.PI / 2);
+
 		let [force] = this.rotateVector(0, 1, turnAngle);
-		if (Math.abs(checkAngle) < consts.TIP_ANGLE) {
-			force *= -1;
-		}
+
+		if (Math.abs(checkAngle) < consts.TIP_ANGLE) force *= -1;
+
 		let canLand = Math.abs(checkAngle) < 0.03
 			&& Math.abs(this.rvel) < 0.001;
 
 		if (canLand) {
 			this.landed = true;
 			this.rvel = 0;
-			this.r = theta - Math.PI / 2;
+			this.r = celToCom - Math.PI / 2;
 		}
-		this.rvel -= force * consts.TIP_SPEED;
+		
+		this.rvel += force * consts.TIP_SPEED;
 	}
 
 	checkModuleCollision(module, body) {