thib8956/js-canvas-playground
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snake: small tweaks

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thib8956
2026-08-05 19:56:25 +02:00
parent 63d5236924
commit 2fc219d7b1
1 changed files with 11 additions and 7 deletions
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snake.ts
+11 -7
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@@ -3,8 +3,8 @@ import { resizeCanvas, fillCircle, lerp, lerpRgb } from "./common.js";
// constants // constants
const SNAKE_RADIUS = 10; const SNAKE_RADIUS = 10;
const SNAKE_PADDING = 10; const SNAKE_PADDING = 5;
const SEGMENT_SPACING = SNAKE_RADIUS + SNAKE_PADDING; const SEGMENT_SPACING = SNAKE_RADIUS * 2 + SNAKE_PADDING;
const HEAD_COLOR = 0xf43f5e; const HEAD_COLOR = 0xf43f5e;
const TAIL_COLOR = 0xf4c3cc; const TAIL_COLOR = 0xf4c3cc;
const APPLE_COLOR = 0x58f474; const APPLE_COLOR = 0x58f474;
@@ -20,7 +20,8 @@ function initSnake(pos: Vec2d, len: number) {
return Array.from({ length: len }, (_, i) => pos.add(DIRECTIONS.left.scale(i * SEGMENT_SPACING))); return Array.from({ length: len }, (_, i) => pos.add(DIRECTIONS.left.scale(i * SEGMENT_SPACING)));
} }
// state // state
let snake = initSnake(new Vec2d(200, 200), 10); let bounds: Vec2d = new Vec2d(0, 0);
let snake = initSnake(new Vec2d(200, 200), 5);
let apple: Vec2d | undefined = undefined; let apple: Vec2d | undefined = undefined;
let velocity: Vec2d = new Vec2d(0, 0); // unit vector let velocity: Vec2d = new Vec2d(0, 0); // unit vector
let speed = 200; // px/s let speed = 200; // px/s
@@ -55,12 +56,15 @@ function drawSnakeTube(ctx: CanvasRenderingContext2D, pts: Vec2d[]) {
ctx.stroke(); ctx.stroke();
} }
function randomApple(bounds: Vec2d) {
return Vec2d.random(bounds.x - 2 * SNAKE_RADIUS + SNAKE_PADDING, bounds.y - 2 * SNAKE_RADIUS + SNAKE_PADDING);
}
function update(ctx: CanvasRenderingContext2D, time: number) { function update(ctx: CanvasRenderingContext2D, time: number) {
if (lastTime == null) lastTime = time; if (lastTime == null) lastTime = time;
const dt = (time - lastTime) / 1000; // s const dt = (time - lastTime) / 1000; // s
lastTime = time; lastTime = time;
apple = apple as Vec2d; apple = apple as Vec2d;
const bounds = new Vec2d(ctx.canvas.width, ctx.canvas.height);
if (!paused) { if (!paused) {
// update head position // update head position
@@ -79,7 +83,6 @@ function update(ctx: CanvasRenderingContext2D, time: number) {
// collisions // collisions
// convert snake_head coords to screen space // convert snake_head coords to screen space
//const head = wrapCoords(snake_body[0], bounds);
const head = snake[0].wrap(bounds) const head = snake[0].wrap(bounds)
if (head.distance(apple) < SNAKE_RADIUS * 2) { if (head.distance(apple) < SNAKE_RADIUS * 2) {
apple = Vec2d.random(bounds.x, bounds.y) apple = Vec2d.random(bounds.x, bounds.y)
@@ -106,8 +109,9 @@ function init() {
const ctx = canvas.getContext("2d") as CanvasRenderingContext2D | null; const ctx = canvas.getContext("2d") as CanvasRenderingContext2D | null;
if (!ctx) throw new Error("unable to get canvas 2D context"); if (!ctx) throw new Error("unable to get canvas 2D context");
resizeCanvas(ctx); resizeCanvas(ctx);
bounds = new Vec2d(ctx.canvas.width, ctx.canvas.height)
apple = Vec2d.random(canvas.width, canvas.height) apple = randomApple(bounds);
canvas.onmousemove = () => {}; canvas.onmousemove = () => {};
@@ -130,7 +134,7 @@ function init() {
if (evt.key === "k" || evt.key === "j") setStatusLine(`interpolation factor: ${interpolation_factor}`) if (evt.key === "k" || evt.key === "j") setStatusLine(`interpolation factor: ${interpolation_factor}`)
if (!new_direction) return; if (!new_direction) return;
if (new_direction.x === -velocity.x && new_direction.y === -velocity.y) return; // no 180° turns if (new_direction.x === -velocity.x && new_direction.y === -velocity.y) return; // no 180° turns
if (new_direction.x === velocity.x && new_direction.y === velocity.y) return; // no 180° turns if (new_direction.x === velocity.x && new_direction.y === velocity.y) return;
velocity = new_direction; velocity = new_direction;
}; };