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VistasDraw grid with hexagons using canvas Html & JavaScript
I try to create a canvas with X * X of size, using hexagon shapes, currently I base on this reference, with some adaptations, my code until now look like this:
const canvas = document.getElementById('canvas');
const context = canvas.getContext('2d');
const shapeType = 6;
const angle = 2 * Math.PI / shapeType;
const radius = 20;
function init() {
drawGrid(5);
}
init();
function drawGrid(size) {
for (let y = radius, i = 0; i < size; i++) {
y += radius * Math.sin(angle);
for (let x = radius, j = 0;
j < size;
x += radius * (1 + Math.cos(angle)), y += (-1) ** j++ * radius * Math.sin(angle)) {
drawHexagon(x, y);
}
}
}
function drawHexagon(x, y) {
context.beginPath();
for (let i = 0; i < shapeType; i++) {
let xx = x + radius * Math.cos(angle * i);
let yy = y + radius * Math.sin(angle * i);
context.lineTo(xx, yy);
}
context.closePath();
context.stroke();
}<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>HexGrid</title>
<style>
.test {
display: flex;
justify-content: space-between;
}
.canvas {
border: 1px solid #000000;
}
</style>
</head>
<body>
<canvas id="canvas" width="500" height="500" class="canvas"></canvas>
<script src="main.js"></script>
</body>
</html>Until now, every thing is good, but just with odd size, but if the size is even, I get this:
As a beginner in JavaScript, I'm blocked in this, any one have any idea how can I solve this please?
·
Juan Pablo Isaza
1 Respuestas
Responde la pregunta0
Regular Hexagon Grid
A grid of hexagons has a regular spacing just like a grid of squares however every 2nd column if offset (down in this case) by half the hexagons height.
To get the x and y grid spacing, and the offset is half the y grid spacing.
RADIUS = 20;
EDGE_LEN = Math.sin(Math.PI / 6) * RADIUS * 2;
GRID_Y_SPACE = Math.cos(Math.PI / 6) * RADIUS * 2;
GRID_X_SPACE = RADIUS * 2 - EDGE_LEN * 0.5;
GRID_Y_OFFSET = GRID_Y_SPACE * 0.5;
The hexagon's position can be calculated using (gx, gy are column, row positions)
function gridToPixel(gx, gy, p = {}) {
p.x = gx * GRID_X_SPACE;
p.y = gy * GRID_Y_SPACE + (gx % 2 ? GRID_Y_OFFSET : 0);
return p;
}
Example
Example fills canvas with hexagon grid.
const ctx = canvas.getContext('2d');
const P2 = (x, y) => ({x,y});
const EDGES = 6;
const RADIUS = 20;
const TAU = 2 * Math.PI;
const EDGE_LEN = Math.sin(Math.PI / EDGES) * RADIUS * 2;
const GRID_Y_SPACE = Math.cos(Math.PI / EDGES) * RADIUS * 2;
const GRID_X_SPACE = RADIUS * 2 - EDGE_LEN * 0.5;
const GRID_Y_OFFSET = GRID_Y_SPACE * 0.5;
const COLS = "=#3c2f18,#01335f,#3f0e77,#204a73,#511d94,#fe1f00,#0060fd,#fe7603,#f0ca1d,#b085e8,#e9cafa".split(",");
const rndItem = arr => arr[Math.random() * arr.length | 0];
drawGrid(1, 1, 15, 13, createPoly(EDGES));
function drawGrid(x, y, w, h, points) {
const p = P2();
var gy, gx;
for (gy = y; gy < y + h; gy++) {
for (gx = x; gx < x + w; gx++) {
ctx.fillStyle = rndItem(COLS);
drawPoly(gridToPixel(gx, gy, p), points);
}
}
}
function gridToPixel(gx, gy, p = {}) {
p.x = gx * GRID_X_SPACE;
p.y = gy * GRID_Y_SPACE + (gx % 2 ? GRID_Y_OFFSET : 0);
return p;
}
function drawPoly(p, points) { // p.x, p.y is center
ctx.setTransform(1, 0, 0, 1, p.x, p.y);
var i = 0;
ctx.beginPath();
while (i < points.length) {
const p2 = points[i++];
ctx.lineTo(p2.x, p2.y);
}
ctx.closePath();
ctx.fill();
ctx.stroke();
}
function createPoly(sides, points = []) {
const step = TAU / sides;
var ang = 0, i = sides;
while (i--) {
points.push(P2(RADIUS * Math.cos(ang), RADIUS * Math.sin(ang)));
ang += step;
}
return points;
}canvas { border: 1px solid #000000; }<canvas id="canvas" width="500" height="500"></canvas>
·
Juan Pablo Isaza
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