I try to create a canvas with X * X of size, using hexagon shapes, currently I base on
As a beginner in JavaScript, I'm blocked in this, any one have any idea how can I solve this please?
CodePudding user response:
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>