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Drawing a hexagonal grid with HTML canvas
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Canvas Hexagonal Map</title>
<style type="text/css">
canvas {
border:0;
display:block;
margin:0 auto;
}
</style>
</head>
<body>
<canvas id="hexmap" width="660" height="624"></canvas>
<script src="hexagons.js"></script>
</body>
</html>
(function(){
var canvas = document.getElementById('hexmap');
var hexHeight,
hexRadius,
hexRectangleHeight,
hexRectangleWidth,
hexagonAngle = 0.523598776, // 30 degrees in radians
sideLength = 36,
boardWidth = 10,
boardHeight = 10;
hexHeight = Math.sin(hexagonAngle) * sideLength;
hexRadius = Math.cos(hexagonAngle) * sideLength;
hexRectangleHeight = sideLength + 2 * hexHeight;
hexRectangleWidth = 2 * hexRadius;
if (canvas.getContext){
var ctx = canvas.getContext('2d');
ctx.fillStyle = "#000000";
ctx.strokeStyle = "#CCCCCC";
ctx.lineWidth = 1;
drawBoard(ctx, boardWidth, boardHeight);
canvas.addEventListener("mousemove", function(eventInfo) {
var x,
y,
hexX,
hexY,
screenX,
screenY;
x = eventInfo.offsetX || eventInfo.layerX;
y = eventInfo.offsetY || eventInfo.layerY;
hexY = Math.floor(y / (hexHeight + sideLength));
hexX = Math.floor((x - (hexY % 2) * hexRadius) / hexRectangleWidth);
screenX = hexX * hexRectangleWidth + ((hexY % 2) * hexRadius);
screenY = hexY * (hexHeight + sideLength);
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawBoard(ctx, boardWidth, boardHeight);
// Check if the mouse's coords are on the board
if(hexX >= 0 && hexX < boardWidth) {
if(hexY >= 0 && hexY < boardHeight) {
ctx.fillStyle = "#000000";
drawHexagon(ctx, screenX, screenY, true);
}
}
});
}
function drawBoard(canvasContext, width, height) {
var i,
j;
for(i = 0; i < width; ++i) {
for(j = 0; j < height; ++j) {
drawHexagon(
ctx,
i * hexRectangleWidth + ((j % 2) * hexRadius),
j * (sideLength + hexHeight),
false
);
}
}
}
function drawHexagon(canvasContext, x, y, fill) {
var fill = fill || false;
canvasContext.beginPath();
canvasContext.moveTo(x + hexRadius, y);
canvasContext.lineTo(x + hexRectangleWidth, y + hexHeight);
canvasContext.lineTo(x + hexRectangleWidth, y + hexHeight + sideLength);
canvasContext.lineTo(x + hexRadius, y + hexRectangleHeight);
canvasContext.lineTo(x, y + sideLength + hexHeight);
canvasContext.lineTo(x, y + hexHeight);
canvasContext.closePath();
if(fill) {
canvasContext.fill();
} else {
canvasContext.stroke();
}
}
})();
Owner

zackthehuman commented Feb 20, 2012

Works in Chrome but my mouse position gather is wrong for Firefox. Working on a fix...

Apreche commented Nov 25, 2012

I'm thinking of making a version of this that scales with window size. Either more hexes will be visible with a larger window, or the map will have a fixed number of hexes that will get bigger and easier to see.

Forked and added a few lines to fix the mouse positioning in FF. Using getBoundingClientRect(), I see the correct behavior in Chrome, FF, IE9, and Opera on Win 7.

ArneBab commented Mar 22, 2015

forked to experiment with conways life in hexagon. Would you allow me to use this under a license which is compatible with GPL?

Great work: I've incorporated your core hex drawing logic into my own project here: https://github.com/JohnRayson/Hexagons_Rebooted
You are currently referenced in the MD file, is there a specific way you would like me to attribute the work to yourself?

Awesome

I search for rotated hexagon grid 1 hour

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