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Drawing a hexagonal grid with HTML canvas
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| <!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> |
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| (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(); | |
| } | |
| } | |
| })(); |
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