<html>
<body>
<script src="Stats.js"></script>
<p id="timing"> </p>
<script>
var requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame;
var stats = new Stats();
document.body.appendChild( stats.getDomElement() );
var blocksize = 8;
var canvas = document.createElement( 'canvas' );
canvas.width = 1024;
canvas.height = 512;
document.body.appendChild( canvas );
var canvasWidth = canvas.width;
var canvasHeight = canvas.height;
var canvasWBlocks = Math.floor((canvasWidth + blocksize-1) / blocksize);
var canvasHBlocks = Math.floor((canvasHeight + blocksize-1) / blocksize);
var context = canvas.getContext( '2d' );
var imagedata = context.getImageData( 0, 0, canvasWidth, canvasHeight );
var data = imagedata.data;
var block_full = new Uint8Array(canvasWBlocks * canvasHBlocks);
// var typedarray = new Uint8ClampedArray( data.length );
// console.log( data instanceof Uint8ClampedArray );
render();
animate();
function animate() {
requestAnimationFrame( animate );
render();
stats.update();
}
function render() {
// clear
for ( var i = 3, l = data.length; i < l; i += 4 ) {
data[ i ] = 0;
}
for (var i = 0, l = block_full.length; i < l; i++) {
block_full[i] = 0;
}
/*
for ( var i = 0; i < 100000; i ++ ) {
var color = Math.random() * 0xffffff;
drawPixel(
Math.floor( Math.random() * canvasWidth ),
Math.floor( Math.random() * canvasHeight ),
color >> 16 & 255,
color >> 8 & 255,
color & 255
);
}
*/
/*
for ( var i = 0; i < 100; i ++ ) {
drawRectangle(
Math.random() * canvasWidth,
Math.random() * canvasHeight,
Math.random() * canvasWidth,
Math.random() * canvasHeight,
Math.random() * 0xffffff
);
}
*/
var startTime = new Date();
for ( var i = 0; i < 1000; i ++ ) {
drawTriangle(
Math.random() * canvasWidth,
Math.random() * canvasHeight,
Math.random() * 0xffffff,
Math.random() * canvasWidth,
Math.random() * canvasHeight,
Math.random() * 0xffffff,
Math.random() * canvasWidth,
Math.random() * canvasHeight,
Math.random() * 0xffffff
);
}
var endTime = new Date();
document.getElementById("timing").innerText = (endTime - startTime) + "ms";
context.putImageData( imagedata, 0, 0 );
}
//
function drawPixel( x, y, r, g, b ) {
var offset = ( x + y * canvasWidth ) * 4;
if ( data[ offset + 3 ] ) return;
data[ offset ] = r;
data[ offset + 1 ] = g;
data[ offset + 2 ] = b;
data[ offset + 3 ] = 255;
}
function drawRectangle( x1, y1, x2, y2, color ) {
var r = color >> 16 & 255;
var g = color >> 8 & 255;
var b = color & 255;
var xmin = Math.min( x1, x2 ) >> 0;
var xmax = Math.max( x1, x2 ) >> 0;
var ymin = Math.min( y1, y2 ) >> 0;
var ymax = Math.max( y1, y2 ) >> 0;
for ( var y = ymin; y < ymax; y ++ ) {
for ( var x = xmin; x < xmax; x ++ ) {
drawPixel( x, y, r, g, b );
}
}
}
function drawTriangle( x1, y1, color1, x2, y2, color2, x3, y3, color3 ) {
// http://devmaster.net/forums/topic/1145-advanced-rasterization/
// 28.4 fixed-point coordinates
var x1 = Math.round( 16 * x1 );
var x2 = Math.round( 16 * x2 );
var x3 = Math.round( 16 * x3 );
var y1 = Math.round( 16 * y1 );
var y2 = Math.round( 16 * y2 );
var y3 = Math.round( 16 * y3 );
// Deltas
var dx12 = x1 - x2, dy12 = y2 - y1;
var dx23 = x2 - x3, dy23 = y3 - y2;
var dx31 = x3 - x1, dy31 = y1 - y3;
// Bounding rectangle
var minx = Math.max( ( Math.min( x1, x2, x3 ) + 0xf ) >> 4, 0 );
var maxx = Math.min( ( Math.max( x1, x2, x3 ) + 0xf ) >> 4, canvasWidth );
var miny = Math.max( ( Math.min( y1, y2, y3 ) + 0xf ) >> 4, 0 );
var maxy = Math.min( ( Math.max( y1, y2, y3 ) + 0xf ) >> 4, canvasHeight );
// Block size, standard 8x8 (must be power of two)
var q = blocksize;
// Start in corner of 8x8 block
minx &= ~(q - 1);
miny &= ~(q - 1);
// Constant part of half-edge functions
var c1 = -dy12 * x1 - dx12 * y1;
var c2 = -dy23 * x2 - dx23 * y2;
var c3 = -dy31 * x3 - dx31 * y3;
// Correct for fill convention
if ( dy12 > 0 || ( dy12 == 0 && dx12 > 0 ) ) c1 ++;
if ( dy23 > 0 || ( dy23 == 0 && dx23 > 0 ) ) c2 ++;
if ( dy31 > 0 || ( dy31 == 0 && dx31 > 0 ) ) c3 ++;
// Note this doesn't kill subpixel precision, but only because we test for >=0 (not >0).
// It's a bit subtle. :)
c1 = (c1 - 1) >> 4;
c2 = (c2 - 1) >> 4;
c3 = (c3 - 1) >> 4;
// Set up min/max corners
var qm1 = q - 1; // for convenience
var nmin1 = 0, nmax1 = 0;
var nmin2 = 0, nmax2 = 0;
var nmin3 = 0, nmax3 = 0;
if (dx12 >= 0) nmax1 -= qm1*dx12; else nmin1 -= qm1*dx12;
if (dy12 >= 0) nmax1 -= qm1*dy12; else nmin1 -= qm1*dy12;
if (dx23 >= 0) nmax2 -= qm1*dx23; else nmin2 -= qm1*dx23;
if (dy23 >= 0) nmax2 -= qm1*dy23; else nmin2 -= qm1*dy23;
if (dx31 >= 0) nmax3 -= qm1*dx31; else nmin3 -= qm1*dx31;
if (dy31 >= 0) nmax3 -= qm1*dy31; else nmin3 -= qm1*dy31;
// Loop through blocks
var linestep = (canvasWidth - q) * 4;
var scale = 255.0 / (c1 + c2 + c3);
for ( var y0 = miny; y0 < maxy; y0 += q ) {
for ( var x0 = minx; x0 < maxx; x0 += q ) {
// Edge functions at top-left corner
var cy1 = c1 + dx12 * y0 + dy12 * x0;
var cy2 = c2 + dx23 * y0 + dy23 * x0;
var cy3 = c3 + dx31 * y0 + dy31 * x0;
// Skip block when at least one edge completely out
if (cy1 < nmax1 || cy2 < nmax2 || cy3 < nmax3) continue;
// Skip writing full block if it's already fully covered
var blockX = (x0 / q) | 0;
var blockY = (y0 / q) | 0;
var blockInd = blockX + blockY * canvasWBlocks;
if (block_full[blockInd]) continue;
// Offset at top-left corner
var offset = (x0 + y0 * canvasWidth) * 4;
// Accept whole block when fully covered
if (cy1 >= nmin1 && cy2 >= nmin2 && cy3 >= nmin3) {
for ( var iy = 0; iy < q; iy ++ ) {
var cx1 = cy1;
var cx2 = cy2;
for ( var ix = 0; ix < q; ix ++ ) {
if (!data[offset + 3]) {
var u = cx1 * scale; // 0-255!
var v = cx2 * scale; // 0-255!
data[offset] = u;
data[offset + 1] = v;
data[offset + 2] = 0;
data[offset + 3] = 255;
}
cx1 += dy12;
cx2 += dy23;
offset += 4;
}
cy1 += dx12;
cy2 += dx23;
offset += linestep;
}
block_full[blockInd] = 1;
} else { // Partially covered block
for ( var iy = 0; iy < q; iy ++ ) {
var cx1 = cy1;
var cx2 = cy2;
var cx3 = cy3;
for ( var ix = 0; ix < q; ix ++ ) {
if ( (cx1 | cx2 | cx3) >= 0 && !data[offset+3]) {
var u = cx1 * scale; // 0-255!
var v = cx2 * scale; // 0-255!
data[offset] = u;
data[offset + 1] = v;
data[offset + 2] = 0;
data[offset + 3] = 255;
}
cx1 += dy12;
cx2 += dy23;
cx3 += dy31;
offset += 4;
}
cy1 += dx12;
cy2 += dx23;
cy3 += dx31;
offset += linestep;
}
}
}
}
}
</script>
</body>
</html>