воскресенье, 4 декабря 2011 г.

Пример - scale



function draw() {
var ctx = document
.getElementById('canvas')
.getContext('2d');
ctx.strokeStyle = "#fc0";
ctx.lineWidth = 1.5;
ctx.fillRect(0,0,300,300);

// Uniform scaling
ctx.save()
ctx.translate(50,50);
drawSpirograph(ctx,22,6,5);

ctx.translate(100,0);
ctx.scale(0.75,0.75);
drawSpirograph(ctx,22,6,5);

ctx.translate(133.333,0);
ctx.scale(0.75,0.75);
drawSpirograph(ctx,22,6,5);
ctx.restore();

// Non uniform scaling (y direction)
ctx.strokeStyle = "#0cf";
ctx.save()
ctx.translate(50,150);
ctx.scale(1,0.75);
drawSpirograph(ctx,22,6,5);

ctx.translate(100,0);
ctx.scale(1,0.75);
drawSpirograph(ctx,22,6,5);

ctx.translate(100,0);
ctx.scale(1,0.75);
drawSpirograph(ctx,22,6,5);
ctx.restore();

// Non uniform scaling (x direction)
ctx.strokeStyle = "#cf0";
ctx.save()
ctx.translate(50,250);
ctx.scale(0.75,1);
drawSpirograph(ctx,22,6,5);

ctx.translate(133.333,0);
ctx.scale(0.75,1);
drawSpirograph(ctx,22,6,5);

ctx.translate(177.777,0);
ctx.scale(0.75,1);
drawSpirograph(ctx,22,6,5);
ctx.restore();

}
function drawSpirograph(ctx,R,r,O){
var x1 = R-O;
var y1 = 0;
var i = 1;
ctx.beginPath();
ctx.moveTo(x1,y1);
do {
if (i>20000) break;
var x2 = (R+r)*Math.cos(i*Math.PI/72)
- (r+O)*Math.cos(((R+r)/r)*(i*Math.PI/72))
var y2 = (R+r)*Math.sin(i*Math.PI/72)
- (r+O)*Math.sin(((R+r)/r)*(i*Math.PI/72))
ctx.lineTo(x2,y2);
x1 = x2;
y1 = y2;
i++;
} while (x2 != R-O && y2 != 0 );
ctx.stroke();
}