使用js画图之正弦曲线

//画正弦曲线

//dot 原点

//amplitude    振幅 -- A

//initialPhase 初相 -- φ

//setover 偏距 -- k

//palstance 角速度 -- ω

//len 周期数

function drawSinusoid(dot, amplitude,initialPhase,palstance,setover, len, opts){

    var color = opts&&opts.color?opts.color:"DarkRed"; //曲线的颜色

    var max = len*2*Math.PI/w; //x的最大值

    //var x = -2*Math.PI/w/3;

    var x = 0; //x的初值

    var pre = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)]; //y的初值

    for(;x < max;x+=5){ //每五个单位画一条线

        var cur = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)];

        drawLine(pre, cur, {color: color}); // 画线

        pre = cur;

    }

    var d = Math.PI/(2*w);

    for(var x =0;x < max;x+=d){//描点

        var cur = [dot[0]+x, dot[1]+(amplitude*Math.sin(palstance*x+initialPhase)+setover)];

        drawPoint({

            pw:3,ph:3,color:'DarkRed',point: cur

        });

    }

    

    var pend = [dot[0]+max, dot[1]+(amplitude*Math.sin(palstance*max+initialPhase)+setover)];

    drawPoint({

        pw:3,ph:3,color:'DarkRed',point: pend

    });

    drawLine(pre, pend);

}