更新时间:2023-11-09 21:15:16
由于您使用的是二次曲线,因此您知道两个点组成一条指向箭头方向"的直线:
Since you're using a quadratic curve, you know two points that make a line that points in the "direction" of your arrow head:
所以扔掉一点三角,你自己就有了解决方案.这是一个通用的函数,可以为你做这件事:
So throw down a smidge of trig and you have yourself a solution. Here's a generalized function that will do it for you:
function drawArrowhead(locx, locy, angle, sizex, sizey) {
var hx = sizex / 2;
var hy = sizey / 2;
ctx.translate((locx ), (locy));
ctx.rotate(angle);
ctx.translate(-hx,-hy);
ctx.beginPath();
ctx.moveTo(0,0);
ctx.lineTo(0,1*sizey);
ctx.lineTo(1*sizex,1*hy);
ctx.closePath();
ctx.fill();
ctx.translate(hx,hy);
ctx.rotate(-angle);
ctx.translate(-locx,-locy);
}
// returns radians
function findAngle(sx, sy, ex, ey) {
// make sx and sy at the zero point
return Math.atan2((ey - sy), (ex - sx));
}