Drawing arcs with AS3

核心提示：If you have ever tried to draw arcs with AS3 (or AS2), you probably smashed your computer on the floor after spending hours with curveTo().That’s not what

If you have ever tried to draw arcs with AS3 (or AS2), you probably smashed your computer on the floor after spending hours with curveTo().

That’s not what we need when we want to draw simple arcs, without any Bezier curve.

That’s why I made my own function.

It’s not that interesting since it only uses a bit of trigonometry, and obviously I did not write it for the sake of writing a function, but at the moment with this script

package　{
　import　flash.display.Sprite;
　public　class　arc　extends　Sprite　{
　　var　my_canvas:Sprite　=　new　Sprite();
　　var　deg_to_rad=0.0174532925;
　　public　function　arc()　{
　　　addChild(my_canvas);
　　　my_canvas.graphics.lineStyle(20,0xff0000,1);
　　　draw_arc(my_canvas,250,200,150,14,180,1);
　　}
　　public　function　draw_arc(movieclip,center_x,center_y,radius,angle_from,angle_to,precision)　{
　　　var　angle_diff=angle_to-angle_from;
　　　var　steps=Math.round(angle_diff*precision);
　　　var　angle=angle_from;
　　　var　px=center_x+radius*Math.cos(angle*deg_to_rad);
　　　var　py=center_y+radius*Math.sin(angle*deg_to_rad);
　　　movieclip.graphics.moveTo(px,py);
　　　for　(var　i:int=1;　i<=steps;　i++)　{
　　　　angle=angle_from+angle_diff/steps*i;
　　　　movieclip.graphics.lineTo(center_x+radius*Math.cos(angle*deg_to_rad),center_y+radius*Math.sin(angle*deg_to_rad));
　　　}
　　}
　}
}