请问如何判断一条多段线中所包含圆弧的时针方向？
<P>有一条多段线是由直线和圆弧组成的，请问我如果判断圆弧的时针方向？</P> <TABLE class=TitleTable cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY>
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<P class=Heading-1>GetBulge Method</P></A></TD></TR></TBODY></TABLE>
<P class=TitleSpacing>
<P class=1-liner>Gets the bulge value at a given index of the polyline.</P>
<P class=h1-access>Signature </P>
<P class=syntax>RetVal = object.GetBulge(Index)
<P class=element>Object</P>
<P class=element-desc><A href="mk:@MSITStore:C:\Program%20Files\Autodesk%20Map%202004\help\acadauto.chm::/idh_lightweightpolyline_object.htm" target="_blank" >LightweightPolyline</A>, <A href="mk:@MSITStore:C:\Program%20Files\Autodesk%20Map%202004\help\acadauto.chm::/idh_polyline_object.htm" target="_blank" >Polyline</A><BR>The object or objects this method applies to.
<P class=element>Index</P>
<P class=element-desc>Integer; input-only<BR>The index location of the vertex you wish to query. The index must be a positive integer beginning with zero.
<P class=element>RetVal</P>
<P class=element-desc>Double<BR>The bulge value for the vertex at the given index.
<P class=Heading-2>Remarks
<P class=body>Polyline: this method will fail if the polyline <A href="mk:@MSITStore:C:\Program%20Files\Autodesk%20Map%202004\help\acadauto.chm::/idh_type.htm" target="_blank" >Type</A> property is not acSimplePoly.
<P class=body>The bulge is the tangent of 1/4 of the included angle for the arc between the selected vertex and the next vertex in the polyline's vertex list. A negative bulge value indicates that the arc goes clockwise from the selected vertex to the next vertex. A bulge of 0 indicates a straight segment, and a bulge of 1 is a semicircle. </P> <P class=1-liner>获取多段线上给定索引位置的凸度值。</P>
<P class=h1-access><A href="http://www.mjtd.com/object/acad2004/getbulge_see_also.htm" target="_blank" >参阅</A> | <A href="http://www.mjtd.com/object/acad2004/ex_getbulge.htm" target="_blank" >示例</A></P>
<P class=Heading-2>语法
<P class=syntax>RetVal = object.GetBulge(Index)
<P class=element>Object</P>
<P class=element-desc><A href="http://www.mjtd.com/object/acad2004/idh_lightweightpolyline_object.htm" target="_blank" >LightweightPolyline</A>, <A href="http://www.mjtd.com/object/acad2004/idh_polyline_object.htm" target="_blank" >Polyline</A><BR>使用该方法的对象。
<P class=element>Index</P>
<P class=element-desc>Integer[整数]; 仅用于输入<BR>想要查询的顶点的索引位置。索引必须是从0开始的正整数。
<P class=element>RetVal</P>
<P class=element-desc>Double[双精度]<BR>给定索引顶点的凸度值。
<P class=Heading-2>说明
<P class=body>Polyline：如果多段线类型 <A href="http://www.mjtd.com/object/acad2004/idh_type.htm" target="_blank" >Type</A> 属性不是 acSimplePoly 则此方法失败。
<P class=body>凸度是多段线顶点列表中选定顶点和下一顶点之间的圆弧所包含角度的 1/4 的正切值。负的凸度值表示圆弧从选定顶点到下一顶点为顺时针方向。凸度为0 表示直线段，凸度为1表示半圆。</P> <P>如果前一个是也是圆弧呢，用凸度也能判断的出吗？</P> <P>凸度是指某段弧的凸度，和前面或后面的弧段或直线段没有关系。</P>
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