[ARX程序]：怎么样画弧线

valuxlin

在画Polyline时选Arc选项,
就会出现一个直线和弧线,
请问要实现这样一个效果用什么函数?

xysyr

AcDbPolyline::setBulgeAt Function   
Acad::ErrorStatus
setBulgeAt(
unsigned int index,
double bulge);
index Input the index (0 based) of the vertex
bulge Input the bulge value for the vertex
This function sets bulge to be the bulge value for the index vertex. This will determine the bulge for the polyline segment which follows the index vertex.

the bulge is the tan of 1/4 of included angle:

double bulge1 = tan( (Endangle - Startangle) / 4);

you must also check if (Endangle - Startangle) is
greater than 0 or not and set the bulge + or -

first Vertext is the Startpoint of the Arc,
second Vertext is the Endpoint of the Arc,

the bulge of first Vertex is bulge1, the
bulge of second Vertex is 0