[编程申请]：在ARX编程中如何用直线模拟画圆弧

yangzj

请教诸位高手,在ARX编程中如何用复合线模拟画圆弧?!
本人经过多次尝试均未成功,特请诸位赐教!
尤其使用startAngle（）和endAngle（）函数返回圆弧的起始角大于终止角时，不知如何计算圆弧上的坐标点，片段程序如下：
   double  satrtangle;  // 圆弧起始角
      double  endangle;  //原户终止角
      double   angle ,ang;  //计算圆弧上点坐标用到的角度、角度步长
      ads_point startpt ,endpt,centerpt;    //
      ang = (startangle-endangle)/100.0  //
      .......
      for( angle=startangle;angle<endangle;angle=angle+ang)
      {
          startpt[X]=centerpt[X]+0.707*cos(angle);
          startpt[Y]=centerpt[Y]+0.707*sin(angle);
          startpt[Z]=centerpt[Z];

          endpt[X]=centerpt[X]+0.707*cos(angle+ang);
          endpt[Y]=centerpt[Y]+0.707*sin(angle+ang);
          sendpt[Z]=centerpt[Z];
          ......
         }

yusongrong

为什么要用直线模拟画圆弧？你把圆弧的弦计算出来，用直线连起来不就行了。

HillMan

1. 
   
2.   [FONT=courier new]
   
3. void
   
4. 
   
5. getSamplePoints(
   
6. 
   
7. double fromParam,
   
8. 
   
9. double toParam,
   
10. 
    
11. double approxEps,
    
12. 
    
13. AcGePoint2dArray& pointArray,
    
14. 
    
15. AcGeDoubleArray& paramArray) const;
    
16. 
    
17. fromParam Input starting parameter
    
18. toParam Input ending parameter
    
19. approxEps Input chord-height tolerance
    
20. pointArray Output array of points on curve between fromParam and toParam
    
21. paramArray Output array of parameters corresponding to points in pointArray
    
22. 
    
23. Returns a list of points on the curve between fromParam and toParam. The line segment between any two consecutive points returned in pointArray does not deviate by more than approxEps from the curve.
    
24. 
    
25. 
    
26. --------------------------------------------------------------------------------
    
27. 
    
28. void
    
29. 
    
30. getSamplePoints(
    
31. 
    
32. int numSample,
    
33. 
    
34. AcGePoint2dArray& unnamed) const;
    
35. 
    
36. numSample Input number of points that are to be returned
    
37. unnamed Output array of sampled points
    
38. 
    
39. Returns the specified number of points on the curve. The points are equally spaced by parameter value. So if the interval of the curve [0,1] and numSample is 5, the parameter values of the returned points will be 0, 0.25, 0.5, 0.75, and 1.
    
40. 
    
41. 
    
42.   [/FONT]
    

复制代码

yangzj

请问斑竹,能否详细介绍getSamplePoints的用法?