📄 4.3.2 橡皮条技术.htm

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<H3 style="TEXT-INDENT: 0cm"><FONT face=楷体_GB2312 size=4><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN">4.3.2 </SPAN><SPAN 
style="FONT-FAMILY: 楷体_GB2312; mso-fareast-language: ZH-CN; mso-ascii-font-family: 'Times New Roman'">橡皮条技术</SPAN><SPAN 
lang=EN-US style="mso-fareast-language: ZH-CN"><o:p></o:p></SPAN></FONT></H3>
<P class=MsoBodyTextIndent><SPAN style="mso-fareast-language: ZH-CN"><FONT 
face=楷体_GB2312 size=4>有时定位操作依赖于环境。比如，在绘图时，已经存在一个圆<SPAN 
lang=EN-US>C和圆外一点A，现在要确定另外一个点B，使二点连线AB与圆C相切。这样的点的确定可通过橡皮条技术的使用而变得容易实现。<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
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<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><FONT face=楷体_GB2312 size=4><!--[if gte vml 1]><v:shapetype id=_x0000_t202 coordsize = "21600,21600" 
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      <P class=MsoNormal><SPAN 
      style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图</SPAN><SPAN 
      lang=EN-US style="FONT-SIZE: 9pt"> 4.3.3 </SPAN><SPAN 
      style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">用橡皮条技术定位（显示线段用异或方式）</SPAN></P></DIV><![if !mso]></TD></TR></TBODY></TABLE><![endif]></v:textbox><w:wrap 
type = "square"></w:wrap></v:shape><![endif]--><![if !vml]><img width=314 height=54src="les432.files/image005.gif" align=left hspace=12alt="文本框: 图 4.3.3 用橡皮条技术定位（显示线段用异或方式）" v:shapes="_x0000_s1026"><![endif]><SPAN 
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<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]>&nbsp;</FONT></SPAN><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4>如果在用定位器移动点<SPAN 
lang=EN-US>B时屏幕上始终有一线段连结AB，犹如有一根橡皮条连结着AB两点一样，这就是橡皮条线段技术。图4.3.3示出了橡皮条线段的处理。</SPAN>有了橡皮条技术，操作员只须在移动<SPAN 
lang=EN-US>B点使AB与圆C相切时按下定位按键，就能准确地定位。</SPAN>橡皮条技术除了用于橡皮条线段外，还可用于其他一些方面。比如橡皮条矩形，橡皮条圆等等（图<SPAN 
lang=EN-US>4.3.4）。<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
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style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><FONT face=楷体_GB2312 size=4><!--[if gte vml 1]><v:shape id=_x0000_s1027 
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      <P class=MsoNormal><SPAN 
      style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">图</SPAN><SPAN 
      lang=EN-US style="FONT-SIZE: 9pt"> 4.3.4 </SPAN><SPAN 
      style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">橡皮条技术图例</SPAN></P></DIV><![if !mso]></TD></TR></TBODY></TABLE><![endif]></v:textbox><w:wrap 
type = "square"></w:wrap></v:shape><![endif]--><![if !vml]><img width=194 height=44src="les432.files/image006.gif" align=left hspace=12alt="文本框: 图 4.3.4 橡皮条技术图例" v:shapes="_x0000_s1027"><![endif]><SPAN 
lang=EN-US style="mso-fareast-language: ZH-CN"><o:p></o:p></SPAN></FONT></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm; TEXT-ALIGN: center" 
align=center><SPAN lang=EN-US style="mso-fareast-language: ZH-CN"><FONT 
face=楷体_GB2312 
size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm; TEXT-ALIGN: center" 
align=center><SPAN lang=EN-US style="mso-fareast-language: ZH-CN"><FONT 
face=楷体_GB2312 
size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
<P class=MsoBodyTextIndent style="TEXT-INDENT: 0cm"><SPAN lang=EN-US 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]></FONT></SPAN><SPAN 
style="mso-fareast-language: ZH-CN"><FONT face=楷体_GB2312 
size=4>橡皮条矩形的一个顶点是固定的。在用定位器移动与该顶点相对的另一个顶点时，始终有一个矩形跟着变化。</FONT></SPAN><SPAN 
style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><FONT 
face=楷体_GB2312 
size=4>橡皮条圆的圆心固定，当圆上一点移动时，生成的圆跟着变化。一旦满意，按下定位键，圆上该点就得到确定。也可以将两点交换，即圆上一点固定，圆心变化。当按下定位键时圆心得到确定。橡皮条棱锥的底多边形是固定的，随着顶点的移动，棱锥的各棱线跟着变化，当按下定位键时，顶点确定，棱锥也随之确定。</FONT></SPAN><FONT 
face=楷体_GB2312 size=4><SPAN lang=EN-US><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><SPAN lang=EN-US><FONT face=楷体_GB2312 size=4><![if !supportEmptyParas]><![endif]>&nbsp;<o:p></o:p></FONT></SPAN></P>
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