Basic Concept 基本概念

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Definitions   定义

l SPINE of the law: any *CRV, *CCV, *LN element    公式脊线：任意*CRV, *CCV, *LN元素

l DEF PT of the law: any *PT belonging to the spine who is used to define the law. The current DEF PT is displayed on the spine by a triangle and by a cross in the Graphic display panel.

公式DEF点: 任意用来定义公式脊线上的点。当前DEF 点用三角形或十字显示在图像展示板上。

l LAW VALUE: defines the value of the law at a given DEF PT.

         公式值：对于每一个DEF 点给出一个公式值   

l LAW RATIO: (or law tangency) defines the value of the law ratio at a given DEF PT. It is the variation of the law for a variation of the curvilinear abscissa along the spine equal to 1 model unit).

         公式比率：（或公式切矢）对于每一个DEF 点给出一个公式比率值，它是脊线曲线横坐标的函数。

A LAW RATIO is displayed in the Graphic display panel by an arrow. This arrow is green if it is free, red otherwise. (see "Free Information and Imposed Information" on page 55).

公式比率用一个箭头显示在图像展示板上，该箭头若在释放状态，则为绿色；否则为红色（见第55页“释放信息和施加信息”）

l LAW TYPE: defines the kind of variation the law must have. (constant, linear, cubic, unspec)

公式类型：定义变量类型（常量、线性、立方、非线性）

l LAW CURVE: is displayed in the graphic display panel. It represents the curve going through all the DEF PT and respecting the law ratio in every DEF PT.

         公式曲线：显示在图形展示板上，该曲线代表了通过所有DEF点的曲线，并表征了每一点的公式比率。

How to Define a DEF PT      怎样定义一个DEF点

l Selection of a point on the spine of the law.  选择一个公式脊线上的点

l Key in the percentage of curvilinear abscissa of this point in the Main law panel (refer to Figure 29 on page 52), in front of the string ABS.

在主公式板中（参考第52页图29），在ABS一行前输入这点的曲线横坐标的百分比。

l Intersection between the plane of a planar curve and the spine. This plane must be normal to the spine.         平面曲线所属平面与脊线所属平面相交，且为正交。

l Projection of any *PT selection onto the spine.      将所选点投影到上。

l Selection of a point in the Graphic display panel (refer to Figure 30 on page 53).      

在图形展示板中选择一点（参考第53页图30）。

l Indication in the Graphic display panel.       图形展示板中显示该点。

How to Give a LAW VALUE   怎样给出公式值

l Key in the value in the Main law panel (refer to refid=lawpn01.) in front of the string VAL.

         在主公式板中（参考refid=lawpn01.），在VAL 一行前输入该值。

l Indication in the Graphic display panel (refer to Figure 30 on page 53). The LAW VALUE of the current DEF PT is the ordinate of the indicate point in the panel.

         图形展示板中显示该值（参考第53页图30）。当前DEF点的公式值是展示板中显示点的纵坐标.

l Parameter of a selected conic curve normal to the spine. 确定一条二次曲线的参数，使其与脊线正交。

How to Give a LAW RATIO  怎样给出公式切矢

l Key in the value in the Main law panel (refer to refid=lawpn01.) in front of the string TGT.      

在主公式板中（参考refid=lawpn01.），在TGT 一行前输入该值。

l First, select the arrow attached to the DEF PT in the Graphic display panel (refer to Figure 30 on page 53). Then indicate a point in the panel. The new arrow will have the direction of the line going throUGh the DEF PT and this indicate point.

图形展示板中DEF点上的箭头（参考第53页图30），再任选一点，新箭头就从DEF点指向新选点。

How to Give a LAW TYPE     怎样给出公式类型

Select the icon in the Main law panel (refer to Figure 29 on page 52) until the right one is displayed.

在主公式板中选择正确图标（参考第52页图29）。

Free Information and Imposed Information释放信息及施加信息

l All user values are mandatory for the law calculation. These values are imposed informations.

        对一个公式计算来说，所有用户输入值都是强制性的，也就是施加信息。

l All default values calculated by the software are free informations for the law calculation.

        软件自带值为释放信息。

For example, during a law definition, the user selects a point along the spine, the default values (VALUE and RATIO) are the current values of the law at this point. If the user wants to let free the value and impose a ratio, he keys only the LAW RATIO. If VALUE or RATIO is omitted, the corresponding value will be free for the law calculation. Both cannot be omitted.

例如：在定义一个公式时，用户在脊线上选择一点，默认值（公式值、公式切矢）就是该点的当前值。若用户想要一个默认公式值并施加一个公式切矢，他只需输入公式切矢值。若公式值、公式切矢被省略，则该公式对应的其他值为释放值，因此，这两个值不能省略。

Note：A tangency which is free is represented in the graphic display panel (refer to Figure 30 on page 53) in green. The color of an imposed one is red.

注：图形展示板显示的释放切矢（参考第53页上图30）为绿色。施加公式切矢为红色。

Created Elements 生成元素

For the moment no geometric element is created, and the law can only be used in BLENSURF function. In fact, the *LAW element is not saved in the model. So, it has to be used immediately in the calling function.

在没生成几何元素时，law仅能用于BLENSURF功能。实际上，*LAW要素不能在模型中保存，只能用于下级功能。

Build of a Law   生成LawMain Law Panel Description    主LAW展示板简介When the new LAW creation software is called, the Main law window (refer to Figure 29 on page 52) is displayed including 3 areas.    生成新LAW时，主LAW展示窗口（参考第52页图29）包括3个区域。1. The switch area.    开关区域。 2. The law value display area.   law值展示区域。3. The icon area.   图标区域。The switch area is at the top of the panel. There are two choices: exit or show / no-show. The exit switch is used to exit the LAW function. The law created is saved for the BLENSURF function. The show / no-show switch is used to show the Graphic display panel (refer to Figure 30 on page 53) if the panel is not displayed, or to hide it if it is visible.开关区在展示板的最上边，有2个选择：退出、。退出键用来退出LAW功能。生成LAW保存用于BLENSURF功能。显示/不显示功能用来显示或隐藏图形展示板。The second area is used to display the law values at the current point and at the two end points (called PT1 and PT2) of the spine.    第二个区域用来显示脊线的端点（PT1和PT2）及当前点的law值。The last area at the bottom of the panel is called icon area. The law is computed according to the selected kind of variation (see Table 1 on page 52)  底部区域叫图标区，law按所选变量进行计算（见第52页表1）。Graphic Display of the Law Form Law的图形展示形式 It looks like the ANALYSIS CATIA function + CURVE item window (refer to Figure 30 on page 53). It is used to display the variation of the Law value with the percentage of curvilinear abscissa along the spine in abscissa and the law value in ordinate.就像ANALYSIS CATIA+ CURVE（参考第53页上图30），图形展示板用来显示Law值沿脊线横坐标、Law值纵坐标的曲线坐标百分比的变化。This display can be used to define or cancel DEF PT, LAW VALUE and RATIO.可以用其来来定义、或删除DEF点，Law值和比率。This display is refreshed any time the law data is calculated.    这种显示可随时计算、随时更新。Law Dialog Description   Law的对话框简介1．SHOW / NO-SHOW switch is always available.    显示/不显示是常用键。2．EXIT switch is always available. 出口开关是常用键。3．Icon choice.  图标键是选用键。The three available icons (refer to Table 1 on page 52) are displayed at the same place. The first one is the unspec, the cubic is displayed over it, and the last one is the linear. Hence, the only one visible at the beginning is the linear icon.3个可用键（参考第52页表1）在同一个地方展示。第一个是非线性的，第二个是三次曲线，最后的一个是线性曲线。开始时，唯一可见的是线性的图标。To change the icon, select it. After the linear one, the cubic appears. After the cubic, the unspec icon appears. After the unspec, the linear icon appears. But in this case it is possible that the number of imposition values can not allow the build of the law (refer to Table 2 on page 56). So all the DEF PT are deleted except the first and the last one. In case of mistake a NO interaction gives back all the deleted points.    选定图标键就可以改变图标。线性曲线后是三次曲线，然后是非线性曲线。非线性曲后再出现线性曲线图标，但此时所有的参数值都得重输入，所有的DEF点，除了第一个和最后的一个点外，全被删除。若错选该键，则在交互对话中选NO，所有的已删除DEF点全部恢复。为NOTE：The number of imposition values is equal to the sum of the number of DEF PT and the number of imposed LAW RATIO.         注：所施加值的数量等于DEF点与施加切矢的和。Table 2．Type of Law regarding the Number of Imposition Values.
3 j5 f! i) i5 W/ K4 q4. Add pt 加点Select a DEF PT (See how to define a DEF PT)   选一DEF点(见怎样定义一个DEF点)Select the LAW VALUE if needed (See how to define LAW VALUE).   必要时选LAW值(见怎样定义LAW值)Select the LAW RATIO if needed (See how to define LAW RATIO). 必要时选LAW切矢(见怎样定义LAW切矢)The DEF PT is added and the Graphic display panel is refreshed.   DEF点增加且图形展示板更新NOTE: In case of indication in the Graphic Display of the Law form, values (Abscissa of DEF PT, LAW VALUE and RATIO at this point are defined, but RATIO is free).注：在图形显示器中给出Law的类型、值（该点的DEF点、Law值和切矢的横坐标被定义，但切矢是释放值）。5．Delete a DEF PT or the LAW RATIO imposed    删除一个DEF点或施加的切矢   Select a DEF PT (See how to define a DEF PT).   选一DEF点(见怎样定义一个DEF点)Select it again. If a RATIO VALUE was imposed, now it is free. Otherwise, this point is deleted.再选它一次，若切矢值是施加值，则变为释放值；若不是，则删除该DEF点To delete a DEF PT which has an imposed RATIO VALUE, free first the RATIO VALUE and then delete the point. In this case to delete a DEF PT, it must be selected four times.要删除有施加切矢值的DEF点，首先释放切矢，然后删除它。这样，要删除DEF点，就须选择它4次。The DEF PT or the RATIO value is canceled and the Graphic display panel is refreshed.DEF点或切矢值被删除，并且，图形展示板被更新。Example Create the cubic law displayed in Figure 30 on page 53.在第53页图30中，显示所生成的三次law。1. The first DEF PT is selected by default at the beginning of the spine. Key in 10 in LAW VALUE.第一个DEF点默认为脊线的起点。Law值输入10。2. Sel DEF PT, by keying 41.5 in the ABS field in the law main panel. Key in 9 in LAW VALUE.在law 主展示板中ABS区域输入41.5来选定一点。Law值输入9。3. Sel SHOW switch. A linear curve is displayed.选择显示开关，一条线性曲线被显示。4. Indicate in the Graphic display panel a point (abscissa = 68, ordinate = 9). The icon display changes from linear to cubic.在图形展示板中选定一点（横轴= 68 纵坐标 = 9），图标由线性曲线变为三次曲线。Take care of the automatic computation of the Graphic panel ordinate.注意图形展示板纵坐标的自动计算5. Indicate in the Graphic display panel a point (abscissa = 84) Key in 4 in LAW VALUE. The law deployed looks like Figure 30 on page 53.在图形显示器展示板中选定一点（横轴= 84），Law值输入4 ，law所生成图形相似于第53页图30。6. Now change the LAW RATIO of the last DEF PT. Select the arrow linked to this point. Indicate a point in the panel. The icon display changes from cubic to unspec  改变最后DEF点的LAW切矢，将箭头连到该点。在图形展示板中选定一点，图标由三次曲线变为非线性曲线。