XGen Tube Based Grooming

Tube Based Grooming is a function in XGen allows user to create guides from tube-shaped polygons.  这个功能允许用户使用管状的多面体模型来生成毛发guides。
The guides created by this function have many benefits: 使用这个功能生成的guides有以下好处：

• The guides perfectly match polygon's shape 能完美贴合模型的形状
• The space between guides / The number of guides is easy to adjust 非常易于调整生成guides的数量和间距
• Automatically got a guide (plus a curve) positioned in the central point of the tube, this will make forming a clump at the exact place you want a lot easier. 自动在管状模型的正中生成一条guide（外加一条曲线），这会更容易在你想要的位置形成发簇。
• Even there's a gap between your hair polygon and the scalp, the guides will be generated to fill the gap. 就算你的头发和头皮模型中间有间隙，guides也是会紧贴头皮生成的。

正常生成的guides

 Notice: 注意：
The polygon must be a tube shape, quads only. That means it can't be a close or half-closed shape, and it can't has any triangle face, otherwise, this function won't work. 用来生成guides的多边体模型必须是管状的四边面模型。这表示此模型不能是封闭或半封闭的形状， 也不能有三角面，否则这个功能就不会生效。

模型必须是管状

• The polygon must be freeze before applying the function, otherwise the guide/curve in the center will be created at wrong place. 用来生成的多面体模型在生成guides前必须先被freeze过，否则生成在正中的guide和曲线位置会出现错误。
• !!! The polygon's direction matters.  多面体模型的方向会产生影响。

1. A polygon doesn't have a direction, you may say, but if the polygon was converted from a nurbs surface, and nurbs surfaces do have directions (UV points). These direction information somehow being memorized by the model even it was converted.  This causes the guides are coming out from the wrong side. 可能你认为多面体不具有模型方向，但如果此多面体是由曲面模型转换而成，曲面模型是具有方向性的（标明U/V的点）。这些方向信息即使在被转换成多面体过 后也会被保存下来。这会导致你的guides是从模型错误的一端生成。
2. The easiest way to check the polygon's direction is click on "Test" button next to "Guide Spacing", it will create some locators at the ROOT of the polygon. If the locators showed up at the tip of the model, means it needs to be reversed direction. 最简易的检查多面体模型的方法是点击“Guide Spacing” 后面的测试按钮，它会在模型的根部创建一些locator，如果locator在模型发尖的位置生成，就表示需要把这个模型的方向反转一下。
3. The easiest way to correct this is open UV Editor, select the geometry, flip its UVs in V direction first then test the locators again. If flipping it in V direction didn't work, try U direction. 最简单纠正这个的方法是打开UV编辑界面，选择模型，在V方向先翻转一下之后测试一下locator的位置。如果V方向翻转不生效，则在U方向尝试。

点击Test会出现表示根部的Locator

A modeler may start modeling from a Nurbs cylinder, and the bottom loop will be the starting point of the shape (has the square point).  And he/she moved this cylinder near the head and change the shape to become a bunch of hair, so the starting point will be at the tip when the model is done. 模型组极有可能会使用曲面圆柱开始建模，模型的最底一圈为起始。他直接把圆柱移动到头部附近开始调整形状来建成一束头发，所以起始点会最终在头发模型的尖端。

Other Tips：

• Guide Spacing, default=1, if you want the tool generate more guides, decrease this number. 引导线间距，此项默认为1，如果你想要生成更多的guides，降低此项数值。
• Cut Param, default=1, set to 0 if you want the guides length follow the polygon perfectly. 剪切值？默认为1，如果想要完美贴合模型的线就设为0，否则会根据发尖弯曲角度生成一些较短的。
• CV Frequency, default=1, set to higher value(5 maybe) to get more vertex on one guide, and the guide will follow the polygon better. 线段(点)频率，默认为1，设到5的话可以得到更贴合模型形状的guides。