Align Normals

法线对齐

When creating surfaces you may sometimes inadvertently create surfaces whose Normals point in the wrong direction. Using Align Normals, you can quickly correct the direction.

在创建表面时，有时候你可能会无意中创建法线指向错误方向的表面。使用“法线对齐” ，您可以快速更正方向。

Several limitations were removed with the introduction of Cinema 4D R19. These are, among others:

随着 Cinema 4D R19的引入，一些限制被消除了，其中包括:

• N-gons are now handled properly when the primary polygon orientation is evaluated (as indivisual polygons and not as x sub-polygons). 当计算主多边形的方向时，N-gons 被正确处理(作为单个多边形而不是作为 x 子多边形)
• Branching polygons (polygons with edges that belong to more than two polygons) will be handled correctly. 分支多边形(边缘属于两个以上多边形的多边形)将得到正确处理

Options

选择

This command has the following options:

这个命令有以下选项:

Normals: If an object has Normal tags with vertex Normals, this option decides if the vertex Normals for the polygons to be aligned should also be reversed or remain exactly as they were saved in the tag.

法线: 如果一个对象有带顶点法线的法线标签，这个选项决定要对齐的多边形的顶点法线是否也应该被反转或者保持与保存在标签中的一样。

Why are Normals needed?

为什么需要法线？

Cinema 4D cannot easily recognize an object’s inner and outer surface without extra information. A basic sphere has an inner and an outer side, but only one surface level, which can be confusing. We need a better definition. Let’s define this single surface level to have an inner and an outer property. Outer designates, in principle, the direction in which the surface Normals point and inner is therefore the opposite direction. This plays a role with texture projection, where you can project textures from only the front or the back.

如果没有额外的信息，Cinema 4d 不能轻易地识别物体的内表面和外表面。一个基本的球体有一个内面和一个外面，但是只有一个表面，这可能会造成混淆。我们需要一个更好的定义。让我们定义这个单一的表面水平，有一个内部和一个外部属性。原则上，表面法线点和表面内法线点的方向是相反的。这在纹理投影中扮演了一个角色，你只能从正面或背面投影纹理。

So, if as many Normals point one way as the other way, how do we decide which is the outer surface? We could either choose randomly or, perhaps, look at the first polygon in the sequence and use its normal as the basis of our calculation — Cinema 4D does the latter.

那么，如果像许多法线指向一个方向和另一个方向一样多，我们如何决定哪一个是外表面呢？我们可以随机选择，或者，也许，观察序列中的第一个多边形，并使用它的法线作为我们计算的基础ー Cinema 4D 做后者。

Why change the direction of the Normals? As described above, the direction of the Normals defines the interior and the exterior of an object. This is important, among other things, for displaying an object in the viewport. Occasionally, when building certain objects, a situation can arise in which some polygons seem invisible. This can happen if Backface Culling is on and the reason is as follows. To save on processor performance you may have enabled backface culling for your scene; this is where only the polygons visible from the front of an object are displayed in the viewport. The polygons positioned directly at the back of an object are not drawn.

为什么要改变法线的方向？如上所述，法线的方向决定了一个物体的内部和外部。这对于在 viewport 中显示对象非常重要。偶尔，当建造某些物体时，会出现某些多边形看起来不可见的情况。这可能会发生，如果反面剔除是在和原因如下。为了节省处理器性能，您可能已经为您的场景启用了背面剔除; 这是只有从一个对象的前面可见的多边形显示在视窗中。直接放置在物体背面的多边形不会被绘制。

When displaying a sphere and other volume objects in the Gouraud Shading mode you may notice no difference, simply because you do not see the back of the sphere anyway. But should you select all the polygons of this sphere and reverse the Normals (see next section), you will now see only the back of the sphere; the front is now transparent since you have inverted the sphere. The inside is now the outside, and this becomes invisible because of the backface culling.

当在 Gouraud 阴影模式下显示一个球体和其他体积对象时，你可能会注意到没有区别，只是因为你看不到球体的背面。但是，如果你选择这个球面的所有多边形并将法线反转(见下一部分) ，你现在只能看到球面的背面，因为你已经将球面反转了，所以前面是透明的。现在内部就是外部，而且由于背面的剔除，这变得无形。

Should you find yourself inadvertently in a situation like this you should switch off backface culling and reverse the Normals of these polygons.

如果你无意中发现自己在这种情况下，你应该关闭背面剔除和反转这些多边形的法线。

The adjustment of these Normals also plays an important role with tools such as Smooth Shift and Extrude. These model tools always move in the direction of the Normals by default. If you should need to move several surfaces with different normal alignments using Smooth Shift you will obtain useless results, since the surfaces are moved in their own respective — and opposite — directions.

这些法线的调整也发挥了重要作用的工具，如平滑移和挤压。默认情况下，这些模型工具总是沿着法线的方向移动。如果你需要使用 Smooth Shift 移动具有不同法向排列的几个表面，你将得到无用的结果，因为这些表面是按照各自的方向移动的。

Another important factor is smoothing with a disabled Angle Limit option (see Phong tag). Cinema 4D determines whether or not to smooth edges based on the angle with which adjoining surfaces lie to each other. If the Normals of two adjoining surfaces have opposing orientations Cinema 4D will receive conflicting angle data, which can result in unwanted results:

另一个重要因素是平滑与禁用角度限制选项(见 Phong 标签)。Cinema 4D 根据相邻表面相对的角度来决定是否平滑边缘。如果两个相邻表面的法线方向相反，Cinema 4D 将接收到冲突的角度数据，这可能导致不希望的结果:

Also, when using the Displacement material channel, the angle of the Normals plays an important role.

此外，在使用位移物质通道时，法线角度也起着重要的作用。