Falloff

The Falloff Texture is used to control the blend of two materials depending on the viewing angle of the material’s geometry.
根据材质几何形状的可视角度，使用 Falloff 纹理来控制两种材质的混合。

Falloff 【衰减贴图（菲尼尔）】 - 图1

HOW TO USE

如何使用
Open the Node editor and prepare the setup as seen in the image below. In this setup, two different materials are linked to the Mix material and amount is controlled by the Falloff Texture. The whiteness towards the edges is actually a classic fresnel result. With the help of the Falloff mode value, you can fake the fresnel effect, and it will adapt itself according to the camera angle. (That said, Glossy and Specular materials produce realistic IOR and Fresnel, so such a cheat is not advised.) In the following example, “Normal vs. eye ray” is used as the Falloff Mode and is explained below.
打开 Node 编辑器，准备如下图所示的设置。在这个设置中，两种不同的材质被连接到混合材质上，并且数量由 Falloff 纹理控制。边缘的白色实际上是经典的菲涅耳效果。借助于弗洛夫模式值，你可以伪造菲涅耳效果，它将根据摄像机的角度自适应。(也就是说，光泽和镜面材料产生真实的 IOR 和菲涅耳，所以这样的欺骗是不被建议的。)在下面的示例中，“ Normal vs. eye ray”用作 Falloff 模式，并在下面解释。

The Falloff texture can be used for a variety of purposes, of course. For example, it can be used to cover your objects with “dust”, or it can be used on fabrics like velvet.
当然，Falloff 纹理可以用于多种用途。例如，它可以用来覆盖你的对象“灰尘”，或者可以用于织物，如天鹅绒。

Falloff 【衰减贴图（菲尼尔）】 - 图2

FALLOFF TEXTURE SETTINGS 设置 FALLOFF 纹理

MODE 模式

The Falloff Texture node has three options available in the Mode menu:
Falloff 纹理节点在模式菜单中有三个选项:

Normal vs. Eye Ray
Normal vs. Vector 90 Degrees
Normal vs. Vector 180 Degrees

The options are explained as follows.
这些选择的解释如下。

NORMAL VS. EYE RAY

This is the default mode where the falloff is calculated from the angle between the surface normal and the eye ray. This mode is more commonly used for reflections and the falloff color range affects faces directly in front of the view and gradually falls at angled faces towards the sides as it falls away from the straight on viewing angle. Therefore, the Falloff Direction parameter does not apply.
这是默认模式，其中的衰减是从表面法线和眼睛射线之间的角度计算出来的。这种模式更常用于反射和衰减的颜色范围影响面对视图直接在前面，并逐渐下降的倾斜面向两侧，因为它从直线上的视角下降。因此，Falloff Direction 参数不适用。

Falloff 【衰减贴图（菲尼尔）】 - 图3

NORMAL VS. VECTOR 90DEG

The falloff is calculated from the angle between the surface normal and the specified direction vector maxing out at 90 degrees. This is similar to the default mode except that it maintains the effect of the color range according to the Falloff Direction x/y/z.
下降量是从表面法线和指定方向向量之间的角度计算出来的，最大值为90度。这类似于默认模式，只是它根据 Falloff Direction x/y/z 保持了颜色范围的效果。

Falloff 【衰减贴图（菲尼尔）】 - 图4

NORMAL VS. VECTOR 180DEG

The falloff is calculated from the angle between the surface normal and the specified direction vector maxing out at 90 degrees. This is similar to the default mode except that it maintains the effect of the color range according to the Falloff Direction X/Y/Z.
下降量是从表面法线和指定方向向量之间的角度计算出来的，最大值为90度。这类似于默认模式，只是它根据 Falloff 方向 x/y/z 保持了颜色范围的效果。
Falloff 【衰减贴图（菲尼尔）】 - 图5

MINIMUM AND MAXIMUM VALUE

The relative amount of the Minimum and Maximum values that are at an angle to the straight on view. 0.1 will lead to almost complete coverage by the grazing value regardless of viewing angle, whereas 1 will lead to almost complete coverage by the normal value.
与直线视图成一定角度的最小值和最大值的相对数量。0.1将导致几乎完全覆盖的放牧值不论视角，而1将导致几乎完全覆盖的正常值。

Falloff 【衰减贴图（菲尼尔）】 - 图6

FALLOFF SKEW FACTOR 衰减斜度系数

This parameter is used to balance the influence of the normal and grazing angles. A low value means that the influence of the grazing angle is stronger — any textures controlled by the falloff Maximum value will cover more of the surface. Higher Skew Factor settings result in a stronger influence of the normal angle — any textures controlled by the Minimum value will cover more of the surface.
该参数用于平衡正掠角的影响。低值意味着掠射角的影响较大ーー任何受衰减最大值控制的结构都会覆盖更多的表面。较高的倾斜因子设置会导致正常角度的影响更大ーー任何由最小值控制的纹理都会覆盖更多的表面。

FALLOFF DIRECTION 减速方向

The direction vector that is used by the Normal vs. Vector 90deg and Normal vs. Vector 180deg modes. For most materials, the fresnel effect (the default mode) is usually correct while falloff direction is used for exceptional cases which can be adjusted relative to the camera. Changing the rotation of the object will not change the orientation of the falloff direction.
方向矢量，用于法向矢量90度和法向矢量180度模式。对于大多数材质来说，菲涅耳效应(默认模式)通常是正确的，而衰减方向用于特殊情况，可以相对于相机进行调整。改变物体的旋转不会改变脱落方向的方向。