由这些常量定义的属性对所有的材质类型都生效，除了Texture Combine Operations只应用于
MeshBasicMaterial，MeshLambertMaterial和MeshPhongMaterial。
v3d.FrontSide
v3d.BackSide
v3d.DoubleSide
定义了哪一边的面将会被渲染 —— 正面，或是反面，还是两个面都渲染。 默认值是FrontSide（只渲染正面）。
v3d.NoBlending
v3d.NormalBlending
v3d.AdditiveBlending
v3d.SubtractiveBlending
v3d.MultiplyBlending
v3d.CustomBlending
这些值控制着源和目标材质中，被发送到WebGLRenderer，来给WebGL使用的包含有RGB和Alpha数据的混合方程。
默认值是NormalBlending。
请注意，CustomBlending必须被设置为自定义混合方程（Custom Blending Equations）常量中的值。
请查看示例：materials / blending。
v3d.NeverDepth
v3d.AlwaysDepth
v3d.LessDepth
v3d.LessEqualDepth
v3d.GreaterEqualDepth
v3d.GreaterDepth
v3d.NotEqualDepth
材质使用这些深度函数来比较输入像素和缓冲器中Z-depth的值。
如果比较的结果为true，则将绘制像素。
NeverDepth 永远不返回true。
AlwaysDepth 总是返回true。
LessDepth 当输入像素Z-depth小于当前缓冲器Z-depth时，返回true。
LessEqualDepth 为默认值，当输入像素Z-depth小于或等于当前缓冲器Z-depth时，返回true。
GreaterEqualDepth 当输入像素Z-depth大于或等于当前缓冲器Z-depth时，返回true。
GreaterDepth 当输入像素Z-depth大于当前缓冲器Z-depth时，返回true。
NotEqualDepth 当输入像素Z-depth不等于当前缓冲器Z-depth时，返回true。
v3d.MultiplyOperation
v3d.MixOperation
v3d.AddOperation
这些常量定义了物体表面颜色与环境贴图（如果存在的话）相结合的结果，
用在MeshBasicMaterial、MeshLambertMaterial和MeshPhongMaterial当中。
MultiplyOperation 是默认值，它将环境贴图和物体表面颜色进行相乘。
MixOperation 使用反射率来混和两种颜色。uses reflectivity to blend between the two colors.
AddOperation 用于对两种颜色进行相加。
v3d.NeverStencilFunc
v3d.LessStencilFunc
v3d.EqualStencilFunc
v3d.LessEqualStencilFunc
v3d.GreaterStencilFunc
v3d.NotEqualStencilFunc
v3d.GreaterEqualStencilFunc
v3d.AlwaysStencilFunc
Which stencil function the material uses to determine whether or not to perform a stencil operation.
NeverStencilFunc will never return true.
LessStencilFunc will return true if the stencil reference value is less than the current stencil value.
EqualStencilFunc will return true if the stencil reference value is equal to the current stencil value.
LessEqualStencilFunc will return true if the stencil reference value is less than or equal to the current stencil value.
GreaterStencilFunc will return true if the stencil reference value is greater than the current stencil value.
NotEqualStencilFunc will return true if the stencil reference value is not equal to the current stencil value.
GreaterEqualStencilFunc will return true if the stencil reference value is greater than or equal to the current stencil value.
AlwaysStencilFunc will always return true.
v3d.ZeroStencilOp
v3d.KeepStencilOp
v3d.ReplaceStencilOp
v3d.IncrementStencilOp
v3d.DecrementStencilOp
v3d.IncrementWrapStencilOp
v3d.DecrementWrapStencilOp
v3d.InvertStencilOp
Which stencil operation the material will perform on the stencil buffer pixel if the provided stencil function passes.
ZeroStencilOp will set the stencil value to 0.
KeepStencilOp will not change the current stencil value.
ReplaceStencilOp will replace the stencil value with the specified stencil reference value.
IncrementStencilOp will increment the current stencil value by 1.
DecrementStencilOp will decrement the current stencil value by 1.
IncrementWrapStencilOp will increment the current stencil value by 1. If the value increments past 255 it will be set to 0.
DecrementWrapStencilOp will increment the current stencil value by 1. If the value decrements below 0 it will be set to 255.
InvertStencilOp will perform a bitwise iversion of the current stencil value.