ShadowMaterial: support fog

src/renderers/shaders/ShaderLib.js

@@ -211,6 +211,7 @@ var ShaderLib = {
 
 		uniforms: UniformsUtils.merge( [
 			UniformsLib.lights,
+			UniformsLib.fog,
 			{
 				color: { value: new Color( 0x00000 ) },
 				opacity: { value: 1.0 }

src/renderers/shaders/ShaderLib/shadow_frag.glsl

@@ -3,6 +3,7 @@ uniform float opacity;
 
 #include <common>
 #include <packing>
+#include <fog_pars_fragment>
 #include <bsdfs>
 #include <lights_pars>
 #include <shadowmap_pars_fragment>
@@ -12,4 +13,6 @@ void main() {
 
 	gl_FragColor = vec4( color, opacity * ( 1.0 - getShadowMask() ) );
 
+	#include <fog_fragment>
+
 }

src/renderers/shaders/ShaderLib/shadow_vert.glsl

+#include <fog_pars_vertex>
 #include <shadowmap_pars_vertex>
 
 void main() {
@@ -6,5 +7,6 @@ void main() {
 	#include <project_vertex>
 	#include <worldpos_vertex>
 	#include <shadowmap_vertex>
+	#include <fog_vertex>
 
 }