MeshDepthMaterial: compute normals for displacement

src/renderers/shaders/ShaderLib/depth_vert.glsl

@@ -12,6 +12,14 @@ void main() {
 
 	#include <skinbase_vertex>
 
+	#ifdef USE_DISPLACEMENTMAP
+
+		#include <beginnormal_vertex>
+		#include <morphnormal_vertex>
+		#include <skinnormal_vertex>
+
+	#endif
+
 	#include <begin_vertex>
 	#include <morphtarget_vertex>
 	#include <skinning_vertex>