In this case, we need to get the UE4 distance filed shadow involved to solve the problem. Using screen pixel depth offset can somehow alleviate the effect by offsetting some shadow area into much far distance but the problem still persists. The way UE4 solve this is to render the geometry and shadow map from both camera point of view(treat light as camera too) and this will end with the result that half of the billboard will be in the shadow. The next step is to set up the directional shadow and ambient occlusion to make the shadow behaves consistent when it switches into the impostor.īecause impostor in principle is actually a rotatable billboard with alpha, so the shadow of the directional light is surely not be all right.

The original plugin did this in a very wasteful way by rendering all channels with alpha in separate RTs and this is what we're going to fix.įig 11: Don’t forget to update the impostor_ThreeFrameBlend material function to connect the packed 4-channels info in specular texture and A channel in Normal texture to G-Buffer output to get a correct result. This is because of the upgrade of the UE4 built-in shader API and the way to solve it is to simply search for all custom nodes in the materials in the plugin and replace ‘Primitive.WorldToLocal’ with: GetPrimitiveData(Parameters.PrimitiveId).WorldToLocalĪs shown in Fig 6, the first thing we need to do is to expand the render target channels to provide enough info for a standard foliage shading model. Shaders should use GetPrimitiveData(Parameters.PrimitiveId).Member instead of Primitive.Member.

Here are some modifications I would like the highlight:įirst of all, if you are using this plugin in the version after 4.21, a compile error will be run into for sure: Shader attempted to bind the Primitive uniform buffer even though Vertex Factory FLocalVertexFactory computes a PrimitiveId per-instance. Fig 5: the impostor at the far distance can be rendered correctly as a real geometry.

Ao pass in arnold for maya