I've Been working on this crosshatching post-process for UE4 to render comic book style scenes.
I wanted an effect that would allow me to make an entire environment and character as quickly as possible, with simple geo and textures so the crosshatching shader could take over.
MEDIUM: UE4, 3DS Max, Photoshop, 3D Coat, Substance Designer
I wanted an effect that would allow me to make an entire environment and character as quickly as possible, with simple geo and textures so the crosshatching shader could take over.
MEDIUM: UE4, 3DS Max, Photoshop, 3D Coat, Substance Designer
Method
The outlines were easy. There is more than enough resources online explaining how it is done, so I wont cover it here. The hard part was the crosshatching. I took heavy notes from the Borderlands 3 2017 GDC talk. Where they had a demo of a crosshatching shader. Most of it seemed self explanatory, but the part that struck me was the fact that the crosshatches were in UV space.
That means that UV information had to be given to the postprocess, and crosshatches had to be generated accordingly.
I had a few options:
That means that UV information had to be given to the postprocess, and crosshatches had to be generated accordingly.
I had a few options:
- Use forward rendering and grab UV information on the Postprocess. Sacrificing performance, shader functionality and time. Maybe when UE4 supports it more.
- Use render to texture to get UV or crosshatching information. SIGNIFICANTLY sacrificing performance.
- Hide crosshatching information in a material channel and receive the information through the Postprocess. Sacrificing crosshatching control through the postprocess.
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first I generated assets with very simple geo and textures. Most of these assets I turned around in less than an hour. Making this shader very valuable for a small team that needs lots of assets very quickly.
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Next I generated this material function, which makes this map appear on the model. The green channel denotes Horizontal hatches while the red denotes vertical. This allows me to blend the hatches with more control inside the postprocess.
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Which looks like this when applied to the scene:
I take this info and blend it against lighting info, etc. etc., which produces the result below.
Multiplied on the original scene we get this result:
I am quite happy with this effect. It is incredibly cheap and adds a lot of character to these very simple textures. With a little extra work on a good postprocess, you can afford to put less work in the rest of your models.
The biggest flaw with this. Is at the moment the crosshatching info is hidden away in the subsurface channel. Meaning you cant use subsurface scattering in the scene if you want to use this shader. I did this because I did not want to waste a few weeks making a custom build of UE4 with custom material output and postprocess inputs for a proof of concept.
Please enjoy some longer turnarounds/explorations of the scene below:
The biggest flaw with this. Is at the moment the crosshatching info is hidden away in the subsurface channel. Meaning you cant use subsurface scattering in the scene if you want to use this shader. I did this because I did not want to waste a few weeks making a custom build of UE4 with custom material output and postprocess inputs for a proof of concept.
Please enjoy some longer turnarounds/explorations of the scene below:
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