AUTUMN SHADER

Again, the Autumn set up is based on something simple. We use World Position UV to sample a color map and use that to drive the autumn color. The right way for doing this should be using RVT and procedural tools. But I was given 2 days to make it work since we need to show it at E3 at that time.

In our system, each vertex has 8 variation floats and the value change in these 8 floats will not break instancing. We put most of the control in a variation flow and the artist can set them in the level editor.

Variation 1 is used to keep between the World Position texture and the existing texture by using clipped transmissive masks. So it will only affect the leaf part.

Variation 2 is used to move the UV around. It allowed artists to fine tune the area based on AD feedback.

Variation 3 is used for the decay amount. It adds another layer of variation to the color. It was originally also affecting the alpha mask. We removed it since it had less impact and doing more math on alpha made the shader a lot more expensive.

Artists also requested to control the UV size based on the type of tree. So we expose the control to the asset level instead of using another variation.

CONCLUSION

This shader required a lot of fast peace communication. The solution needs to be figured out and applied in a very short amount of time. We had one day to build the foundation for the approval. Once it is approved. We have 3 weeks to polish it and make it work for a whole track.