Masking out water

Water is masked out of the boat hull interior

There are two ways of masking out water:

1. Using M_WaterInvalidator material that gets water removed from the volume covered by the mesh it is assigned to. Mesh should be ceiled.

Check the BP_Boat. There's a hull_mask static mesh attached with the M_WaterInvalidator material assigned. Mesh covers the whole volume of the boat hull.

1. Using distance field mask. In the M_OceanFFT check the reroute node called Masking Out Water that is unused. Plug it into the Opacity Mask input in the root node. Opacity Mask accepts either 0 or 1 value per-pixel and discards the pixel based on this value.

This mask removes water wherever the distance field is negative, meaning it affects the interior of the mesh. Use the Mask Offset parameter to adjust the mask's position. Ensure that the distance field is enabled on the mesh you want to exclude water from.

The distance field method gives you less control as it will be applied for every mesh that has distance field enabled. Whereas the first method, which is based on the material, give you full control over the areas you want to exclude water from.