Fluids can only cast raytraced shadows onto objects.
To cast raytraced shadows onto objects
- Select the fluid container for the fluid you want to cast shadows.
- Turn on Cast Shadows in the Render Stats section of the fluidShape Attribute Editor.
- Select the light you want to cast shadows.
- In the Attribute Editor for the light, expand Shadows and under Raytrace Shadow Attributes, turn on Use Ray Trace Shadows.
- Select the object and turn on Receive Shadows in the Render Stats section of the object’s Attribute Editor.