ShadowDrawer is a custom shader for Unity, which draws regions of shadows with a given color.
- Unity 5.1 or later versions.
- Works only on Forward rendering path.
- Conflicts with skyboxes. Use a solid color or a screen-sized quad for a background.
Create a material and change shader to Custom/ShadowDrawer. You can specify a color (rgb) and opacity (a) of shadows with the Shadow Color property.
Set this material to objects that receives shadows. Besides that, you should turn off the Cast Shadows property on these objects.
This is not mandatory but gives proper results in most cases.