Fractional opacity mixing with pure black is still not the most physically accurate shadow, because in the real world ambient light is mixed in with shadow, and also the color of the object casting shadow (and the surface the shadow is cast on) also creates color casts on a second light bounce from off-angle ambient light hitting an object, which influences shadow color in a way that's not "black on top of surface color." The algorithm for blending drop shadows doesn't take these things into account. https://willkempartschool.com/the-secret-to-painting-realist...
The link above also has an example of the use of multiple shadows to create a more naturalistic feel, namely that in the real world we are accustomed to, one source of light creates multiple kinds of shadows because of reflections from clouds, objects, etc.
This is all linked to physical realism, to help carry over our expectations of what the world looks like into a (in this case) digital space.
The link above also has an example of the use of multiple shadows to create a more naturalistic feel, namely that in the real world we are accustomed to, one source of light creates multiple kinds of shadows because of reflections from clouds, objects, etc.
This is all linked to physical realism, to help carry over our expectations of what the world looks like into a (in this case) digital space.