Alternative to decals for simple retro blob shadow?

Development Rendering
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1

Hello,

I’m making a 3D platformer, and it’s heavily stylized so I don’t need realistic shadowing on the character. I really need a simple blob shadow; a circle that is projected from the player’s feet downwards.

A few things i’ve already tried, and decided won’t work well enough:

  1. decals. the shadow needs to reach far beneath the player’s feet when in the air, and decals fade out near the edge of their extents. Because of the fading, if you use a long decal at your player’s feet to overlap the ground while far away from it, your shadow will fade out completely the closer to the ground you get (since decals project the strongest at their exact middle), which is the opposite of what should happen. There is also an issue where even if I went with a large dimension decal, it will go through the ground completely (standing on a platform, the circle will cast on the ground below it, too; even when completely occluded).
  2. line trace and plane. the shadow will hover in the air when you’re next to a ledge, which looks really awful.

I’d like the smooth overlap of decals, without the issues. If this is possible with some sort of material/shader trickery, please let me know. I figured something seemingly so simple would be in high demand, seeing as how it’s a concept used in so many games!

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2

Could you do a combination of the two and dynamically move & scale the decal so that it starts just above the closest ground element to the player?

3

That’s sort of what i’m doing right now: casting a line trace under the player and placing the decal there. It still has its issues though. To cast correctly down the side of slopes, the decal needs to be fairly large in order to prevent the material from being cut off or faded out completely, which unfortunately causes it to project up the side of walls you go near.

I suppose what i’d really want is a way to project a texture along a volume (in a single direction so it can’t hit ceilings or the sides of walls etc), and allow the projection to be occluded as well. So if you were half-on a platform, your shadow gets cut in half and lands on the ground below you as well as the platform you stand on.