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Shadow Geometry: Umbra and Penumbra — 2D

Side-view 2D ray diagram of real shadow-puppet geometry — drag the silhouette between an extended lamp and a screen to watch the sharp umbra and soft penumbra gradient reshape via similar-triangles optics.

Physics & Mechanics2DEasy60 FPS📱 Mobile-adapted⇄ 3D version

⚙ Under the hood

Side-view 2D ray diagram where dragging a shadow-puppet silhouette between an extended lamp and a screen reshapes the sharp umbra and soft penumbra gradient via similar-triangles optics.

shadow-geometryumbrapenumbraopticshalloween

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install