Theater Set Design Simulation

Set Pieces

Click the stage floor to place the selected piece; click a placed piece to remove it.

Stage & House

Stage rake 4°

Auditorium rake 8°

Actor mark (downstage → upstage) 2.5 m

Sightline Readout

Clear sightlines

— %

Blocked seats

—

Pieces on stage

How it works

A raked stage tilts upward toward the back so upstage action isn't hidden behind downstage actors. For rake angle θ, a point at depth z from the downstage lip sits at height

y(z) = z · tan(θ)

Every set piece's base is placed on this ramp. To check whether a seat can see the actor mark, the sim casts a real 3D ray from the seat's eye position to the mark and tests it against each piece's axis-aligned bounding box using the slab method:

ray = eye + t·dir,  t ∈ (0, distance)
blocked  if  ray ∩ box  exists with  0 < t < distance

Auditorium seating is raked too: row r's eye height rises by tan(φ) · r · rowSpacing, where φ is the auditorium rake — steeper seating lets rows further back see over the heads (and set pieces) in front of them.

Furniture / Platform / Flat — three heights of masking piece (0.6 m, 1.4 m, 2.6 m); pick a type, then click the stage to place or remove it on a 1 m grid.
Stage rake — raises upstage relative to downstage, changing how much of a tall piece intrudes into a given sightline.
Auditorium rake — raises each row's eye height, the house's own countermeasure against masking.
Actor mark — the point every seat's sightline is tested against; drag it upstage to see how masking pieces near the back bite harder.

Real-world relevance: technical directors and set designers run exactly this check — often with a physical sightline string or a CAD sun-path style plot — before a flat or platform is built full-scale, because a beautiful set that blocks a third of the house is a very expensive mistake to discover on load-in day.

Clear sightline Blocked sightline Furniture Platform Flat / wall

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