# Fake Interiors / Windows AC/Row/Infinite (GAT #48)

Source: https://simonschreibt.de/gat/windows-ac-row-ininite/
Author: Simon Schreibt. Captured 2026-10-16.

## Summary
Different approaches for faking interiors in Assassin's Creed 3, Saints Row 3, and BioShock Infinite—avoid building real rooms or expensive transparency.

## AC3 (also GAT #12)
- Night windows look like slightly lit rooms; no real room geometry.
- Suspected: cubemap with slowed parallax so the reflection plane appears *behind* glass (standard cubemap moves too fast → looks in front).
- Day: both standard cubemap and slow “interior” cubemap together; interior colors cooler when exterior is warm and vice versa.
- Related observation: frosted/milky tiled texture moved via Bump Offset Mapping for period-appropriate glass.

## Saints Row 3
- Sharp tiled room textures with bump-offset parallax (not blurry like AC3).
- Posters as a separate layer on top of the room texture.
- Tiling creates plausible room corners; narrow viewing angles reveal the cheat.

## BioShock Infinite
- Looks like wooden room + billboard objects, but wireframe + texture channels prove shader trick.
- Red channel masks “eagle” area that behaves like a camera-facing element (not a real billboard mesh).
- Separate background texture so parallax layers don’t leave gaps.
- Dual bump-offset parallax layers.
- At grazing angles: glass goes to total reflection (blueish)—hides texture deformation and sells glass.
- Motivation: artist time (shader on surfaces vs hand-building rooms); avoid transparency sorting/fog artifacts.

## Updates (community)
Interior mapping variants: Amplify, SimCity 5 / bgolus / Layla Unreal, Destiny 2, Matrix Awakens, American Truck Simulator parallax interiors tool, Humus/Oogst ray-traced room boxes (more geometry simulation than simple bump offset).