wsg/lib/examples/effects/README.md

Effects: HDR, Post-process & Showcase

Examples covering HDR / tone mapping and post-process effects, plus the full showcase that combines everything.

Example	Run command	What it shows
demo	cargo run -p wsg-lib --example demo	Full showcase: 6 LOD primitives, 3 lights, shadows, HDR/ACES, bloom, culling, orbital camera
bloom	cargo run -p wsg-lib --example bloom	Post-process bloom (glow around bright areas)
hdr	cargo run -p wsg-lib --example hdr	HDR + tone mapping (ACES) + runtime exposure control
msaa	cargo run -p wsg-lib --example msaa	MSAA 4× (multisample anti-aliasing, smooth edges)
fog	cargo run -p wsg-lib --example fog --features "all-prims"	Distance fog (3 modes: linear, exp, exp²)
dof	cargo run -p wsg-lib --example dof --features "all-prims"	Depth of field (cinematic bokeh, focus presets)

All commands run from the repo root. All effects are opt-in — a disabled effect allocates nothing and executes nothing.

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demo — Full Showcase

Combines all effects: LOD primitives, procedural textures, lights (directional + point + spot), shadows, HDR/ACES, exposure, emissive, bloom, culling.

cargo run -p wsg-lib --example demo

Keys

Key	Action
Drag (LMB)	Orbit camera
Wheel	Zoom
R	Reset camera
1 / 2 / 3	Presets: front / side / top
+ / -	Exposure ×1.3 / ÷1.3
0	Reset exposure

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bloom — Post-process Bloom

Two emissive spheres (orange intensity 2.0, blue intensity 3.0) produce a visible halo. The cube and floor serve as reference (non-emissive).

Bloom is a 4-pass GPU pipeline: threshold → blur H → blur V → composite.

cargo run -p wsg-lib --example bloom

Keys

Key	Action
Drag (LMB)	Orbit camera
Wheel	Zoom
R	Reset camera
+ / -	Bloom threshold +0.1 / −0.1
[ / ]	Bloom intensity +0.1 / −0.1
I / O	Bloom radius +0.5 / −0.5
E / Q	Exposure ×1.3 / ÷1.3
0	Reset exposure

What to observe

• Low threshold (0.0): the entire image "blooms" (very diffuse effect).
• High threshold (2.0+): only the bright emissive spheres produce glow.
• Intensity 0.0: no visible glow (even though the threshold extracts pixels).
• Large radius (10+): the glow spreads over a large area.

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hdr — HDR + Tone Mapping

Demonstrates HDR rendering with the ACES Filmic curve. Three objects:

• Cube: normal lighting (no emissive) — LDR reference.
• Bright sphere (emissive 3.0): without HDR, it would be clamped to white. With ACES, highlights "roll off" smoothly toward white.
• Dark sphere (emissive 0.3): stays dark even at high exposure.

cargo run -p wsg-lib --example hdr

Keys

Key	Action
Drag (LMB)	Orbit camera
Wheel	Zoom
R	Reset camera
E	Exposure ×1.3 (brighter)
Q	Exposure ÷1.3 (darker)
0	Reset exposure to 1.0

What to observe

• At exposure 1.0: the bright sphere is white but with detail (ACES rolloff).
• At high exposure (E×E×E): the scene brightens, the bright sphere stays white (saturated), but the cube gains detail.
• At low exposure (Q×Q): everything darkens, the bright sphere becomes orange (HDR values > 1.0 are compressed).

Note

: the tone mapper is compiled into the pipeline at build time. To compare ACES vs Reinhard, change ToneMapper::Aces → ToneMapper::Reinhard in the source.

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msaa — MSAA 4× (Anti-aliasing)

Demonstrates multisample anti-aliasing: object edges (cube, sphere) are smooth instead of "stair-stepped". The scene contains a cube (sharp edges), a sphere (curved silhouette), and a small cube near the camera (maximum aliasing).

cargo run -p wsg-lib --example msaa

Keys

Key	Action
Drag (LMB)	Orbit camera
Wheel	Zoom
R	Reset camera
M	Show sample count

To compare with/without MSAA

Remove the .with_msaa(4) line in the source and recompile: the scene is identical, only the edges differ (stair-stepped vs smooth).

Note

: MSAA is a build-time setting (multisample texture allocation). It works independently of HDR: with HDR, the MSAA texture is Rgba16Float and resolves into the HDR texture before bloom/TM.

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fog — Distance Fog

Demonstrates the 3 fog modes: linear, exponential, exponential². The scene contains a row of cubes receding into the distance and scattered spheres on a large floor plane. Fog blends objects toward a background color, creating the illusion of an infinite world.

cargo run -p wsg-lib --example fog --features "all-prims"

Keys: 1 = linear, 2 = exp, 3 = exp², 4 = off, R = reset.

Fog is applied in the main fragment shader (after lighting, before tone mapping). It uses the Euclidean distance from the fragment to the camera.

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dof — Depth of Field (Cinematic Bokeh)

Demonstrates depth of field blur: an object at the focus plane stays sharp while foreground and background blur according to their distance from the focus plane. Creates a natural attention effect (cinematic style).

The scene contains 20 cubes in a row along Z (z=3 to z=-25.5) and 5 spheres to the sides, on a floor plane. Focus presets at 3 m / 8 m / 15 m.

cargo run -p wsg-lib --example dof --features "all-prims"

Keys: 1 = cinematic, 2 = subtle, 3 = focus 3 m, 4 = focus 15 m, 5 = off, R = reset.

DoF operates in linear HDR (after bloom, before tone mapping). Two passes: CoC (depth → per-pixel blur radius) then 12-tap disc blur with variable radius.