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Bloom
Bloom is a camera/display response to bright HDR signal. Establish scene exposure and emissive luminance before tuning blur.
Workflow
- Inspect pre-tone-map luminance.
- Choose which scene values should bloom.
- Choose a single-node or dual selective-render ownership model.
- Calibrate threshold, radius, smooth width, and strength in HDR.
- Restore all substituted materials transactionally for selective passes.
- Composite before exposure/tone mapping.
- Validate base, contribution, and final views.
Read references/hdr-bloom-system.md for the HDR ordering, dual selective-bloom transaction, compact emissive hierarchy, and the costs and limits of each ownership model.
Apply the material substitution/restoration ownership pattern in the reference before adding selective bloom to a composed scene.
Failure conditions
- bloom creates the only visible form of an effect;
- all bright materials share one arbitrary emission multiplier;
- threshold is tuned after tone mapping;
- selective bloom requires mutating scene materials every frame without restoration guarantees;
- transparent particles disappear from extraction because pass ownership is unclear;
- bloom radius changes wildly with resolution;
- highlights become gray because energy is clamped too early.
Routing boundary
Use $threejs-exposure-color-grading for metering, adaptation, tone mapping, and LUTs. Load $threejs-image-pipeline only when bloom must be composed with several shared image-space systems. A per-pixel ray integrator that owns its own reduced-resolution target and accumulation history keeps its bloom internal; route that to $threejs-raymarched-space-effects.
