These screenshots were rendered in BabylonJS with the default IBL strength dialed down to help the glow stand out. The second screenshot has an optional "Bloom" effect applied using the BabylonJS Default Rendering Pipeline.
This model tests if the KHR_materials_emissive_strength extension is available in a
given implementation. If it is not, the cubes will all emit the same shade of
light blue. For implementations that support this extension, the cubes will be
progressively brighter to the right.
The basic emissive color of all the cubes is [0.1, 0.5, 0.9] in the glTF file, which
is expected to undergo the usual linear-to-sRGB transfer before being shown to the viewer.
The cube on the far left has no emissive strength extension (1x), and each subsequent
cube doubles the strength (2x, 4x, 8x, and 16x).
With a simple output mapping, the cube on the far right may appear as plain white, due to all of its color components being clamped to the 1.0 upper limit. If "bloom" effects are enabled, some cubes may appear to glow. In a path-tracing engine, all of these cubes may emit light, but the ones on the right should emit substantially more light.
If a given implementation does not support KHR_materials_emissive_strength, the
boxes will all appear to emit the same color. For example:
Copyright 2022 Analytical Graphics, Inc. CC-BY 4.0 https://creativecommons.org/licenses/by/4.0/ Model and textures by Ed Mackey.