From 238a23b2deddbf88bdacbbb3c44ee1fbbf39e2b1 Mon Sep 17 00:00:00 2001 From: Ben Houston Date: Mon, 13 Nov 2023 12:40:11 -0500 Subject: [PATCH] improve the json to match dispersion spec --- extensions/2.0/Khronos/KHR_materials_dispersion/README.md | 4 ++-- .../schema/material.KHR_materials_dispersion.schema.json | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-) diff --git a/extensions/2.0/Khronos/KHR_materials_dispersion/README.md b/extensions/2.0/Khronos/KHR_materials_dispersion/README.md index 944a4fc52b..a52ba23b3d 100644 --- a/extensions/2.0/Khronos/KHR_materials_dispersion/README.md +++ b/extensions/2.0/Khronos/KHR_materials_dispersion/README.md @@ -33,7 +33,7 @@ The Abbe number \( $V$ \) is computed from the index of refraction at three wave $$V = \frac{n_d - 1}{n_F - n_C}$$ -To calculate the index of refraction at a specific wavelength \( $\lambda$ \), given an Abbe number \( $V$ \) and the central index of refraction (assumed to be at the central wavelength, \( $N_d$ \), as specified by the KHR_materials_ior extension): +To calculate the index of refraction at a specific wavelength \( $\lambda$ \), given an Abbe number \( $V$ \) and the central index of refraction as specified by the KHR_materials_ior extension (assumed to be at the central wavelength, \( $N_d$ \)): $$ B = \frac{n_d - 1}{V \left( {\lambda_F^{-2}} - {\lambda_C^{-2}} \right)} @@ -79,7 +79,7 @@ Factor and texture are combined by multiplication to describe a single value. |-|----|-----------|--------| | **dispersion** | `number` | The strength of the dispersion effect, specified as 20/Abbe number. | No, default: `0`| -The default value of 0 has a special meaning in that no dispersion should be used. This is the default value for backwards compatibility. Any value in the valid range [0, 100] other than zero is considered to be a valid dispersion value, although the range between [0 , 1] is the range of realistic values. +The default value of 0 has a special meaning in that no dispersion should be used. This is the default value for backwards compatibility. Any value zero or larger is considered to be a valid dispersion value, although the range between [0 , 1] is the range of realistic values. Here is a table of some material dispersion Abbe numbers, including the outlier of Rutile which is a very high dispersion material: diff --git a/extensions/2.0/Khronos/KHR_materials_dispersion/schema/material.KHR_materials_dispersion.schema.json b/extensions/2.0/Khronos/KHR_materials_dispersion/schema/material.KHR_materials_dispersion.schema.json index 658585ca62..0ec509ae7f 100644 --- a/extensions/2.0/Khronos/KHR_materials_dispersion/schema/material.KHR_materials_dispersion.schema.json +++ b/extensions/2.0/Khronos/KHR_materials_dispersion/schema/material.KHR_materials_dispersion.schema.json @@ -9,9 +9,8 @@ "type": "number", "description": "The strength of the dispersion.", "default": 0.0, - "minimum": 1.0, - "maximum": 1000.0, - "gltf_detailedDescription": "This parameter defines dispersion in terms of the Abby number formulation." + "minimum": 0.0, + "gltf_detailedDescription": "This parameter defines dispersion in terms of the 20/Abbe number formulation." }, "extensions": { }, "extras": { }