From b7f3e982614b3aa94e412169632bf760b6ebccb3 Mon Sep 17 00:00:00 2001 From: Jamie Portsmouth Date: Tue, 14 May 2024 21:38:56 +0100 Subject: [PATCH] Update the coat_darkening parameter to default to 1 (#193) --- index.html | 5 ++--- parametrization.md.html | 2 +- reference/open_pbr_surface.mtlx | 2 +- 3 files changed, 4 insertions(+), 5 deletions(-) diff --git a/index.html b/index.html index 779792e..533c78f 100644 --- a/index.html +++ b/index.html @@ -881,7 +881,7 @@ **`coat_roughness`** | Roughness | `float` | $ [0, 1] $ | | $ 0 $ | Roughness of NDF of coat BSDF $f_\mathrm{coat}$ **`coat_roughness_anisotropy`** | Anisotropy | `float` | $ [0, 1] $ | | $ 0 $ | Anisotropy of NDF of coat BSDF $f_\mathrm{coat}$ **`coat_ior`** | IOR | `float` | $ (0, \infty) $ | $ [1, 3] $ | $ 1.6 $ | Refractive index of $V_\mathrm{coat}$ -**`coat_darkening`** | Darkening | `float` | $ [0, 1] $ | | $ 0 $ | Modulates the physical coat [darkening](index.html#model/coat/darkening) effect. +**`coat_darkening`** | Darkening | `float` | $ [0, 1] $ | | $ 1 $ | Modulates the physical coat [darkening](index.html#model/coat/darkening) effect. ![](images/coat_0.png width=90% align=right) ![](images/coat_1.png width=90% align=left)
@@ -904,14 +904,13 @@ where $r_\mathrm{B}=$ **`specular_roughness`** and $r_\mathrm{C}=$ **`coat_roughness`**. - ### Darkening Figure [coat_darkening_grid] shows the physically-correct change in appearance (at normal incidence) of a textured diffuse base with a wood texture and smooth clear-coat as the IOR of the clear-coat is varied, exhibiting darkening of the base -- due to the internal reflections in the coat -- which increases as IOR increases. ![Figure [coat_darkening_grid]: Diffuse base with a clear-coat, for coats of different relative IOR $\eta_c$](images/coat_darkening_grid.png width="60%") -However this darkening may not always be desirable artistically, as in some applications it is beneficial for the observed color of the coated color to "match" the input base color (in a sense defined more precisely below in equation [undarkened_coat_albedo]). We allow for this by introducing a **`coat_darkening`** parameter, $\delta$. In the case **`coat_darkening`** $\delta$ = $1$, the physically correct darkening effect due to internal reflections occurs as normal. In the case **`coat_darkening`** $\delta$ = $0$ (the default), the base albedo is instead _boosted_ uniformly by just enough to counteract the darkening effect. The boost factor is reduced to 1 linearly as $\delta \rightarrow 1$. +However this darkening may not always be desirable artistically, as in some applications it is beneficial for the observed color of the coated color to "match" the input base color (in a sense defined more precisely below in equation [undarkened_coat_albedo]). We allow for this by introducing a **`coat_darkening`** parameter, $\delta$. By default $\delta$ = $1$, in which case the physically correct darkening effect due to internal reflections occurs as normal. In the case $\delta$ = $0$ however, the base albedo is instead _boosted_ uniformly by just enough to counteract the darkening effect. The boost factor is reduced to 1 linearly as $\delta \rightarrow 1$. What we mean by "counteract the darkening" is defined as the albedo of the coated base viewed at normal incidence, $E_c$, being equal to the "un-darkened" albedo \begin{equation} \label{undarkened_coat_albedo} diff --git a/parametrization.md.html b/parametrization.md.html index ee57090..eb37cb0 100644 --- a/parametrization.md.html +++ b/parametrization.md.html @@ -52,7 +52,7 @@ | `coat_roughness` | Roughness | `float` | $ [0, 1] $ | | $ 0 $ | | | `coat_roughness_anisotropy` | Anisotropy | `float` | $ [0, 1] $ | | $ 0 $ | | | `coat_ior` | IOR | `float` | $ (0, \infty) $ | $ [1, 3] $ | $ 1.6 $ | | -| `coat_darkening` | Darkening | `float` | $ [0, 1] $ | | $ 0.0 $ | | +| `coat_darkening` | Darkening | `float` | $ [0, 1] $ | | $ 1 $ | | | **Fuzz** | | `fuzz_weight` | Weight | `float` | $ [0, 1] $ | | $ 0 $ | | | `fuzz_color` | Color | `color3` | $ [0, 1]^3 $ | | $ (1, 1, 1) $ | | diff --git a/reference/open_pbr_surface.mtlx b/reference/open_pbr_surface.mtlx index a26c332..c3bc95f 100644 --- a/reference/open_pbr_surface.mtlx +++ b/reference/open_pbr_surface.mtlx @@ -63,7 +63,7 @@ doc="The directional bias of the roughness of the clear-coat layer, resulting in increasingly stretched highlights along the coat tangent direction." /> -