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Merged
jstone-lucasfilm merged 3 commits into from
Apr 14, 2023
Merged

MDL 1.7 dielectric and generalized schlick improvements #1321

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8becd4f
Change the dielectric implementation to use custom curve instead of f…
krohmerNV Mar 6, 2023
024bcb7
Improve generalized schlick MDL implementation
krohmerNV Mar 1, 2023
6c7bffa
Merge branch 'main' into PR-MDL-1-7-dielectric-and-generalized-schlick
jstone-lucasfilm Apr 13, 2023
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46 changes: 46 additions & 0 deletions resources/Materials/TestSuite/pbrlib/bsdf/generalized_schlick.mtlx
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Original file line number Diff line number Diff line change
Expand Up @@ -45,5 +45,51 @@
<input name="bsdf" type="BSDF" nodename="layer_RT" />
</surface>
<output name="layer_RT_out" type="surfaceshader" nodename="surface_layer_RT" />

<generalized_schlick_bsdf name="schlick_R2" type="BSDF">
<input name="weight" type="float" value="1.0" />
<input name="color0" type="color3" value="0.5, 0.0, 0.0" />
<input name="color90" type="color3" value="0.0, 1.0, 0.0" />
<input name="exponent" type="float" value="5.0" />
<input name="scatter_mode" type="string" value="R" />
</generalized_schlick_bsdf>
<surface name="surface_R2" type="surfaceshader">
<input name="bsdf" type="BSDF" nodename="schlick_R2" />
</surface>
<output name="R2_out" type="surfaceshader" nodename="surface_R2" />

<generalized_schlick_bsdf name="schlick_T2" type="BSDF">
<input name="weight" type="float" value="1.0" />
<input name="color0" type="color3" value="0.5, 0.0, 0.0" />
<input name="color90" type="color3" value="0.0, 1.0, 0.0" />
<input name="exponent" type="float" value="5.0" />
<input name="scatter_mode" type="string" value="T" />
</generalized_schlick_bsdf>
<surface name="surface_T2" type="surfaceshader">
<input name="bsdf" type="BSDF" nodename="schlick_T2" />
</surface>
<output name="T2_out" type="surfaceshader" nodename="surface_T2" />

<generalized_schlick_bsdf name="schlick_RT2" type="BSDF">
<input name="weight" type="float" value="1.0" />
<input name="color0" type="color3" value="0.5, 0.0, 0.0" />
<input name="color90" type="color3" value="0.0, 1.0, 0.0" />
<input name="exponent" type="float" value="5.0" />
<input name="scatter_mode" type="string" value="RT" />
</generalized_schlick_bsdf>
<surface name="surface_RT2" type="surfaceshader">
<input name="bsdf" type="BSDF" nodename="schlick_RT2" />
</surface>
<output name="RT2_out" type="surfaceshader" nodename="surface_RT2" />

<layer name="layer_RT2" type="BSDF">
<input name="top" type="BSDF" nodename="schlick_R2" />
<input name="base" type="BSDF" nodename="schlick_T2" />
</layer>
<surface name="surface_layer_RT2" type="surfaceshader">
<input name="bsdf" type="BSDF" nodename="layer_RT2" />
</surface>
<output name="layer_RT2_out" type="surfaceshader" nodename="surface_layer_RT2" />

</nodegraph>
</materialx>
83 changes: 54 additions & 29 deletions source/MaterialXGenMdl/mdl/materialx/pbrlib.mdl
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Expand Up @@ -159,11 +159,16 @@ export material mx_dielectric_bsdf(
]]
= let {
float coatIor = mxp_thinfilm_ior <= 0.0 ? 1.0 : mxp_thinfilm_ior;
float grazing_refl = math::max((1.0 - math::average(mxp_roughness)), 0.0);
float root_r = (mxp_ior-1)/(mxp_ior+1);
bsdf bsdf_R = df::thin_film(
thickness: mxp_thinfilm_thickness,
ior: color(coatIor),
base: df::fresnel_layer(
ior: mxp_ior,
// fresnel layer has issues if base is a diffuse transmission, use custom curve for now
// this will break thin_film but improves standard_surface with diffuse transmission
base: df::custom_curve_layer(
normal_reflectivity: root_r*root_r,
grazing_reflectivity: grazing_refl,
weight: mxp_weight,
layer: df::microfacet_ggx_smith_bsdf(
roughness_u: mxp_roughness.x,
Expand All @@ -172,16 +177,16 @@ export material mx_dielectric_bsdf(
tangent_u: mxp_tangent,
mode: df::scatter_reflect),
base: mxp_base.surface.scattering,
normal: mxp_normal));
normal: mxp_normal));

bsdf bsdf_T = df::weighted_layer(
weight: mxp_weight,
layer: df::microfacet_ggx_smith_bsdf(
roughness_u: mxp_roughness.x,
roughness_v: mxp_roughness.y,
tint: mxp_tint,
tangent_u: mxp_tangent,
mode: df::scatter_transmit),
roughness_u: mxp_roughness.x,
roughness_v: mxp_roughness.y,
tint: mxp_tint,
tangent_u: mxp_tangent,
mode: df::scatter_transmit),
normal: mxp_normal);

bsdf bsdf_RT = df::weighted_layer(
Expand Down Expand Up @@ -255,7 +260,7 @@ export material mx_generalized_schlick_bsdf(
color mxp_color0 = color(1.0),
color mxp_color90 = color(1.0),
float mxp_exponent = 5.0,
float2 mxp_roughness = float2(0.0),
float2 mxp_roughness = float2(0.05),
float3 mxp_normal = state::normal(),
float3 mxp_tangent = state::texture_tangent_u(0),
uniform mx_distribution_type mxp_distribution = mx_distribution_type_ggx [[ anno::unused() ]],
Expand All @@ -268,31 +273,51 @@ export material mx_generalized_schlick_bsdf(
]]
= let {
float coatIor = mxp_thinfilm_ior <= 0.0 ? 1.0 : mxp_thinfilm_ior;
df::scatter_mode mode = ::mx_map_scatter_mode(mxp_scatter_mode);
bsdf ggx_model = df::microfacet_ggx_smith_bsdf(
roughness_u: mxp_roughness.x * mxp_roughness.x,
roughness_v: mxp_roughness.y * mxp_roughness.y,
float avgF0 = math::average(float3(mxp_color0));
bsdf ggx_model_R = df::microfacet_ggx_smith_bsdf(
roughness_u: mxp_roughness.x,
roughness_v: mxp_roughness.y,
tint: color(1.0),
tangent_u: mxp_tangent,
mode: df::scatter_reflect);

bsdf ggx_model_T = df::microfacet_ggx_smith_bsdf(
roughness_u: mxp_roughness.x,
roughness_v: mxp_roughness.y,
tint: color(1.0),
tangent_u: mxp_tangent,
mode: mode);
mode: df::scatter_transmit);
} in material(
surface: material_surface(
scattering: df::thin_film(
thickness: mxp_thinfilm_thickness,
ior: color(coatIor),
base: df::color_custom_curve_layer(
normal_reflectivity: mxp_color0,
grazing_reflectivity: mxp_color90,
exponent: mxp_exponent,
weight: color(mxp_weight),
layer: ggx_model,
base: mxp_base.surface.scattering,
normal: mxp_normal
)
scattering: df::weighted_layer(
weight: mxp_weight,
layer: mxp_scatter_mode == mx_scatter_mode_T
? df::color_custom_curve_layer(
normal_reflectivity: mxp_color0,
grazing_reflectivity: mxp_color90,
exponent: mxp_exponent,
layer: bsdf(),
base: ggx_model_T)
: df::thin_film(
thickness: mxp_thinfilm_thickness,
ior: color(coatIor),
base: df::color_custom_curve_layer(
normal_reflectivity: mxp_color0,
grazing_reflectivity: mxp_color90,
exponent: mxp_exponent,
layer: ggx_model_R,
base: mxp_scatter_mode == mx_scatter_mode_R
? mxp_base.surface.scattering
: ggx_model_T)),
base: mxp_base.surface.scattering,
normal: mxp_normal
)
),
// we can't use the computed ior here because it's varying
// assuming that we have something glass like when transmission is used
ior: color(1.5), // color(mx_f0_to_ior(avgF0))

// we need to carry volume properties along for SSS
ior: mxp_base.ior,
volume: mxp_base.volume
);

Expand Down Expand Up @@ -513,7 +538,7 @@ export material mx_surface(
material mxp_bsdf = material() [[ anno::usage( "materialx:bsdf") ]],
material mxp_edf = material() [[ anno::usage( "materialx:edf") ]],
float mxp_opacity = 1.0,
uniform float mxp_transmission_ior = 1.0 // extra parameter for setting transmission IOR
uniform float mxp_transmission_ior = 0.0 // extra parameter for setting transmission IOR
) [[
anno::usage( "materialx:surfaceshader")
]]
Expand All @@ -528,7 +553,7 @@ export material mx_surface(
scattering: bsdf_node,
emission: edf_node
),
ior: color(mxp_transmission_ior),
ior: mxp_transmission_ior > 0.0 ? color(mxp_transmission_ior) : mxp_bsdf.ior,
volume: bsdf_volume,
geometry: material_geometry(
cutout_opacity: mxp_opacity
Expand Down
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