Extract _pbr_surf_lib (#53)

* Extract `_pbr_surf_lib` * Update references
metashade · Feb 8, 2025 · a5a7f45 · a5a7f45
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diff --git a/src/_impl/_pbr_surf_lib.py b/src/_impl/_pbr_surf_lib.py
@@ -0,0 +1,105 @@
+"""
+Common PBR surface functions that don't change with permutations.
+TODO: generate once and include in all pixel shaders.
+"""
+
+# Copyright 2020 Pavlo Penenko
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import math
+
+def generate(sh):
+    sh.struct('PbrParams')(
+        rgbDiffuse = sh.RgbF,
+        rgbF0 = sh.RgbF,
+        fPerceptualRoughness = sh.Float,
+        fOpacity = sh.Float
+    )
+
+    sh // "https://google.github.io/filament/Filament.md.html#materialsystem/specularbrdf/normaldistributionfunction(speculard)"
+    sh // ""
+    with sh.function('D_Ggx', sh.Float)(
+        NdotH = sh.Float, fAlphaRoughness = sh.Float
+    ):
+        sh.fASqr = sh.fAlphaRoughness * sh.fAlphaRoughness
+        sh.fF = (sh.NdotH * sh.fASqr - sh.NdotH) * sh.NdotH + sh.Float(1.0)
+        sh.return_(
+            (sh.fASqr / (sh.Float(math.pi) * sh.fF * sh.fF )).saturate()
+        )
+
+    with sh.function('F_Schlick', sh.RgbF)(LdotH = sh.Float, rgbF0 = sh.RgbF):
+        sh.return_(
+            sh.rgbF0 + (sh.RgbF(1.0) - sh.rgbF0)
+                * (sh.Float(1.0) - sh.LdotH).pow(sh.Float(5.0))
+        )
+
+    sh // "https://google.github.io/filament/Filament.md.html#materialsystem/specularbrdf/geometricshadowing(specularg)"
+    sh // ""
+    with sh.function('V_SmithGgxCorrelated', sh.Float)(
+        NdotV = sh.Float, NdotL = sh.Float, fAlphaRoughness = sh.Float
+    ):
+        sh.fASqr = sh.fAlphaRoughness * sh.fAlphaRoughness
+        sh.fGgxL = sh.NdotV * (
+            (sh.NdotL - sh.NdotL * sh.fASqr) * sh.NdotL + sh.fASqr
+        ).sqrt()
+        sh.fGgxV = sh.NdotL * (
+            (sh.NdotV - sh.NdotV * sh.fASqr) * sh.NdotV + sh.fASqr
+        ).sqrt()
+        sh.fV = sh.Float(0.5) / (sh.fGgxL + sh.fGgxV)
+        sh.return_(sh.fV.saturate())
+
+    with sh.function('Fd_Lambert', sh.Float)():
+        sh.return_( sh.Float( 1.0 / math.pi ) )
+
+    with sh.function('pbrBrdf', sh.RgbF)(
+        L = sh.Vector3f, N = sh.Vector3f, V = sh.Vector3f,
+        pbrParams = sh.PbrParams
+    ):
+        sh.NdotV = (sh.N @ sh.V).abs()
+        sh.NdotL = (sh.N @ sh.L).saturate()
+
+        sh.H = (sh.V + sh.L).normalize()
+        sh.NdotH = (sh.N @ sh.H).saturate()
+        sh.LdotH = (sh.L @ sh.H).saturate()
+
+        sh.fAlphaRoughness = ( sh.pbrParams.fPerceptualRoughness
+            * sh.pbrParams.fPerceptualRoughness
+        )
+
+        sh.fD = sh.D_Ggx(
+            NdotH = sh.NdotH,
+            fAlphaRoughness = sh.fAlphaRoughness
+        )
+        sh.rgbF = sh.F_Schlick(
+            LdotH = sh.LdotH, rgbF0 = sh.pbrParams.rgbF0
+        )
+        sh.fV = sh.V_SmithGgxCorrelated(
+            NdotV = sh.NdotV,
+            NdotL = sh.NdotL,
+            fAlphaRoughness = sh.fAlphaRoughness
+        )
+
+        sh.rgbFr = (sh.fD * sh.fV) * sh.rgbF
+        sh.rgbFd = sh.pbrParams.rgbDiffuse * sh.Fd_Lambert()
+
+        sh.return_(sh.NdotL * (sh.rgbFr + sh.rgbFd))
+
+    with sh.function('getRangeAttenuation', sh.Float)(
+        light = sh.Light, d = sh.Float
+    ):
+        # https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_lights_punctual/README.md#range-property
+        # TODO: handle undefined/unlimited ranges
+        sh.return_(
+            (sh.d / sh.light.fRange).lerp(sh.Float(1), sh.Float(0)).saturate()
+        )
diff --git a/src/_impl/ps.py b/src/_impl/ps.py
@@ -12,13 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import math
 from typing import Any, NamedTuple
 
 from metashade.hlsl.sm6 import ps_6_0
 from metashade.glsl import frag
 
-from . import common, _uniforms
+from . import common, _pbr_surf_lib, _uniforms
 
 def generate_ps(ps_file, material, primitive):
     sh = ps_6_0.Generator(
@@ -33,6 +32,8 @@ def generate_ps(ps_file, material, primitive):
     with sh.ps_output('PsOut') as PsOut:
         PsOut.SV_Target('rgbaColor', sh.RgbaF)
 
+    _pbr_surf_lib.generate(sh)
+
     # Generating texture bindings
     class _MaterialTexture(NamedTuple):
         gltf_texture : Any
@@ -150,13 +151,6 @@ def _sample_material_texture(texture_name : str):
         # Return a reference to the local variable
         return getattr(sh, sample_var_name)
 
-    sh.struct('PbrParams')(
-        rgbDiffuse = sh.RgbF,
-        rgbF0 = sh.RgbF,
-        fPerceptualRoughness = sh.Float,
-        fOpacity = sh.Float
-    )
-
     with sh.function('metallicRoughness', sh.PbrParams)(psIn = sh.VsOut):
         sh.rgbaBaseColor = (sh.g_sBaseColor @ sh.g_tBaseColor)(
             sh.psIn.uv0, lod_bias = sh.g_lodBias
@@ -195,83 +189,6 @@ def _sample_material_texture(texture_name : str):
         sh.pbrParams.fOpacity = sh.rgbaBaseColor.a
         sh.return_(sh.pbrParams)
 
-    sh // "https://google.github.io/filament/Filament.md.html#materialsystem/specularbrdf/normaldistributionfunction(speculard)"
-    sh // ""
-    with sh.function('D_Ggx', sh.Float)(
-        NdotH = sh.Float, fAlphaRoughness = sh.Float
-    ):
-        sh.fASqr = sh.fAlphaRoughness * sh.fAlphaRoughness
-        sh.fF = (sh.NdotH * sh.fASqr - sh.NdotH) * sh.NdotH + sh.Float(1.0)
-        sh.return_(
-            (sh.fASqr / (sh.Float(math.pi) * sh.fF * sh.fF )).saturate()
-        )
-
-    with sh.function('F_Schlick', sh.RgbF)(LdotH = sh.Float, rgbF0 = sh.RgbF):
-        sh.return_(
-            sh.rgbF0 + (sh.RgbF(1.0) - sh.rgbF0)
-                * (sh.Float(1.0) - sh.LdotH).pow(sh.Float(5.0))
-        )
-
-    sh // "https://google.github.io/filament/Filament.md.html#materialsystem/specularbrdf/geometricshadowing(specularg)"
-    sh // ""
-    with sh.function('V_SmithGgxCorrelated', sh.Float)(
-        NdotV = sh.Float, NdotL = sh.Float, fAlphaRoughness = sh.Float
-    ):
-        sh.fASqr = sh.fAlphaRoughness * sh.fAlphaRoughness
-        sh.fGgxL = sh.NdotV * (
-            (sh.NdotL - sh.NdotL * sh.fASqr) * sh.NdotL + sh.fASqr
-        ).sqrt()
-        sh.fGgxV = sh.NdotL * (
-            (sh.NdotV - sh.NdotV * sh.fASqr) * sh.NdotV + sh.fASqr
-        ).sqrt()
-        sh.fV = sh.Float(0.5) / (sh.fGgxL + sh.fGgxV)
-        sh.return_(sh.fV.saturate())
-
-    with sh.function('Fd_Lambert', sh.Float)():
-        sh.return_( sh.Float( 1.0 / math.pi ) )
-
-    with sh.function('pbrBrdf', sh.RgbF)(
-        L = sh.Vector3f, N = sh.Vector3f, V = sh.Vector3f,
-        pbrParams = sh.PbrParams
-    ):
-        sh.NdotV = (sh.N @ sh.V).abs()
-        sh.NdotL = (sh.N @ sh.L).saturate()
-
-        sh.H = (sh.V + sh.L).normalize()
-        sh.NdotH = (sh.N @ sh.H).saturate()
-        sh.LdotH = (sh.L @ sh.H).saturate()
-
-        sh.fAlphaRoughness = ( sh.pbrParams.fPerceptualRoughness
-            * sh.pbrParams.fPerceptualRoughness
-        )
-
-        sh.fD = sh.D_Ggx(
-            NdotH = sh.NdotH,
-            fAlphaRoughness = sh.fAlphaRoughness
-        )
-        sh.rgbF = sh.F_Schlick(
-            LdotH = sh.LdotH, rgbF0 = sh.pbrParams.rgbF0
-        )
-        sh.fV = sh.V_SmithGgxCorrelated(
-            NdotV = sh.NdotV,
-            NdotL = sh.NdotL,
-            fAlphaRoughness = sh.fAlphaRoughness
-        )
-
-        sh.rgbFr = (sh.fD * sh.fV) * sh.rgbF
-        sh.rgbFd = sh.pbrParams.rgbDiffuse * sh.Fd_Lambert()
-
-        sh.return_(sh.NdotL * (sh.rgbFr + sh.rgbFd))
-
-    with sh.function('getRangeAttenuation', sh.Float)(
-        light = sh.Light, d = sh.Float
-    ):
-        # https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_lights_punctual/README.md#range-property
-        # TODO: handle undefined/unlimited ranges
-        sh.return_(
-            (sh.d / sh.light.fRange).lerp(sh.Float(1), sh.Float(0)).saturate()
-        )
-
     with sh.function('getPcfShadow', sh.Float)(
         uv = sh.Float2,
         fCompareValue = sh.Float

diff --git a/tests/ref b/tests/ref