From 18aeca8ab504a2537b55a12e7f6c855db4ddb26b Mon Sep 17 00:00:00 2001
From: Bernard Kwok <kwokcb@gmail.com>
Date: Mon, 29 Jan 2024 12:25:02 -0500
Subject: [PATCH] Updates: - Change specular color to specular intensity with
 default 1 - Change back to using warm and cool colours to drive diffuse -
 Keep the paper's additive color mixing for diffuse.

---
 libraries/nprlib/nprlib_defs.mtlx             | 16 ++---
 libraries/nprlib/nprlib_ng.mtlx               | 66 ++++++-------------
 .../TestSuite/nprlib/gooch_shade.mtlx         | 29 ++++----
 3 files changed, 43 insertions(+), 68 deletions(-)

diff --git a/libraries/nprlib/nprlib_defs.mtlx b/libraries/nprlib/nprlib_defs.mtlx
index 71bae945e8..cfb0c023b0 100644
--- a/libraries/nprlib/nprlib_defs.mtlx
+++ b/libraries/nprlib/nprlib_defs.mtlx
@@ -44,16 +44,12 @@
     Compute Gooch Shading.
   -->
   <nodedef name="ND_gooch_shade" node="gooch_shade" nodegroup="npr" doc="Compute Gooch shading">
-    <input name="diffuse_color" type="color3" value="0.8, 0.8, 0.8" doc="Diffuse Color" uiname="Diffuse Color" />
-    <input name="blue_tone" type="float" value="0.55" uimin="0" uimax="1" doc="Blue tone" uiname="Blue Tone" />
-    <input name="yellow_tone" type="float" value="0.3" uimin="0" uimax="1" doc="Yellow Tone" uiname="Yellow Tone" />
-    <input name="diffuse_strength" type="float" value="0.25" uimin="0" uimax="1" doc="Diffuse Strength" uiname="Diffuse Strength" />
-    <input name="luminance_shift" type="float" value="0.5" uimin="0" uimax="1" doc="Luminance Shift" uiname="Luminance Shift" />
-    <input name="shininess" type="float" value="32" uimin="1" uimax="64" uiname="Shininess" doc="Specular shininess" />
-    <input name="specular_color" type="color3" value="1, 1, 1" uiname="Specular Color" doc="Specular color" />
-    <input name="light_direction" type="vector3" value="1, -0.5, -0.5" uiname="Light Direction" doc="Light vector" />
-    <output name="out" type="color3" />
+    <input name="warm_color" type="color3" value="0.8, 0.8, 0.7" uiname="Warm Color" doc="Warm color" />
+    <input name="cool_color" type="color3" value="0.3, 0.3, 0.8" uiname="Cool Color" doc="Cool color" />
+    <input name="specular_intensity" type="float" value="1" uimin="0" uimax="1" uiname="Specular Intensity" doc="Specular Intensity" />
+    <input name="shininess" type="float" value="64" uimin="1" uimax="64" uiname="Shininess" doc="Specular Power" />
+    <input name="light_direction" type="vector3" value="1, -0.5, -0.5" uiname="Light Direction" doc="Light vector in world space" />
+    <output name="out" type="color3"/>
   </nodedef>
 
-
 </materialx>
diff --git a/libraries/nprlib/nprlib_ng.mtlx b/libraries/nprlib/nprlib_ng.mtlx
index 94ec4e3bb0..f148cfcb8b 100644
--- a/libraries/nprlib/nprlib_ng.mtlx
+++ b/libraries/nprlib/nprlib_ng.mtlx
@@ -55,10 +55,10 @@
       <input name="in" type="vector3" interfacename="light_direction" />
     </normalize>
     <dotproduct name="NdotL" type="float">
-      <input name="in1" type="vector3" nodename="N" />
+      <input name="in1" type="vector3" nodename="normalize_vector4" />
       <input name="in2" type="vector3" nodename="normalized_light_dir" />
     </dotproduct>
-    <power name="specular" type="float">
+    <power name="specular_power" type="float">
       <input name="in1" type="float" nodename="max1" />
       <input name="in2" type="float" interfacename="shininess" />
     </power>
@@ -97,26 +97,10 @@
       <input name="in1" type="vector3" nodename="normalize_vector3" />
       <input name="in2" type="vector3" nodename="NdotI_N_2" />
     </subtract>
-    <multiply name="multiply_color3FA" type="color3">
-      <input name="in2" type="float" nodename="specular" />
-      <input name="in1" type="color3" interfacename="specular_color" />
-    </multiply>
-    <add name="final_color" type="color3">
-      <input name="in1" type="color3" nodename="diffuse" />
-      <input name="in2" type="color3" nodename="multiply_color3FA" />
-    </add>
     <multiply name="invert_light_dir" type="vector3">
       <input name="in1" type="vector3" nodename="normalized_light_dir" />
       <input name="in2" type="vector3" value="-1, -1, -1" />
     </multiply>
-    <swizzle name="swizzle_float_color3" type="color3">
-      <input name="in" type="float" interfacename="blue_tone" />
-      <input name="channels" type="string" value="00b" />
-    </swizzle>
-    <swizzle name="swizzle_float_color4" type="color3">
-      <input name="in" type="float" interfacename="yellow_tone" />
-      <input name="channels" type="string" value="rg0" />
-    </swizzle>
     <add name="one_plus_NdotL" type="float">
       <input name="in2" type="float" nodename="NdotL" />
       <input name="in1" type="float" value="1" />
@@ -125,42 +109,30 @@
       <input name="in1" type="float" nodename="one_plus_NdotL" />
       <input name="in2" type="float" value="2" />
     </divide>
-    <subtract name="one_minus_NdotL" type="float">
-      <input name="in2" type="float" nodename="NdotL" />
+    <add name="diffuse" type="color3">
+      <input name="in1" type="color3" nodename="cool" />
+      <input name="in2" type="color3" nodename="warm" />
+    </add>
+    <subtract name="subtract_float" type="float">
+      <input name="in2" type="float" nodename="one_plus_NdotL_div_2" />
       <input name="in1" type="float" value="1" />
     </subtract>
-    <divide name="one_minus_NdotL_div_2" type="float">
-      <input name="in1" type="float" nodename="one_minus_NdotL" />
-      <input name="in2" type="float" value="2" />
-    </divide>
-    <multiply name="multiply_color3" type="color3">
-      <input name="in1" type="color3" interfacename="diffuse_color" />
-      <input name="in2" type="float" interfacename="diffuse_strength" />
-    </multiply>
-    <add name="k_cool" type="color3">
-      <input name="in1" type="color3" nodename="multiply_color3" />
-      <input name="in2" type="color3" nodename="swizzle_float_color3" />
-    </add>
-    <add name="k_warm" type="color3">
-      <input name="in2" type="color3" nodename="swizzle_float_color4" />
-      <input name="in1" type="color3" nodename="multiply_color4" />
-    </add>
-    <multiply name="multiply_color4" type="color3">
-      <input name="in1" type="color3" interfacename="diffuse_color" />
-      <input name="in2" type="float" interfacename="luminance_shift" />
+    <multiply name="warm" type="color3">
+      <input name="in1" type="color3" interfacename="warm_color" />
+      <input name="in2" type="float" nodename="subtract_float" />
     </multiply>
     <multiply name="cool" type="color3">
-      <input name="in1" type="color3" nodename="k_cool" />
       <input name="in2" type="float" nodename="one_plus_NdotL_div_2" />
+      <input name="in1" type="color3" interfacename="cool_color" />
     </multiply>
-    <multiply name="warm" type="color3">
-      <input name="in1" type="color3" nodename="k_warm" />
-      <input name="in2" type="float" nodename="one_minus_NdotL_div_2" />
-    </multiply>
-    <add name="diffuse" type="color3">
-      <input name="in1" type="color3" nodename="cool" />
-      <input name="in2" type="color3" nodename="warm" />
+    <add name="final_color" type="color3">
+      <input name="in2" type="float" nodename="specular" />
+      <input name="in1" type="color3" nodename="diffuse" />
     </add>
+    <multiply name="specular" type="float">
+      <input name="in1" type="float" interfacename="specular_intensity" />
+      <input name="in2" type="float" nodename="specular_power" />
+    </multiply>
     <output name="out" type="color3" nodename="final_color" />
   </nodegraph>
   
diff --git a/resources/Materials/TestSuite/nprlib/gooch_shade.mtlx b/resources/Materials/TestSuite/nprlib/gooch_shade.mtlx
index 00ad79df6b..05220a22ed 100644
--- a/resources/Materials/TestSuite/nprlib/gooch_shade.mtlx
+++ b/resources/Materials/TestSuite/nprlib/gooch_shade.mtlx
@@ -1,20 +1,27 @@
 <?xml version="1.0"?>
 <materialx version="1.38">
-  <gooch_shade name="gooch1" type="color3">
-    <input name="diffuse_strength" type="float" value="0.269" />
-    <input name="diffuse_color" type="color3" value="0, 0.535452, 0.068077" />
-    <input name="luminance_shift" type="float" value="0.374" />
-    <input name="yellow_tone" type="float" value="0.325" />
-    <input name="blue_tone" type="float" value="0.491" />
-    <input name="light_direction" type="vector3" value="-1, -0.5, -0.5" />
-    <input name="shininess" type="float" value="5" />
-  </gooch_shade>
+  <gooch_shade name="default_gooch" type="color3" />
   <surface_unlit name="unlit_surface" type="surfaceshader">
-    <input name="emission_color" type="color3" nodename="gooch1" />
+    <input name="emission_color" type="color3" nodename="default_gooch" />
     <input name="opacity" type="float" value="1.0" />
   </surface_unlit>
-  <surfacematerial name="surfacematerial" type="material">
+  <surfacematerial name="default_gooch_material" type="material">
     <input name="surfaceshader" type="surfaceshader" nodename="unlit_surface" />
     <input name="displacementshader" type="displacementshader" value="" />
   </surfacematerial>
+  <gooch_shade name="red_blue_gooch" type="color3">
+    <input name="warm_color" type="color3" value="1, 0, 0" />
+    <input name="cool_color" type="color3" value="0, 2.38419e-07, 1" />
+    <input name="specular_intensity" type="float" value="0.5" />
+    <input name="shininess" type="float" value="32" />
+    <input name="light_direction" type="vector3" value="-1, -0.5, -0.5" />
+  </gooch_shade>
+  <surface_unlit name="unlit_surface2" type="surfaceshader">
+    <input name="emission_color" type="color3" nodename="red_blue_gooch" />
+    <input name="opacity" type="float" value="1.0" />
+  </surface_unlit>
+  <surfacematerial name="redblue_gooch_material" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="unlit_surface2" />
+    <input name="displacementshader" type="displacementshader" value="" />
+  </surfacematerial>
 </materialx>