Updated the MaterialX graph to incorporate emission_weight

Author: portsmouth

reference/open_pbr_surface.mtlx

@@ -71,6 +71,8 @@
            doc="The thickness of the thin-film layer on the base (in micrometers)." />
     <input name="thin_film_ior" type="float" value="1.4" uimin="0.0" uisoftmin="1.0" uisoftmax="3.0" uiname="Thin Film Index of Refraction" uifolder="Thin Film" uiadvanced="true"
            doc="The index of refraction of the thin-film." />
+    <input name="emission_weight" type="float" value="0.0" uimin="0.0" uimax="1.0" uiname="Emission Weight" uifolder="Emission"
+           doc="Emission weight luminance multiplier." />
     <input name="emission_luminance" type="float" value="0.0" uimin="0.0" uisoftmax="1000.0" uiname="Emission Luminance" uifolder="Emission"
            doc="The amount of emitted light, as a luminance in nits." />
     <input name="emission_color" type="color3" value="1, 1, 1" uimin="0,0,0" uimax="1,1,1" uiname="Emission Color" uifolder="Emission"
@@ -584,12 +586,16 @@
       <input name="in1" type="float" nodename="coat_ior_to_F0_sqrt" />
       <input name="in2" type="float" nodename="coat_ior_to_F0_sqrt" />
     </multiply>
-    <multiply name="emission_weight" type="color3">
-      <input name="in1" type="color3" interfacename="emission_color" />
+    <multiply name="weighted_emission_luminance" type="float">
+      <input name="in1" type="float" interfacename="emission_weight" />
       <input name="in2" type="float" interfacename="emission_luminance" />
     </multiply>
+    <multiply name="emission_color_weight" type="color3">
+      <input name="in1" type="color3" interfacename="emission_color" />
+      <input name="in2" type="float" nodename="weighted_emission_luminance" />
+    </multiply>
     <uniform_edf name="uncoated_emission_edf" type="EDF">
-      <input name="color" type="color3" nodename="emission_weight" />
+      <input name="color" type="color3" nodename="emission_color_weight" />
     </uniform_edf>
     <multiply name="coat_tinted_emission_edf" type="EDF">
       <input name="in1" type="EDF" nodename="uncoated_emission_edf" />