Update overlay node logic to match reference (#1539)

This commit changes the overlay node to match the overlay operation in the Adobe PDF spec. It also changes the implementation to graph based instead of code snippets.
AcademySoftwareFoundation · Oct 19, 2023 · 78d2762 · 78d2762
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diff --git a/documents/Specification/MaterialX.Specification.md b/documents/Specification/MaterialX.Specification.md
@@ -1496,7 +1496,7 @@ Blend nodes take two 1-4 channel inputs and apply the same operator to all chann
 | **`burn`** | 1-(1-B)/F | float, color<em>N</em> |
 | **`dodge`** | B/(1-F) | float, color<em>N</em> |
 | **`screen`** | 1-(1-F)(1-B) | float, color<em>N</em> |
-| **`overlay`** | 2FB if F&lt;0.5;<br> 1-(1-F)(1-B) if F>=0.5 | float, color<em>N</em> |
+| **`overlay`** | 2FB if B&lt;0.5;<br> 1-2(1-F)(1-B) if B>=0.5 | float, color<em>N</em> |
 
 
 #### Merge Nodes

diff --git a/libraries/stdlib/genglsl/mx_overlay.glsl b/libraries/stdlib/genglsl/mx_overlay.glsl
diff --git a/libraries/stdlib/genglsl/mx_overlay_color3.glsl b/libraries/stdlib/genglsl/mx_overlay_color3.glsl
diff --git a/libraries/stdlib/genglsl/mx_overlay_color4.glsl b/libraries/stdlib/genglsl/mx_overlay_color4.glsl
diff --git a/libraries/stdlib/genglsl/stdlib_genglsl_impl.mtlx b/libraries/stdlib/genglsl/stdlib_genglsl_impl.mtlx
@@ -560,11 +560,6 @@
   <implementation name="IM_screen_color3_genglsl" nodedef="ND_screen_color3" target="genglsl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1.0 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
   <implementation name="IM_screen_color4_genglsl" nodedef="ND_screen_color4" target="genglsl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1.0 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
 
-  <!-- <overlay> -->
-  <implementation name="IM_overlay_float_genglsl" nodedef="ND_overlay_float" target="genglsl" sourcecode="({{fg}} < 0.5) ? ({{mix}}*2.0*{{fg}}*{{bg}}) + ((1.0-{{mix}})*{{bg}}) : ({{mix}}*(1.0-(1.0-{{fg}})*(1.0-{{bg}}))) + ((1.0-{{mix}})*{{bg}})" />
-  <implementation name="IM_overlay_color3_genglsl" nodedef="ND_overlay_color3" file="mx_overlay_color3.glsl" function="mx_overlay_color3" target="genglsl" />
-  <implementation name="IM_overlay_color4_genglsl" nodedef="ND_overlay_color4" file="mx_overlay_color4.glsl" function="mx_overlay_color4" target="genglsl" />
-
   <!-- <disjointover> -->
   <implementation name="IM_disjointover_color4_genglsl" nodedef="ND_disjointover_color4" file="mx_disjointover_color4.glsl" function="mx_disjointover_color4" target="genglsl" />
 

diff --git a/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx b/libraries/stdlib/genmdl/stdlib_genmdl_impl.mtlx
@@ -568,11 +568,6 @@
   <implementation name="IM_screen_color3_genmdl" nodedef="ND_screen_color3" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" target="genmdl" />
   <implementation name="IM_screen_color4_genmdl" nodedef="ND_screen_color4" sourcecode="mx::stdlib::mx_screen_color4({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
 
-  <!-- <overlay> -->
-  <implementation name="IM_overlay_float_genmdl" nodedef="ND_overlay_float" sourcecode="mx::stdlib::mx_overlay_float({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
-  <implementation name="IM_overlay_color3_genmdl" nodedef="ND_overlay_color3" sourcecode="mx::stdlib::mx_overlay_color3({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
-  <implementation name="IM_overlay_color4_genmdl" nodedef="ND_overlay_color4" sourcecode="mx::stdlib::mx_overlay_color4({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
-
   <!-- <disjointover> -->
   <implementation name="IM_disjointover_color4_genmdl" nodedef="ND_disjointover_color4" sourcecode="mx::stdlib::mx_disjointover_color4({{fg}}, {{bg}}, {{mix}})" target="genmdl" />
 

diff --git a/libraries/stdlib/genmsl/stdlib_genmsl_impl.mtlx b/libraries/stdlib/genmsl/stdlib_genmsl_impl.mtlx
@@ -560,11 +560,6 @@
   <implementation name="IM_screen_color3_genmsl" nodedef="ND_screen_color3" target="genmsl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1.0 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
   <implementation name="IM_screen_color4_genmsl" nodedef="ND_screen_color4" target="genmsl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1.0 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
 
-  <!-- <overlay> -->
-  <implementation name="IM_overlay_float_genmsl" nodedef="ND_overlay_float" target="genmsl" sourcecode="({{fg}} < 0.5) ? ({{mix}}*2.0*{{fg}}*{{bg}}) + ((1.0-{{mix}})*{{bg}}) : ({{mix}}*(1.0-(1.0-{{fg}})*(1.0-{{bg}}))) + ((1.0-{{mix}})*{{bg}})" />
-  <implementation name="IM_overlay_color3_genmsl" nodedef="ND_overlay_color3" file="../genglsl/mx_overlay_color3.glsl" function="mx_overlay_color3" target="genmsl" />
-  <implementation name="IM_overlay_color4_genmsl" nodedef="ND_overlay_color4" file="../genglsl/mx_overlay_color4.glsl" function="mx_overlay_color4" target="genmsl" />
-
   <!-- <disjointover> -->
   <implementation name="IM_disjointover_color4_genmsl" nodedef="ND_disjointover_color4" file="../genglsl/mx_disjointover_color4.glsl" function="mx_disjointover_color4" target="genmsl" />
 

diff --git a/libraries/stdlib/genosl/mx_overlay_color3.osl b/libraries/stdlib/genosl/mx_overlay_color3.osl
diff --git a/libraries/stdlib/genosl/mx_overlay_color4.osl b/libraries/stdlib/genosl/mx_overlay_color4.osl
diff --git a/libraries/stdlib/genosl/stdlib_genosl_impl.mtlx b/libraries/stdlib/genosl/stdlib_genosl_impl.mtlx
@@ -561,11 +561,6 @@
   <implementation name="IM_screen_color3_genosl" nodedef="ND_screen_color3" target="genosl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
   <implementation name="IM_screen_color4_genosl" nodedef="ND_screen_color4" target="genosl" sourcecode="({{mix}}*((1.0 - (1.0 - {{fg}}) * (1 - {{bg}})))) + ((1.0-{{mix}})*{{bg}})" />
 
-  <!-- <overlay> -->
-  <implementation name="IM_overlay_float_genosl" nodedef="ND_overlay_float" target="genosl" sourcecode="({{fg}} < 0.5) ? ({{mix}}*2.0*{{fg}}*{{bg}}) + ((1.0-{{mix}})*{{bg}}) : ({{mix}}*(1.0-(1.0-{{fg}})*(1.0-{{bg}}))) + ((1.0-{{mix}})*{{bg}})" />
-  <implementation name="IM_overlay_color3_genosl" nodedef="ND_overlay_color3" file="mx_overlay_color3.osl" function="mx_overlay_color3" target="genosl" />
-  <implementation name="IM_overlay_color4_genosl" nodedef="ND_overlay_color4" file="mx_overlay_color4.osl" function="mx_overlay_color4" target="genosl" />
-
   <!-- <disjointover> -->
   <implementation name="IM_disjointover_color4_genosl" nodedef="ND_disjointover_color4" file="mx_disjointover_color4.osl" function="mx_disjointover_color4" target="genosl" />
 

diff --git a/libraries/stdlib/stdlib_defs.mtlx b/libraries/stdlib/stdlib_defs.mtlx
@@ -3343,8 +3343,8 @@
   <!--
     Node: <overlay>
     Take two 1-4 channel inputs and apply the same operator to all channels:
-      2FB if F<0.5;
-      1-(1-F)(1-B) if F>=0.5
+      2FB if B<0.5;
+      1-2(1-F)(1-B) if B>=0.5
   -->
   <nodedef name="ND_overlay_float" node="overlay" nodegroup="compositing">
     <input name="fg" type="float" value="0.0" />

diff --git a/libraries/stdlib/stdlib_ng.mtlx b/libraries/stdlib/stdlib_ng.mtlx
@@ -3391,6 +3391,118 @@
   <!-- Compositing nodes                                                        -->
   <!-- ======================================================================== -->
 
+  <!--
+    Node: <overlay>
+    Overlay is a compositing node which is a combination of multiply and screen.
+  -->
+  <nodegraph name="NG_overlay_float" nodedef="ND_overlay_float">
+    <output name="out" type="float" nodename="N_mix" />
+    <ifgreatereq name="N_ifgreatereq0_overlay_r" type="float" nodedef="ND_ifgreatereq_float">
+      <input name="value1" type="float" interfacename="bg" />
+      <input name="value2" type="float" value="0.5" />
+      <input name="in1" type="float" nodename="N_subtract_lower_one" />
+      <input name="in2" type="float" nodename="N_multiply_upper_two" />
+    </ifgreatereq>
+    <multiply name="N_multiply_upper_fg_bg" type="float" nodedef="ND_multiply_float">
+      <input name="in1" type="float" interfacename="fg" />
+      <input name="in2" type="float" interfacename="bg" />
+    </multiply>
+    <multiply name="N_multiply_upper_two" type="float" nodedef="ND_multiply_float">
+      <input name="in1" type="float" nodename="N_multiply_upper_fg_bg" />
+      <input name="in2" type="float" value="2" />
+    </multiply>
+    <subtract name="N_subtract_lower_one_bg" type="float" nodedef="ND_subtract_float">
+      <input name="in1" type="float" value="1" />
+      <input name="in2" type="float" interfacename="bg" />
+    </subtract>
+    <subtract name="N_subtract_lower_one_fg" type="float" nodedef="ND_subtract_float">
+      <input name="in1" type="float" value="1" />
+      <input name="in2" type="float" interfacename="fg" />
+    </subtract>
+    <multiply name="N_multiply_lower_fg_bg" type="float" nodedef="ND_multiply_float">
+      <input name="in1" type="float" nodename="N_subtract_lower_one_bg" />
+      <input name="in2" type="float" nodename="N_subtract_lower_one_fg" />
+    </multiply>
+    <subtract name="N_subtract_lower_one" type="float" nodedef="ND_subtract_float">
+      <input name="in1" type="float" value="1" />
+      <input name="in2" type="float" nodename="N_multiply_lower_two" />
+    </subtract>
+    <mix name="N_mix" type="float" nodedef="ND_mix_float">
+      <input name="fg" type="float" nodename="N_ifgreatereq0_overlay_r" />
+      <input name="bg" type="float" interfacename="bg" />
+      <input name="mix" type="float" interfacename="mix" />
+    </mix>
+    <multiply name="N_multiply_lower_two" type="float" nodedef="ND_multiply_float">
+      <input name="in1" type="float" nodename="N_multiply_lower_fg_bg" />
+      <input name="in2" type="float" value="2" />
+    </multiply>
+  </nodegraph>
+  <nodegraph name="NG_overlay_color3" nodedef="ND_overlay_color3">
+    <output name="out" type="color3" nodename="N_combine" />
+    <separate3 name="N_split_color3_fg" type="multioutput" nodedef="ND_separate3_color3">
+      <input name="in" type="color3" interfacename="fg" />
+    </separate3>
+    <separate3 name="N_split_color3_bg" type="multioutput" nodedef="ND_separate3_color3">
+      <input name="in" type="color3" interfacename="bg" />
+    </separate3>
+    <combine3 name="N_combine" type="color3" nodedef="ND_combine3_color3">
+      <input name="in1" type="float" nodename="N_overlay_r" />
+      <input name="in2" type="float" nodename="N_overlay_g" />
+      <input name="in3" type="float" nodename="N_overlay_b" />
+    </combine3>
+    <overlay name="N_overlay_r" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_color3_fg" output="outr" />
+      <input name="bg" type="float" nodename="N_split_color3_bg" output="outr" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <overlay name="N_overlay_g" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_color3_fg" output="outg" />
+      <input name="bg" type="float" nodename="N_split_color3_bg" output="outg" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <overlay name="N_overlay_b" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_color3_fg" output="outb" />
+      <input name="bg" type="float" nodename="N_split_color3_bg" output="outb" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+  </nodegraph>
+  <nodegraph name="NG_overlay_color4" nodedef="ND_overlay_color4">
+    <output name="out" type="color4" nodename="N_combine" />
+    <separate4 name="N_split_fg" type="multioutput" nodedef="ND_separate4_color4">
+      <input name="in" type="color4" interfacename="fg" />
+    </separate4>
+    <separate4 name="N_split_bg" type="multioutput" nodedef="ND_separate4_color4">
+      <input name="in" type="color4" interfacename="bg" />
+    </separate4>
+    <overlay name="N_overlay_r" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_fg" output="outr" />
+      <input name="bg" type="float" nodename="N_split_bg" output="outr" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <overlay name="N_overlay_g" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_fg" output="outg" />
+      <input name="bg" type="float" nodename="N_split_bg" output="outg" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <overlay name="N_overlay_b" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_fg" output="outb" />
+      <input name="bg" type="float" nodename="N_split_bg" output="outb" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <overlay name="N_overlay_a" type="float" nodedef="ND_overlay_float">
+      <input name="fg" type="float" nodename="N_split_fg" output="outa" />
+      <input name="bg" type="float" nodename="N_split_bg" output="outa" />
+      <input name="mix" type="float" interfacename="mix" />
+    </overlay>
+    <combine4 name="N_combine" type="color4" nodedef="ND_combine4_color4">
+      <input name="in1" type="float" nodename="N_overlay_r" />
+      <input name="in2" type="float" nodename="N_overlay_g" />
+      <input name="in3" type="float" nodename="N_overlay_b" />
+      <input name="in4" type="float" nodename="N_overlay_a" />
+    </combine4>
+  </nodegraph>
+
+
   <!-- ======================================================================== -->
   <!-- Conditional nodes                                                        -->
   <!-- ======================================================================== -->

diff --git a/resources/Materials/TestSuite/stdlib/compositing/compositing.mtlx b/resources/Materials/TestSuite/stdlib/compositing/compositing.mtlx
@@ -183,24 +183,24 @@
   </nodegraph>
   <nodegraph name="overlay_float">
     <overlay name="overlay1" type="float">
-      <input name="fg" type="float" value="0.5000" />
-      <input name="bg" type="float" value="0.5000" />
+      <input name="fg" type="float" value="0.2" />
+      <input name="bg" type="float" value="0.6" />
       <input name="mix" type="float" value="0.5000" />
     </overlay>
     <output name="out" type="float" nodename="overlay1" />
   </nodegraph>
   <nodegraph name="overlay_color3">
     <overlay name="overlay1" type="color3">
-      <input name="fg" type="color3" value="0.5000, 0.0, 0.0" />
-      <input name="bg" type="color3" value="0.5000, 1.0000, 0.0" />
+      <input name="fg" type="color3" value="0.2, 0.6, 0.6" />
+      <input name="bg" type="color3" value="0.8, 0.2, 0.4" />
       <input name="mix" type="float" value="0.5000" />
     </overlay>
     <output name="out" type="color3" nodename="overlay1" />
   </nodegraph>
   <nodegraph name="overlay_color4">
     <overlay name="overlay1" type="color4">
-      <input name="fg" type="color4" value="0.5000, 0.0, 0.0, 1.0" />
-      <input name="bg" type="color4" value="0.5000, 1.0000, 0.0, 1.0000" />
+      <input name="fg" type="color4" value="0.6, 0.8, 0.8, 1.0" />
+      <input name="bg" type="color4" value="0.6, 0.2, 0.4, 1.0" />
       <input name="mix" type="float" value="0.5000" />
     </overlay>
     <output name="out" type="color4" nodename="overlay1" />

diff --git a/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl b/source/MaterialXGenMdl/mdl/materialx/stdlib.mdl
@@ -2777,66 +2777,6 @@ export color4 mx_screen_color4(
 	return color4(rgb,a);
 }
 
-float mx_overlay(float mxp_fg, float mxp_bg)
-{
-	return (mxp_fg < 0.5) ? (2 * mxp_fg * mxp_bg) : (1 - (1 - mxp_fg) * (1 - mxp_bg));
-}
-float2 mx_overlay(float2 mxp_fg, float2 mxp_bg) [[ anno::unused() ]]
-{
-	return float2(
-		mx_overlay(mxp_fg.x, mxp_bg.x),
-		mx_overlay(mxp_fg.y, mxp_bg.y)
-	);
-}
-color mx_overlay(color mxp_fg, color mxp_bg)
-{
-	float3 fg(mxp_fg);
-	float3 bg(mxp_bg);
-	return color(
-		mx_overlay(fg.x, bg.x),
-		mx_overlay(fg.y, bg.y),
-		mx_overlay(fg.z, bg.z)
-	);
-}
-
-export float mx_overlay_float(
-	float mxp_fg = 0.0,
-	float mxp_bg = 0.0,
-	float mxp_mix = 1.0
-)
-	[[
-		anno::description("Node Group: compositing")
-	]]
-{
-	return mxp_mix * mx_overlay(mxp_fg, mxp_bg) + (1-mxp_mix) * mxp_bg;
-}
-
-export color mx_overlay_color3(
-	color mxp_fg = color(0.0),
-	color mxp_bg = color(0.0),
-	float mxp_mix = 1.0
-)
-	[[
-		anno::description("Node Group: compositing")
-	]]
-{
-	return mxp_mix * mx_overlay(mxp_fg, mxp_bg) + (1-mxp_mix) * mxp_bg;
-}
-
-export color4 mx_overlay_color4(
-	color4 mxp_fg = mk_color4(0.0, 0.0, 0.0, 0.0),
-	color4 mxp_bg = mk_color4(0.0, 0.0, 0.0, 0.0),
-	float mxp_mix = float(1.0)
-)
-	[[
-		anno::description("Node Group: compositing")
-	]]
-{
-	color rgb = mxp_mix * mx_overlay(mxp_fg.rgb, mxp_bg.rgb) + (1-mxp_mix) * mxp_bg.rgb;
-	float   a = mxp_mix * mx_overlay(mxp_fg.a  , mxp_bg.a  ) + (1-mxp_mix) * mxp_bg.a;
-	return color4(rgb,a);
-}
-
 export color4 mx_disjointover_color4(
 	color4 mxp_fg = mk_color4(0.0, 0.0, 0.0, 0.0),
 	color4 mxp_bg = mk_color4(0.0, 0.0, 0.0, 0.0),