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Fix ADD accumulation in testrender closure walkers #2152

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Merged
lgritz merged 1 commit into from
Aug 25, 2026
Merged

Fix ADD accumulation in testrender closure walkers #2152

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50 changes: 30 additions & 20 deletions src/testrender/shading.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1208,17 +1208,19 @@ evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,
int stack_idx = 0;
const ClosureColor* ptr_stack[STACK_SIZE];
Color3 weight_stack[STACK_SIZE];
Color3 weight = Color3(1.0f);
// Track the active branch separately from completed branch contributions.
Color3 branch_weight = Color3(1.0f);
Color3 accumulated_weight = Color3(0.0f);

while (closure) {
switch (closure->id) {
case ClosureColor::MUL:
weight *= closure->as_mul()->weight;
branch_weight *= closure->as_mul()->weight;
closure = closure->as_mul()->closure;
break;
case ClosureColor::ADD:
ptr_stack[stack_idx] = closure->as_add()->closureB;
weight_stack[stack_idx++] = weight;
weight_stack[stack_idx++] = branch_weight;
closure = closure->as_add()->closureA;
break;
default: {
Expand All @@ -1229,21 +1231,21 @@ evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,
const MxLayerParams* srcparams = comp->as<MxLayerParams>();
closure = srcparams->top;
ptr_stack[stack_idx] = srcparams->base;
weight_stack[stack_idx++] = weight * w;
weight_stack[stack_idx++] = branch_weight * w;
break;
}
case REFLECTION_ID:
case FRESNEL_REFLECTION_ID: {
Reflection bsdf(*comp->as<ReflectionParams>());
weight *= w * bsdf.get_albedo(-sg.I);
branch_weight *= w * bsdf.get_albedo(-sg.I);
closure = nullptr;
break;
}
case MxDielectric::closureid(): {
const MxDielectric::Data& params
= *comp->as<MxDielectric::Data>();
MxDielectric d(params, -sg.I, sg.backfacing, path_roughness);
weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
branch_weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
closure = nullptr;
break;
}
Expand All @@ -1257,13 +1259,13 @@ evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,
}
MxGeneralizedSchlick d(params, -sg.I, sg.backfacing,
path_roughness);
weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
branch_weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
break;
}
case MxSheen::closureid(): {
const MxSheen::Data& params = *comp->as<MxSheen::Data>();
MxSheen d(params, -sg.I, sg.backfacing, path_roughness);
weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
branch_weight *= w * (Color3(1) - d.filter_o(-sg.I).toRGB(0));
closure = nullptr;
break;
}
Expand All @@ -1273,12 +1275,15 @@ evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,
}
}
}
if (closure == nullptr && stack_idx > 0) {
closure = ptr_stack[--stack_idx];
weight = weight_stack[stack_idx];
if (closure == nullptr) {
accumulated_weight += branch_weight;
if (stack_idx > 0) {
closure = ptr_stack[--stack_idx];
branch_weight = weight_stack[stack_idx];
}
}
}
return weight;
return accumulated_weight;
}

OSL_HOSTDEVICE void
Expand Down Expand Up @@ -1716,33 +1721,38 @@ process_background_closure(const ClosureColor* closure)
int stack_idx = 0;
const ClosureColor* ptr_stack[STACK_SIZE];
Color3 weight_stack[STACK_SIZE];
Color3 weight = Color3(1.0f);
// Track the active branch separately from completed branch contributions.
Color3 branch_weight = Color3(1.0f);
Color3 accumulated_weight = Color3(0.0f);

while (closure) {
switch (closure->id) {
case ClosureColor::MUL: {
weight *= closure->as_mul()->weight;
branch_weight *= closure->as_mul()->weight;
closure = closure->as_mul()->closure;
break;
}
case ClosureColor::ADD: {
ptr_stack[stack_idx] = closure->as_add()->closureB;
weight_stack[stack_idx++] = weight;
weight_stack[stack_idx++] = branch_weight;
closure = closure->as_add()->closureA;
break;
}
case BACKGROUND_ID: {
weight *= closure->as_comp()->w;
branch_weight *= closure->as_comp()->w;
closure = nullptr;
break;
}
}
if (closure == nullptr && stack_idx > 0) {
closure = ptr_stack[--stack_idx];
weight = weight_stack[stack_idx];
if (closure == nullptr) {
accumulated_weight += branch_weight;
if (stack_idx > 0) {
closure = ptr_stack[--stack_idx];
branch_weight = weight_stack[stack_idx];
}
}
}
return weight;
return accumulated_weight;
}

OSL_HOSTDEVICE Color3
Expand Down
3 changes: 2 additions & 1 deletion testsuite/render-background/envmap.osl
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Original file line number Diff line number Diff line change
Expand Up @@ -11,5 +11,6 @@ shader envmap(float Kb = 1, string filename = "")
float tu = 0.5 + r * cos(radial);
float tv = 0.5 - r * sin(radial);
color c = texture(filename, tu, tv);
Ci = Kb * c * background();
Ci = Kb * c * color(1, 1, 0) * background()
+ Kb * c * color(0, 0, 1) * background();
}
18 changes: 18 additions & 0 deletions testsuite/render-mx-layer/layer_add.osl
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
// Copyright Contributors to the Open Shading Language project.
// SPDX-License-Identifier: BSD-3-Clause
// https://github.com/AcademySoftwareFoundation/OpenShadingLanguage

surface layer_add(int distributed = 0)
{
closure color red
= oren_nayar_diffuse_bsdf(N, color(1, 0, 0), 0.3);
closure color blue
= oren_nayar_diffuse_bsdf(N, color(0, 0, 1), 0.3);
closure color green
= oren_nayar_diffuse_bsdf(N, color(0, 1, 0), 0.3);

if (distributed)
Ci = 0.5 * layer(red, green) + 0.5 * layer(blue, green);
else
Ci = layer(0.5 * red + 0.5 * blue, green);
}
Binary file added testsuite/render-mx-layer/ref/out_add.exr
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3 changes: 2 additions & 1 deletion testsuite/render-mx-layer/run.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,5 +8,6 @@
hardfail = 0.05
idiff_program = "idiff"

outputs = [ "out.exr" ]
outputs = [ "out.exr", "out_add.exr" ]
command = testrender("-r 160 120 -aa 6 scene.xml out.exr")
command += testrender("-r 160 120 -aa 6 scene_add.xml out_add.exr")
20 changes: 20 additions & 0 deletions testsuite/render-mx-layer/scene_add.xml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
<World>
<Camera eye="0, 0, 10" look_at="0,0,0" fov="30" />

<ShaderGroup>
shader envmap layer1;
</ShaderGroup>
<Background resolution="1024" />

<ShaderGroup>
param int distributed 0;
shader layer_add layer1;
</ShaderGroup>
<Quad corner="-2,-1,0" edge_x="2,0,0" edge_y="0,2,0" />

<ShaderGroup>
param int distributed 1;
shader layer_add layer1;
</ShaderGroup>
<Quad corner="0,-1,0" edge_x="2,0,0" edge_y="0,2,0" />
</World>
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