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Add testrender volumes #2053

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5 changes: 4 additions & 1 deletion src/cmake/testing.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -362,6 +362,7 @@ macro (osl_add_all_tests)
render-cornell
render-displacement
render-furnace-diffuse
render-mx-anisotropic-vdf
render-mx-furnace-burley-diffuse
render-mx-furnace-oren-nayar
render-mx-furnace-sheen
Expand All @@ -371,7 +372,9 @@ macro (osl_add_all_tests)
render-mx-generalized-schlick render-mx-generalized-schlick-glass
render-mx-layer
render-mx-sheen
render-microfacet render-oren-nayar
render-mx-medium-vdf
render-mx-medium-vdf-glass
render-microfacet render-oren-nayar
render-spi-thinlayer
render-uv render-veachmis render-ward
render-raytypes
Expand Down
242 changes: 202 additions & 40 deletions src/testrender/shading.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1513,6 +1513,92 @@ struct ZeltnerBurleySheen final : public BSDF, MxSheenParams {
}
};


struct HenyeyGreenstein final : public BSDF {
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@fpsunflower fpsunflower Jan 29, 2026

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There is already an implementation of this in the BSDL headers - is it possible to re-use that one?

const float g;
OSL_HOSTDEVICE HenyeyGreenstein(float g) : BSDF(this), g(g) {}

static OSL_HOSTDEVICE float PhaseHG(float cos_theta, float g)
{
const float denom = 1 + g * g + 2 * g * cos_theta;
return (1 - g * g) / (4 * M_PI * denom * sqrtf(denom));
}

OSL_HOSTDEVICE Sample eval(const Vec3& wo, const Vec3& wi) const
{
const float pdf = PhaseHG(dot(wo, wi), g);
return { wi, Color3(pdf), pdf, 0.0f };
}

OSL_HOSTDEVICE Sample sample(const Vec3& wo, float rx, float ry,
float rz) const
{
TangentFrame frame = TangentFrame::from_normal(wo);

float cos_theta;
if (abs(g) < 1e-3f) {
cos_theta = 1.0f - 2.0f * rx;
} else {
float sqr_term = (1 - g * g) / (1 - g + 2 * g * rx);
cos_theta = (1 + g * g - sqr_term * sqr_term) / (2 * g);
cos_theta = OIIO::clamp(cos_theta, -1.0f, 1.0f);
}

float sin_theta = sqrtf(
OIIO::clamp(1.0f - cos_theta * cos_theta, 0.0f, 1.0f));
float phi = 2 * M_PI * ry;
Vec3 local_wi = Vec3(sin_theta * cosf(phi), sin_theta * sinf(phi),
cos_theta);

Vec3 wi = frame.toworld(local_wi);
float pdf_val = PhaseHG(cos_theta, g);

return { wi, Color3(1.0f), pdf_val, 0.0f };
}
};

struct HomogeneousMedium final : public Medium {
MediumParams params;
HenyeyGreenstein phase_func;

OSL_HOSTDEVICE HomogeneousMedium(const MediumParams& params)
: Medium(this), params(params), phase_func(params.medium_g)
{
}

OSL_HOSTDEVICE BSDF::Sample sample_phase_func(const Vec3& wo, float rx,
float ry, float rz) const
{
return phase_func.sample(wo, rx, ry, rz);
}

OSL_HOSTDEVICE const MediumParams* get_params() const { return &params; }
};

struct EmptyMedium final : public Medium {
MediumParams params;
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@fpsunflower fpsunflower Jan 29, 2026

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If even the empty medium needs to have MediumParams - maybe the field should be in the base class?

Do we even need a class hierarchy here given that this medium tracking is only ever going to support homogeneous media?


OSL_HOSTDEVICE EmptyMedium(const MediumParams& params)
: Medium(this), params(params)
{
}

OSL_HOSTDEVICE const MediumParams* get_params() const { return &params; }

OSL_HOSTDEVICE Medium::Sample sample(Ray& ray, Sampler& sampler,
Intersection& hit) const
{
return { 0.0f, Color3(1.0f), Color3(1.0f) };
}

OSL_HOSTDEVICE BSDF::Sample sample_phase_func(const Vec3& wo, float rx,
float ry, float rz) const
{
return { Vec3(1.0f), Color3(1.0f), 0.0f, 0.0f };
}
};


OSL_HOSTDEVICE Color3
evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,
const ClosureColor* closure)
Expand Down Expand Up @@ -1606,8 +1692,8 @@ evaluate_layer_opacity(const ShaderGlobalsType& sg, float path_roughness,

OSL_HOSTDEVICE void
process_medium_closure(const ShaderGlobalsType& sg, float path_roughness,
ShadingResult& result, const ClosureColor* closure,
const Color3& w)
ShadingResult& result, MediumStack& medium_stack,
const ClosureColor* closure, const Color3& w)
{
if (!closure)
return;
Expand Down Expand Up @@ -1649,37 +1735,72 @@ process_medium_closure(const ShaderGlobalsType& sg, float path_roughness,
const ClosureComponent* comp = closure->as_comp();
Color3 cw = weight * comp->w;
const auto& params = *comp->as<MxAnisotropicVdfParams>();
result.sigma_t = cw * params.extinction;
result.sigma_s = params.albedo * result.sigma_t;
result.medium_g = params.anisotropy;
closure = nullptr;
result.medium_data.sigma_t = cw * params.extinction;
result.medium_data.sigma_s = params.albedo
* result.medium_data.sigma_t;
result.medium_data.medium_g = params.anisotropy;
result.medium_data.priority = 0;

if (!sg.backfacing) { // if entering
if (result.medium_data.is_vaccum()) {
medium_stack.add_medium<EmptyMedium>(result.medium_data);
} else {
medium_stack.add_medium<HomogeneousMedium>(
result.medium_data);
}
}

closure = nullptr;
break;
}
case MX_MEDIUM_VDF_ID: {
const ClosureComponent* comp = closure->as_comp();
Color3 cw = weight * comp->w;
const auto& params = *comp->as<MxMediumVdfParams>();
result.sigma_t = { -OIIO::fast_log(params.transmission_color.x),
-OIIO::fast_log(params.transmission_color.y),
-OIIO::fast_log(params.transmission_color.z) };
// NOTE: closure weight scales the extinction parameter
result.sigma_t *= cw / params.transmission_depth;
result.sigma_s = params.albedo * result.sigma_t;
result.medium_g = params.anisotropy;
// TODO: properly track a medium stack here ...
result.refraction_ior = sg.backfacing ? 1.0f / params.ior
: params.ior;
result.priority = params.priority;
closure = nullptr;

result.medium_data.sigma_t
= Color3(-OIIO::fast_log(params.transmission_color.x),
-OIIO::fast_log(params.transmission_color.y),
-OIIO::fast_log(params.transmission_color.z));

result.medium_data.sigma_t *= cw / params.transmission_depth;
result.medium_data.sigma_s = params.albedo
* result.medium_data.sigma_t;
result.medium_data.medium_g = params.anisotropy;

result.medium_data.refraction_ior = sg.backfacing
? 1.0f / params.ior
: params.ior;
result.medium_data.priority = params.priority;

if (!sg.backfacing) { // if entering
if (result.medium_data.is_vaccum()) {
medium_stack.add_medium<EmptyMedium>(result.medium_data);
} else {
medium_stack.add_medium<HomogeneousMedium>(
result.medium_data);
}
}

closure = nullptr;
break;
}
case MxDielectric::closureid(): {
const ClosureComponent* comp = closure->as_comp();
const MxDielectric::Data& params = *comp->as<MxDielectric::Data>();
if (!is_black(weight * comp->w * params.refr_tint)) {
// TODO: properly track a medium stack here ...
result.refraction_ior = sg.backfacing ? 1.0f / params.IOR
: params.IOR;
float new_ior = sg.backfacing ? 1.0f / params.IOR : params.IOR;

result.medium_data.refraction_ior = new_ior;

const MediumParams* current_params
= medium_stack.get_current_params();
if (current_params
&& result.medium_data.priority
<= current_params->priority) {
result.medium_data.refraction_ior
= current_params->refraction_ior;
}
}
closure = nullptr;
break;
Expand All @@ -1688,13 +1809,23 @@ process_medium_closure(const ShaderGlobalsType& sg, float path_roughness,
const ClosureComponent* comp = closure->as_comp();
const auto& params = *comp->as<MxGeneralizedSchlickParams>();
if (!is_black(weight * comp->w * params.transmission_tint)) {
// TODO: properly track a medium stack here ...
float avg_F0 = clamp((params.f0.x + params.f0.y + params.f0.z)
/ 3.0f,
0.0f, 0.99f);
float sqrt_F0 = sqrtf(avg_F0);
float ior = (1 + sqrt_F0) / (1 - sqrt_F0);
result.refraction_ior = sg.backfacing ? 1.0f / ior : ior;
float new_ior = sg.backfacing ? 1.0f / ior : ior;

result.medium_data.refraction_ior = new_ior;

const MediumParams* current_params
= medium_stack.get_current_params();
if (current_params
&& result.medium_data.priority
<= current_params->priority) {
result.medium_data.refraction_ior
= current_params->refraction_ior;
}
}
closure = nullptr;
break;
Expand All @@ -1711,8 +1842,9 @@ process_medium_closure(const ShaderGlobalsType& sg, float path_roughness,
// recursively walk through the closure tree, creating bsdfs as we go
OSL_HOSTDEVICE void
process_bsdf_closure(const ShaderGlobalsType& sg, float path_roughness,
ShadingResult& result, const ClosureColor* closure,
const Color3& w, bool light_only)
ShadingResult& result, MediumStack& medium_stack,
const ClosureColor* closure, const Color3& w,
bool light_only)
{
static const ustringhash uh_ggx("ggx");
static const ustringhash uh_beckmann("beckmann");
Expand Down Expand Up @@ -1845,9 +1977,16 @@ process_bsdf_closure(const ShaderGlobalsType& sg, float path_roughness,
case MxDielectric::closureid(): {
const MxDielectric::Data& params
= *comp->as<MxDielectric::Data>();
ok = result.bsdf.add_bsdf<MxDielectric>(cw, params, -sg.I,
sg.backfacing,
path_roughness);

if (medium_stack.false_intersection_with(
result.medium_data)) {
ok = result.bsdf.add_bsdf<Transparent>(cw);
} else {
ok = result.bsdf.add_bsdf<MxDielectric>(cw, params,
-sg.I,
sg.backfacing,
path_roughness);
}
break;
}
case MxConductor::closureid(): {
Expand All @@ -1860,15 +1999,21 @@ process_bsdf_closure(const ShaderGlobalsType& sg, float path_roughness,
case MX_GENERALIZED_SCHLICK_ID: {
const MxGeneralizedSchlickParams& params
= *comp->as<MxGeneralizedSchlickParams>();
if (is_black(params.transmission_tint))
ok = result.bsdf.add_bsdf<MxMicrofacet<
MxGeneralizedSchlickParams, GGXDist, false>>(cw,
params,
1.0f);
else
ok = result.bsdf.add_bsdf<MxMicrofacet<
MxGeneralizedSchlickParams, GGXDist, true>>(
cw, params, result.refraction_ior);

if (medium_stack.false_intersection_with(
result.medium_data)) {
ok = result.bsdf.add_bsdf<Transparent>(cw);
} else {
if (is_black(params.transmission_tint)) {
ok = result.bsdf.add_bsdf<MxMicrofacet<
MxGeneralizedSchlickParams, GGXDist, false>>(
cw, params, 1.0f);
} else {
ok = result.bsdf.add_bsdf<MxMicrofacet<
MxGeneralizedSchlickParams, GGXDist, true>>(
cw, params, result.medium_data.refraction_ior);
}
}
break;
};
case MX_TRANSLUCENT_ID: {
Expand Down Expand Up @@ -1957,11 +2102,14 @@ process_bsdf_closure(const ShaderGlobalsType& sg, float path_roughness,

OSL_HOSTDEVICE void
process_closure(const ShaderGlobalsType& sg, float path_roughness,
ShadingResult& result, const ClosureColor* Ci, bool light_only)
ShadingResult& result, MediumStack& medium_stack,
const ClosureColor* Ci, bool light_only)
{
if (!light_only)
process_medium_closure(sg, path_roughness, result, Ci, Color3(1));
process_bsdf_closure(sg, path_roughness, result, Ci, Color3(1), light_only);
process_medium_closure(sg, path_roughness, result, medium_stack, Ci,
Color3(1));
process_bsdf_closure(sg, path_roughness, result, medium_stack, Ci,
Color3(1), light_only);
}

OSL_HOSTDEVICE Vec3
Expand Down Expand Up @@ -2022,5 +2170,19 @@ BSDF::sample_vrtl(const Vec3& wo, float rx, float ry, float rz) const
return dispatch([&](auto bsdf) { return bsdf.sample(wo, rx, ry, rz); });
}

OSL_HOSTDEVICE BSDF::Sample
Medium::sample_phase_func_vrtl(const Vec3& wo, float rx, float ry,
float rz) const
{
return dispatch([&](const auto& medium) {
return medium.sample_phase_func(wo, rx, ry, rz);
});
}

OSL_HOSTDEVICE const MediumParams*
Medium::get_params_vrtl() const
{
return dispatch([&](const auto& medium) { return medium.get_params(); });
}

OSL_NAMESPACE_END
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