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// Copyright 2009 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "BSDF.ih"
#include "ShadingContext.ih"
OSPRAY_BEGIN_ISPC_NAMESPACE
struct MultiBSDF_Child
{
float weight;
float importance;
};
#define DEFINE_MULTIBSDF(size) \
BSDF super; \
float importanceSum; \
MultiBSDF_Child children[size]
struct MultiBSDF
{
DEFINE_MULTIBSDF(1);
};
inline void MultiBSDF_add(varying MultiBSDF *uniform self,
const uniform int id,
const varying BSDF *uniform bsdf,
float weight = 1.f,
float importance = 1.f)
{
self->super.albedo = self->super.albedo + bsdf->albedo * weight;
self->super.scatteringType |= bsdf->scatteringType;
if (!self->super.frame) // use first frame TODO use dominant frame
self->super.frame = bsdf->frame;
self->children[id].weight = weight;
unmasked
{
self->children[id].importance = 0.f;
}
self->children[id].importance = importance;
self->importanceSum += importance;
}
inline void MultiBSDF_Constructor(
varying MultiBSDF *uniform self, const uniform int count)
{
BSDF_Constructor(
&self->super, make_vec3f(0.f), BSDF_NONE, BSDF_TYPE_MULTI_BSDF, NULL);
unmasked
{
self->importanceSum = 0.0f;
for (uniform int i = 0; i < count; i++) {
self->children[i].weight = 0.f;
self->children[i].importance = 0.f;
}
}
}
OSPRAY_END_ISPC_NAMESPACE
// Eval macros
#define MULTIBSDF_EVAL_BEGIN() \
BSDF_EvalRes eRes = make_BSDF_EvalRes_zero(); \
const int choice = -1
#define MULTIBSDF_EVAL_CHILD(id, child_bsdf, eval_fn) \
if ((self->children[id].importance > 0.f) && (choice != id)) { \
BSDF_EvalRes cur = eval_fn(child_bsdf, wo, wi); \
cur.value = cur.value * self->children[id].weight; \
eRes.value = eRes.value + cur.value; \
eRes.pdf += cur.pdf * self->children[id].importance; \
}
#define MULTIBSDF_EVAL_END() eRes.pdf *= rcp(self->importanceSum)
#define MULTIBSDF_EVAL_GET() eRes
// Sample macros
#define MULTIBSDF_SAMPLE_BEGIN() \
BSDF_SampleRes res = make_BSDF_SampleRes_zero(); \
float x = ss * self->importanceSum; \
int choice = 0; \
float prefixSum = 0.f; \
if (self->importanceSum == 0.f) { \
return res
#define MULTIBSDF_SAMPLE_CHILD(id, child_bsdf, sample_fn) \
} \
else if (x < (prefixSum += self->children[id].importance)) \
{ \
choice = id; \
\
ss = (x + self->children[id].importance - prefixSum) \
* rcp(self->children[id].importance); \
\
res = sample_fn(child_bsdf, wo, s, ss); \
res.weight = res.weight * self->children[id].weight
#define MULTIBSDF_SAMPLE_EVAL() \
} \
if (eq(res.weight, make_vec3f(0.0f)) || (res.pdf == 0.0f)) \
return make_BSDF_SampleRes_zero(); \
\
/* if the sampled BSDF is specular (has a delta distribution), we cannot add \
* the contributions from the other BSDFs [Pharr et al., 2016, "Physically \
* Based Rendering", 3rd Edition, Section 14.1.6] */ \
if (res.type & BSDF_SPECULAR) { \
/* scale by rcp(selection pdf) */ \
res.weight = res.weight \
* (self->importanceSum * rcp(self->children[choice].importance)); \
return res; \
} \
BSDF_EvalRes eRes; \
eRes.value = res.weight * res.pdf; \
res.pdf *= self->children[choice].importance; \
eRes.pdf = res.pdf; \
const vec3f wi = res.wi
#define MULTIBSDF_SAMPLE_END() \
res.pdf = eRes.pdf; \
res.pdf *= rcp(self->importanceSum); \
res.weight = eRes.value * rcp(res.pdf)
#define MULTIBSDF_SAMPLE_GET() res
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