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[✨ feature] Scene: allow bypassing ray intersection acceleration data structures #297

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[✨ feature] Scene: allow bypassing ray intersection acceleration data structures #297

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b9a5c38
Mesh: support naive ray intersection
merlinND Sep 30, 2022
c06cf69
Scene: support using naive queries
merlinND Sep 30, 2022
dd0c7d4
Tests for naive ray intersections
merlinND Sep 30, 2022
52d24f6
WIP AABB custom shape
merlinND Oct 6, 2022
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12 changes: 12 additions & 0 deletions include/mitsuba/render/mesh.h
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Original file line number Diff line number Diff line change
Expand Up @@ -264,6 +264,18 @@ class MI_EXPORT_LIB Mesh : public Shape<Float, Spectrum> {
MI_DECLARE_RAY_INTERSECT_TRI_PACKET(8)
MI_DECLARE_RAY_INTERSECT_TRI_PACKET(16)

template <typename FloatP, typename Ray3fP>
std::tuple<FloatP, Point<FloatP, 2>, dr::uint32_array_t<FloatP>,
dr::uint32_array_t<FloatP>>
ray_intersect_preliminary_impl(const Ray3fP &ray,
dr::mask_t<FloatP> active) const;

template <typename FloatP, typename Ray3fP>
dr::mask_t<FloatP> ray_test_impl(const Ray3fP &ray,
dr::mask_t<FloatP> active) const;
MI_SHAPE_DEFINE_RAY_INTERSECT_METHODS()


#if defined(MI_ENABLE_EMBREE)
/// Return the Embree version of this shape
virtual RTCGeometry embree_geometry(RTCDevice device) override;
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1 change: 1 addition & 0 deletions include/mitsuba/render/scene.h
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Expand Up @@ -574,6 +574,7 @@ class MI_EXPORT_LIB Scene : public Object {
ScalarFloat m_emitter_pmf;

bool m_shapes_grad_enabled;
bool m_use_naive_intersection;
};

/// Dummy function which can be called to ensure that the librender shared library is loaded
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53 changes: 27 additions & 26 deletions include/mitsuba/render/shape.h
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Expand Up @@ -581,56 +581,57 @@ class MI_EXPORT_LIB Shape : public Object {
MI_EXTERN_CLASS(Shape)
NAMESPACE_END(mitsuba)

#define MI_IMPLEMENT_RAY_INTERSECT_PACKET(N) \
using typename Base::FloatP##N; \
using typename Base::UInt32P##N; \
using typename Base::MaskP##N; \
using typename Base::Point2fP##N; \
using typename Base::Point3fP##N; \
using typename Base::Ray3fP##N; \
std::tuple<FloatP##N, Point2fP##N, UInt32P##N, UInt32P##N> \
ray_intersect_preliminary_packet( \
const Ray3fP##N &ray, MaskP##N active) const override { \
(void) ray; (void) active; \
if constexpr (!dr::is_cuda_v<Float>) \
return ray_intersect_preliminary_impl<FloatP##N>(ray, active); \
#define MI_IMPLEMENT_RAY_INTERSECT_PACKET(N) \
std::tuple<typename Base::FloatP##N, typename Base::Point2fP##N, \
typename Base::UInt32P##N, typename Base::UInt32P##N> \
ray_intersect_preliminary_packet(const typename Base::Ray3fP##N &ray, \
typename Base::MaskP##N active) \
const override { \
(void) ray; \
(void) active; \
if constexpr (!dr::is_cuda_v<Float>) \
return ray_intersect_preliminary_impl<typename Base::FloatP##N>( \
ray, active); \
else \
Throw("ray_intersect_preliminary_packet() CUDA not supported"); \
} \
MaskP##N ray_test_packet(const Ray3fP##N &ray, MaskP##N active) \
typename Base::MaskP##N ray_test_packet( \
const typename Base::Ray3fP##N &ray, typename Base::MaskP##N active) \
const override { \
(void) ray; (void) active; \
if constexpr (!dr::is_cuda_v<Float>) \
return ray_test_impl<FloatP##N>(ray, active); \
(void) ray; \
(void) active; \
if constexpr (!dr::is_cuda_v<Float>) \
return ray_test_impl<typename Base::FloatP##N>(ray, active); \
else \
Throw("ray_intersect_preliminary_packet() CUDA not supported"); \
}

// Macro to define ray intersection methods given an *_impl() templated implementation
#define MI_SHAPE_DEFINE_RAY_INTERSECT_METHODS() \
#define MI_SHAPE_DEFINE_RAY_INTERSECT_METHODS() \
PreliminaryIntersection3f ray_intersect_preliminary( \
const Ray3f &ray, Mask active) const override { \
MI_MASK_ARGUMENT(active); \
PreliminaryIntersection3f pi = dr::zeros<PreliminaryIntersection3f>(); \
MI_MASK_ARGUMENT(active); \
PreliminaryIntersection3f pi = dr::zeros<PreliminaryIntersection3f>(); \
std::tie(pi.t, pi.prim_uv, pi.shape_index, pi.prim_index) = \
ray_intersect_preliminary_impl<Float>(ray, active); \
pi.shape = this; \
return pi; \
} \
Mask ray_test(const Ray3f &ray, Mask active) const override { \
MI_MASK_ARGUMENT(active); \
MI_MASK_ARGUMENT(active); \
return ray_test_impl<Float>(ray, active); \
} \
using typename Base::ScalarRay3f; \
std::tuple<ScalarFloat, ScalarPoint2f, ScalarUInt32, ScalarUInt32> \
ray_intersect_preliminary_scalar(const ScalarRay3f &ray) const override { \
ray_intersect_preliminary_scalar(const typename Base::ScalarRay3f &ray) \
const override { \
return ray_intersect_preliminary_impl<ScalarFloat>(ray, true); \
} \
ScalarMask ray_test_scalar(const ScalarRay3f &ray) const override { \
ScalarMask ray_test_scalar(const typename Base::ScalarRay3f &ray) \
const override { \
return ray_test_impl<ScalarFloat>(ray, true); \
} \
MI_IMPLEMENT_RAY_INTERSECT_PACKET(4) \
MI_IMPLEMENT_RAY_INTERSECT_PACKET(8) \
MI_IMPLEMENT_RAY_INTERSECT_PACKET(4) \
MI_IMPLEMENT_RAY_INTERSECT_PACKET(8) \
MI_IMPLEMENT_RAY_INTERSECT_PACKET(16)

// -----------------------------------------------------------------------
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39 changes: 39 additions & 0 deletions src/render/mesh.cpp
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Expand Up @@ -621,6 +621,45 @@ Mesh<Float, Spectrum>::barycentric_coordinates(const SurfaceInteraction3f &si,
return {w, u, v};
}

MI_VARIANT
template <typename FloatP, typename Ray3fP>
std::tuple<FloatP, Point<FloatP, 2>, dr::uint32_array_t<FloatP>,
dr::uint32_array_t<FloatP>>
Mesh<Float, Spectrum>::ray_intersect_preliminary_impl(
const Ray3fP &ray, dr::mask_t<FloatP> active) const {
MI_MASK_ARGUMENT(active);

FloatP t = dr::Infinity<FloatP>;
Point<FloatP, 2> uv = dr::NaN<FloatP>;
dr::uint32_array_t<FloatP> prim_index = (uint32_t) -1;
for (size_t index = 0; index < m_face_count; ++index) {
auto [prim_t, prim_uv] = ray_intersect_triangle_impl<FloatP>(index, ray, active);
dr::mask_t<FloatP> valid = dr::isfinite(prim_t) && (prim_t < t);
dr::masked(t, valid) = prim_t;
dr::masked(uv, valid) = prim_uv;
dr::masked(prim_index, valid) = index;
}

// Cannot determine the shape index, will be up to the caller.
uint32_t shape_index = (uint32_t) -1;
return { t, uv, shape_index, prim_index };
}

MI_VARIANT
template <typename FloatP, typename Ray3fP>
dr::mask_t<FloatP>
Mesh<Float, Spectrum>::ray_test_impl(const Ray3fP &ray,
dr::mask_t<FloatP> active) const {
MI_MASK_ARGUMENT(active);

dr::mask_t<FloatP> hit = false;
for (size_t index = 0; index < m_face_count; ++index) {
FloatP prim_t = ray_intersect_triangle_impl<FloatP>(index, ray, active).first;
hit |= dr::neq(prim_t, dr::Infinity<FloatP>);
}

return hit;
}

MI_VARIANT typename Mesh<Float, Spectrum>::SurfaceInteraction3f
Mesh<Float, Spectrum>::compute_surface_interaction(const Ray3f &ray,
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105 changes: 86 additions & 19 deletions src/render/scene.cpp
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Expand Up @@ -61,10 +61,22 @@ MI_VARIANT Scene<Float, Spectrum>::Scene(const Properties &props) {
for (Sensor *sensor: m_sensors)
sensor->set_scene(this);

if constexpr (dr::is_cuda_v<Float>)
accel_init_gpu(props);
else
accel_init_cpu(props);
// Decide whether to use acceleration data structures for ray intersections
// TODO: do we even want a heuristic? Could lead to surprising changes in performance for the user.
bool naive_intersection_desirable = m_shapes.size() <= 5;
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@merlinND merlinND Sep 30, 2022

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As discussed with @Speierers, we may not want to enable this feature unless the user explicitly asks for it. The downside is that users may not find out it exists, but it's probably better than creating surprising performance jumps due to this heuristic.

m_use_naive_intersection =
props.get<bool>("use_naive_intersection", naive_intersection_desirable);
if (m_use_naive_intersection)
Log(Info, "The scene will not use acceleration data structures "
"for ray intersections.");

// Build acceleration data structures if needed
if (!m_use_naive_intersection) {
if constexpr (dr::is_cuda_v<Float>)
accel_init_gpu(props);
else
accel_init_cpu(props);
}

if (!m_emitters.empty()) {
// Inform environment emitters etc. about the scene bounds
Expand All @@ -84,10 +96,12 @@ MI_VARIANT Scene<Float, Spectrum>::Scene(const Properties &props) {
}

MI_VARIANT Scene<Float, Spectrum>::~Scene() {
if constexpr (dr::is_cuda_v<Float>)
accel_release_gpu();
else
accel_release_cpu();
if (!m_use_naive_intersection) {
if constexpr (dr::is_cuda_v<Float>)
accel_release_gpu();
else
accel_release_cpu();
}

// Trigger deallocation of all instances
m_emitters.clear();
Expand All @@ -111,6 +125,27 @@ Scene<Float, Spectrum>::ray_intersect(const Ray3f &ray, uint32_t ray_flags, Mask
MI_MASKED_FUNCTION(ProfilerPhase::RayIntersect, active);
DRJIT_MARK_USED(coherent);

if (m_use_naive_intersection) {
// Naive intersection mode: bypass all acceleration data structures,
// test for intersections explicitly against each shape.
PreliminaryIntersection3f pi = dr::zeros<PreliminaryIntersection3f>();

for (size_t shape_index = 0; shape_index < m_shapes.size(); ++shape_index) {
PreliminaryIntersection3f prim_pi =
m_shapes[shape_index]->ray_intersect_preliminary(ray, active);
// TODO: fix masked struct assignment
Mask valid = prim_pi.is_valid() && prim_pi.t < pi.t;
dr::masked(pi.t, valid) = prim_pi.t;
dr::masked(pi.prim_uv, valid) = prim_pi.prim_uv;
dr::masked(pi.prim_index, valid) = prim_pi.prim_index;
dr::masked(pi.shape, valid) = prim_pi.shape;
dr::masked(pi.instance, valid) = prim_pi.instance;
dr::masked(pi.shape_index, valid) = shape_index;
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@merlinND merlinND Sep 30, 2022

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Need to fix this. Currently encountering a compilation error if trying to do a masked assignment to pi, something about type computation from masked arrays of Shape:

In file included from /home/merlin/Code/mitsuba3-master/src/render/scene.cpp:3:
In file included from /home/merlin/Code/mitsuba3-master/include/mitsuba/render/bsdf.h:4:
/home/merlin/Code/mitsuba3-master/include/mitsuba/render/interaction.h:560:36: error: no type named 'Ray3f' in 'drjit::detail::MaskedArray<mitsuba::Shape<dr::DiffArray<dr::CUDAArray<float>>, Color<dr::DiffArray<dr::CUDAArray<float>>, 3>>>'
    using Ray3f = typename Shape_::Ray3f;
                  ~~~~~~~~~~~~~~~~~^~~~~
/home/merlin/Code/mitsuba3-master/ext/drjit/include/drjit/array_router.h:2044:21: note: in instantiation of template class 'mitsuba::PreliminaryIntersection<drjit::detail::MaskedArray<drjit::DiffArray<CUDAArray<float>>>, drjit::detail::MaskedArray<mitsuba::Shape<dr::DiffArray<dr::CUDAArray<float>>, Color<dr::DiffArray<dr::CUDAArray<float>>, 3>>>>' requested here
        masked_t<T> result;
                    ^
/home/merlin/Code/mitsuba3-master/src/render/scene.cpp:138:17: note: in instantiation of function template specialization 'drjit::masked<mitsuba::PreliminaryIntersection<drjit::DiffArray<CUDAArray<float>>, mitsuba::Shape<dr::DiffArray<dr::CUDAArray<float>>, Color<dr::DiffArray<dr::CUDAArray<float>>, 3>>>, drjit::DiffArray<drjit::CUDAArray<bool>>>' requested here
            dr::masked(pi, valid) = prim_pi;
                ^
/home/merlin/Code/mitsuba3-master/src/render/scene.cpp:460:22: note: in instantiation of member function 'mitsuba::Scene<drjit::DiffArray<CUDAArray<float>>, mitsuba::Color<drjit::DiffArray<CUDAArray<float>>, 3>>::ray_intersect' requested here
MI_INSTANTIATE_CLASS(Scene)
                     ^

}
return pi.compute_surface_interaction(ray, ray_flags,
active && pi.is_valid());
}

if constexpr (dr::is_cuda_v<Float>)
return ray_intersect_gpu(ray, ray_flags, active);
else
Expand All @@ -120,6 +155,28 @@ Scene<Float, Spectrum>::ray_intersect(const Ray3f &ray, uint32_t ray_flags, Mask
MI_VARIANT typename Scene<Float, Spectrum>::PreliminaryIntersection3f
Scene<Float, Spectrum>::ray_intersect_preliminary(const Ray3f &ray, Mask coherent, Mask active) const {
DRJIT_MARK_USED(coherent);

if (m_use_naive_intersection) {
// Naive intersection mode: bypass all acceleration data structures,
// test for intersections explicitly against each shape.
PreliminaryIntersection3f pi = dr::zeros<PreliminaryIntersection3f>();

for (size_t shape_index = 0; shape_index < m_shapes.size(); ++shape_index) {
PreliminaryIntersection3f prim_pi =
m_shapes[shape_index]->ray_intersect_preliminary(ray, active);
// TODO: fix masked struct assignment
Mask valid = prim_pi.is_valid() && prim_pi.t < pi.t;
dr::masked(pi.t, valid) = prim_pi.t;
dr::masked(pi.prim_uv, valid) = prim_pi.prim_uv;
dr::masked(pi.prim_index, valid) = prim_pi.prim_index;
dr::masked(pi.shape, valid) = prim_pi.shape;
dr::masked(pi.instance, valid) = prim_pi.instance;
dr::masked(pi.shape_index, valid) = shape_index;
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@merlinND merlinND Sep 30, 2022

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Likewise.

}

return pi;
}

if constexpr (dr::is_cuda_v<Float>)
return ray_intersect_preliminary_gpu(ray, active);
else
Expand All @@ -131,6 +188,14 @@ Scene<Float, Spectrum>::ray_test(const Ray3f &ray, Mask coherent, Mask active) c
MI_MASKED_FUNCTION(ProfilerPhase::RayTest, active);
DRJIT_MARK_USED(coherent);

if (m_use_naive_intersection) {
Mask hit = false;
for (const auto &shape : m_shapes) {
hit |= shape->ray_test(ray, active);
}
return hit;
}

if constexpr (dr::is_cuda_v<Float>)
return ray_test_gpu(ray, active);
else
Expand Down Expand Up @@ -299,18 +364,20 @@ MI_VARIANT void Scene<Float, Spectrum>::parameters_changed(const std::vector<std
if (m_environment)
m_environment->set_scene(this); // TODO use parameters_changed({"scene"})

bool accel_is_dirty = false;
for (auto &s : m_shapes) {
accel_is_dirty = s->dirty();
if (accel_is_dirty)
break;
}
if (!m_use_naive_intersection) {
bool accel_is_dirty = false;
for (auto &s : m_shapes) {
accel_is_dirty = s->dirty();
if (accel_is_dirty)
break;
}

if (accel_is_dirty) {
if constexpr (dr::is_cuda_v<Float>)
accel_parameters_changed_gpu();
else
accel_parameters_changed_cpu();
if (accel_is_dirty) {
if constexpr (dr::is_cuda_v<Float>)
accel_parameters_changed_gpu();
else
accel_parameters_changed_cpu();
}
}

// Check whether any shape parameters have gradient tracking enabled
Expand Down
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