Is it possible to use Embree for intersection computation in 2D ?

ImperatorS79 — Tue, 09 Sep 2025 15:43:22 GMT

I see there is RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE, but despite all my attemps, I do not maange to make it work. Here is my last attempt:

#include <array>

#include <vector>

#include <string>

#include <stdexcept>

#include <iostream>

#include <limits>

#include <embree4/rtcore.h>

std::string translateEmbreeError(RTCError error)

{

switch(error)

{

case RTC_ERROR_NONE:

return "no error occured";

case RTC_ERROR_INVALID_ARGUMENT:

return "an unknown error has occured";

case RTC_ERROR_INVALID_OPERATION:

return "the operation is not allowed for the specified object";

case RTC_ERROR_OUT_OF_MEMORY:

return "there is not enough memory left to complete the operation";

case RTC_ERROR_UNSUPPORTED_CPU:

return "the CPU is not supported as it does not support the lowest ISA Embree is compiled for";

case RTC_ERROR_CANCELLED:

return "the operation got canceled by a memory monitor callback or progress monitor callback function";

default:

return "unknown error";

}

struct RayQueryContext

{

RTCRayQueryContext context;

unsigned int skipFacet;

};

void intersectionFilter(const RTCFilterFunctionNArguments* args);

int main()

{

RTCDevice device = rtcNewDevice("set_affinity=1");

if(device == NULL)

throw std::runtime_error("failed to create embree device: " + translateEmbreeError(rtcGetDeviceError(NULL)));

RTCScene scene = rtcNewScene(device);

RTCError error = rtcGetDeviceError(device);

if(scene == NULL)

throw std::runtime_error("failed to create embree scene: " + translateEmbreeError(error));

rtcSetSceneFlags(scene, RTC_SCENE_FLAG_FILTER_FUNCTION_IN_ARGUMENTS | RTC_SCENE_FLAG_ROBUST);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to set embree scene flags: " + translateEmbreeError(error));

RTCGeometry geom = rtcNewGeometry(device, RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE);

error = rtcGetDeviceError(device);

if(geom == NULL)

throw std::runtime_error("failed to create embree geometry: " + translateEmbreeError(error));

rtcSetGeometryEnableFilterFunctionFromArguments(geom, true);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to set embree geometry flags: " + translateEmbreeError(error));

std::vector<std::array<double, 3>> points = {

{0.0f, 0.0f, 0.0f}, {1.0f, 0.0f, 0.0f},

{1.0f, 0.0f, 0.0f}, {1.0f, -1.0f, 0.0f},

{1.0f, -1.0f, 0.0f}, {0.0f, -1.0f, 0.0f},

{0.0f, -1.0f, 0.0f}, {0.0f, 0.0f, 0.0f}

};

float* vb = static_cast<float*>(rtcSetNewGeometryBuffer(geom,

RTC_BUFFER_TYPE_VERTEX, 0, RTC_FORMAT_FLOAT4, 4*sizeof(float), points.size()));

const size_t segmentsCount = points.size()/2;

for(std::size_t s = 0 ; s < segmentsCount ; ++s)

{

//First point of segment

vb[8*s + 0] = points[2*s + 0][0];

vb[8*s + 1] = points[2*s + 0][1];

vb[8*s + 2] = 0.0f;

vb[8*s + 3] = 0.1f;

//Second point of segment

vb[8*s + 4] = points[2*s + 1][0];

vb[8*s + 5] = points[2*s + 1][1];

vb[8*s + 6] = 0.0f;

vb[8*s + 7] = 0.1f;

}

unsigned int* ib = static_cast<unsigned int*>(rtcSetNewGeometryBuffer(geom,

RTC_BUFFER_TYPE_INDEX, 0, RTC_FORMAT_UINT, sizeof(unsigned int), segmentsCount));

for(std::size_t s = 0 ; s < segmentsCount ; ++s)

ib[s] = 2*s;

rtcCommitGeometry(geom);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to commit embree geometry: " + translateEmbreeError(error));

rtcAttachGeometry(scene, geom);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to attach embree geometry: " + translateEmbreeError(error));

rtcReleaseGeometry(geom);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to release embree geoemtry: " + translateEmbreeError(error));

rtcCommitScene(scene);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

throw std::runtime_error("failed to commit embree scene: " + translateEmbreeError(error));

RTCRayHit rayHit;

rayHit.ray.org_x = 0.5f; rayHit.ray.org_y = 1.0f; rayHit.ray.org_z = 0.0f;

rayHit.ray.dir_x = 0.0f; rayHit.ray.dir_y = -1.0f; rayHit.ray.dir_z = 0.0f;

rayHit.ray.tnear = 0.0f;

rayHit.ray.tfar = std::numeric_limits<float>::infinity();

rayHit.hit.geomID = RTC_INVALID_GEOMETRY_ID;

unsigned int facetToSkip = 3000;

RayQueryContext context;

context.skipFacet = facetToSkip;

rtcInitRayQueryContext(&context.context);

RTCIntersectArguments args;

rtcInitIntersectArguments(&args);

args.context = &context.context;

args.filter = intersectionFilter;

rtcIntersect1(scene, &rayHit, &args);

if(rayHit.hit.geomID == RTC_INVALID_GEOMETRY_ID)

throw std::runtime_error("You did not intersect while you should ?");

rtcReleaseScene(scene);

error = rtcGetDeviceError(device);

if(error != RTC_ERROR_NONE)

std::cerr << "failed to delete embree scene: " + translateEmbreeError(error) << std::endl;

rtcReleaseDevice(device);

return 0;

}

void intersectionFilter(const RTCFilterFunctionNArguments* args)

{

//When Using rtcIntersect1, only one ray to filter

RTCHit* pHit = reinterpret_cast<RTCHit*>(args->hit);

RayQueryContext* context = reinterpret_cast<RayQueryContext*>(args->context);

unsigned int skipFacetUInt = context->skipFacet;

if(pHit->primID == skipFacetUInt)

args->valid[0] = 0;

else

args->valid[0] = -1;

}

Re: Is it possible to use Embree for intersection computation in 2D ?

SvenW_Intel — Wed, 10 Sep 2025 04:23:46 GMT

Please initialize all rayHit.ray members, in particular rayHit.ray.mask = -1 should be set, otherwise ray mask is likely 0 and no geometry will be hit.

Re: Is it possible to use Embree for intersection computation in 2D ?

ImperatorS79 — Fri, 19 Dec 2025 10:47:23 GMT

Sorry for the late reply, but you are right, this was my problem.

Thanks for the solution !

topic Is it possible to use Embree for intersection computation in 2D ? in Intel® Embree Ray Tracing Kernels

Is it possible to use Embree for intersection computation in 2D ?

Re: Is it possible to use Embree for intersection computation in 2D ?

Re: Is it possible to use Embree for intersection computation in 2D ?