embree-hello-triangle.cpp

#define __forceinline inline

#include <iostream>

#include <embree2/rtcore.h>
#include <embree2/rtcore_ray.h>

// yuck. Required by Embree.
#include <xmmintrin.h>
#include <pmmintrin.h>

int main(int argc, char** argv)
{
    // MM_YUCK. Required by Embree.
    _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
    _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);

    RTCDevice device = rtcNewDevice(NULL);

    if (rtcDeviceGetError(device) != RTC_NO_ERROR) {
        std::cout << "Failed to create device.\n";
        return 1;
    }

    RTCScene scene = rtcDeviceNewScene(device,
            RTC_SCENE_DYNAMIC,     /* allowed to update our scene */
            RTC_INTERSECT1);    /* trace single rays, not packets */

    if (rtcDeviceGetError(device) != RTC_NO_ERROR) {
        std::cout << "Failed to create scene.\n";
        return 1;
    }
    
    // static, deformable, or dynamic
    RTCGeometryFlags geomFlags = RTC_GEOMETRY_STATIC; 
    size_t numTriangles = 1;
    size_t numVertices = 3;
    unsigned geomID = rtcNewTriangleMesh(scene, geomFlags,
                    numTriangles, numVertices, 1);

    if (rtcDeviceGetError(device) != RTC_NO_ERROR) {
        std::cout << "Failed to create geom.\n";
        return 1;
    }

    struct Vertex   { float x, y, z, a; };
    struct Triangle { int v0, v1, v2; };

    Vertex* v = (Vertex*) rtcMapBuffer(scene, geomID, RTC_VERTEX_BUFFER);
    // fill vertices here
    v[0].x = -10; v[0].y = -10; v[0].z = 10;
    v[1].x =  20; v[1].y = -10; v[1].z = 10;
    v[2].x =  20; v[2].y =  20; v[2].z = 10;
    rtcUnmapBuffer(scene, geomID, RTC_VERTEX_BUFFER);

    Triangle* t = (Triangle*) rtcMapBuffer(scene, geomID, RTC_INDEX_BUFFER);
    // fill triangle indices here
    t[0].v0 = 0;
    t[0].v1 = 1;
    t[0].v2 = 2;
    rtcUnmapBuffer(scene, geomID, RTC_INDEX_BUFFER);    
    rtcCommit(scene);

    RTCRay ray;
    ray.org[0] = 0.0;
    ray.org[1] = 0.0;
    ray.org[2] = 0.0;

    ray.dir[0] = 0.0;
    ray.dir[1] = 0.0;
    ray.dir[2] = 20.0;

    ray.tnear = 0.0;
    ray.tfar = 1.0;
    ray.geomID = RTC_INVALID_GEOMETRY_ID;

    rtcIntersect(scene, ray);

    if (rtcDeviceGetError(device) != RTC_NO_ERROR) {
        std::cout << "Query failed.\n";
        return 1;
    } else {
        std::cout << "Hit: " 
                << (ray.geomID == RTC_INVALID_GEOMETRY_ID 
                                ? -1 : (int)ray.geomID)
                << " known: " << geomID << "\n";
    }

    rtcDeleteScene(scene);
    rtcDeleteDevice(device);

    return 0;
}