Function derivHermite

tutorials/pathtracer/pathtracer_device.cpp:1022–1066

}

inline Vec3fa derivHermite(const ISPCHairSet* mesh, const unsigned int primID, const float u, const float time)
{
  Vec3fa p0, p1, t0, t1;
  const int i = mesh->hairs[primID].vertex;
  
  if (mesh->numTimeSteps == 1)
  {
    p0 = mesh->positions[0][i+0];
    p1 = mesh->positions[0][i+1];
    t0 = mesh->tangents[0][i+0];
    t1 = mesh->tangents[0][i+1];
  }
  else
  {
    float f = mesh->numTimeSteps*time;
    int itime = clamp((int)floor(f),0,(int)mesh->numTimeSteps-2);
    float time1 = f-itime;
    float time0 = 1.0f-time1;
    const Vec3fa ap0 = mesh->positions[itime+0][i+0];
    const Vec3fa ap1 = mesh->positions[itime+0][i+1];
    const Vec3fa at0 = mesh->tangents[itime+0][i+0];
    const Vec3fa at1 = mesh->tangents[itime+0][i+1];
    const Vec3fa bp0 = mesh->positions[itime+1][i+0];
    const Vec3fa bp1 = mesh->positions[itime+1][i+1];
    const Vec3fa bt0 = mesh->tangents[itime+1][i+0];
    const Vec3fa bt1 = mesh->tangents[itime+1][i+1];
    p0 = time0*ap0 + time1*bp0;
    p1 = time0*ap1 + time1*bp1;
    t0 = time0*at0 + time1*bt0;
    t1 = time0*at1 + time1*bt1;
  }
  const Vec3fa p00 = p0;
  const Vec3fa p01 = p0+(1.0f/3.0f)*t0;
  const Vec3fa p02 = p1-(1.0f/3.0f)*t1;
  const Vec3fa p03 = p1;
    
  const float u0 = 1.0f - u, u1 = u;
  const Vec3fa p10 = p00 * u0 + p01 * u1;
  const Vec3fa p11 = p01 * u0 + p02 * u1;
  const Vec3fa p12 = p02 * u0 + p03 * u1;
  const Vec3fa p20 = p10 * u0 + p11 * u1;
  const Vec3fa p21 = p11 * u0 + p12 * u1;
  //const Vec3fa p30 = p20 * u0 + p21 * u1;
  return Vec3fa(3.0f*(p21-p20));
}

inline Vec3fa derivBSpline(const ISPCHairSet* mesh, const unsigned int primID, const float t, const float time)
{