Ejemplo n.º 1
0
    void BVH8iIntersector8Hybrid<TriangleIntersector8>::occluded(avxb* valid_i, BVH8i* bvh, Ray8& ray)
    {
      /* load ray */
      const avxb valid = *valid_i;
      avxb terminated = !valid;
      avx3f ray_org = ray.org, ray_dir = ray.dir;
      avxf ray_tnear = ray.tnear, ray_tfar  = ray.tfar;
#if defined(__FIX_RAYS__)
      const avxf float_range = 0.1f*FLT_MAX;
      ray_org = clamp(ray_org,avx3f(-float_range),avx3f(+float_range));
      ray_dir = clamp(ray_dir,avx3f(-float_range),avx3f(+float_range));
      ray_tnear = max(ray_tnear,FLT_MIN); 
      ray_tfar  = min(ray_tfar,float(inf)); 
#endif
      const avx3f rdir = rcp_safe(ray_dir);
      const avx3f org(ray_org), org_rdir = org * rdir;
      ray_tnear = select(valid,ray_tnear,avxf(pos_inf));
      ray_tfar  = select(valid,ray_tfar ,avxf(neg_inf));
      const avxf inf = avxf(pos_inf);
      
      /* compute near/far per ray */
      avx3i nearXYZ;
      nearXYZ.x = select(rdir.x >= 0.0f,avxi(0*(int)sizeof(avxf)),avxi(1*(int)sizeof(avxf)));
      nearXYZ.y = select(rdir.y >= 0.0f,avxi(2*(int)sizeof(avxf)),avxi(3*(int)sizeof(avxf)));
      nearXYZ.z = select(rdir.z >= 0.0f,avxi(4*(int)sizeof(avxf)),avxi(5*(int)sizeof(avxf)));

      /* allocate stack and push root node */
      avxf    stack_near[stackSizeChunk];
      NodeRef stack_node[stackSizeChunk];
      stack_node[0] = BVH4i::invalidNode;
      stack_near[0] = inf;
      stack_node[1] = bvh->root;
      stack_near[1] = ray_tnear; 
      NodeRef* stackEnd = stack_node+stackSizeChunk;
      NodeRef* __restrict__ sptr_node = stack_node + 2;
      avxf*    __restrict__ sptr_near = stack_near + 2;

      const Node     * __restrict__ nodes = (Node    *)bvh->nodePtr();
      const Triangle * __restrict__ accel = (Triangle*)bvh->triPtr();
      
      while (1)
      {
        /* pop next node from stack */
        assert(sptr_node > stack_node);
        sptr_node--;
        sptr_near--;
        NodeRef curNode = *sptr_node;
        if (unlikely(curNode == BVH4i::invalidNode)) {
          assert(sptr_node == stack_node);
          break;
        }

        /* cull node if behind closest hit point */
        avxf curDist = *sptr_near;
        const avxb active = curDist < ray_tfar;
        if (unlikely(none(active))) 
          continue;
        
        /* switch to single ray traversal */
#if !defined(__WIN32__) || defined(__X86_64__)
        size_t bits = movemask(active);
        if (unlikely(__popcnt(bits) <= SWITCH_THRESHOLD)) {
          for (size_t i=__bsf(bits); bits!=0; bits=__btc(bits,i), i=__bsf(bits)) {
            if (occluded1(bvh,curNode,i,ray,ray_org,ray_dir,rdir,ray_tnear,ray_tfar,nearXYZ))
              terminated[i] = -1;
          }
          if (all(terminated)) break;
          ray_tfar = select(terminated,avxf(neg_inf),ray_tfar);
          continue;
        }
#endif
                
        while (1)
        {
          /* test if this is a leaf node */
          if (unlikely(curNode.isLeaf()))
            break;
          
          const avxb valid_node = ray_tfar > curDist;
          STAT3(shadow.trav_nodes,1,popcnt(valid_node),8);
          const Node* __restrict__ const node = (Node*)curNode.node(nodes);
          
          /* pop of next node */
          assert(sptr_node > stack_node);
          sptr_node--;
          sptr_near--;
          curNode = *sptr_node;
          curDist = *sptr_near;
          
          for (unsigned i=0; i<8; i++)
          {
            const NodeRef child = node->children[i];
            if (unlikely(child == BVH4i::emptyNode)) break;
            
#if defined(__AVX2__)
            const avxf lclipMinX = msub(node->lower_x[i],rdir.x,org_rdir.x);
            const avxf lclipMinY = msub(node->lower_y[i],rdir.y,org_rdir.y);
            const avxf lclipMinZ = msub(node->lower_z[i],rdir.z,org_rdir.z);
            const avxf lclipMaxX = msub(node->upper_x[i],rdir.x,org_rdir.x);
            const avxf lclipMaxY = msub(node->upper_y[i],rdir.y,org_rdir.y);
            const avxf lclipMaxZ = msub(node->upper_z[i],rdir.z,org_rdir.z);
            const avxf lnearP = maxi(maxi(mini(lclipMinX, lclipMaxX), mini(lclipMinY, lclipMaxY)), mini(lclipMinZ, lclipMaxZ));
            const avxf lfarP  = mini(mini(maxi(lclipMinX, lclipMaxX), maxi(lclipMinY, lclipMaxY)), maxi(lclipMinZ, lclipMaxZ));
            const avxb lhit   = maxi(lnearP,ray_tnear) <= mini(lfarP,ray_tfar);      
#else
            const avxf lclipMinX = (node->lower_x[i] - org.x) * rdir.x;
            const avxf lclipMinY = (node->lower_y[i] - org.y) * rdir.y;
            const avxf lclipMinZ = (node->lower_z[i] - org.z) * rdir.z;
            const avxf lclipMaxX = (node->upper_x[i] - org.x) * rdir.x;
            const avxf lclipMaxY = (node->upper_y[i] - org.y) * rdir.y;
            const avxf lclipMaxZ = (node->upper_z[i] - org.z) * rdir.z;
            const avxf lnearP = max(max(min(lclipMinX, lclipMaxX), min(lclipMinY, lclipMaxY)), min(lclipMinZ, lclipMaxZ));
            const avxf lfarP  = min(min(max(lclipMinX, lclipMaxX), max(lclipMinY, lclipMaxY)), max(lclipMinZ, lclipMaxZ));
            const avxb lhit   = max(lnearP,ray_tnear) <= min(lfarP,ray_tfar);      
#endif
            
            /* if we hit the child we choose to continue with that child if it 
               is closer than the current next child, or we push it onto the stack */
            if (likely(any(lhit)))
            {
              assert(sptr_node < stackEnd);
              assert(child != BVH4i::emptyNode);
              const avxf childDist = select(lhit,lnearP,inf);
              sptr_node++;
              sptr_near++;
              
              /* push cur node onto stack and continue with hit child */
              if (any(childDist < curDist))
              {
                *(sptr_node-1) = curNode;
                *(sptr_near-1) = curDist; 
                curDist = childDist;
                curNode = child;
              }
              
              /* push hit child onto stack */
              else {
                *(sptr_node-1) = child;
                *(sptr_near-1) = childDist; 
              }
            }	      
          }
        }
        
        /* return if stack is empty */
        if (unlikely(curNode == BVH4i::invalidNode)) {
          assert(sptr_node == stack_node);
          break;
        }
        
        /* intersect leaf */
        const avxb valid_leaf = ray_tfar > curDist;
        STAT3(shadow.trav_leaves,1,popcnt(valid_leaf),8);
        size_t items; const Triangle* prim = (Triangle*) curNode.leaf(accel,items);
        terminated |= TriangleIntersector8::occluded(!terminated,ray,prim,items,bvh->geometry);
        if (all(terminated)) break;
        ray_tfar = select(terminated,avxf(neg_inf),ray_tfar);
      }
      store8i(valid & terminated,&ray.geomID,0);
      AVX_ZERO_UPPER();
    }
Ejemplo n.º 2
0
  __forceinline bool occludedT(const BVH4* bvh, Ray& ray)
  {
    typedef typename TriangleIntersector::Triangle Triangle;
    typedef StackItemT<size_t> StackItem;
    typedef typename BVH4::NodeRef NodeRef;
    typedef typename BVH4::Node Node;

    /*! stack state */
    NodeRef stack[1+3*BVH4::maxDepth];  //!< stack of nodes that still need to get traversed
    NodeRef* stackPtr = stack+1;        //!< current stack pointer
    stack[0]  = bvh->root;
  
    /*! load the ray into SIMD registers */
    const avxf pos_neg = avxf(ssef(+0.0f),ssef(-0.0f));
    const avxf neg_pos = avxf(ssef(-0.0f),ssef(+0.0f));
    const avxf flipSignX = swapX ? neg_pos : pos_neg;
    const avxf flipSignY = swapY ? neg_pos : pos_neg;
    const avxf flipSignZ = swapZ ? neg_pos : pos_neg;
    const avx3f norg(-ray.org.x,-ray.org.y,-ray.org.z);
    const Vector3f ray_rdir = rcp_safe(ray.dir);
    const avx3f rdir(ray_rdir.x^flipSignX,ray_rdir.y^flipSignY,ray_rdir.z^flipSignZ);
    const avx3f org_rdir(avx3f(ray.org.x,ray.org.y,ray.org.z)*rdir);
    const avxf rayNearFar(ssef(ray.tnear),-ssef(ray.tfar));

    const void* nodePtr = bvh->nodePtr();
    const void* triPtr  = bvh->triPtr();
    
    /* pop loop */
    while (true) pop:
    {
      /*! pop next node */
      if (unlikely(stackPtr == stack)) break;
      stackPtr--;
      NodeRef cur = (NodeRef) *stackPtr;
      
      /* downtraversal loop */
      while (true)
      {
        /*! stop if we found a leaf */
        if (unlikely(cur.isLeaf())) break;
        STAT3(shadow.trav_nodes,1,1,1);
	
        /*! single ray intersection with 4 boxes */
        const Node* node = cur.node(nodePtr);
       
#if defined (__AVX2__) || defined(__MIC__)
        const avxf tLowerUpperX = msub(avxf::load(&node->lower_x), rdir.x, org_rdir.x);
        const avxf tLowerUpperY = msub(avxf::load(&node->lower_y), rdir.y, org_rdir.y);
        const avxf tLowerUpperZ = msub(avxf::load(&node->lower_z), rdir.z, org_rdir.z);
#else
        const avxf tLowerUpperX = (norg.x + avxf::load(&node->lower_x)) * rdir.x;
        const avxf tLowerUpperY = (norg.y + avxf::load(&node->lower_y)) * rdir.y;
        const avxf tLowerUpperZ = (norg.z + avxf::load(&node->lower_z)) * rdir.z;
#endif
        const avxf tNearFarX = swapX ? shuffle<1,0>(tLowerUpperX) : tLowerUpperX;
        const avxf tNearFarY = swapY ? shuffle<1,0>(tLowerUpperY) : tLowerUpperY;
        const avxf tNearFarZ = swapZ ? shuffle<1,0>(tLowerUpperZ) : tLowerUpperZ;
        const avxf tNearFar = max(tNearFarX,tNearFarY,tNearFarZ,rayNearFar);
        const ssef tNear = extract<0>(tNearFar);
        const ssef tFar  = extract<1>(tNearFar);
        size_t mask = movemask(-tNear >= tFar);
        
        /*! if no child is hit, pop next node */
        if (unlikely(mask == 0))
          goto pop;

        /*! one child is hit, continue with that child */
        size_t r = __bsf(mask); mask = __btc(mask,r);
        if (likely(mask == 0)) {
          cur = node->child(r);
          continue;
        }

        /*! two children are hit, push far child, and continue with closer child */
        NodeRef c0 = node->child(r); const float d0 = tNear[r];
        r = __bsf(mask); mask = __btc(mask,r);
        NodeRef c1 = node->child(r); const float d1 = tNear[r];
        if (likely(mask == 0)) {
          if (d0 < d1) { *stackPtr = c1; stackPtr++; cur = c0; continue; }
          else         { *stackPtr = c0; stackPtr++; cur = c1; continue; }
        }
        *stackPtr = c0; stackPtr++;
        *stackPtr = c1; stackPtr++;

        /*! three children are hit */
        r = __bsf(mask); mask = __btc(mask,r);
        cur = node->child(r); *stackPtr = cur; stackPtr++;
        if (likely(mask == 0)) {
          stackPtr--;
          continue;
        }

        /*! four children are hit */
        cur = node->child(3);
      }

      /*! this is a leaf node */
      STAT3(shadow.trav_leaves,1,1,1);
      size_t num; Triangle* tri = (Triangle*) cur.leaf(triPtr,num);
      for (size_t i=0; i<num; i++) {
        if (TriangleIntersector::occluded(ray,tri[i],bvh->vertices)) {
          AVX_ZERO_UPPER();
          return true;
        }
      }
    }
   
    AVX_ZERO_UPPER();
    return false;
  }
Ejemplo n.º 3
0
  __forceinline void intersectT(const BVH4* bvh, Ray& ray)
  {
    typedef typename TriangleIntersector::Triangle Triangle;
    typedef StackItemT<size_t> StackItem;
    typedef typename BVH4::NodeRef NodeRef;
    typedef typename BVH4::Node Node;

    /*! stack state */
    StackItem stack[1+3*BVH4::maxDepth];  //!< stack of nodes 
    StackItem* stackPtr = stack+1;        //!< current stack pointer
    stack[0].ptr  = bvh->root;
    stack[0].dist = neg_inf;

    /*! load the ray into SIMD registers */
    const avxf pos_neg = avxf(ssef(+0.0f),ssef(-0.0f));
    const avxf neg_pos = avxf(ssef(-0.0f),ssef(+0.0f));
    const avxf flipSignX = swapX ? neg_pos : pos_neg;
    const avxf flipSignY = swapY ? neg_pos : pos_neg;
    const avxf flipSignZ = swapZ ? neg_pos : pos_neg;
    const Vector3f ray_rdir = rcp_safe(ray.dir);
    const avx3f norg(-ray.org.x,-ray.org.y,-ray.org.z);
    const avx3f rdir(ray_rdir.x^flipSignX,ray_rdir.y^flipSignY,ray_rdir.z^flipSignZ);
    const avx3f org_rdir(avx3f(ray.org.x,ray.org.y,ray.org.z)*rdir);
    avxf rayNearFar(ssef(ray.tnear),-ssef(ray.tfar));

    const void* nodePtr = bvh->nodePtr();
    const void* triPtr  = bvh->triPtr();
     
    /* pop loop */
    while (true) pop:
    {
      /*! pop next node */
      if (unlikely(stackPtr == stack)) break;
      stackPtr--;
      NodeRef cur = NodeRef(stackPtr->ptr);
      
      /*! if popped node is too far, pop next one */
      if (unlikely(stackPtr->dist > ray.tfar))
        continue;

      /* downtraversal loop */
      while (true)
      {
        /*! stop if we found a leaf */
        if (unlikely(cur.isLeaf())) break;
        STAT3(normal.trav_nodes,1,1,1);

        /*! single ray intersection with 4 boxes */
        const Node* node = cur.node(nodePtr);

#if defined (__AVX2__) || defined(__MIC__)
        const avxf tLowerUpperX = msub(avxf::load(&node->lower_x), rdir.x, org_rdir.x);
        const avxf tLowerUpperY = msub(avxf::load(&node->lower_y), rdir.y, org_rdir.y);
        const avxf tLowerUpperZ = msub(avxf::load(&node->lower_z), rdir.z, org_rdir.z);
#else
        const avxf tLowerUpperX = (norg.x + avxf::load(&node->lower_x)) * rdir.x;
        const avxf tLowerUpperY = (norg.y + avxf::load(&node->lower_y)) * rdir.y;
        const avxf tLowerUpperZ = (norg.z + avxf::load(&node->lower_z)) * rdir.z;
#endif
        const avxf tNearFarX = swapX ? shuffle<1,0>(tLowerUpperX) : tLowerUpperX;
        const avxf tNearFarY = swapY ? shuffle<1,0>(tLowerUpperY) : tLowerUpperY;
        const avxf tNearFarZ = swapZ ? shuffle<1,0>(tLowerUpperZ) : tLowerUpperZ;
        const avxf tNearFar = max(tNearFarX,tNearFarY,tNearFarZ,rayNearFar);
        const ssef tNear = extract<0>(tNearFar);
        const ssef tFar  = extract<1>(tNearFar);
        size_t mask = movemask(-tNear >= tFar);
                
        /*! if no child is hit, pop next node */
        if (unlikely(mask == 0))
          goto pop;

        /*! one child is hit, continue with that child */
        size_t r = __bsf(mask); mask = __btc(mask,r);
        if (likely(mask == 0)) {
          cur = node->child(r);
          continue;
        }

        /*! two children are hit, push far child, and continue with closer child */
        NodeRef c0 = node->child(r); const float d0 = tNear[r];
        r = __bsf(mask); mask = __btc(mask,r);
        NodeRef c1 = node->child(r); const float d1 = tNear[r];
        if (likely(mask == 0)) {
          if (d0 < d1) { stackPtr->ptr = c1; stackPtr->dist = d1; stackPtr++; cur = c0; continue; }
          else         { stackPtr->ptr = c0; stackPtr->dist = d0; stackPtr++; cur = c1; continue; }
        }

        /*! Here starts the slow path for 3 or 4 hit children. We push
         *  all nodes onto the stack to sort them there. */
        stackPtr->ptr = c0; stackPtr->dist = d0; stackPtr++;
        stackPtr->ptr = c1; stackPtr->dist = d1; stackPtr++;

        /*! three children are hit, push all onto stack and sort 3 stack items, continue with closest child */
        r = __bsf(mask); mask = __btc(mask,r);
        NodeRef c = node->child(r); float d = tNear[r]; stackPtr->ptr = c; stackPtr->dist = d; stackPtr++;
        if (likely(mask == 0)) {
          sort(stackPtr[-1],stackPtr[-2],stackPtr[-3]);
          cur = (NodeRef) stackPtr[-1].ptr; stackPtr--;
          continue;
        }

        /*! four children are hit, push all onto stack and sort 4 stack items, continue with closest child */
        r = __bsf(mask); mask = __btc(mask,r);
        c = node->child(r); d = tNear[r]; stackPtr->ptr = c; stackPtr->dist = d; stackPtr++;
        sort(stackPtr[-1],stackPtr[-2],stackPtr[-3],stackPtr[-4]);
        cur = (NodeRef) stackPtr[-1].ptr; stackPtr--;
      }

      /*! this is a leaf node */
      STAT3(normal.trav_leaves,1,1,1);
      size_t num; Triangle* tri = (Triangle*) cur.leaf(triPtr,num);
      for (size_t i=0; i<num; i++)
        TriangleIntersector::intersect(ray,tri[i],bvh->vertices);
      
      rayNearFar = insert<1>(rayNearFar,-ssef(ray.tfar));
    }
  }
Ejemplo n.º 4
0
    void BVH4Intersector8Hybrid<PrimitiveIntersector8>::intersect(avxb* valid_i, BVH4* bvh, Ray8& ray)
    {
      /* load ray */
      const avxb valid0 = *valid_i;
      avx3f ray_org = ray.org, ray_dir = ray.dir;
      avxf ray_tnear = ray.tnear, ray_tfar  = ray.tfar;
#if defined(__FIX_RAYS__)
      const avxf float_range = 1.8E19;
      ray_org = clamp(ray_org,avx3f(-float_range),avx3f(+float_range));
      ray_dir = clamp(ray_dir,avx3f(-float_range),avx3f(+float_range));
      ray_tnear = max(ray_tnear,FLT_MIN); 
      ray_tfar  = min(ray_tfar,float(inf)); 
#endif
      const avx3f rdir = rcp_safe(ray_dir);
      const avx3f org(ray_org), org_rdir = org * rdir;
      ray_tnear = select(valid0,ray_tnear,avxf(pos_inf));
      ray_tfar  = select(valid0,ray_tfar ,avxf(neg_inf));
      const avxf inf = avxf(pos_inf);

      /* allocate stack and push root node */
      avxf    stack_near[stackSizeChunk];
      NodeRef stack_node[stackSizeChunk];
      stack_node[0] = BVH4::invalidNode;
      stack_near[0] = inf;
      stack_node[1] = bvh->root;
      stack_near[1] = ray_tnear; 
      NodeRef* stackEnd = stack_node+stackSizeChunk;
      NodeRef* __restrict__ sptr_node = stack_node + 2;
      avxf*    __restrict__ sptr_near = stack_near + 2;
      
      while (1)
      {
        /* pop next node from stack */
        assert(sptr_node > stack_node);
        sptr_node--;
        sptr_near--;
        NodeRef curNode = *sptr_node;
        if (unlikely(curNode == BVH4::invalidNode)) {
          assert(sptr_node == stack_node);
          break;
        }
        
        /* cull node if behind closest hit point */
        avxf curDist = *sptr_near;
        const avxb active = curDist < ray_tfar;
        if (unlikely(none(active)))
          continue;
        
        /* switch to single ray traversal */
#if !defined(__WIN32__) || defined(__X86_64__)
        size_t bits = movemask(active);
        if (unlikely(__popcnt(bits) <= SWITCH_THRESHOLD)) {
          for (size_t i=__bsf(bits); bits!=0; bits=__btc(bits,i), i=__bsf(bits)) {
            intersect1(bvh,curNode,i,ray,ray_org,ray_dir,rdir,ray_tnear,ray_tfar);
          }
          ray_tfar = ray.tfar;
          continue;
        }
#endif

        while (1)
        {
          /* test if this is a leaf node */
          if (unlikely(curNode.isLeaf()))
            break;
          
          const avxb valid_node = ray_tfar > curDist;
          STAT3(normal.trav_nodes,1,popcnt(valid_node),8);
          const Node* __restrict__ const node = curNode.node();
          
          /* pop of next node */
          assert(sptr_node > stack_node);
          sptr_node--;
          sptr_near--;
          curNode = *sptr_node;
          curDist = *sptr_near;
          
#pragma unroll(4)
          for (unsigned i=0; i<4; i++)
          {
            const NodeRef child = node->children[i];
            if (unlikely(child == BVH4::emptyNode)) break;
            
#if defined(__AVX2__)
            const avxf lclipMinX = msub(node->lower_x[i],rdir.x,org_rdir.x);
            const avxf lclipMinY = msub(node->lower_y[i],rdir.y,org_rdir.y);
            const avxf lclipMinZ = msub(node->lower_z[i],rdir.z,org_rdir.z);
            const avxf lclipMaxX = msub(node->upper_x[i],rdir.x,org_rdir.x);
            const avxf lclipMaxY = msub(node->upper_y[i],rdir.y,org_rdir.y);
            const avxf lclipMaxZ = msub(node->upper_z[i],rdir.z,org_rdir.z);
            const avxf lnearP = maxi(maxi(mini(lclipMinX, lclipMaxX), mini(lclipMinY, lclipMaxY)), mini(lclipMinZ, lclipMaxZ));
            const avxf lfarP  = mini(mini(maxi(lclipMinX, lclipMaxX), maxi(lclipMinY, lclipMaxY)), maxi(lclipMinZ, lclipMaxZ));
            const avxb lhit   = maxi(lnearP,ray_tnear) <= mini(lfarP,ray_tfar);      
#else
            const avxf lclipMinX = (node->lower_x[i] - org.x) * rdir.x;
            const avxf lclipMinY = (node->lower_y[i] - org.y) * rdir.y;
            const avxf lclipMinZ = (node->lower_z[i] - org.z) * rdir.z;
            const avxf lclipMaxX = (node->upper_x[i] - org.x) * rdir.x;
            const avxf lclipMaxY = (node->upper_y[i] - org.y) * rdir.y;
            const avxf lclipMaxZ = (node->upper_z[i] - org.z) * rdir.z;
            const avxf lnearP = max(max(min(lclipMinX, lclipMaxX), min(lclipMinY, lclipMaxY)), min(lclipMinZ, lclipMaxZ));
            const avxf lfarP  = min(min(max(lclipMinX, lclipMaxX), max(lclipMinY, lclipMaxY)), max(lclipMinZ, lclipMaxZ));
            const avxb lhit   = max(lnearP,ray_tnear) <= min(lfarP,ray_tfar);      
#endif
            
            /* if we hit the child we choose to continue with that child if it 
               is closer than the current next child, or we push it onto the stack */
            if (likely(any(lhit)))
            {
              assert(sptr_node < stackEnd);
              const avxf childDist = select(lhit,lnearP,inf);
              const NodeRef child = node->children[i];
              assert(child != BVH4::emptyNode);
              sptr_node++;
              sptr_near++;
              
              /* push cur node onto stack and continue with hit child */
              if (any(childDist < curDist))
              {
                *(sptr_node-1) = curNode;
                *(sptr_near-1) = curDist; 
                curDist = childDist;
                curNode = child;
              }
              
              /* push hit child onto stack */
              else {
                *(sptr_node-1) = child;
                *(sptr_near-1) = childDist; 
              }
            }	      
          }
        }
        
        /* return if stack is empty */
        if (unlikely(curNode == BVH4::invalidNode)) {
          assert(sptr_node == stack_node);
          break;
        }
        
        /* intersect leaf */
        const avxb valid_leaf = ray_tfar > curDist;
        STAT3(normal.trav_leaves,1,popcnt(valid_leaf),8);
        size_t items; const Primitive* prim = (Primitive*) curNode.leaf(items);
        PrimitiveIntersector8::intersect(valid_leaf,ray,prim,items,bvh->geometry);
        ray_tfar = select(valid_leaf,ray.tfar,ray_tfar);
      }
      AVX_ZERO_UPPER();
    }