// ======================================================================== //
// Copyright 2009-2017 Intel Corporation                                    //
//                                                                          //
// Licensed under the Apache License, Version 2.0 (the "License");          //
// you may not use this file except in compliance with the License.         //
// You may obtain a copy of the License at                                  //
//                                                                          //
//     http://www.apache.org/licenses/LICENSE-2.0                           //
//                                                                          //
// Unless required by applicable law or agreed to in writing, software      //
// distributed under the License is distributed on an "AS IS" BASIS,        //
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. //
// See the License for the specific language governing permissions and      //
// limitations under the License.                                           //
// ======================================================================== //

#pragma once

#include "primitive.h"

namespace embree
{
  /* Precalculated representation for M triangles. Stores for each
     triangle a base vertex, two edges, and the geometry normal to
     speed up intersection calculations */
  template<int M>
  struct TriangleM
  {
    typedef Vec3<vfloat<M>> Vec3vfM;

  public:
    struct Type : public PrimitiveType 
    {
      Type();
      size_t size(const char* This) const;
    };
    static Type type;
    
  public:

    /* Returns maximal number of stored triangles */
    static __forceinline size_t max_size() { return M; }
    
    /* Returns required number of primitive blocks for N primitives */
    static __forceinline size_t blocks(size_t N) { return (N+max_size()-1)/max_size(); }

  public:

    /* Default constructor */
    __forceinline TriangleM() {}

    /* Construction from vertices and IDs */
    __forceinline TriangleM(const Vec3vfM& v0, const Vec3vfM& v1, const Vec3vfM& v2, const vint<M>& geomIDs, const vint<M>& primIDs)
      : v0(v0), e1(v0-v1), e2(v2-v0), Ng(cross(e1,e2)), geomIDs(geomIDs), primIDs(primIDs) {}

    /* Returns a mask that tells which triangles are valid */
    __forceinline vbool<M> valid() const { return geomIDs != vint<M>(-1); }

    /* Returns true if the specified triangle is valid */
    __forceinline bool valid(const size_t i) const { assert(i<M); return geomIDs[i] != -1; }
    
    /* Returns the number of stored triangles */
    __forceinline size_t size() const { return __bsf(~movemask(valid()));  }

    /* Returns the geometry IDs */
    __forceinline vint<M> geomID() const { return geomIDs;  }
    __forceinline int geomID(const size_t i) const { assert(i<M); return geomIDs[i]; }

    /* Returns the primitive IDs */
    __forceinline vint<M> primID() const { return primIDs; }
    __forceinline int  primID(const size_t i) const { assert(i<M); return primIDs[i]; }

    /* Calculate the bounds of the triangle */
    __forceinline BBox3fa bounds() const 
    {
      Vec3vfM p0 = v0;
      Vec3vfM p1 = v0-e1;
      Vec3vfM p2 = v0+e2;
      Vec3vfM lower = min(p0,p1,p2);
      Vec3vfM upper = max(p0,p1,p2);
      vbool<M> mask = valid();
      lower.x = select(mask,lower.x,vfloat<M>(pos_inf));
      lower.y = select(mask,lower.y,vfloat<M>(pos_inf));
      lower.z = select(mask,lower.z,vfloat<M>(pos_inf));
      upper.x = select(mask,upper.x,vfloat<M>(neg_inf));
      upper.y = select(mask,upper.y,vfloat<M>(neg_inf));
      upper.z = select(mask,upper.z,vfloat<M>(neg_inf));
      return BBox3fa(Vec3fa(reduce_min(lower.x),reduce_min(lower.y),reduce_min(lower.z)),
                     Vec3fa(reduce_max(upper.x),reduce_max(upper.y),reduce_max(upper.z)));
    }

    /* Non temporal store */
    __forceinline static void store_nt(TriangleM* dst, const TriangleM& src)
    {
      vfloat<M>::store_nt(&dst->v0.x,src.v0.x);
      vfloat<M>::store_nt(&dst->v0.y,src.v0.y);
      vfloat<M>::store_nt(&dst->v0.z,src.v0.z);
      vfloat<M>::store_nt(&dst->e1.x,src.e1.x);
      vfloat<M>::store_nt(&dst->e1.y,src.e1.y);
      vfloat<M>::store_nt(&dst->e1.z,src.e1.z);
      vfloat<M>::store_nt(&dst->e2.x,src.e2.x);
      vfloat<M>::store_nt(&dst->e2.y,src.e2.y);
      vfloat<M>::store_nt(&dst->e2.z,src.e2.z);
      vfloat<M>::store_nt(&dst->Ng.x,src.Ng.x);
      vfloat<M>::store_nt(&dst->Ng.y,src.Ng.y);
      vfloat<M>::store_nt(&dst->Ng.z,src.Ng.z);
      vint<M>::store_nt(&dst->geomIDs,src.geomIDs);
      vint<M>::store_nt(&dst->primIDs,src.primIDs);
    }

    /* Fill triangle from triangle list */
    __forceinline void fill(const PrimRef* prims, size_t& begin, size_t end, Scene* scene)
    {
      vint<M> vgeomID = -1, vprimID = -1;
      Vec3vfM v0 = zero, v1 = zero, v2 = zero;
      
      for (size_t i=0; i<M && begin<end; i++, begin++)
      {
	const PrimRef& prim = prims[begin];
        const unsigned geomID = prim.geomID();
        const unsigned primID = prim.primID();
        const TriangleMesh* __restrict__ const mesh = scene->getTriangleMesh(geomID);
        const TriangleMesh::Triangle& tri = mesh->triangle(primID);
        const Vec3fa& p0 = mesh->vertex(tri.v[0]);
        const Vec3fa& p1 = mesh->vertex(tri.v[1]);
        const Vec3fa& p2 = mesh->vertex(tri.v[2]);
        vgeomID [i] = geomID;
        vprimID [i] = primID;
        v0.x[i] = p0.x; v0.y[i] = p0.y; v0.z[i] = p0.z;
        v1.x[i] = p1.x; v1.y[i] = p1.y; v1.z[i] = p1.z;
        v2.x[i] = p2.x; v2.y[i] = p2.y; v2.z[i] = p2.z;
      }
      TriangleM::store_nt(this,TriangleM(v0,v1,v2,vgeomID,vprimID));
    }

    /* Updates the primitive */
    __forceinline BBox3fa update(TriangleMesh* mesh)
    {
      BBox3fa bounds = empty;
      vint<M> vgeomID = -1, vprimID = -1;
      Vec3vfM v0 = zero, v1 = zero, v2 = zero;

	  for (size_t i=0; i<M; i++)
      {
        if (unlikely(geomID(i) == -1)) break;
        const unsigned geomId = geomID(i);
        const unsigned primId = primID(i);
        const TriangleMesh::Triangle& tri = mesh->triangle(primId);
        const Vec3fa p0 = mesh->vertex(tri.v[0]);
        const Vec3fa p1 = mesh->vertex(tri.v[1]);
        const Vec3fa p2 = mesh->vertex(tri.v[2]);
        bounds.extend(merge(BBox3fa(p0),BBox3fa(p1),BBox3fa(p2)));
        vgeomID [i] = geomId;
        vprimID [i] = primId;
        v0.x[i] = p0.x; v0.y[i] = p0.y; v0.z[i] = p0.z;
        v1.x[i] = p1.x; v1.y[i] = p1.y; v1.z[i] = p1.z;
        v2.x[i] = p2.x; v2.y[i] = p2.y; v2.z[i] = p2.z;
      }
      TriangleM::store_nt(this,TriangleM(v0,v1,v2,vgeomID,vprimID));
      return bounds;
    }

  public:
    Vec3vfM v0;      // base vertex of the triangles
    Vec3vfM e1;      // 1st edge of the triangles (v0-v1)
    Vec3vfM e2;      // 2nd edge of the triangles (v2-v0)
    Vec3vfM Ng;      // geometry normal of the triangles (cross(e1,e2))
    vint<M> geomIDs; // geometry IDs
    vint<M> primIDs; // primitive IDs
  };

  template<int M>
  typename TriangleM<M>::Type TriangleM<M>::type;

  typedef TriangleM<4> Triangle4;
}