// ======================================================================== //
// Copyright 2009-2014 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.                                           //
// ======================================================================== //

#include "../common/tutorial/tutorial_device.h"
#include "../common/tutorial/scene_device.h"



/* scene data */
extern "C" ISPCScene* g_ispc_scene;
RTCScene g_scene = NULL;

/* render function to use */
renderPixelFunc renderPixel;

/* error reporting function */
void error_handler(const RTCError code, const int8* str)
{
  printf("Embree: ");
  switch (code) {
  case RTC_UNKNOWN_ERROR    : printf("RTC_UNKNOWN_ERROR"); break;
  case RTC_INVALID_ARGUMENT : printf("RTC_INVALID_ARGUMENT"); break;
  case RTC_INVALID_OPERATION: printf("RTC_INVALID_OPERATION"); break;
  case RTC_OUT_OF_MEMORY    : printf("RTC_OUT_OF_MEMORY"); break;
  case RTC_UNSUPPORTED_CPU  : printf("RTC_UNSUPPORTED_CPU"); break;
  default                   : printf("invalid error code"); break;
  }
  if (str) { 
    printf(" ("); 
    while (*str) putchar(*str++); 
    printf(")\n"); 
  }
  abort();
}

Vec3fa renderPixelEyeLight(float x, float y, const Vec3fa& vx, const Vec3fa& vy, const Vec3fa& vz, const Vec3fa& p);


/* called by the C++ code for initialization */
extern "C" void device_init (int8* cfg)
{
  /* initialize ray tracing core */
  rtcInit(cfg);

  /* set error handler */
  rtcSetErrorFunction(error_handler);

  /* set start render mode */
  renderPixel = renderPixelStandard;
  //renderPixel = renderPixelEyeLight;	
}

RTCScene convertScene(ISPCScene* scene_in)
{
  /* create scene */
  RTCScene scene_out = rtcNewScene(RTC_SCENE_STATIC,RTC_INTERSECT1);


  /* add all meshes to the scene */
  for (int i=0; i<scene_in->numMeshes; i++)
  {
    /* get ith mesh */
    ISPCMesh* mesh = scene_in->meshes[i];

    /* create a triangle mesh */
    unsigned int geometry = rtcNewTriangleMesh (scene_out, RTC_GEOMETRY_STATIC, mesh->numTriangles, mesh->numVertices);

    /* share vertex buffer */
    rtcSetBuffer(scene_out, geometry, RTC_VERTEX_BUFFER, mesh->positions, 0, sizeof(Vec3fa      ));
    rtcSetBuffer(scene_out, geometry, RTC_INDEX_BUFFER,  mesh->triangles, 0, sizeof(ISPCTriangle));
  }

  /* commit changes to scene */
  return scene_out;
}

/* task that renders a single screen tile */
Vec3fa renderPixelStandard(float x, float y, const Vec3fa& vx, const Vec3fa& vy, const Vec3fa& vz, const Vec3fa& p)
{
  /* initialize ray */
  RTCRay ray;
  ray.org = p;
  ray.dir = normalize(x*vx + y*vy + vz);
  ray.tnear = 0.0f;
  ray.tfar = inf;
  ray.geomID = RTC_INVALID_GEOMETRY_ID;
  ray.primID = RTC_INVALID_GEOMETRY_ID;
  ray.mask = -1;
  ray.time = 0;
  
  /* intersect ray with scene */
  rtcIntersect(g_scene,ray);
  
  /* shade background black */
  if (ray.geomID == RTC_INVALID_GEOMETRY_ID) return Vec3fa(0.0f);
  
  /* shade all rays that hit something */
  Vec3fa color = Vec3fa(0.0f);
  Vec3fa Ns = Vec3fa(0.0f);

#if 1 // FIXME: pointer gather not implemented on ISPC for Xeon Phi
  ISPCMesh* mesh = g_ispc_scene->meshes[ray.geomID];
  ISPCTriangle* tri = &mesh->triangles[ray.primID];

  /* load material ID */
  int materialID = tri->materialID;

  /* interpolate shading normal */
  if (mesh->normals) {
    Vec3fa n0 = Vec3fa(mesh->normals[tri->v0]);
    Vec3fa n1 = Vec3fa(mesh->normals[tri->v1]);
    Vec3fa n2 = Vec3fa(mesh->normals[tri->v2]);
    float u = ray.u, v = ray.v, w = 1.0f-ray.u-ray.v;
    Ns = normalize(w*n0 + u*n1 + v*n2);
  } else {
    Ns = normalize(ray.Ng);
  }

#else

  int materialID = 0;
  foreach_unique (geomID in ray.geomID) 
  {
    ISPCMesh* mesh = g_ispc_scene->meshes[geomID];
    
    foreach_unique (primID in ray.primID) 
    {
      ISPCTriangle* tri = &mesh->triangles[primID];
      
      /* load material ID */
      materialID = tri->materialID;

      /* interpolate shading normal */
      if (mesh->normals) {
        Vec3fa n0 = Vec3fa(mesh->normals[tri->v0]);
        Vec3fa n1 = Vec3fa(mesh->normals[tri->v1]);
        Vec3fa n2 = Vec3fa(mesh->normals[tri->v2]);
        float u = ray.u, v = ray.v, w = 1.0f-ray.u-ray.v;
        Ns = w*n0 + u*n1 + v*n2;
      } else {
        Ns = normalize(ray.Ng);
      }
    }
  }
  Ns = normalize(Ns);
#endif
  OBJMaterial* material = (OBJMaterial*) &g_ispc_scene->materials[materialID];
  color = Vec3fa(material->Kd);

  /* apply ambient light */
  Vec3fa Nf = faceforward(Ns,neg(ray.dir),Ns);
  //Vec3fa Ng = normalize(ray.Ng);
  //Vec3fa Nf = dot(ray.dir,Ng) < 0.0f ? Ng : neg(Ng);
  color = color*dot(ray.dir,Nf);   // FIXME: *=
  return color;
}

/* task that renders a single screen tile */
void renderTile(int taskIndex, int* pixels,
                     const int width,
                     const int height, 
                     const float time,
                     const Vec3fa& vx, 
                     const Vec3fa& vy, 
                     const Vec3fa& vz, 
                     const Vec3fa& p,
                     const int numTilesX, 
                     const int numTilesY)
{
  const int tileY = taskIndex / numTilesX;
  const int tileX = taskIndex - tileY * numTilesX;
  const int x0 = tileX * TILE_SIZE_X;
  const int x1 = min(x0+TILE_SIZE_X,width);
  const int y0 = tileY * TILE_SIZE_Y;
  const int y1 = min(y0+TILE_SIZE_Y,height);

  for (int y = y0; y<y1; y++) for (int x = x0; x<x1; x++)
  {
    /* calculate pixel color */
    Vec3fa color = renderPixel(x,y,vx,vy,vz,p);

    /* write color to framebuffer */
    unsigned int r = (unsigned int) (255.0f * clamp(color.x,0.0f,1.0f));
    unsigned int g = (unsigned int) (255.0f * clamp(color.y,0.0f,1.0f));
    unsigned int b = (unsigned int) (255.0f * clamp(color.z,0.0f,1.0f));
    pixels[y*width+x] = (b << 16) + (g << 8) + r;
  }
}

/* rtcCommitThread called by all ISPC worker threads to enable parallel build */
#if defined(PARALLEL_COMMIT)
task void parallelCommit(RTCScene scene) {
  rtcCommitThread (scene,threadIndex,threadCount); 
}
#endif

/* called by the C++ code to render */
extern "C" void device_render (int* pixels,
                           const int width,
                           const int height, 
                           const float time,
                           const Vec3fa& vx, 
                           const Vec3fa& vy, 
                           const Vec3fa& vz, 
                           const Vec3fa& p)
{
  /* create scene */
  if (g_scene == NULL)
  { 
    g_scene = convertScene(g_ispc_scene);
#if !defined(PARALLEL_COMMIT)
  rtcCommit (g_scene);
#else
  launch[ getNumHWThreads() ] parallelCommit(g_scene); 
#endif
  }

  /* render image */
  const int numTilesX = (width +TILE_SIZE_X-1)/TILE_SIZE_X;
  const int numTilesY = (height+TILE_SIZE_Y-1)/TILE_SIZE_Y;
  launch_renderTile(numTilesX*numTilesY,pixels,width,height,time,vx,vy,vz,p,numTilesX,numTilesY); 
  rtcDebug();
}

/* called by the C++ code for cleanup */
extern "C" void device_cleanup ()
{
  rtcDeleteScene (g_scene);
  rtcExit();
}