// Copyright 2009-2021 Intel Corporation
// SPDX-License-Identifier: Apache-2.0

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

namespace embree {

/* configuration */
#define MIN_EDGE_LEVEL 2.0f
#define MAX_EDGE_LEVEL 64.0f
#define LEVEL_FACTOR 64.0f
#define EDGE_LEVEL 256.0f

/* scene data */
RTCScene g_scene = nullptr;

/* previous camera position */
Vec3fa old_p;

__aligned(16) float cube_vertices[8][4] =
{
  { -1.0f, -1.0f, -1.0f, 0.0f },
  {  1.0f, -1.0f, -1.0f, 0.0f },
  {  1.0f, -1.0f,  1.0f, 0.0f },
  { -1.0f, -1.0f,  1.0f, 0.0f },
  { -1.0f,  1.0f, -1.0f, 0.0f },
  {  1.0f,  1.0f, -1.0f, 0.0f },
  {  1.0f,  1.0f,  1.0f, 0.0f },
  { -1.0f,  1.0f,  1.0f, 0.0f }
};

__aligned(16) float cube_colors[8][4] =
{
  {  0.0f,  0.0f,  0.0f, 0.0f },
  {  1.0f,  0.0f,  0.0f, 0.0f },
  {  1.0f,  0.0f,  1.0f, 0.0f },
  {  0.0f,  0.0f,  1.0f, 0.0f },
  {  0.0f,  1.0f,  0.0f, 0.0f },
  {  1.0f,  1.0f,  0.0f, 0.0f },
  {  1.0f,  1.0f,  1.0f, 0.0f },
  {  0.0f,  1.0f,  1.0f, 0.0f }
};

__aligned(16) float cube_vertex_crease_weights[8] = {
  inf, inf,inf, inf, inf, inf, inf, inf
};

__aligned(16) unsigned int cube_vertex_crease_indices[8] = {
  0,1,2,3,4,5,6,7
};

__aligned(16) float cube_edge_crease_weights[12] = {
  inf, inf, inf, inf, inf, inf, inf, inf, inf, inf, inf, inf
};

__aligned(16) unsigned int cube_edge_crease_indices[24] =
{
  0,1, 1,2, 2,3, 3,0,
  4,5, 5,6, 6,7, 7,4,
  0,4, 1,5, 2,6, 3,7,
};

#if 1

#define NUM_INDICES 24
#define NUM_FACES 6
#define FACE_SIZE 4

unsigned int cube_indices[24] = {
  0, 4, 5, 1,
  1, 5, 6, 2,
  2, 6, 7, 3,
  0, 3, 7, 4,
  4, 7, 6, 5,
  0, 1, 2, 3,
};

unsigned int cube_faces[6] = {
  4, 4, 4, 4, 4, 4
};

#else

#define NUM_INDICES 36
#define NUM_FACES 12
#define FACE_SIZE 3

unsigned int cube_indices[36] = {
  1, 4, 5,  0, 4, 1,
  2, 5, 6,  1, 5, 2,
  3, 6, 7,  2, 6, 3,
  4, 3, 7,  0, 3, 4,
  5, 7, 6,  4, 7, 5,
  3, 1, 2,  0, 1, 3
};

unsigned int cube_faces[12] = {
  3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
};

#endif

/* adds a cube to the scene */
unsigned int addCube (RTCScene scene_i)
{
  /* create a triangulated cube with 6 quads and 8 vertices */
  RTCGeometry geom = rtcNewGeometry(g_device, RTC_GEOMETRY_TYPE_SUBDIVISION);

  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_VERTEX, 0, RTC_FORMAT_FLOAT3, cube_vertices, 0, sizeof(Vec3fa), 8);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_INDEX, 0, RTC_FORMAT_UINT, cube_indices, 0, sizeof(unsigned int), NUM_INDICES);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_FACE, 0, RTC_FORMAT_UINT, cube_faces, 0, sizeof(unsigned int), NUM_FACES);

  /* edge and vertex creases disabled */
#if 0  
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_EDGE_CREASE_INDEX,    0, RTC_FORMAT_UINT2, cube_edge_crease_indices,   0, 2*sizeof(unsigned int), 12);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_EDGE_CREASE_WEIGHT,   0, RTC_FORMAT_FLOAT, cube_edge_crease_weights,   0, sizeof(float), 12);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_VERTEX_CREASE_INDEX,  0, RTC_FORMAT_UINT,  cube_vertex_crease_indices, 0, sizeof(unsigned int), 8);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_VERTEX_CREASE_WEIGHT, 0, RTC_FORMAT_FLOAT, cube_vertex_crease_weights, 0, sizeof(float), 8);
#endif
  
  rtcSetGeometryVertexAttributeCount(geom,1);
  rtcSetSharedGeometryBuffer(geom, RTC_BUFFER_TYPE_VERTEX_ATTRIBUTE, 0, RTC_FORMAT_FLOAT3, cube_colors, 0, sizeof(Vec3fa), 8);

  float* level = (float*) rtcSetNewGeometryBuffer(geom, RTC_BUFFER_TYPE_LEVEL, 0, RTC_FORMAT_FLOAT, sizeof(float), NUM_INDICES);
  for (unsigned int i=0; i<NUM_INDICES; i++)
    level[i] = EDGE_LEVEL;

  rtcCommitGeometry(geom);
  unsigned int geomID = rtcAttachGeometry(scene_i, geom);
  rtcReleaseGeometry(geom);
  return geomID;
}

/* adds a ground plane to the scene */
unsigned int addGroundPlane (RTCScene scene_i)
{
  /* create a triangulated plane with 2 triangles and 4 vertices */
  RTCGeometry geom = rtcNewGeometry(g_device, RTC_GEOMETRY_TYPE_TRIANGLE);

  /* set vertices */
  Vertex* vertices = (Vertex*) rtcSetNewGeometryBuffer(geom, RTC_BUFFER_TYPE_VERTEX, 0, RTC_FORMAT_FLOAT3, sizeof(Vertex), 4);
  vertices[0].x = -10; vertices[0].y = -2; vertices[0].z = -10;
  vertices[1].x = -10; vertices[1].y = -2; vertices[1].z = +10;
  vertices[2].x = +10; vertices[2].y = -2; vertices[2].z = -10;
  vertices[3].x = +10; vertices[3].y = -2; vertices[3].z = +10;

  /* set triangles */
  Triangle* triangles = (Triangle*) rtcSetNewGeometryBuffer(geom, RTC_BUFFER_TYPE_INDEX, 0, RTC_FORMAT_UINT3, sizeof(Triangle), 2);
  triangles[0].v0 = 0; triangles[0].v1 = 1; triangles[0].v2 = 2;
  triangles[1].v0 = 1; triangles[1].v1 = 3; triangles[1].v2 = 2;

  rtcCommitGeometry(geom);
  unsigned int geomID = rtcAttachGeometry(scene_i, geom);
  rtcReleaseGeometry(geom);
  return geomID;
}

/* called by the C++ code for initialization */
extern "C" void device_init (char* cfg)
{
  /* create scene */
  g_scene = rtcNewScene(g_device);

  /* add ground plane */
  addGroundPlane(g_scene);

  /* add cube */
  addCube(g_scene);

  /* commit changes to scene */
  rtcCommitScene (g_scene);
}

/* task that renders a single screen tile */
Vec3fa renderPixelStandard(float x, float y, const ISPCCamera& camera, RayStats& stats)
{
  /* initialize ray */
  Ray ray(Vec3fa(camera.xfm.p), Vec3fa(normalize(x*camera.xfm.l.vx + y*camera.xfm.l.vy + camera.xfm.l.vz)), 0.0f, inf);

  /* intersect ray with scene */
  rtcIntersect1(g_scene,RTCRayHit_(ray));
  RayStats_addRay(stats);

  /* shade pixels */
  Vec3fa color = Vec3fa(0.0f);
  if (ray.geomID != RTC_INVALID_GEOMETRY_ID)
  {
    Vec3fa diffuse = ray.geomID != 0 ? Vec3fa(0.9f,0.6f,0.5f) : Vec3fa(0.8f,0.0f,0.0f);

    Vec3fa Ng = ray.Ng;
    if (ray.geomID > 0) {
      Vec3fa dPdu,dPdv;
      auto geomID = ray.geomID; {
        rtcInterpolate1(rtcGetGeometry(g_scene,geomID),ray.primID,ray.u,ray.v,RTC_BUFFER_TYPE_VERTEX,0,nullptr,&dPdu.x,&dPdv.x,3);
      }
      Ng = cross(dPdu,dPdv);
    }

    color = color + diffuse*0.5f;
    Vec3fa lightDir = normalize(Vec3fa(-1,-1,-1));

    /* initialize shadow ray */
    Ray shadow(ray.org + ray.tfar*ray.dir, neg(lightDir), 0.001f, inf);

    /* trace shadow ray */
    rtcOccluded1(g_scene,RTCRay_(shadow));
    RayStats_addShadowRay(stats);

    /* add light contribution */
    if (shadow.tfar >= 0.0f)
      color = color + diffuse*clamp(-dot(lightDir,normalize(Ng)),0.0f,1.0f);
  }
  return color;
}

/* renders a single screen tile */
void renderTileStandard(int taskIndex,
                        int threadIndex,
                        int* pixels,
                        const unsigned int width,
                        const unsigned int height,
                        const float time,
                        const ISPCCamera& camera,
                        const int numTilesX,
                        const int numTilesY)
{
  const unsigned int tileY = taskIndex / numTilesX;
  const unsigned int tileX = taskIndex - tileY * numTilesX;
  const unsigned int x0 = tileX * TILE_SIZE_X;
  const unsigned int x1 = min(x0+TILE_SIZE_X,width);
  const unsigned int y0 = tileY * TILE_SIZE_Y;
  const unsigned int y1 = min(y0+TILE_SIZE_Y,height);

  for (unsigned int y=y0; y<y1; y++) for (unsigned int x=x0; x<x1; x++)
  {
    /* calculate pixel color */
    Vec3fa color = renderPixelStandard((float)x,(float)y,camera,g_stats[threadIndex]);

    /* 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;
  }
}

/* task that renders a single screen tile */
void renderTileTask (int taskIndex, int threadIndex, int* pixels,
                         const unsigned int width,
                         const unsigned int height,
                         const float time,
                         const ISPCCamera& camera,
                         const int numTilesX,
                         const int numTilesY)
{
  renderTileStandard(taskIndex,threadIndex,pixels,width,height,time,camera,numTilesX,numTilesY);
}

extern "C" void renderFrameStandard (int* pixels,
                          const unsigned int width,
                          const unsigned int height,
                          const float time,
                          const ISPCCamera& camera)
{
  /* render image */
  const int numTilesX = (width +TILE_SIZE_X-1)/TILE_SIZE_X;
  const int numTilesY = (height+TILE_SIZE_Y-1)/TILE_SIZE_Y;
  parallel_for(size_t(0),size_t(numTilesX*numTilesY),[&](const range<size_t>& range) {
    const int threadIndex = (int)TaskScheduler::threadIndex();
    for (size_t i=range.begin(); i<range.end(); i++)
      renderTileTask((int)i,threadIndex,pixels,width,height,time,camera,numTilesX,numTilesY);
  }); 
}

/* called by the C++ code to render */
extern "C" void device_render (int* pixels,
                           const unsigned int width,
                           const unsigned int height,
                           const float time,
                           const ISPCCamera& camera)
{
}

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

} // namespace embree