/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2005 Blender Foundation.
 * All rights reserved.
 */

/** \file
 * \ingroup gpu
 *
 * Mesh drawing using OpenGL VBO (Vertex Buffer Objects)
 */

#include <limits.h>
#include <stddef.h>
#include <string.h>

#include "MEM_guardedalloc.h"

#include "BLI_bitmap.h"
#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_ghash.h"

#include "DNA_meshdata_types.h"

#include "BKE_ccg.h"
#include "BKE_DerivedMesh.h"
#include "BKE_paint.h"
#include "BKE_mesh.h"
#include "BKE_pbvh.h"

#include "GPU_buffers.h"
#include "GPU_draw.h"
#include "GPU_immediate.h"
#include "GPU_batch.h"

#include "bmesh.h"

/* XXX: the rest of the code in this file is used for optimized PBVH
 * drawing and doesn't interact at all with the buffer code above */

struct GPU_PBVH_Buffers {
  GPUIndexBuf *index_buf, *index_buf_fast;
  GPUIndexBuf *index_lines_buf, *index_lines_buf_fast;
  GPUVertBuf *vert_buf;

  GPUBatch *lines;
  GPUBatch *lines_fast;
  GPUBatch *triangles;
  GPUBatch *triangles_fast;

  /* mesh pointers in case buffer allocation fails */
  const MPoly *mpoly;
  const MLoop *mloop;
  const MLoopTri *looptri;
  const MVert *mvert;

  const int *face_indices;
  int face_indices_len;

  /* grid pointers */
  CCGKey gridkey;
  CCGElem **grids;
  const DMFlagMat *grid_flag_mats;
  BLI_bitmap *const *grid_hidden;
  const int *grid_indices;
  int totgrid;

  bool use_bmesh;

  uint tot_tri, tot_quad;

  short material_index;

  /* The PBVH ensures that either all faces in the node are
   * smooth-shaded or all faces are flat-shaded */
  bool smooth;

  bool show_mask;
};

static struct {
  uint pos, nor, msk, col;
} g_vbo_id = {0};

/** \} */

/* -------------------------------------------------------------------- */
/** \name PBVH Utils
 * \{ */

/* Allocates a non-initialized buffer to be sent to GPU.
 * Return is false it indicates that the memory map failed. */
static bool gpu_pbvh_vert_buf_data_set(GPU_PBVH_Buffers *buffers, uint vert_len)
{
  /* Keep so we can test #GPU_USAGE_DYNAMIC buffer use.
   * Not that format initialization match in both blocks.
   * Do this to keep braces balanced - otherwise indentation breaks. */
#if 0
  if (buffers->vert_buf == NULL) {
    /* Initialize vertex buffer (match 'VertexBufferFormat'). */
    static GPUVertFormat format = {0};
    if (format.attr_len == 0) {
      g_vbo_id.pos = GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
      g_vbo_id.nor = GPU_vertformat_attr_add(
          &format, "nor", GPU_COMP_I16, 3, GPU_FETCH_INT_TO_FLOAT_UNIT);
      g_vbo_id.msk = GPU_vertformat_attr_add(&format, "msk", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
    }
    buffers->vert_buf = GPU_vertbuf_create_with_format_ex(&format, GPU_USAGE_DYNAMIC);
    GPU_vertbuf_data_alloc(buffers->vert_buf, vert_len);
  }
  else if (vert_len != buffers->vert_buf->vertex_len) {
    GPU_vertbuf_data_resize(buffers->vert_buf, vert_len);
  }
#else
  if (buffers->vert_buf == NULL) {
    /* Initialize vertex buffer (match 'VertexBufferFormat'). */
    static GPUVertFormat format = {0};
    if (format.attr_len == 0) {
      g_vbo_id.pos = GPU_vertformat_attr_add(&format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
      g_vbo_id.nor = GPU_vertformat_attr_add(
          &format, "nor", GPU_COMP_I16, 3, GPU_FETCH_INT_TO_FLOAT_UNIT);
      /* TODO: Do not allocate these `.msk` and `.col` when they are not used. */
      g_vbo_id.msk = GPU_vertformat_attr_add(&format, "msk", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
      g_vbo_id.col = GPU_vertformat_attr_add(
          &format, "ac", GPU_COMP_U8, 4, GPU_FETCH_INT_TO_FLOAT_UNIT);
    }
    buffers->vert_buf = GPU_vertbuf_create_with_format_ex(&format, GPU_USAGE_STATIC);
  }
  GPU_vertbuf_data_alloc(buffers->vert_buf, vert_len);
#endif
  return buffers->vert_buf->data != NULL;
}

static void gpu_pbvh_batch_init(GPU_PBVH_Buffers *buffers, GPUPrimType prim)
{
  /* force flushing to the GPU */
  if (buffers->vert_buf->data) {
    GPU_vertbuf_use(buffers->vert_buf);
  }

  if (buffers->triangles == NULL) {
    buffers->triangles = GPU_batch_create(prim,
                                          buffers->vert_buf,
                                          /* can be NULL if buffer is empty */
                                          buffers->index_buf);
  }

  if ((buffers->triangles_fast == NULL) && buffers->index_buf_fast) {
    buffers->triangles_fast = GPU_batch_create(prim, buffers->vert_buf, buffers->index_buf_fast);
  }

  if (buffers->lines == NULL) {
    buffers->lines = GPU_batch_create(GPU_PRIM_LINES,
                                      buffers->vert_buf,
                                      /* can be NULL if buffer is empty */
                                      buffers->index_lines_buf);
  }

  if ((buffers->lines_fast == NULL) && buffers->index_lines_buf_fast) {
    buffers->lines_fast = GPU_batch_create(
        GPU_PRIM_LINES, buffers->vert_buf, buffers->index_lines_buf_fast);
  }
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Mesh PBVH
 * \{ */

void GPU_pbvh_mesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                  const MVert *mvert,
                                  const int *vert_indices,
                                  int totvert,
                                  const float *vmask,
                                  const MLoopCol *vcol,
                                  const int (*face_vert_indices)[3],
                                  const int update_flags)
{
  const bool show_mask = (update_flags & GPU_PBVH_BUFFERS_SHOW_MASK) != 0;
  const bool show_vcol = (update_flags & GPU_PBVH_BUFFERS_SHOW_VCOL) != 0;
  bool empty_mask = true;

  {
    int totelem = (buffers->smooth ? totvert : (buffers->tot_tri * 3));

    /* Build VBO */
    if (gpu_pbvh_vert_buf_data_set(buffers, totelem)) {
      /* Vertex data is shared if smooth-shaded, but separate
       * copies are made for flat shading because normals
       * shouldn't be shared. */
      if (buffers->smooth) {
        for (uint i = 0; i < totvert; ++i) {
          const MVert *v = &mvert[vert_indices[i]];
          GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, i, v->co);
          GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, i, v->no);
        }

        if (vmask && show_mask) {
          for (uint i = 0; i < buffers->face_indices_len; i++) {
            const MLoopTri *lt = &buffers->looptri[buffers->face_indices[i]];
            for (uint j = 0; j < 3; j++) {
              int vidx = face_vert_indices[i][j];
              int v_index = buffers->mloop[lt->tri[j]].v;
              float fmask = vmask[v_index];
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vidx, &fmask);
              empty_mask = empty_mask && (fmask == 0.0f);
            }
          }
        }

        if (vcol && show_vcol) {
          for (uint i = 0; i < buffers->face_indices_len; i++) {
            const MLoopTri *lt = &buffers->looptri[buffers->face_indices[i]];
            for (int j = 0; j < 3; j++) {
              const int loop_index = lt->tri[j];
              const int vidx = face_vert_indices[i][j];
              const uchar *elem = &vcol[loop_index].r;
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vidx, elem);
            }
          }
        }
      }
      else {
        /* calculate normal for each polygon only once */
        uint mpoly_prev = UINT_MAX;
        short no[3];
        int vbo_index = 0;

        for (uint i = 0; i < buffers->face_indices_len; i++) {
          const MLoopTri *lt = &buffers->looptri[buffers->face_indices[i]];
          const uint vtri[3] = {
              buffers->mloop[lt->tri[0]].v,
              buffers->mloop[lt->tri[1]].v,
              buffers->mloop[lt->tri[2]].v,
          };

          if (paint_is_face_hidden(lt, mvert, buffers->mloop)) {
            continue;
          }

          /* Face normal and mask */
          if (lt->poly != mpoly_prev) {
            const MPoly *mp = &buffers->mpoly[lt->poly];
            float fno[3];
            BKE_mesh_calc_poly_normal(mp, &buffers->mloop[mp->loopstart], mvert, fno);
            normal_float_to_short_v3(no, fno);
            mpoly_prev = lt->poly;
          }

          float fmask = 0.0f;
          if (vmask && show_mask) {
            fmask = (vmask[vtri[0]] + vmask[vtri[1]] + vmask[vtri[2]]) / 3.0f;
          }

          for (uint j = 0; j < 3; j++) {
            const MVert *v = &mvert[vtri[j]];

            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, vbo_index, v->co);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index, no);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &fmask);

            if (vcol && show_vcol) {
              const uint loop_index = lt->tri[j];
              const uchar *elem = &vcol[loop_index].r;
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, elem);
            }

            vbo_index++;
          }

          empty_mask = empty_mask && (fmask == 0.0f);
        }
      }

      gpu_pbvh_batch_init(buffers, GPU_PRIM_TRIS);
    }
  }

  /* Get material index from the first face of this buffer. */
  const MLoopTri *lt = &buffers->looptri[buffers->face_indices[0]];
  const MPoly *mp = &buffers->mpoly[lt->poly];
  buffers->material_index = mp->mat_nr;

  buffers->show_mask = !empty_mask;
  buffers->mvert = mvert;
}

GPU_PBVH_Buffers *GPU_pbvh_mesh_buffers_build(const int (*face_vert_indices)[3],
                                              const MPoly *mpoly,
                                              const MLoop *mloop,
                                              const MLoopTri *looptri,
                                              const MVert *mvert,
                                              const int *face_indices,
                                              const int face_indices_len)
{
  GPU_PBVH_Buffers *buffers;
  int i, tottri;

  buffers = MEM_callocN(sizeof(GPU_PBVH_Buffers), "GPU_Buffers");

  /* smooth or flat for all */
  buffers->smooth = mpoly[looptri[face_indices[0]].poly].flag & ME_SMOOTH;

  buffers->show_mask = false;

  /* Count the number of visible triangles */
  for (i = 0, tottri = 0; i < face_indices_len; ++i) {
    const MLoopTri *lt = &looptri[face_indices[i]];
    if (!paint_is_face_hidden(lt, mvert, mloop)) {
      tottri++;
    }
  }

  if (tottri == 0) {
    buffers->tot_tri = 0;

    buffers->mpoly = mpoly;
    buffers->mloop = mloop;
    buffers->looptri = looptri;
    buffers->face_indices = face_indices;
    buffers->face_indices_len = 0;

    return buffers;
  }

  GPU_BATCH_DISCARD_SAFE(buffers->triangles);
  GPU_BATCH_DISCARD_SAFE(buffers->lines);
  GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
  GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);

  /* An element index buffer is used for smooth shading, but flat
   * shading requires separate vertex normals so an index buffer
   * can't be used there. */
  if (buffers->smooth) {
    /* Fill the triangle and line buffers. */
    GPUIndexBufBuilder elb, elb_lines;
    GPU_indexbuf_init(&elb, GPU_PRIM_TRIS, tottri, INT_MAX);
    GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, tottri * 3, INT_MAX);

    for (i = 0; i < face_indices_len; ++i) {
      const MLoopTri *lt = &looptri[face_indices[i]];

      /* Skip hidden faces */
      if (paint_is_face_hidden(lt, mvert, mloop)) {
        continue;
      }

      GPU_indexbuf_add_tri_verts(&elb, UNPACK3(face_vert_indices[i]));

      /* TODO skip "non-real" edges. */
      GPU_indexbuf_add_line_verts(&elb_lines, face_vert_indices[i][0], face_vert_indices[i][1]);
      GPU_indexbuf_add_line_verts(&elb_lines, face_vert_indices[i][1], face_vert_indices[i][2]);
      GPU_indexbuf_add_line_verts(&elb_lines, face_vert_indices[i][2], face_vert_indices[i][0]);
    }
    buffers->index_buf = GPU_indexbuf_build(&elb);
    buffers->index_lines_buf = GPU_indexbuf_build(&elb_lines);
  }
  else {
    /* Fill the only the line buffer. */
    GPUIndexBufBuilder elb_lines;
    GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, tottri * 3, INT_MAX);
    int vert_idx = 0;

    for (i = 0; i < face_indices_len; ++i) {
      const MLoopTri *lt = &looptri[face_indices[i]];

      /* Skip hidden faces */
      if (paint_is_face_hidden(lt, mvert, mloop)) {
        continue;
      }

      /* TODO skip "non-real" edges. */
      GPU_indexbuf_add_line_verts(&elb_lines, vert_idx * 3 + 0, vert_idx * 3 + 1);
      GPU_indexbuf_add_line_verts(&elb_lines, vert_idx * 3 + 1, vert_idx * 3 + 2);
      GPU_indexbuf_add_line_verts(&elb_lines, vert_idx * 3 + 2, vert_idx * 3 + 0);
      vert_idx++;
    }
    buffers->index_lines_buf = GPU_indexbuf_build(&elb_lines);
  }

  buffers->tot_tri = tottri;

  buffers->mpoly = mpoly;
  buffers->mloop = mloop;
  buffers->looptri = looptri;

  buffers->face_indices = face_indices;
  buffers->face_indices_len = face_indices_len;

  return buffers;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Grid PBVH
 * \{ */

static void gpu_pbvh_grid_fill_index_buffers(
    GPU_PBVH_Buffers *buffers, int *grid_indices, uint visible_quad_len, int totgrid, int gridsize)
{
  GPUIndexBufBuilder elb, elb_lines;
  GPUIndexBufBuilder elb_fast, elb_lines_fast;

  GPU_indexbuf_init(&elb, GPU_PRIM_TRIS, 2 * visible_quad_len, INT_MAX);
  GPU_indexbuf_init(&elb_fast, GPU_PRIM_TRIS, 2 * totgrid, INT_MAX);
  GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, 2 * totgrid * gridsize * (gridsize - 1), INT_MAX);
  GPU_indexbuf_init(&elb_lines_fast, GPU_PRIM_LINES, 4 * totgrid, INT_MAX);

  if (buffers->smooth) {
    uint offset = 0;
    const uint grid_vert_len = gridsize * gridsize;
    for (int i = 0; i < totgrid; i++, offset += grid_vert_len) {
      uint v0, v1, v2, v3;
      bool grid_visible = false;

      BLI_bitmap *gh = buffers->grid_hidden[grid_indices[i]];

      for (int j = 0; j < gridsize - 1; ++j) {
        for (int k = 0; k < gridsize - 1; ++k) {
          /* Skip hidden grid face */
          if (gh && paint_is_grid_face_hidden(gh, gridsize, k, j)) {
            continue;
          }
          /* Indices in a Clockwise QUAD disposition. */
          v0 = offset + j * gridsize + k;
          v1 = v0 + 1;
          v2 = v1 + gridsize;
          v3 = v2 - 1;

          GPU_indexbuf_add_tri_verts(&elb, v0, v2, v1);
          GPU_indexbuf_add_tri_verts(&elb, v0, v3, v2);

          GPU_indexbuf_add_line_verts(&elb_lines, v0, v1);
          GPU_indexbuf_add_line_verts(&elb_lines, v0, v3);

          if (j + 2 == gridsize) {
            GPU_indexbuf_add_line_verts(&elb_lines, v2, v3);
          }
          grid_visible = true;
        }
        GPU_indexbuf_add_line_verts(&elb_lines, v1, v2);
      }

      if (grid_visible) {
        /* Grid corners */
        v0 = offset;
        v1 = offset + gridsize - 1;
        v2 = offset + grid_vert_len - 1;
        v3 = offset + grid_vert_len - gridsize;

        GPU_indexbuf_add_tri_verts(&elb_fast, v0, v2, v1);
        GPU_indexbuf_add_tri_verts(&elb_fast, v0, v3, v2);

        GPU_indexbuf_add_line_verts(&elb_lines_fast, v0, v1);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v1, v2);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v2, v3);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v3, v0);
      }
    }
  }
  else {
    uint offset = 0;
    const uint grid_vert_len = SQUARE(gridsize - 1) * 4;
    for (int i = 0; i < totgrid; i++, offset += grid_vert_len) {
      bool grid_visible = false;

      BLI_bitmap *gh = buffers->grid_hidden[grid_indices[i]];

      uint v0, v1, v2, v3;
      for (int j = 0; j < gridsize - 1; j++) {
        for (int k = 0; k < gridsize - 1; k++) {
          /* Skip hidden grid face */
          if (gh && paint_is_grid_face_hidden(gh, gridsize, k, j)) {
            continue;
          }
          /* VBO data are in a Clockwise QUAD disposition. */
          v0 = offset + (j * (gridsize - 1) + k) * 4;
          v1 = v0 + 1;
          v2 = v0 + 2;
          v3 = v0 + 3;

          GPU_indexbuf_add_tri_verts(&elb, v0, v2, v1);
          GPU_indexbuf_add_tri_verts(&elb, v0, v3, v2);

          GPU_indexbuf_add_line_verts(&elb_lines, v0, v1);
          GPU_indexbuf_add_line_verts(&elb_lines, v0, v3);

          if (j + 2 == gridsize) {
            GPU_indexbuf_add_line_verts(&elb_lines, v2, v3);
          }
          grid_visible = true;
        }
        GPU_indexbuf_add_line_verts(&elb_lines, v1, v2);
      }

      if (grid_visible) {
        /* Grid corners */
        v0 = offset;
        v1 = offset + (gridsize - 1) * 4 - 3;
        v2 = offset + grid_vert_len - 2;
        v3 = offset + grid_vert_len - (gridsize - 1) * 4 + 3;

        GPU_indexbuf_add_tri_verts(&elb_fast, v0, v2, v1);
        GPU_indexbuf_add_tri_verts(&elb_fast, v0, v3, v2);

        GPU_indexbuf_add_line_verts(&elb_lines_fast, v0, v1);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v1, v2);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v2, v3);
        GPU_indexbuf_add_line_verts(&elb_lines_fast, v3, v0);
      }
    }
  }

  buffers->index_buf = GPU_indexbuf_build(&elb);
  buffers->index_buf_fast = GPU_indexbuf_build(&elb_fast);
  buffers->index_lines_buf = GPU_indexbuf_build(&elb_lines);
  buffers->index_lines_buf_fast = GPU_indexbuf_build(&elb_lines_fast);
}

void GPU_pbvh_grid_buffers_update(GPU_PBVH_Buffers *buffers,
                                  CCGElem **grids,
                                  const DMFlagMat *grid_flag_mats,
                                  int *grid_indices,
                                  int totgrid,
                                  const CCGKey *key,
                                  const int update_flags)
{
  const bool show_mask = (update_flags & GPU_PBVH_BUFFERS_SHOW_MASK) != 0;
  const bool show_vcol = (update_flags & GPU_PBVH_BUFFERS_SHOW_VCOL) != 0;
  bool empty_mask = true;
  int i, j, k, x, y;

  const bool smooth = grid_flag_mats[grid_indices[0]].flag & ME_SMOOTH;

  /* Build VBO */
  const int has_mask = key->has_mask;

  uint vert_per_grid = (smooth) ? key->grid_area : (SQUARE(key->grid_size - 1) * 4);
  uint vert_count = totgrid * vert_per_grid;

  if (buffers->smooth != smooth) {
    buffers->smooth = smooth;
    GPU_BATCH_DISCARD_SAFE(buffers->triangles);
    GPU_BATCH_DISCARD_SAFE(buffers->triangles_fast);
    GPU_BATCH_DISCARD_SAFE(buffers->lines);
    GPU_BATCH_DISCARD_SAFE(buffers->lines_fast);

    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf_fast);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf_fast);
  }

  if (buffers->index_buf == NULL) {
    uint visible_quad_len = BKE_pbvh_count_grid_quads(
        (BLI_bitmap **)buffers->grid_hidden, grid_indices, totgrid, key->grid_size);

    /* totally hidden node, return here to avoid BufferData with zero below. */
    if (visible_quad_len == 0) {
      return;
    }

    gpu_pbvh_grid_fill_index_buffers(
        buffers, grid_indices, visible_quad_len, totgrid, key->grid_size);
  }

  uint vbo_index_offset = 0;
  /* Build VBO */
  if (gpu_pbvh_vert_buf_data_set(buffers, vert_count)) {
    GPUIndexBufBuilder elb_lines;

    if (buffers->index_lines_buf == NULL) {
      GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, totgrid * key->grid_area * 2, vert_count);
    }

    for (i = 0; i < totgrid; ++i) {
      CCGElem *grid = grids[grid_indices[i]];
      int vbo_index = vbo_index_offset;

      if (buffers->smooth) {
        for (y = 0; y < key->grid_size; y++) {
          for (x = 0; x < key->grid_size; x++) {
            CCGElem *elem = CCG_grid_elem(key, grid, x, y);
            GPU_vertbuf_attr_set(
                buffers->vert_buf, g_vbo_id.pos, vbo_index, CCG_elem_co(key, elem));

            short no_short[3];
            normal_float_to_short_v3(no_short, CCG_elem_no(key, elem));
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index, no_short);

            if (has_mask && show_mask) {
              float fmask = *CCG_elem_mask(key, elem);
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index, &fmask);
              empty_mask = empty_mask && (fmask == 0.0f);
            }

            if (show_vcol) {
              char vcol[4] = {255, 255, 255, 255};
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index, &vcol);
            }

            vbo_index += 1;
          }
        }
        vbo_index_offset += key->grid_area;
      }
      else {
        for (j = 0; j < key->grid_size - 1; j++) {
          for (k = 0; k < key->grid_size - 1; k++) {
            CCGElem *elems[4] = {
                CCG_grid_elem(key, grid, k, j),
                CCG_grid_elem(key, grid, k + 1, j),
                CCG_grid_elem(key, grid, k + 1, j + 1),
                CCG_grid_elem(key, grid, k, j + 1),
            };
            float *co[4] = {
                CCG_elem_co(key, elems[0]),
                CCG_elem_co(key, elems[1]),
                CCG_elem_co(key, elems[2]),
                CCG_elem_co(key, elems[3]),
            };

            float fno[3];
            short no_short[3];
            /* Note: Clockwise indices ordering, that's why we invert order here. */
            normal_quad_v3(fno, co[3], co[2], co[1], co[0]);
            normal_float_to_short_v3(no_short, fno);

            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, vbo_index + 0, co[0]);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index + 0, no_short);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, vbo_index + 1, co[1]);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index + 1, no_short);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, vbo_index + 2, co[2]);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index + 2, no_short);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.pos, vbo_index + 3, co[3]);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.nor, vbo_index + 3, no_short);

            if (has_mask && show_mask) {
              float fmask = (*CCG_elem_mask(key, elems[0]) + *CCG_elem_mask(key, elems[1]) +
                             *CCG_elem_mask(key, elems[2]) + *CCG_elem_mask(key, elems[3])) *
                            0.25f;
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 0, &fmask);
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 1, &fmask);
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 2, &fmask);
              GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.msk, vbo_index + 3, &fmask);
              empty_mask = empty_mask && (fmask == 0.0f);
            }

            char vcol[4] = {255, 255, 255, 255};
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 0, &vcol);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 1, &vcol);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 2, &vcol);
            GPU_vertbuf_attr_set(buffers->vert_buf, g_vbo_id.col, vbo_index + 3, &vcol);
            vbo_index += 4;
          }
        }
        vbo_index_offset += SQUARE(key->grid_size - 1) * 4;
      }
    }

    gpu_pbvh_batch_init(buffers, GPU_PRIM_TRIS);
  }

  /* Get material index from the first face of this buffer. */
  buffers->material_index = grid_flag_mats[grid_indices[0]].mat_nr;

  buffers->grids = grids;
  buffers->grid_indices = grid_indices;
  buffers->totgrid = totgrid;
  buffers->grid_flag_mats = grid_flag_mats;
  buffers->gridkey = *key;
  buffers->show_mask = !empty_mask;
}

GPU_PBVH_Buffers *GPU_pbvh_grid_buffers_build(int totgrid, BLI_bitmap **grid_hidden)
{
  GPU_PBVH_Buffers *buffers;

  buffers = MEM_callocN(sizeof(GPU_PBVH_Buffers), "GPU_Buffers");
  buffers->grid_hidden = grid_hidden;
  buffers->totgrid = totgrid;

  buffers->show_mask = false;

  return buffers;
}

#undef FILL_QUAD_BUFFER

/** \} */

/* -------------------------------------------------------------------- */
/** \name BMesh PBVH
 * \{ */

/* Output a BMVert into a VertexBufferFormat array
 *
 * The vertex is skipped if hidden, otherwise the output goes into
 * index '*v_index' in the 'vert_data' array and '*v_index' is
 * incremented.
 */
static void gpu_bmesh_vert_to_buffer_copy__gwn(BMVert *v,
                                               GPUVertBuf *vert_buf,
                                               int *v_index,
                                               const float fno[3],
                                               const float *fmask,
                                               const int cd_vert_mask_offset,
                                               const bool show_mask,
                                               const bool show_vcol,
                                               bool *empty_mask)
{
  if (!BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {

    /* Set coord, normal, and mask */
    GPU_vertbuf_attr_set(vert_buf, g_vbo_id.pos, *v_index, v->co);

    short no_short[3];
    normal_float_to_short_v3(no_short, fno ? fno : v->no);
    GPU_vertbuf_attr_set(vert_buf, g_vbo_id.nor, *v_index, no_short);

    if (show_mask) {
      float effective_mask = fmask ? *fmask : BM_ELEM_CD_GET_FLOAT(v, cd_vert_mask_offset);
      GPU_vertbuf_attr_set(vert_buf, g_vbo_id.msk, *v_index, &effective_mask);
      *empty_mask = *empty_mask && (effective_mask == 0.0f);
    }

    if (show_vcol) {
      static char vcol[4] = {255, 255, 255, 255};
      GPU_vertbuf_attr_set(vert_buf, g_vbo_id.col, *v_index, &vcol);
    }

    /* Assign index for use in the triangle index buffer */
    /* note: caller must set:  bm->elem_index_dirty |= BM_VERT; */
    BM_elem_index_set(v, (*v_index)); /* set_dirty! */

    (*v_index)++;
  }
}

/* Return the total number of vertices that don't have BM_ELEM_HIDDEN set */
static int gpu_bmesh_vert_visible_count(GSet *bm_unique_verts, GSet *bm_other_verts)
{
  GSetIterator gs_iter;
  int totvert = 0;

  GSET_ITER (gs_iter, bm_unique_verts) {
    BMVert *v = BLI_gsetIterator_getKey(&gs_iter);
    if (!BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {
      totvert++;
    }
  }
  GSET_ITER (gs_iter, bm_other_verts) {
    BMVert *v = BLI_gsetIterator_getKey(&gs_iter);
    if (!BM_elem_flag_test(v, BM_ELEM_HIDDEN)) {
      totvert++;
    }
  }

  return totvert;
}

/* Return the total number of visible faces */
static int gpu_bmesh_face_visible_count(GSet *bm_faces)
{
  GSetIterator gh_iter;
  int totface = 0;

  GSET_ITER (gh_iter, bm_faces) {
    BMFace *f = BLI_gsetIterator_getKey(&gh_iter);

    if (!BM_elem_flag_test(f, BM_ELEM_HIDDEN)) {
      totface++;
    }
  }

  return totface;
}

/* Creates a vertex buffer (coordinate, normal, color) and, if smooth
 * shading, an element index buffer. */
void GPU_pbvh_bmesh_buffers_update(GPU_PBVH_Buffers *buffers,
                                   BMesh *bm,
                                   GSet *bm_faces,
                                   GSet *bm_unique_verts,
                                   GSet *bm_other_verts,
                                   const int update_flags)
{
  const bool show_mask = (update_flags & GPU_PBVH_BUFFERS_SHOW_MASK) != 0;
  const bool show_vcol = (update_flags & GPU_PBVH_BUFFERS_SHOW_VCOL) != 0;
  int tottri, totvert, maxvert = 0;
  bool empty_mask = true;
  BMFace *f;

  /* Count visible triangles */
  tottri = gpu_bmesh_face_visible_count(bm_faces);

  if (buffers->smooth) {
    /* Smooth needs to recreate index buffer, so we have to invalidate the batch. */
    GPU_BATCH_DISCARD_SAFE(buffers->triangles);
    GPU_BATCH_DISCARD_SAFE(buffers->lines);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
    /* Count visible vertices */
    totvert = gpu_bmesh_vert_visible_count(bm_unique_verts, bm_other_verts);
  }
  else {
    GPU_BATCH_DISCARD_SAFE(buffers->lines);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);
    totvert = tottri * 3;
  }

  if (!tottri) {
    if (BLI_gset_len(bm_faces) != 0) {
      /* Node is just hidden. */
    }
    else {
      GPU_BATCH_DISCARD_SAFE(buffers->triangles);
      GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
      GPU_VERTBUF_DISCARD_SAFE(buffers->vert_buf);
    }
    buffers->tot_tri = 0;
    return;
  }

  /* TODO, make mask layer optional for bmesh buffer */
  const int cd_vert_mask_offset = CustomData_get_offset(&bm->vdata, CD_PAINT_MASK);

  /* Fill vertex buffer */
  if (gpu_pbvh_vert_buf_data_set(buffers, totvert)) {
    int v_index = 0;

    if (buffers->smooth) {
      GSetIterator gs_iter;

      /* Vertices get an index assigned for use in the triangle
       * index buffer */
      bm->elem_index_dirty |= BM_VERT;

      GSET_ITER (gs_iter, bm_unique_verts) {
        gpu_bmesh_vert_to_buffer_copy__gwn(BLI_gsetIterator_getKey(&gs_iter),
                                           buffers->vert_buf,
                                           &v_index,
                                           NULL,
                                           NULL,
                                           cd_vert_mask_offset,
                                           show_mask,
                                           show_vcol,
                                           &empty_mask);
      }

      GSET_ITER (gs_iter, bm_other_verts) {
        gpu_bmesh_vert_to_buffer_copy__gwn(BLI_gsetIterator_getKey(&gs_iter),
                                           buffers->vert_buf,
                                           &v_index,
                                           NULL,
                                           NULL,
                                           cd_vert_mask_offset,
                                           show_mask,
                                           show_vcol,
                                           &empty_mask);
      }

      maxvert = v_index;
    }
    else {
      GSetIterator gs_iter;

      GPUIndexBufBuilder elb_lines;
      GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, tottri * 3, totvert);

      GSET_ITER (gs_iter, bm_faces) {
        f = BLI_gsetIterator_getKey(&gs_iter);

        BLI_assert(f->len == 3);

        if (!BM_elem_flag_test(f, BM_ELEM_HIDDEN)) {
          BMVert *v[3];
          float fmask = 0.0f;
          int i;

          BM_face_as_array_vert_tri(f, v);

          /* Average mask value */
          for (i = 0; i < 3; i++) {
            fmask += BM_ELEM_CD_GET_FLOAT(v[i], cd_vert_mask_offset);
          }
          fmask /= 3.0f;

          GPU_indexbuf_add_line_verts(&elb_lines, v_index + 0, v_index + 1);
          GPU_indexbuf_add_line_verts(&elb_lines, v_index + 1, v_index + 2);
          GPU_indexbuf_add_line_verts(&elb_lines, v_index + 2, v_index + 0);

          for (i = 0; i < 3; i++) {
            gpu_bmesh_vert_to_buffer_copy__gwn(v[i],
                                               buffers->vert_buf,
                                               &v_index,
                                               f->no,
                                               &fmask,
                                               cd_vert_mask_offset,
                                               show_mask,
                                               show_vcol,
                                               &empty_mask);
          }
        }
      }

      buffers->index_lines_buf = GPU_indexbuf_build(&elb_lines);
      buffers->tot_tri = tottri;
    }

    /* gpu_bmesh_vert_to_buffer_copy sets dirty index values */
    bm->elem_index_dirty |= BM_VERT;
  }
  else {
    /* Memory map failed */
    return;
  }

  if (buffers->smooth) {
    /* Fill the triangle buffer */
    GPUIndexBufBuilder elb, elb_lines;
    GPU_indexbuf_init(&elb, GPU_PRIM_TRIS, tottri, maxvert);
    GPU_indexbuf_init(&elb_lines, GPU_PRIM_LINES, tottri * 3, maxvert);

    /* Fill triangle index buffer */
    {
      GSetIterator gs_iter;

      GSET_ITER (gs_iter, bm_faces) {
        f = BLI_gsetIterator_getKey(&gs_iter);

        if (!BM_elem_flag_test(f, BM_ELEM_HIDDEN)) {
          BMVert *v[3];

          BM_face_as_array_vert_tri(f, v);

          uint idx[3] = {
              BM_elem_index_get(v[0]), BM_elem_index_get(v[1]), BM_elem_index_get(v[2])};
          GPU_indexbuf_add_tri_verts(&elb, idx[0], idx[1], idx[2]);

          GPU_indexbuf_add_line_verts(&elb_lines, idx[0], idx[1]);
          GPU_indexbuf_add_line_verts(&elb_lines, idx[1], idx[2]);
          GPU_indexbuf_add_line_verts(&elb_lines, idx[2], idx[0]);
        }
      }

      buffers->tot_tri = tottri;

      if (buffers->index_buf == NULL) {
        buffers->index_buf = GPU_indexbuf_build(&elb);
      }
      else {
        GPU_indexbuf_build_in_place(&elb, buffers->index_buf);
      }

      buffers->index_lines_buf = GPU_indexbuf_build(&elb_lines);
    }
  }

  /* Get material index from the last face we iterated on. */
  buffers->material_index = f->mat_nr;

  buffers->show_mask = !empty_mask;

  gpu_pbvh_batch_init(buffers, GPU_PRIM_TRIS);
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Generic
 * \{ */

GPU_PBVH_Buffers *GPU_pbvh_bmesh_buffers_build(bool smooth_shading)
{
  GPU_PBVH_Buffers *buffers;

  buffers = MEM_callocN(sizeof(GPU_PBVH_Buffers), "GPU_Buffers");
  buffers->use_bmesh = true;
  buffers->smooth = smooth_shading;
  buffers->show_mask = true;

  return buffers;
}

GPUBatch *GPU_pbvh_buffers_batch_get(GPU_PBVH_Buffers *buffers, bool fast, bool wires)
{
  if (wires) {
    return (fast && buffers->lines_fast) ? buffers->lines_fast : buffers->lines;
  }
  else {
    return (fast && buffers->triangles_fast) ? buffers->triangles_fast : buffers->triangles;
  }
}

bool GPU_pbvh_buffers_has_mask(GPU_PBVH_Buffers *buffers)
{
  return buffers->show_mask;
}

short GPU_pbvh_buffers_material_index_get(GPU_PBVH_Buffers *buffers)
{
  return buffers->material_index;
}

void GPU_pbvh_buffers_free(GPU_PBVH_Buffers *buffers)
{
  if (buffers) {
    GPU_BATCH_DISCARD_SAFE(buffers->lines);
    GPU_BATCH_DISCARD_SAFE(buffers->lines_fast);
    GPU_BATCH_DISCARD_SAFE(buffers->triangles);
    GPU_BATCH_DISCARD_SAFE(buffers->triangles_fast);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf_fast);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_lines_buf);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf_fast);
    GPU_INDEXBUF_DISCARD_SAFE(buffers->index_buf);
    GPU_VERTBUF_DISCARD_SAFE(buffers->vert_buf);

    MEM_freeN(buffers);
  }
}

/** \} */

void GPU_pbvh_fix_linking()
{
}