/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
 *
 * SPDX-License-Identifier: Apache-2.0 */

#pragma once

#ifdef WITH_NANOVDB
#  include "kernel/util/nanovdb.h"
#endif

CCL_NAMESPACE_BEGIN

/* Make template functions private so symbols don't conflict between kernels with different
 * instruction sets. */
namespace {

#define SET_CUBIC_SPLINE_WEIGHTS(u, t) \
  { \
    u[0] = (((-1.0f / 6.0f) * t + 0.5f) * t - 0.5f) * t + (1.0f / 6.0f); \
    u[1] = ((0.5f * t - 1.0f) * t) * t + (2.0f / 3.0f); \
    u[2] = ((-0.5f * t + 0.5f) * t + 0.5f) * t + (1.0f / 6.0f); \
    u[3] = (1.0f / 6.0f) * t * t * t; \
  } \
  (void)0

ccl_device_inline float frac(float x, int *ix)
{
  int i = float_to_int(x) - ((x < 0.0f) ? 1 : 0);
  *ix = i;
  return x - (float)i;
}

template<typename TexT, typename OutT = float4> struct TextureInterpolator {

  static ccl_always_inline OutT zero()
  {
    if constexpr (std::is_same<OutT, float4>::value) {
      return zero_float4();
    }
    else {
      return 0.0f;
    }
  }

  static ccl_always_inline float4 read(float4 r)
  {
    return r;
  }

  static ccl_always_inline float4 read(uchar4 r)
  {
    const float f = 1.0f / 255.0f;
    return make_float4(r.x * f, r.y * f, r.z * f, r.w * f);
  }

  static ccl_always_inline float read(uchar r)
  {
    return r * (1.0f / 255.0f);
  }

  static ccl_always_inline float read(float r)
  {
    return r;
  }

  static ccl_always_inline float4 read(half4 r)
  {
    return half4_to_float4_image(r);
  }

  static ccl_always_inline float read(half r)
  {
    return half_to_float_image(r);
  }

  static ccl_always_inline float read(uint16_t r)
  {
    return r * (1.0f / 65535.0f);
  }

  static ccl_always_inline float4 read(ushort4 r)
  {
    const float f = 1.0f / 65535.0f;
    return make_float4(r.x * f, r.y * f, r.z * f, r.w * f);
  }

  /* Read 2D Texture Data
   * Does not check if data request is in bounds. */
  static ccl_always_inline OutT read(const TexT *data, int x, int y, int width, int height)
  {
    return read(data[y * width + x]);
  }

  /* Read 2D Texture Data Clip
   * Returns transparent black if data request is out of bounds. */
  static ccl_always_inline OutT read_clip(const TexT *data, int x, int y, int width, int height)
  {
    if (x < 0 || x >= width || y < 0 || y >= height) {
      return zero();
    }
    return read(data[y * width + x]);
  }

  /* Read 3D Texture Data
   * Does not check if data request is in bounds. */
  static ccl_always_inline OutT
  read(const TexT *data, int x, int y, int z, int width, int height, int depth)
  {
    return read(data[x + y * width + z * width * height]);
  }

  /* Read 3D Texture Data Clip
   * Returns transparent black if data request is out of bounds. */
  static ccl_always_inline OutT
  read_clip(const TexT *data, int x, int y, int z, int width, int height, int depth)
  {
    if (x < 0 || x >= width || y < 0 || y >= height || z < 0 || z >= depth) {
      return zero();
    }
    return read(data[x + y * width + z * width * height]);
  }

  /* Trilinear Interpolation */
  static ccl_always_inline OutT
  trilinear_lookup(const TexT *data,
                   float tx,
                   float ty,
                   float tz,
                   int ix,
                   int iy,
                   int iz,
                   int nix,
                   int niy,
                   int niz,
                   int width,
                   int height,
                   int depth,
                   OutT read(const TexT *, int, int, int, int, int, int))
  {
    OutT r = (1.0f - tz) * (1.0f - ty) * (1.0f - tx) *
             read(data, ix, iy, iz, width, height, depth);
    r += (1.0f - tz) * (1.0f - ty) * tx * read(data, nix, iy, iz, width, height, depth);
    r += (1.0f - tz) * ty * (1.0f - tx) * read(data, ix, niy, iz, width, height, depth);
    r += (1.0f - tz) * ty * tx * read(data, nix, niy, iz, width, height, depth);

    r += tz * (1.0f - ty) * (1.0f - tx) * read(data, ix, iy, niz, width, height, depth);
    r += tz * (1.0f - ty) * tx * read(data, nix, iy, niz, width, height, depth);
    r += tz * ty * (1.0f - tx) * read(data, ix, niy, niz, width, height, depth);
    r += tz * ty * tx * read(data, nix, niy, niz, width, height, depth);
    return r;
  }

  /** Tricubic Interpolation */
  static ccl_always_inline OutT
  tricubic_lookup(const TexT *data,
                  float tx,
                  float ty,
                  float tz,
                  const int xc[4],
                  const int yc[4],
                  const int zc[4],
                  int width,
                  int height,
                  int depth,
                  OutT read(const TexT *, int, int, int, int, int, int))
  {
    float u[4], v[4], w[4];

    /* Some helper macros to keep code size reasonable.
     * Lets the compiler inline all the matrix multiplications.
     */
#define DATA(x, y, z) (read(data, xc[x], yc[y], zc[z], width, height, depth))
#define COL_TERM(col, row) \
  (v[col] * (u[0] * DATA(0, col, row) + u[1] * DATA(1, col, row) + u[2] * DATA(2, col, row) + \
             u[3] * DATA(3, col, row)))
#define ROW_TERM(row) \
  (w[row] * (COL_TERM(0, row) + COL_TERM(1, row) + COL_TERM(2, row) + COL_TERM(3, row)))

    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);
    SET_CUBIC_SPLINE_WEIGHTS(w, tz);
    /* Actual interpolation. */
    return ROW_TERM(0) + ROW_TERM(1) + ROW_TERM(2) + ROW_TERM(3);

#undef COL_TERM
#undef ROW_TERM
#undef DATA
  }

  static ccl_always_inline int wrap_periodic(int x, int width)
  {
    x %= width;
    if (x < 0) {
      x += width;
    }
    return x;
  }

  static ccl_always_inline int wrap_clamp(int x, int width)
  {
    return clamp(x, 0, width - 1);
  }

  static ccl_always_inline int wrap_mirror(int x, int width)
  {
    const int m = abs(x + (x < 0)) % (2 * width);
    if (m >= width)
      return 2 * width - m - 1;
    return m;
  }

  /* ********  2D interpolation ******** */

  static ccl_always_inline OutT interp_closest(const TextureInfo &info, float x, float y)
  {
    const int width = info.width;
    const int height = info.height;
    int ix, iy;
    frac(x * (float)width, &ix);
    frac(y * (float)height, &iy);
    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        iy = wrap_periodic(iy, height);
        break;
      case EXTENSION_CLIP:
        /* No samples are inside the clip region. */
        if (ix < 0 || ix >= width || iy < 0 || iy >= height) {
          return zero();
        }
        break;
      case EXTENSION_EXTEND:
        ix = wrap_clamp(ix, width);
        iy = wrap_clamp(iy, height);
        break;
      case EXTENSION_MIRROR:
        ix = wrap_mirror(ix, width);
        iy = wrap_mirror(iy, height);
        break;
      default:
        kernel_assert(0);
        return zero();
    }

    const TexT *data = (const TexT *)info.data;
    return read((const TexT *)data, ix, iy, width, height);
  }

  static ccl_always_inline OutT interp_linear(const TextureInfo &info, float x, float y)
  {
    const int width = info.width;
    const int height = info.height;

    /* A -0.5 offset is used to center the linear samples around the sample point. */
    int ix, iy;
    int nix, niy;
    const float tx = frac(x * (float)width - 0.5f, &ix);
    const float ty = frac(y * (float)height - 0.5f, &iy);
    const TexT *data = (const TexT *)info.data;

    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        nix = wrap_periodic(ix + 1, width);

        iy = wrap_periodic(iy, height);
        niy = wrap_periodic(iy + 1, height);
        break;
      case EXTENSION_CLIP:
        /* No linear samples are inside the clip region. */
        if (ix < -1 || ix >= width || iy < -1 || iy >= height) {
          return zero();
        }
        nix = ix + 1;
        niy = iy + 1;
        return (1.0f - ty) * (1.0f - tx) * read_clip(data, ix, iy, width, height) +
               (1.0f - ty) * tx * read_clip(data, nix, iy, width, height) +
               ty * (1.0f - tx) * read_clip(data, ix, niy, width, height) +
               ty * tx * read_clip(data, nix, niy, width, height);
      case EXTENSION_EXTEND:
        nix = wrap_clamp(ix + 1, width);
        ix = wrap_clamp(ix, width);
        niy = wrap_clamp(iy + 1, height);
        iy = wrap_clamp(iy, height);
        break;
      case EXTENSION_MIRROR:
        nix = wrap_mirror(ix + 1, width);
        ix = wrap_mirror(ix, width);
        niy = wrap_mirror(iy + 1, height);
        iy = wrap_mirror(iy, height);
        break;
      default:
        kernel_assert(0);
        return zero();
    }

    return (1.0f - ty) * (1.0f - tx) * read(data, ix, iy, width, height) +
           (1.0f - ty) * tx * read(data, nix, iy, width, height) +
           ty * (1.0f - tx) * read(data, ix, niy, width, height) +
           ty * tx * read(data, nix, niy, width, height);
  }

  static ccl_always_inline OutT interp_cubic(const TextureInfo &info, float x, float y)
  {
    const int width = info.width;
    const int height = info.height;

    /* A -0.5 offset is used to center the cubic samples around the sample point. */
    int ix, iy;
    const float tx = frac(x * (float)width - 0.5f, &ix);
    const float ty = frac(y * (float)height - 0.5f, &iy);

    int pix, piy;
    int nix, niy;
    int nnix, nniy;

    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        pix = wrap_periodic(ix - 1, width);
        nix = wrap_periodic(ix + 1, width);
        nnix = wrap_periodic(ix + 2, width);

        iy = wrap_periodic(iy, height);
        piy = wrap_periodic(iy - 1, height);
        niy = wrap_periodic(iy + 1, height);
        nniy = wrap_periodic(iy + 2, height);
        break;
      case EXTENSION_CLIP:
        /* No cubic samples are inside the clip region. */
        if (ix < -2 || ix > width || iy < -2 || iy > height) {
          return zero();
        }

        pix = ix - 1;
        nix = ix + 1;
        nnix = ix + 2;

        piy = iy - 1;
        niy = iy + 1;
        nniy = iy + 2;
        break;
      case EXTENSION_EXTEND:
        pix = wrap_clamp(ix - 1, width);
        nix = wrap_clamp(ix + 1, width);
        nnix = wrap_clamp(ix + 2, width);
        ix = wrap_clamp(ix, width);

        piy = wrap_clamp(iy - 1, height);
        niy = wrap_clamp(iy + 1, height);
        nniy = wrap_clamp(iy + 2, height);
        iy = wrap_clamp(iy, height);
        break;
      case EXTENSION_MIRROR:
        pix = wrap_mirror(ix - 1, width);
        nix = wrap_mirror(ix + 1, width);
        nnix = wrap_mirror(ix + 2, width);
        ix = wrap_mirror(ix, width);

        piy = wrap_mirror(iy - 1, height);
        niy = wrap_mirror(iy + 1, height);
        nniy = wrap_mirror(iy + 2, height);
        iy = wrap_mirror(iy, height);
        break;
      default:
        kernel_assert(0);
        return zero();
    }

    const TexT *data = (const TexT *)info.data;
    const int xc[4] = {pix, ix, nix, nnix};
    const int yc[4] = {piy, iy, niy, nniy};
    float u[4], v[4];

    /* Some helper macros to keep code size reasonable.
     * Lets the compiler inline all the matrix multiplications.
     */
#define DATA(x, y) (read_clip(data, xc[x], yc[y], width, height))
#define TERM(col) \
  (v[col] * \
   (u[0] * DATA(0, col) + u[1] * DATA(1, col) + u[2] * DATA(2, col) + u[3] * DATA(3, col)))

    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);

    /* Actual interpolation. */
    return TERM(0) + TERM(1) + TERM(2) + TERM(3);
#undef TERM
#undef DATA
  }

  static ccl_always_inline OutT interp(const TextureInfo &info, float x, float y)
  {
    switch (info.interpolation) {
      case INTERPOLATION_CLOSEST:
        return interp_closest(info, x, y);
      case INTERPOLATION_LINEAR:
        return interp_linear(info, x, y);
      default:
        return interp_cubic(info, x, y);
    }
  }

  /* ********  3D interpolation ******** */

  static ccl_always_inline OutT interp_3d_closest(const TextureInfo &info,
                                                  float x,
                                                  float y,
                                                  float z)
  {
    const int width = info.width;
    const int height = info.height;
    const int depth = info.depth;
    int ix, iy, iz;

    frac(x * (float)width, &ix);
    frac(y * (float)height, &iy);
    frac(z * (float)depth, &iz);

    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        iy = wrap_periodic(iy, height);
        iz = wrap_periodic(iz, depth);
        break;
      case EXTENSION_CLIP:
        /* No samples are inside the clip region. */
        if (ix < 0 || ix >= width || iy < 0 || iy >= height || iz < 0 || iz >= depth) {
          return zero();
        }
        break;
      case EXTENSION_EXTEND:
        ix = wrap_clamp(ix, width);
        iy = wrap_clamp(iy, height);
        iz = wrap_clamp(iz, depth);
        break;
      case EXTENSION_MIRROR:
        ix = wrap_mirror(ix, width);
        iy = wrap_mirror(iy, height);
        iz = wrap_mirror(iz, depth);
        break;
      default:
        kernel_assert(0);
        return zero();
    }

    const TexT *data = (const TexT *)info.data;
    return read(data, ix, iy, iz, width, height, depth);
  }

  static ccl_always_inline OutT interp_3d_linear(const TextureInfo &info,
                                                 float x,
                                                 float y,
                                                 float z)
  {
    const int width = info.width;
    const int height = info.height;
    const int depth = info.depth;
    int ix, iy, iz;
    int nix, niy, niz;

    /* A -0.5 offset is used to center the linear samples around the sample point. */
    float tx = frac(x * (float)width - 0.5f, &ix);
    float ty = frac(y * (float)height - 0.5f, &iy);
    float tz = frac(z * (float)depth - 0.5f, &iz);

    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        nix = wrap_periodic(ix + 1, width);

        iy = wrap_periodic(iy, height);
        niy = wrap_periodic(iy + 1, height);

        iz = wrap_periodic(iz, depth);
        niz = wrap_periodic(iz + 1, depth);
        break;
      case EXTENSION_CLIP:
        /* No linear samples are inside the clip region. */
        if (ix < -1 || ix >= width || iy < -1 || iy >= height || iz < -1 || iz >= depth) {
          return zero();
        }

        nix = ix + 1;
        niy = iy + 1;
        niz = iz + 1;

        /* All linear samples are inside the clip region. */
        if (ix >= 0 && nix < width && iy >= 0 && niy < height && iz >= 0 && niz < depth) {
          break;
        }

        /* The linear samples span the clip border.
         * #read_clip is used to ensure proper interpolation across the clip border. */
        return trilinear_lookup((const TexT *)info.data,
                                tx,
                                ty,
                                tz,
                                ix,
                                iy,
                                iz,
                                nix,
                                niy,
                                niz,
                                width,
                                height,
                                depth,
                                read_clip);
      case EXTENSION_EXTEND:
        nix = wrap_clamp(ix + 1, width);
        ix = wrap_clamp(ix, width);

        niy = wrap_clamp(iy + 1, height);
        iy = wrap_clamp(iy, height);

        niz = wrap_clamp(iz + 1, depth);
        iz = wrap_clamp(iz, depth);
        break;
      case EXTENSION_MIRROR:
        nix = wrap_mirror(ix + 1, width);
        ix = wrap_mirror(ix, width);

        niy = wrap_mirror(iy + 1, height);
        iy = wrap_mirror(iy, height);

        niz = wrap_mirror(iz + 1, depth);
        iz = wrap_mirror(iz, depth);
        break;
      default:
        kernel_assert(0);
        return zero();
    }

    return trilinear_lookup((const TexT *)info.data,
                            tx,
                            ty,
                            tz,
                            ix,
                            iy,
                            iz,
                            nix,
                            niy,
                            niz,
                            width,
                            height,
                            depth,
                            read);
  }

  /* Tricubic b-spline interpolation.
   *
   * TODO(sergey): For some unspeakable reason both GCC-6 and Clang-3.9 are
   * causing stack overflow issue in this function unless it is inlined.
   *
   * Only happens for AVX2 kernel and global __KERNEL_SSE__ vectorization
   * enabled.
   */
#if defined(__GNUC__) || defined(__clang__)
  static ccl_always_inline
#else
  static ccl_never_inline
#endif
      OutT
      interp_3d_cubic(const TextureInfo &info, float x, float y, float z)
  {
    int width = info.width;
    int height = info.height;
    int depth = info.depth;
    int ix, iy, iz;

    /* A -0.5 offset is used to center the cubic samples around the sample point. */
    const float tx = frac(x * (float)width - 0.5f, &ix);
    const float ty = frac(y * (float)height - 0.5f, &iy);
    const float tz = frac(z * (float)depth - 0.5f, &iz);

    int pix, piy, piz;
    int nix, niy, niz;
    int nnix, nniy, nniz;

    switch (info.extension) {
      case EXTENSION_REPEAT:
        ix = wrap_periodic(ix, width);
        pix = wrap_periodic(ix - 1, width);
        nix = wrap_periodic(ix + 1, width);
        nnix = wrap_periodic(ix + 2, width);

        iy = wrap_periodic(iy, height);
        niy = wrap_periodic(iy + 1, height);
        piy = wrap_periodic(iy - 1, height);
        nniy = wrap_periodic(iy + 2, height);

        iz = wrap_periodic(iz, depth);
        piz = wrap_periodic(iz - 1, depth);
        niz = wrap_periodic(iz + 1, depth);
        nniz = wrap_periodic(iz + 2, depth);
        break;
      case EXTENSION_CLIP: {
        /* No cubic samples are inside the clip region. */
        if (ix < -2 || ix > width || iy < -2 || iy > height || iz < -2 || iz > depth) {
          return zero();
        }

        pix = ix - 1;
        nnix = ix + 2;
        nix = ix + 1;

        piy = iy - 1;
        niy = iy + 1;
        nniy = iy + 2;

        piz = iz - 1;
        niz = iz + 1;
        nniz = iz + 2;

        /* All cubic samples are inside the clip region. */
        if (pix >= 0 && nnix < width && piy >= 0 && nniy < height && piz >= 0 && nniz < depth) {
          break;
        }

        /* The Cubic samples span the clip border.
         * read_clip is used to ensure proper interpolation across the clip border. */
        const int xc[4] = {pix, ix, nix, nnix};
        const int yc[4] = {piy, iy, niy, nniy};
        const int zc[4] = {piz, iz, niz, nniz};
        return tricubic_lookup(
            (const TexT *)info.data, tx, ty, tz, xc, yc, zc, width, height, depth, read_clip);
      }
      case EXTENSION_EXTEND:
        pix = wrap_clamp(ix - 1, width);
        nix = wrap_clamp(ix + 1, width);
        nnix = wrap_clamp(ix + 2, width);
        ix = wrap_clamp(ix, width);

        piy = wrap_clamp(iy - 1, height);
        niy = wrap_clamp(iy + 1, height);
        nniy = wrap_clamp(iy + 2, height);
        iy = wrap_clamp(iy, height);

        piz = wrap_clamp(iz - 1, depth);
        niz = wrap_clamp(iz + 1, depth);
        nniz = wrap_clamp(iz + 2, depth);
        iz = wrap_clamp(iz, depth);
        break;
      case EXTENSION_MIRROR:
        pix = wrap_mirror(ix - 1, width);
        nix = wrap_mirror(ix + 1, width);
        nnix = wrap_mirror(ix + 2, width);
        ix = wrap_mirror(ix, width);

        piy = wrap_mirror(iy - 1, height);
        niy = wrap_mirror(iy + 1, height);
        nniy = wrap_mirror(iy + 2, height);
        iy = wrap_mirror(iy, height);

        piz = wrap_mirror(iz - 1, depth);
        niz = wrap_mirror(iz + 1, depth);
        nniz = wrap_mirror(iz + 2, depth);
        iz = wrap_mirror(iz, depth);
        break;
      default:
        kernel_assert(0);
        return zero();
    }
    const int xc[4] = {pix, ix, nix, nnix};
    const int yc[4] = {piy, iy, niy, nniy};
    const int zc[4] = {piz, iz, niz, nniz};
    const TexT *data = (const TexT *)info.data;
    return tricubic_lookup(data, tx, ty, tz, xc, yc, zc, width, height, depth, read);
  }

  static ccl_always_inline OutT
  interp_3d(const TextureInfo &info, float x, float y, float z, InterpolationType interp)
  {
    switch ((interp == INTERPOLATION_NONE) ? info.interpolation : interp) {
      case INTERPOLATION_CLOSEST:
        return interp_3d_closest(info, x, y, z);
      case INTERPOLATION_LINEAR:
        return interp_3d_linear(info, x, y, z);
      default:
        return interp_3d_cubic(info, x, y, z);
    }
  }
};

#ifdef WITH_NANOVDB
template<typename TexT, typename OutT> struct NanoVDBInterpolator {

  static ccl_always_inline float read(float r)
  {
    return r;
  }

  static ccl_always_inline float4 read(const packed_float3 r)
  {
    return make_float4(r.x, r.y, r.z, 1.0f);
  }

  template<typename Acc>
  static ccl_always_inline OutT interp_3d_closest(const Acc &acc, float x, float y, float z)
  {
    const nanovdb::Coord coord((int32_t)floorf(x), (int32_t)floorf(y), (int32_t)floorf(z));
    return read(acc.getValue(coord));
  }

  template<typename Acc>
  static ccl_always_inline OutT interp_3d_linear(const Acc &acc, float x, float y, float z)
  {
    int ix, iy, iz;
    const float tx = frac(x - 0.5f, &ix);
    const float ty = frac(y - 0.5f, &iy);
    const float tz = frac(z - 0.5f, &iz);

    return mix(mix(mix(read(acc.getValue(nanovdb::Coord(ix, iy, iz))),
                       read(acc.getValue(nanovdb::Coord(ix, iy, iz + 1))),
                       tz),
                   mix(read(acc.getValue(nanovdb::Coord(ix, iy + 1, iz + 1))),
                       read(acc.getValue(nanovdb::Coord(ix, iy + 1, iz))),
                       1.0f - tz),
                   ty),
               mix(mix(read(acc.getValue(nanovdb::Coord(ix + 1, iy + 1, iz))),
                       read(acc.getValue(nanovdb::Coord(ix + 1, iy + 1, iz + 1))),
                       tz),
                   mix(read(acc.getValue(nanovdb::Coord(ix + 1, iy, iz + 1))),
                       read(acc.getValue(nanovdb::Coord(ix + 1, iy, iz))),
                       1.0f - tz),
                   1.0f - ty),
               tx);
  }

  /* Tricubic b-spline interpolation. */
  template<typename Acc>
#  if defined(__GNUC__) || defined(__clang__)
  static ccl_always_inline
#  else
  static ccl_never_inline
#  endif
      OutT
      interp_3d_cubic(const Acc &acc, float x, float y, float z)
  {
    int ix, iy, iz;
    int nix, niy, niz;
    int pix, piy, piz;
    int nnix, nniy, nniz;

    /* A -0.5 offset is used to center the cubic samples around the sample point. */
    const float tx = frac(x - 0.5f, &ix);
    const float ty = frac(y - 0.5f, &iy);
    const float tz = frac(z - 0.5f, &iz);

    pix = ix - 1;
    piy = iy - 1;
    piz = iz - 1;
    nix = ix + 1;
    niy = iy + 1;
    niz = iz + 1;
    nnix = ix + 2;
    nniy = iy + 2;
    nniz = iz + 2;

    const int xc[4] = {pix, ix, nix, nnix};
    const int yc[4] = {piy, iy, niy, nniy};
    const int zc[4] = {piz, iz, niz, nniz};
    float u[4], v[4], w[4];

    /* Some helper macros to keep code size reasonable.
     * Lets the compiler inline all the matrix multiplications.
     */
#  define DATA(x, y, z) (read(acc.getValue(nanovdb::Coord(xc[x], yc[y], zc[z]))))
#  define COL_TERM(col, row) \
    (v[col] * (u[0] * DATA(0, col, row) + u[1] * DATA(1, col, row) + u[2] * DATA(2, col, row) + \
               u[3] * DATA(3, col, row)))
#  define ROW_TERM(row) \
    (w[row] * (COL_TERM(0, row) + COL_TERM(1, row) + COL_TERM(2, row) + COL_TERM(3, row)))

    SET_CUBIC_SPLINE_WEIGHTS(u, tx);
    SET_CUBIC_SPLINE_WEIGHTS(v, ty);
    SET_CUBIC_SPLINE_WEIGHTS(w, tz);

    /* Actual interpolation. */
    return ROW_TERM(0) + ROW_TERM(1) + ROW_TERM(2) + ROW_TERM(3);

#  undef COL_TERM
#  undef ROW_TERM
#  undef DATA
  }

  static ccl_always_inline OutT
  interp_3d(const TextureInfo &info, float x, float y, float z, InterpolationType interp)
  {
    using namespace nanovdb;

    NanoGrid<TexT> *const grid = (NanoGrid<TexT> *)info.data;

    switch ((interp == INTERPOLATION_NONE) ? info.interpolation : interp) {
      case INTERPOLATION_CLOSEST: {
        ReadAccessor<TexT> acc(grid->tree().root());
        return interp_3d_closest(acc, x, y, z);
      }
      case INTERPOLATION_LINEAR: {
        CachedReadAccessor<TexT> acc(grid->tree().root());
        return interp_3d_linear(acc, x, y, z);
      }
      default: {
        CachedReadAccessor<TexT> acc(grid->tree().root());
        return interp_3d_cubic(acc, x, y, z);
      }
    }
  }
};
#endif

#undef SET_CUBIC_SPLINE_WEIGHTS

ccl_device float4 kernel_tex_image_interp(KernelGlobals kg, int id, float x, float y)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  if (UNLIKELY(!info.data)) {
    return zero_float4();
  }

  switch (info.data_type) {
    case IMAGE_DATA_TYPE_HALF: {
      const float f = TextureInterpolator<half, float>::interp(info, x, y);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_BYTE: {
      const float f = TextureInterpolator<uchar, float>::interp(info, x, y);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_USHORT: {
      const float f = TextureInterpolator<uint16_t, float>::interp(info, x, y);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_FLOAT: {
      const float f = TextureInterpolator<float, float>::interp(info, x, y);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_HALF4:
      return TextureInterpolator<half4>::interp(info, x, y);
    case IMAGE_DATA_TYPE_BYTE4:
      return TextureInterpolator<uchar4>::interp(info, x, y);
    case IMAGE_DATA_TYPE_USHORT4:
      return TextureInterpolator<ushort4>::interp(info, x, y);
    case IMAGE_DATA_TYPE_FLOAT4:
      return TextureInterpolator<float4>::interp(info, x, y);
    default:
      assert(0);
      return make_float4(
          TEX_IMAGE_MISSING_R, TEX_IMAGE_MISSING_G, TEX_IMAGE_MISSING_B, TEX_IMAGE_MISSING_A);
  }
}

ccl_device float4 kernel_tex_image_interp_3d(KernelGlobals kg,
                                             int id,
                                             float3 P,
                                             InterpolationType interp)
{
  const TextureInfo &info = kernel_data_fetch(texture_info, id);

  if (UNLIKELY(!info.data)) {
    return zero_float4();
  }

  if (info.use_transform_3d) {
    P = transform_point(&info.transform_3d, P);
  }
  switch (info.data_type) {
    case IMAGE_DATA_TYPE_HALF: {
      const float f = TextureInterpolator<half, float>::interp_3d(info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_BYTE: {
      const float f = TextureInterpolator<uchar, float>::interp_3d(info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_USHORT: {
      const float f = TextureInterpolator<uint16_t, float>::interp_3d(info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_FLOAT: {
      const float f = TextureInterpolator<float, float>::interp_3d(info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_HALF4:
      return TextureInterpolator<half4>::interp_3d(info, P.x, P.y, P.z, interp);
    case IMAGE_DATA_TYPE_BYTE4:
      return TextureInterpolator<uchar4>::interp_3d(info, P.x, P.y, P.z, interp);
    case IMAGE_DATA_TYPE_USHORT4:
      return TextureInterpolator<ushort4>::interp_3d(info, P.x, P.y, P.z, interp);
    case IMAGE_DATA_TYPE_FLOAT4:
      return TextureInterpolator<float4>::interp_3d(info, P.x, P.y, P.z, interp);
#ifdef WITH_NANOVDB
    case IMAGE_DATA_TYPE_NANOVDB_FLOAT: {
      const float f = NanoVDBInterpolator<float, float>::interp_3d(info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_NANOVDB_FLOAT3:
      return NanoVDBInterpolator<packed_float3, float4>::interp_3d(info, P.x, P.y, P.z, interp);
    case IMAGE_DATA_TYPE_NANOVDB_FPN: {
      const float f = NanoVDBInterpolator<nanovdb::FpN, float>::interp_3d(
          info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
    case IMAGE_DATA_TYPE_NANOVDB_FP16: {
      const float f = NanoVDBInterpolator<nanovdb::Fp16, float>::interp_3d(
          info, P.x, P.y, P.z, interp);
      return make_float4(f, f, f, 1.0f);
    }
#endif
    default:
      assert(0);
      return make_float4(
          TEX_IMAGE_MISSING_R, TEX_IMAGE_MISSING_G, TEX_IMAGE_MISSING_B, TEX_IMAGE_MISSING_A);
  }
}

} /* Namespace. */

CCL_NAMESPACE_END
