cycles/kernel/kernel_bake.h

/*
 * Copyright 2011-2013 Blender Foundation
 *
 * 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.
 */

CCL_NAMESPACE_BEGIN

#ifdef __BAKING__

ccl_device_noinline void compute_light_pass(
    KernelGlobals *kg, ShaderData *sd, PathRadiance *L, uint rng_hash, int pass_filter, int sample)
{
  kernel_assert(kernel_data.film.use_light_pass);

  float3 throughput = make_float3(1.0f, 1.0f, 1.0f);

  /* Emission and indirect shader data memory used by various functions. */
  ShaderDataTinyStorage emission_sd_storage;
  ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
  ShaderData indirect_sd;

  /* Init radiance. */
  path_radiance_init(kg, L);

  /* Init path state. */
  PathState state;
  path_state_init(kg, emission_sd, &state, rng_hash, sample, NULL);

  /* Evaluate surface shader. */
  shader_eval_surface(kg, sd, &state, NULL, state.flag);

  /* TODO, disable more closures we don't need besides transparent */
  shader_bsdf_disable_transparency(kg, sd);

  /* Init ray. */
  Ray ray;
  ray.P = sd->P + sd->Ng;
  ray.D = -sd->Ng;
  ray.t = FLT_MAX;
#  ifdef __CAMERA_MOTION__
  ray.time = 0.5f;
#  endif

#  ifdef __BRANCHED_PATH__
  if (!kernel_data.integrator.branched) {
    /* regular path tracer */
#  endif

    /* sample ambient occlusion */
    if (pass_filter & BAKE_FILTER_AO) {
      kernel_path_ao(kg, sd, emission_sd, L, &state, throughput, shader_bsdf_alpha(kg, sd));
    }

    /* sample emission */
    if ((pass_filter & BAKE_FILTER_EMISSION) && (sd->flag & SD_EMISSION)) {
      float3 emission = indirect_primitive_emission(kg, sd, 0.0f, state.flag, state.ray_pdf);
      path_radiance_accum_emission(kg, L, &state, throughput, emission);
    }

    bool is_sss_sample = false;

#  ifdef __SUBSURFACE__
    /* sample subsurface scattering */
    if ((pass_filter & BAKE_FILTER_DIFFUSE) && (sd->flag & SD_BSSRDF)) {
      /* When mixing BSSRDF and BSDF closures we should skip BSDF lighting
       * if scattering was successful. */
      SubsurfaceIndirectRays ss_indirect;
      kernel_path_subsurface_init_indirect(&ss_indirect);
      if (kernel_path_subsurface_scatter(
              kg, sd, emission_sd, L, &state, &ray, &throughput, &ss_indirect)) {
        while (ss_indirect.num_rays) {
          kernel_path_subsurface_setup_indirect(kg, &ss_indirect, &state, &ray, L, &throughput);
          kernel_path_indirect(kg, &indirect_sd, emission_sd, &ray, throughput, &state, L);
        }
        is_sss_sample = true;
      }
    }
#  endif

    /* sample light and BSDF */
    if (!is_sss_sample && (pass_filter & (BAKE_FILTER_DIRECT | BAKE_FILTER_INDIRECT))) {
      kernel_path_surface_connect_light(kg, sd, emission_sd, throughput, &state, L);

      if (kernel_path_surface_bounce(kg, sd, &throughput, &state, &L->state, &ray)) {
#  ifdef __LAMP_MIS__
        state.ray_t = 0.0f;
#  endif
        /* compute indirect light */
        kernel_path_indirect(kg, &indirect_sd, emission_sd, &ray, throughput, &state, L);

        /* sum and reset indirect light pass variables for the next samples */
        path_radiance_sum_indirect(L);
        path_radiance_reset_indirect(L);
      }
    }
#  ifdef __BRANCHED_PATH__
  }
  else {
    /* branched path tracer */

    /* sample ambient occlusion */
    if (pass_filter & BAKE_FILTER_AO) {
      kernel_branched_path_ao(kg, sd, emission_sd, L, &state, throughput);
    }

    /* sample emission */
    if ((pass_filter & BAKE_FILTER_EMISSION) && (sd->flag & SD_EMISSION)) {
      float3 emission = indirect_primitive_emission(kg, sd, 0.0f, state.flag, state.ray_pdf);
      path_radiance_accum_emission(kg, L, &state, throughput, emission);
    }

#    ifdef __SUBSURFACE__
    /* sample subsurface scattering */
    if ((pass_filter & BAKE_FILTER_DIFFUSE) && (sd->flag & SD_BSSRDF)) {
      /* When mixing BSSRDF and BSDF closures we should skip BSDF lighting
       * if scattering was successful. */
      kernel_branched_path_subsurface_scatter(
          kg, sd, &indirect_sd, emission_sd, L, &state, &ray, throughput);
    }
#    endif

    /* sample light and BSDF */
    if (pass_filter & (BAKE_FILTER_DIRECT | BAKE_FILTER_INDIRECT)) {
#    if defined(__EMISSION__)
      /* direct light */
      if (kernel_data.integrator.use_direct_light) {
        int all = kernel_data.integrator.sample_all_lights_direct;
        kernel_branched_path_surface_connect_light(
            kg, sd, emission_sd, &state, throughput, 1.0f, L, all);
      }
#    endif

      /* indirect light */
      kernel_branched_path_surface_indirect_light(
          kg, sd, &indirect_sd, emission_sd, throughput, 1.0f, &state, L);
    }
  }
#  endif
}

/* this helps with AA but it's not the real solution as it does not AA the geometry
 *  but it's better than nothing, thus committed */
ccl_device_inline float bake_clamp_mirror_repeat(float u, float max)
{
  /* use mirror repeat (like opengl texture) so that if the barycentric
   * coordinate goes past the end of the triangle it is not always clamped
   * to the same value, gives ugly patterns */
  u /= max;
  float fu = floorf(u);
  u = u - fu;

  return ((((int)fu) & 1) ? 1.0f - u : u) * max;
}

ccl_device_inline float3 kernel_bake_shader_bsdf(KernelGlobals *kg,
                                                 ShaderData *sd,
                                                 const ShaderEvalType type)
{
  switch (type) {
    case SHADER_EVAL_DIFFUSE:
      return shader_bsdf_diffuse(kg, sd);
    case SHADER_EVAL_GLOSSY:
      return shader_bsdf_glossy(kg, sd);
    case SHADER_EVAL_TRANSMISSION:
      return shader_bsdf_transmission(kg, sd);
    default:
      kernel_assert(!"Unknown bake type passed to BSDF evaluate");
      return make_float3(0.0f, 0.0f, 0.0f);
  }
}

ccl_device float3 kernel_bake_evaluate_direct_indirect(KernelGlobals *kg,
                                                       ShaderData *sd,
                                                       PathState *state,
                                                       float3 direct,
                                                       float3 indirect,
                                                       const ShaderEvalType type,
                                                       const int pass_filter)
{
  float3 color;
  const bool is_color = (pass_filter & BAKE_FILTER_COLOR) != 0;
  const bool is_direct = (pass_filter & BAKE_FILTER_DIRECT) != 0;
  const bool is_indirect = (pass_filter & BAKE_FILTER_INDIRECT) != 0;
  float3 out = make_float3(0.0f, 0.0f, 0.0f);

  if (is_color) {
    if (is_direct || is_indirect) {
      /* Leave direct and diffuse channel colored. */
      color = make_float3(1.0f, 1.0f, 1.0f);
    }
    else {
      /* surface color of the pass only */
      shader_eval_surface(kg, sd, state, NULL, 0);
      return kernel_bake_shader_bsdf(kg, sd, type);
    }
  }
  else {
    shader_eval_surface(kg, sd, state, NULL, 0);
    color = kernel_bake_shader_bsdf(kg, sd, type);
  }

  if (is_direct) {
    out += safe_divide_even_color(direct, color);
  }

  if (is_indirect) {
    out += safe_divide_even_color(indirect, color);
  }

  return out;
}

ccl_device void kernel_bake_evaluate(
    KernelGlobals *kg, ccl_global float *buffer, int sample, int x, int y, int offset, int stride)
{
  /* Setup render buffers. */
  const int index = offset + x + y * stride;
  const int pass_stride = kernel_data.film.pass_stride;
  buffer += index * pass_stride;

  ccl_global float *primitive = buffer + kernel_data.film.pass_bake_primitive;
  ccl_global float *differential = buffer + kernel_data.film.pass_bake_differential;
  ccl_global float *output = buffer + kernel_data.film.pass_combined;

  int prim = __float_as_uint(primitive[1]);
  if (prim == -1)
    return;

  prim += kernel_data.bake.tri_offset;

  /* Random number generator. */
  uint rng_hash = hash_uint2(x, y) ^ kernel_data.integrator.seed;
  int num_samples = kernel_data.integrator.aa_samples;

  float filter_x, filter_y;
  if (sample == 0) {
    filter_x = filter_y = 0.5f;
  }
  else {
    path_rng_2D(kg, rng_hash, sample, num_samples, PRNG_FILTER_U, &filter_x, &filter_y);
  }

  /* Barycentric UV with subpixel offset. */
  float u = primitive[2];
  float v = primitive[3];

  float dudx = differential[0];
  float dudy = differential[1];
  float dvdx = differential[2];
  float dvdy = differential[3];

  if (sample > 0) {
    u = bake_clamp_mirror_repeat(u + dudx * (filter_x - 0.5f) + dudy * (filter_y - 0.5f), 1.0f);
    v = bake_clamp_mirror_repeat(v + dvdx * (filter_x - 0.5f) + dvdy * (filter_y - 0.5f),
                                 1.0f - u);
  }

  /* Shader data setup. */
  int object = kernel_data.bake.object_index;
  int shader;
  float3 P, Ng;

  triangle_point_normal(kg, object, prim, u, v, &P, &Ng, &shader);

  ShaderData sd;
  shader_setup_from_sample(
      kg,
      &sd,
      P,
      Ng,
      Ng,
      shader,
      object,
      prim,
      u,
      v,
      1.0f,
      0.5f,
      !(kernel_tex_fetch(__object_flag, object) & SD_OBJECT_TRANSFORM_APPLIED),
      LAMP_NONE);
  sd.I = sd.N;

  /* Setup differentials. */
  sd.dP.dx = sd.dPdu * dudx + sd.dPdv * dvdx;
  sd.dP.dy = sd.dPdu * dudy + sd.dPdv * dvdy;
  sd.du.dx = dudx;
  sd.du.dy = dudy;
  sd.dv.dx = dvdx;
  sd.dv.dy = dvdy;

  /* Set RNG state for shaders that use sampling. */
  PathState state = {0};
  state.rng_hash = rng_hash;
  state.rng_offset = 0;
  state.sample = sample;
  state.num_samples = num_samples;
  state.min_ray_pdf = FLT_MAX;

  /* Light passes if we need more than color. */
  PathRadiance L;
  int pass_filter = kernel_data.bake.pass_filter;

  if (kernel_data.bake.pass_filter & ~BAKE_FILTER_COLOR)
    compute_light_pass(kg, &sd, &L, rng_hash, pass_filter, sample);

  float3 out = make_float3(0.0f, 0.0f, 0.0f);

  ShaderEvalType type = (ShaderEvalType)kernel_data.bake.type;
  switch (type) {
    /* data passes */
    case SHADER_EVAL_NORMAL:
    case SHADER_EVAL_ROUGHNESS:
    case SHADER_EVAL_EMISSION: {
      if (type != SHADER_EVAL_NORMAL || (sd.flag & SD_HAS_BUMP)) {
        int path_flag = (type == SHADER_EVAL_EMISSION) ? PATH_RAY_EMISSION : 0;
        shader_eval_surface(kg, &sd, &state, NULL, path_flag);
      }

      if (type == SHADER_EVAL_NORMAL) {
        float3 N = sd.N;
        if (sd.flag & SD_HAS_BUMP) {
          N = shader_bsdf_average_normal(kg, &sd);
        }

        /* encoding: normal = (2 * color) - 1 */
        out = N * 0.5f + make_float3(0.5f, 0.5f, 0.5f);
      }
      else if (type == SHADER_EVAL_ROUGHNESS) {
        float roughness = shader_bsdf_average_roughness(&sd);
        out = make_float3(roughness, roughness, roughness);
      }
      else {
        out = shader_emissive_eval(&sd);
      }
      break;
    }
    case SHADER_EVAL_UV: {
      out = primitive_uv(kg, &sd);
      break;
    }
#  ifdef __PASSES__
    /* light passes */
    case SHADER_EVAL_AO: {
      out = L.ao;
      break;
    }
    case SHADER_EVAL_COMBINED: {
      if ((pass_filter & BAKE_FILTER_COMBINED) == BAKE_FILTER_COMBINED) {
        float alpha;
        out = path_radiance_clamp_and_sum(kg, &L, &alpha);
        break;
      }

      if ((pass_filter & BAKE_FILTER_DIFFUSE_DIRECT) == BAKE_FILTER_DIFFUSE_DIRECT)
        out += L.direct_diffuse;
      if ((pass_filter & BAKE_FILTER_DIFFUSE_INDIRECT) == BAKE_FILTER_DIFFUSE_INDIRECT)
        out += L.indirect_diffuse;

      if ((pass_filter & BAKE_FILTER_GLOSSY_DIRECT) == BAKE_FILTER_GLOSSY_DIRECT)
        out += L.direct_glossy;
      if ((pass_filter & BAKE_FILTER_GLOSSY_INDIRECT) == BAKE_FILTER_GLOSSY_INDIRECT)
        out += L.indirect_glossy;

      if ((pass_filter & BAKE_FILTER_TRANSMISSION_DIRECT) == BAKE_FILTER_TRANSMISSION_DIRECT)
        out += L.direct_transmission;
      if ((pass_filter & BAKE_FILTER_TRANSMISSION_INDIRECT) == BAKE_FILTER_TRANSMISSION_INDIRECT)
        out += L.indirect_transmission;

      if ((pass_filter & BAKE_FILTER_EMISSION) != 0)
        out += L.emission;

      break;
    }
    case SHADER_EVAL_SHADOW: {
      out = L.shadow;
      break;
    }
    case SHADER_EVAL_DIFFUSE: {
      out = kernel_bake_evaluate_direct_indirect(
          kg, &sd, &state, L.direct_diffuse, L.indirect_diffuse, type, pass_filter);
      break;
    }
    case SHADER_EVAL_GLOSSY: {
      out = kernel_bake_evaluate_direct_indirect(
          kg, &sd, &state, L.direct_glossy, L.indirect_glossy, type, pass_filter);
      break;
    }
    case SHADER_EVAL_TRANSMISSION: {
      out = kernel_bake_evaluate_direct_indirect(
          kg, &sd, &state, L.direct_transmission, L.indirect_transmission, type, pass_filter);
      break;
    }
#  endif

    /* extra */
    case SHADER_EVAL_ENVIRONMENT: {
      /* setup ray */
      Ray ray;

      ray.P = make_float3(0.0f, 0.0f, 0.0f);
      ray.D = normalize(P);
      ray.t = 0.0f;
#  ifdef __CAMERA_MOTION__
      ray.time = 0.5f;
#  endif

#  ifdef __RAY_DIFFERENTIALS__
      ray.dD = differential3_zero();
      ray.dP = differential3_zero();
#  endif

      /* setup shader data */
      shader_setup_from_background(kg, &sd, &ray);

      /* evaluate */
      int path_flag = 0; /* we can't know which type of BSDF this is for */
      shader_eval_surface(kg, &sd, &state, NULL, path_flag | PATH_RAY_EMISSION);
      out = shader_background_eval(&sd);
      break;
    }
    default: {
      /* no real shader, returning the position of the verts for debugging */
      out = normalize(P);
      break;
    }
  }

  /* write output */
  const float4 result = make_float4(out.x, out.y, out.z, 1.0f);
  kernel_write_pass_float4(output, result);
}

#endif /* __BAKING__ */

ccl_device void kernel_displace_evaluate(KernelGlobals *kg,
                                         ccl_global uint4 *input,
                                         ccl_global float4 *output,
                                         int i)
{
  ShaderData sd;
  PathState state = {0};
  uint4 in = input[i];

  /* setup shader data */
  int object = in.x;
  int prim = in.y;
  float u = __uint_as_float(in.z);
  float v = __uint_as_float(in.w);

  shader_setup_from_displace(kg, &sd, object, prim, u, v);

  /* evaluate */
  float3 P = sd.P;
  shader_eval_displacement(kg, &sd, &state);
  float3 D = sd.P - P;

  object_inverse_dir_transform(kg, &sd, &D);

  /* write output */
  output[i] += make_float4(D.x, D.y, D.z, 0.0f);
}

ccl_device void kernel_background_evaluate(KernelGlobals *kg,
                                           ccl_global uint4 *input,
                                           ccl_global float4 *output,
                                           int i)
{
  ShaderData sd;
  PathState state = {0};
  uint4 in = input[i];

  /* setup ray */
  Ray ray;
  float u = __uint_as_float(in.x);
  float v = __uint_as_float(in.y);

  ray.P = make_float3(0.0f, 0.0f, 0.0f);
  ray.D = equirectangular_to_direction(u, v);
  ray.t = 0.0f;
#ifdef __CAMERA_MOTION__
  ray.time = 0.5f;
#endif

#ifdef __RAY_DIFFERENTIALS__
  ray.dD = differential3_zero();
  ray.dP = differential3_zero();
#endif

  /* setup shader data */
  shader_setup_from_background(kg, &sd, &ray);

  /* evaluate */
  int path_flag = 0; /* we can't know which type of BSDF this is for */
  shader_eval_surface(kg, &sd, &state, NULL, path_flag | PATH_RAY_EMISSION);
  float3 color = shader_background_eval(&sd);

  /* write output */
  output[i] += make_float4(color.x, color.y, color.z, 0.0f);
}

CCL_NAMESPACE_END