void compute_ibl_bssrdf_sampling(
SamplingContext& sampling_context,
const ShadingContext& shading_context,
const EnvironmentEDF& environment_edf,
const BSSRDF& bssrdf,
const void* bssrdf_data,
const ShadingPoint& incoming_point,
const ShadingPoint& outgoing_point,
const Dual3d& outgoing,
const size_t bssrdf_sample_count,
const size_t env_sample_count,
Spectrum& radiance)
{
assert(is_normalized(outgoing.get_value()));
radiance.set(0.0f);
sampling_context.split_in_place(2, bssrdf_sample_count);
for (size_t i = 0; i < bssrdf_sample_count; ++i)
{
// Generate a uniform sample in [0,1)^2.
const Vector2d s = sampling_context.next_vector2<2>();
// Sample the BSSRDF (hemisphere cosine).
Vector3d incoming = sample_hemisphere_cosine(s);
const double cos_in = incoming.y;
const double bssrdf_prob = cos_in * RcpPi;
incoming = incoming_point.get_shading_basis().transform_to_parent(incoming);
if (incoming_point.get_side() == ObjectInstance::BackSide)
incoming = -incoming;
assert(is_normalized(incoming));
// Discard occluded samples.
const double transmission =
shading_context.get_tracer().trace(
incoming_point,
incoming,
VisibilityFlags::ShadowRay);
if (transmission == 0.0)
continue;
// Evaluate the BSSRDF.
Spectrum bssrdf_value;
bssrdf.evaluate(
bssrdf_data,
outgoing_point,
outgoing.get_value(),
incoming_point,
incoming,
bssrdf_value);
// Evaluate the environment's EDF.
InputEvaluator input_evaluator(shading_context.get_texture_cache());
Spectrum env_value;
double env_prob;
environment_edf.evaluate(
shading_context,
input_evaluator,
incoming,
env_value,
env_prob);
// Compute MIS weight.
const double mis_weight =
mis_power2(
bssrdf_sample_count * bssrdf_prob,
env_sample_count * env_prob);
// Add the contribution of this sample to the illumination.
env_value *= static_cast<float>(transmission * cos_in / bssrdf_prob * mis_weight);
env_value *= bssrdf_value;
radiance += env_value;
}
if (bssrdf_sample_count > 1)
radiance /= static_cast<float>(bssrdf_sample_count);
}
void DiagnosticSurfaceShader::evaluate(
SamplingContext& sampling_context,
const PixelContext& pixel_context,
const ShadingContext& shading_context,
const ShadingPoint& shading_point,
ShadingResult& shading_result) const
{
switch (m_shading_mode)
{
case Color:
{
shading_result.set_main_to_opaque_pink_linear_rgba();
const Material* material = shading_point.get_material();
if (material)
{
const Material::RenderData& material_data = material->get_render_data();
#ifdef APPLESEED_WITH_OSL
// Execute the OSL shader if there is one.
if (material_data.m_shader_group)
{
shading_context.execute_osl_shading(
*material_data.m_shader_group,
shading_point);
}
#endif
if (material_data.m_bsdf)
{
InputEvaluator input_evaluator(shading_context.get_texture_cache());
material_data.m_bsdf->evaluate_inputs(
shading_context,
input_evaluator,
shading_point);
const Vector3d direction = -normalize(shading_point.get_ray().m_dir);
material_data.m_bsdf->evaluate(
input_evaluator.data(),
false,
false,
shading_point.get_geometric_normal(),
shading_point.get_shading_basis(),
direction,
direction,
ScatteringMode::All,
shading_result.m_main.m_color);
shading_result.m_color_space = ColorSpaceSpectral;
}
}
}
break;
case Coverage:
shading_result.set_main_to_linear_rgb(Color3f(1.0f));
break;
case Barycentric:
shading_result.set_main_to_linear_rgb(
vector2_to_color(shading_point.get_bary()));
break;
case UV:
shading_result.set_main_to_linear_rgb(
uvs_to_color(shading_point.get_uv(0)));
break;
case Tangent:
case Bitangent:
case ShadingNormal:
{
#ifdef APPLESEED_WITH_OSL
const Material* material = shading_point.get_material();
if (material)
{
const Material::RenderData& material_data = material->get_render_data();
// Execute the OSL shader if there is one.
if (material_data.m_shader_group)
{
sampling_context.split_in_place(2, 1);
shading_context.execute_osl_bump(
*material_data.m_shader_group,
shading_point,
sampling_context.next_vector2<2>());
}
}
#endif
const Vector3d v =
m_shading_mode == ShadingNormal ? shading_point.get_shading_basis().get_normal() :
m_shading_mode == Tangent ? shading_point.get_shading_basis().get_tangent_u() :
shading_point.get_shading_basis().get_tangent_v();
shading_result.set_main_to_linear_rgb(vector3_to_color(v));
}
break;
case GeometricNormal:
shading_result.set_main_to_linear_rgb(
vector3_to_color(shading_point.get_geometric_normal()));
break;
case OriginalShadingNormal:
shading_result.set_main_to_linear_rgb(
vector3_to_color(shading_point.get_original_shading_normal()));
break;
case WorldSpacePosition:
{
const Vector3d& p = shading_point.get_point();
shading_result.set_main_to_linear_rgb(
Color3f(Color3d(p.x, p.y, p.z)));
}
break;
case Sides:
shading_result.set_main_to_linear_rgb(
shading_point.get_side() == ObjectInstance::FrontSide
? Color3f(0.0f, 0.0f, 1.0f)
: Color3f(1.0f, 0.0f, 0.0f));
break;
case Depth:
shading_result.set_main_to_linear_rgb(
Color3f(static_cast<float>(shading_point.get_distance())));
break;
case ScreenSpaceWireframe:
{
// Initialize the shading result to the background color.
shading_result.set_main_to_linear_rgba(Color4f(0.0f, 0.0f, 0.8f, 0.5f));
if (shading_point.is_triangle_primitive())
{
// Film space thickness of the wires.
const double SquareWireThickness = square(0.00025);
// Retrieve the time, the scene and the camera.
const double time = shading_point.get_time().m_absolute;
const Scene& scene = shading_point.get_scene();
const Camera& camera = *scene.get_camera();
// Compute the film space coordinates of the intersection point.
Vector2d point_ndc;
camera.project_point(time, shading_point.get_point(), point_ndc);
// Loop over the triangle edges.
for (size_t i = 0; i < 3; ++i)
{
// Retrieve the end points of this edge.
const size_t j = (i + 1) % 3;
const Vector3d vi = shading_point.get_vertex(i);
const Vector3d vj = shading_point.get_vertex(j);
// Compute the film space coordinates of the edge's end points.
Vector2d vi_ndc, vj_ndc;
if (!camera.project_segment(time, vi, vj, vi_ndc, vj_ndc))
continue;
// Compute the film space distance from the intersection point to the edge.
const double d = square_distance_point_segment(point_ndc, vi_ndc, vj_ndc);
// Shade with the wire's color if the hit point is close enough to the edge.
if (d < SquareWireThickness)
{
shading_result.set_main_to_linear_rgba(Color4f(1.0f));
break;
}
}
}
else
{
assert(shading_point.is_curve_primitive());
// todo: implement.
}
}
break;
case WorldSpaceWireframe:
{
// Initialize the shading result to the background color.
shading_result.set_main_to_linear_rgba(Color4f(0.0f, 0.0f, 0.8f, 0.5f));
if (shading_point.is_triangle_primitive())
{
// World space thickness of the wires.
const double SquareWireThickness = square(0.0015);
// Retrieve the world space intersection point.
const Vector3d& point = shading_point.get_point();
// Loop over the triangle edges.
for (size_t i = 0; i < 3; ++i)
{
// Retrieve the end points of this edge.
const size_t j = (i + 1) % 3;
const Vector3d& vi = shading_point.get_vertex(i);
const Vector3d& vj = shading_point.get_vertex(j);
// Compute the world space distance from the intersection point to the edge.
const double d = square_distance_point_segment(point, vi, vj);
// Shade with the wire's color if the hit point is close enough to the edge.
if (d < SquareWireThickness)
{
shading_result.set_main_to_linear_rgba(Color4f(1.0f));
break;
}
}
}
else
{
assert(shading_point.is_curve_primitive());
// todo: implement.
}
}
break;
case AmbientOcclusion:
{
// Compute the occlusion.
const double occlusion =
compute_ambient_occlusion(
sampling_context,
sample_hemisphere_uniform<double>,
shading_context.get_intersector(),
shading_point,
m_ao_max_distance,
m_ao_samples);
// Return a gray scale value proportional to the accessibility.
const float accessibility = static_cast<float>(1.0 - occlusion);
shading_result.set_main_to_linear_rgb(Color3f(accessibility));
}
break;
case AssemblyInstances:
shading_result.set_main_to_linear_rgb(
integer_to_color(shading_point.get_assembly_instance().get_uid()));
break;
case ObjectInstances:
shading_result.set_main_to_linear_rgb(
integer_to_color(shading_point.get_object_instance().get_uid()));
break;
case Regions:
{
const uint32 h =
mix_uint32(
static_cast<uint32>(shading_point.get_object_instance().get_uid()),
static_cast<uint32>(shading_point.get_region_index()));
shading_result.set_main_to_linear_rgb(integer_to_color(h));
}
break;
case Primitives:
{
const uint32 h =
mix_uint32(
static_cast<uint32>(shading_point.get_object_instance().get_uid()),
static_cast<uint32>(shading_point.get_region_index()),
static_cast<uint32>(shading_point.get_primitive_index()));
shading_result.set_main_to_linear_rgb(integer_to_color(h));
}
break;
case Materials:
{
const Material* material = shading_point.get_material();
if (material)
shading_result.set_main_to_linear_rgb(integer_to_color(material->get_uid()));
else shading_result.set_main_to_opaque_pink_linear_rgba();
}
break;
case RaySpread:
{
const ShadingRay& ray = shading_point.get_ray();
if (!ray.m_has_differentials)
break;
const Material* material = shading_point.get_material();
if (material)
{
const Material::RenderData& material_data = material->get_render_data();
#ifdef APPLESEED_WITH_OSL
// Execute the OSL shader if there is one.
if (material_data.m_shader_group)
{
shading_context.execute_osl_shading(
*material_data.m_shader_group,
shading_point);
}
#endif
if (material_data.m_bsdf)
{
const Dual3d outgoing(
-ray.m_dir,
ray.m_dir - ray.m_rx.m_dir,
ray.m_dir - ray.m_ry.m_dir);
InputEvaluator input_evaluator(shading_context.get_texture_cache());
material_data.m_bsdf->evaluate_inputs(
shading_context,
input_evaluator,
shading_point);
const void* bsdf_data = input_evaluator.data();
BSDFSample sample(shading_point, outgoing);
material_data.m_bsdf->sample(
sampling_context,
bsdf_data,
false,
false,
sample);
if (!sample.m_incoming.has_derivatives())
break;
// The 3.0 factor is chosen so that ray spread from Lambertian BRDFs is approximately 1.
const double spread =
max(
norm(sample.m_incoming.get_dx()),
norm(sample.m_incoming.get_dy())) * 3.0;
shading_result.set_main_to_linear_rgb(
Color3f(static_cast<float>(spread)));
}
}
}
break;
case FacingRatio:
{
const Vector3d& normal = shading_point.get_shading_normal();
const Vector3d& view = shading_point.get_ray().m_dir;
const double facing = abs(dot(normal, view));
shading_result.set_main_to_linear_rgb(
Color3f(static_cast<float>(facing)));
}
break;
default:
assert(false);
shading_result.set_main_to_transparent_black_linear_rgba();
break;
}
}