void ShadingEngine::shade_hit_point(
SamplingContext& sampling_context,
const PixelContext& pixel_context,
const ShadingContext& shading_context,
const ShadingPoint& shading_point,
ShadingResult& shading_result) const
{
// Retrieve the material of the intersected surface.
const Material* material = shading_point.get_material();
// Compute the alpha channel of the main output.
if (material && material->get_alpha_map())
{
// There is an alpha map: evaluate it.
material->get_alpha_map()->evaluate(
shading_context.get_texture_cache(),
shading_point.get_uv(0),
shading_result.m_main.m_alpha);
}
else
{
// No alpha map: solid sample.
shading_result.m_main.m_alpha = Alpha(1.0f);
}
#ifdef WITH_OSL
if (material && material->get_osl_surface() && material->get_osl_surface()->has_transparency())
{
Alpha a;
shading_context.execute_osl_transparency(
*material->get_osl_surface(),
shading_point,
a);
shading_result.m_main.m_alpha *= a;
}
#endif
if (shading_result.m_main.m_alpha[0] > 0.0f || material->shade_alpha_cutouts())
{
// Use the diagnostic surface shader if there is one.
const SurfaceShader* surface_shader = m_diagnostic_surface_shader.get();
if (surface_shader == 0)
{
if (material == 0)
{
// The intersected surface has no material: return solid pink.
shading_result.set_main_to_opaque_pink_linear_rgba();
shading_result.set_aovs_to_transparent_black_linear_rgba();
return;
}
// Use the surface shader of the intersected surface.
surface_shader = material->get_surface_shader();
if (surface_shader == 0)
{
// The intersected surface has no surface shader: return solid pink.
shading_result.set_main_to_opaque_pink_linear_rgba();
shading_result.set_aovs_to_transparent_black_linear_rgba();
return;
}
}
// Execute the surface shader.
surface_shader->evaluate(
sampling_context,
pixel_context,
shading_context,
shading_point,
shading_result);
// Set AOVs.
shading_result.set_entity_aov(shading_point.get_assembly());
shading_result.set_entity_aov(shading_point.get_assembly_instance());
shading_result.set_entity_aov(shading_point.get_object());
shading_result.set_entity_aov(shading_point.get_object_instance());
if (material)
shading_result.set_entity_aov(*material);
shading_result.set_entity_aov(*surface_shader);
}
else
{
// Alpha is zero: shade as transparent black.
shading_result.set_main_to_transparent_black_linear_rgba();
shading_result.set_aovs_to_transparent_black_linear_rgba();
}
}
size_t SubsurfaceSampler::sample(
SamplingContext& sampling_context,
const ShadingPoint& outgoing_point,
const BSSRDF& bssrdf,
const void* bssrdf_data,
SubsurfaceSample samples[],
const size_t max_sample_count)
{
assert(max_sample_count > 0);
// Sample the diffusion profile.
BSSRDFSample bssrdf_sample(sampling_context);
if (!bssrdf.sample(bssrdf_data, bssrdf_sample))
return 0;
// Reject points too far away.
// This introduces negligible bias in comparison to the other approximations.
const Vector2d& point(bssrdf_sample.get_point());
const double radius2 = square_norm(point);
const double rmax2 = bssrdf_sample.get_rmax2();
if (radius2 > rmax2)
return 0;
// Evaluate the PDF of the diffusion profile.
const double radius = sqrt(radius2);
const double bssrdf_sample_pdf =
bssrdf.evaluate_pdf(bssrdf_data, bssrdf_sample.get_channel(), radius);
// Pick a sampling basis.
sampling_context.split_in_place(1, 1);
Axis sampling_axis;
Basis3d sampling_basis;
double sampling_basis_pdf;
pick_sampling_basis(
outgoing_point.get_shading_basis(),
sampling_context.next_double2(),
sampling_axis,
sampling_basis,
sampling_basis_pdf);
// Compute height of sample point on (positive) hemisphere of radius Rmax.
assert(rmax2 >= radius2);
const double h = sqrt(rmax2 - radius2);
// Compute sphere entry and exit points.
Vector3d entry_point, exit_point;
entry_point = exit_point = outgoing_point.get_point();
entry_point += sampling_basis.transform_to_parent(Vector3d(point[0], +h, point[1]));
exit_point += sampling_basis.transform_to_parent(Vector3d(point[0], -h, point[1]));
assert(feq(norm(exit_point - entry_point), 2.0 * h, 1.0e-9));
// Build a probe ray inscribed inside the sphere of radius Rmax.
ShadingRay probe_ray(
entry_point,
-sampling_basis.get_normal(),
0.0,
2.0 * h,
outgoing_point.get_time(),
VisibilityFlags::ProbeRay,
outgoing_point.get_ray().m_depth + 1);
const Material* material = outgoing_point.get_material();
ShadingPoint shading_points[2];
size_t shading_point_index = 0;
ShadingPoint* parent_shading_point = 0;
size_t sample_count = 0;
// Trace the ray and return all intersections (or up to max_sample_count of them) found inside the sphere.
while (true)
{
// Continue tracing the ray.
shading_points[shading_point_index].clear();
if (!m_shading_context.get_intersector().trace(
probe_ray,
shading_points[shading_point_index],
parent_shading_point))
break;
// Only consider points lying on surfaces with the same material as the outgoing point.
if (shading_points[shading_point_index].get_material() == material)
{
// Execute the OSL shader if we have one. Needed for bump mapping.
#ifdef APPLESEED_WITH_OSL
if (material->has_osl_surface())
{
sampling_context.split_in_place(1, 1);
m_shading_context.execute_osl_bump(
*material->get_osl_surface(),
shading_points[shading_point_index],
sampling_context.next_double2());
}
#endif
SubsurfaceSample& sample = samples[sample_count++];
sample.m_point = shading_points[shading_point_index];
// Compute sample probability.
sample.m_probability =
bssrdf_sample_pdf
* sampling_basis_pdf
* abs(dot(sampling_basis.get_normal(), sample.m_point.get_geometric_normal())); // todo: or shading normal?
// Weight sample probability with multiple importance sampling.
sample.m_probability /=
compute_mis_weight(
bssrdf,
bssrdf_data,
bssrdf_sample.get_channel(),
sampling_basis,
sampling_axis,
sample.m_probability,
outgoing_point.get_point(),
sample.m_point.get_point(),
sample.m_point.get_geometric_normal()); // todo: or shading normal?
// Return the relative index of refraction.
sample.m_eta = bssrdf_sample.get_eta();
if (sample_count == max_sample_count)
break;
}
// Move the ray's origin past the hit surface.
probe_ray.m_org = shading_points[shading_point_index].get_point();
probe_ray.m_tmax = norm(exit_point - probe_ray.m_org);
// Swap the current and parent shading points.
parent_shading_point = &shading_points[shading_point_index];
shading_point_index = 1 - shading_point_index;
}
return 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;
}
}
bool Intersector::do_trace_same_material(
const ShadingRay& ray,
const ShadingPoint& parent_shading_point,
const bool offset_origin,
ShadingPoint& shading_point) const
{
ShadingRay up_ray(ray);
ShadingRay down_ray(ray);
down_ray.m_dir = -down_ray.m_dir;
if (offset_origin)
{
parent_shading_point.refine_and_offset();
const Vector3d offset =
parent_shading_point.get_offset_point(down_ray.m_dir) - parent_shading_point.get_point();
up_ray.m_org += offset;
}
const Material* parent_material = parent_shading_point.get_material();
// Trace the ray.
ShadingPoint up_shading_point;
trace_back_sides(
up_ray,
up_shading_point);
// Discard objects with different materials.
if (up_shading_point.hit())
{
if (up_shading_point.get_opposite_material() != parent_material)
up_shading_point.clear();
}
// Trace the opposite ray.
ShadingPoint down_shading_point;
trace_back_sides(
down_ray,
down_shading_point);
// Discard objects with different materials.
if (down_shading_point.hit())
{
if (down_shading_point.get_opposite_material() != parent_material)
down_shading_point.clear();
}
// Keep the nearest hit, if any.
if (up_shading_point.hit() && down_shading_point.hit())
{
shading_point =
up_shading_point.get_distance() < down_shading_point.get_distance() ? up_shading_point : down_shading_point;
return true;
}
else if (up_shading_point.hit())
{
shading_point = up_shading_point;
return true;
}
else if (down_shading_point.hit())
{
shading_point = down_shading_point;
return true;
}
return false;
}