Cycles: reduce shadow terminator artifacts
Offset rays from the flat surface to match where they would be for a smooth surface as specified by the normals. In the shading panel there is now a Shading Offset (existing option) and Geometry Offset (new). The Geometry Offset works as follows: * 0: disabled * 0.001: only terminated triangles (normal points to the light, geometry doesn't) are affected * 0.1 (default): triangles at grazing angles are affected, and the effect fades out * 1: all triangles are affected Limitations: * The artifact is still visible in some cases, it could be that some quads require to be treated specifically as quads. * Inconsistent normals cause artifacts. * If small objects cast shadows to a big low poly surface, the shadows can appear to be in a wrong place - because the surface moved slightly above the geometry. This can be noticed only at grazing angles to light. * Approximated surfaces of two non-intersecting low-poly objects can overlap that causes off-the-wall shadows. Generally, using one or a few levels of subdivision can get rid of artifacts faster than before. Differential Revision: https://developer.blender.org/D11065
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parent
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commit
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Notes:
blender-bot
2023-05-29 09:17:12 +02:00
Referenced by issue #100227, Smooth Shaded Mesh parallel to light blocking mesh allows light "through" Referenced by issue #90423, Cycles - Render Pass contains black pixels with no values Referenced by issue #89523, 3.0 Split kernel error: failed to load kernel_path_init with OpenCL on Linux
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@ -1254,12 +1254,19 @@ class CyclesObjectSettings(bpy.types.PropertyGroup):
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)
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shadow_terminator_offset: FloatProperty(
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name="Shadow Terminator Offset",
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name="Shadow Terminator Shading Offset",
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description="Push the shadow terminator towards the light to hide artifacts on low poly geometry",
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min=0.0, max=1.0,
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default=0.0,
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)
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shadow_terminator_geometry_offset: FloatProperty(
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name="Shadow Terminator Geometry Offset",
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description="Offset rays from the surface to reduce shadow terminator artifact on low poly geometry. Only affects triangles at grazing angles to light",
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min=0.0, max=1.0,
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default=0.1,
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)
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is_shadow_catcher: BoolProperty(
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name="Shadow Catcher",
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description="Only render shadows on this object, for compositing renders into real footage",
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@ -1223,20 +1223,31 @@ class CYCLES_OBJECT_PT_shading(CyclesButtonsPanel, Panel):
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@classmethod
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def poll(cls, context):
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return CyclesButtonsPanel.poll(context) and (context.object)
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if not CyclesButtonsPanel.poll(context):
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return False
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ob = context.object
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return ob and has_geometry_visibility(ob)
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def draw(self, context):
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pass
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class CYCLES_OBJECT_PT_shading_shadow_terminator(CyclesButtonsPanel, Panel):
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bl_label = "Shadow Terminator"
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bl_parent_id = "CYCLES_OBJECT_PT_shading"
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bl_context = "object"
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def draw(self, context):
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layout = self.layout
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layout.use_property_split = True
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flow = layout.grid_flow(row_major=False, columns=0, even_columns=True, even_rows=False, align=False)
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layout = self.layout
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flow = layout.grid_flow(row_major=False, columns=0, even_columns=True, even_rows=False, align=True)
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ob = context.object
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cob = ob.cycles
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if has_geometry_visibility(ob):
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col = flow.column()
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col.prop(cob, "shadow_terminator_offset")
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flow.prop(cob, "shadow_terminator_geometry_offset", text="Geometry Offset")
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flow.prop(cob, "shadow_terminator_offset", text="Shading Offset")
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class CYCLES_OBJECT_PT_visibility(CyclesButtonsPanel, Panel):
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@ -2316,6 +2327,7 @@ classes = (
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CYCLES_PT_context_material,
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CYCLES_OBJECT_PT_motion_blur,
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CYCLES_OBJECT_PT_shading,
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CYCLES_OBJECT_PT_shading_shadow_terminator,
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CYCLES_OBJECT_PT_visibility,
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CYCLES_OBJECT_PT_visibility_ray_visibility,
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CYCLES_OBJECT_PT_visibility_culling,
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@ -290,8 +290,12 @@ Object *BlenderSync::sync_object(BL::Depsgraph &b_depsgraph,
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bool is_shadow_catcher = get_boolean(cobject, "is_shadow_catcher");
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object->set_is_shadow_catcher(is_shadow_catcher);
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float shadow_terminator_offset = get_float(cobject, "shadow_terminator_offset");
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object->set_shadow_terminator_offset(shadow_terminator_offset);
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float shadow_terminator_shading_offset = get_float(cobject, "shadow_terminator_offset");
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object->set_shadow_terminator_shading_offset(shadow_terminator_shading_offset);
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float shadow_terminator_geometry_offset = get_float(cobject,
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"shadow_terminator_geometry_offset");
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object->set_shadow_terminator_geometry_offset(shadow_terminator_geometry_offset);
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/* sync the asset name for Cryptomatte */
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BL::Object parent = b_ob.parent();
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@ -71,6 +71,85 @@ ccl_device_inline float3 ray_offset(float3 P, float3 Ng)
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#endif
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}
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/* This function should be used to compute a modified ray start position for
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* rays leaving from a surface. The algorithm slightly distorts flat surface
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* of a triangle. Surface is lifted by amount h along normal n in the incident
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* point. */
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ccl_device_inline float3 smooth_surface_offset(KernelGlobals *kg, ShaderData *sd, float3 Ng)
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{
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float3 V[3], N[3];
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triangle_vertices_and_normals(kg, sd->prim, V, N);
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const float u = sd->u, v = sd->v;
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const float w = 1 - u - v;
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float3 P = V[0] * u + V[1] * v + V[2] * w; /* Local space */
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float3 n = N[0] * u + N[1] * v + N[2] * w; /* We get away without normalization */
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n = transform_direction(&(sd->ob_tfm), n); /* Normal x scale, world space */
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/* Parabolic approximation */
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float a = dot(N[2] - N[0], V[0] - V[2]);
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float b = dot(N[2] - N[1], V[1] - V[2]);
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float c = dot(N[1] - N[0], V[1] - V[0]);
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float h = a * u * (u - 1) + (a + b + c) * u * v + b * v * (v - 1);
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/* Check flipped normals */
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if (dot(n, Ng) > 0) {
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/* Local linear envelope */
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float h0 = max(max(dot(V[1] - V[0], N[0]), dot(V[2] - V[0], N[0])), 0.0f);
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float h1 = max(max(dot(V[0] - V[1], N[1]), dot(V[2] - V[1], N[1])), 0.0f);
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float h2 = max(max(dot(V[0] - V[2], N[2]), dot(V[1] - V[2], N[2])), 0.0f);
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h0 = max(dot(V[0] - P, N[0]) + h0, 0.0f);
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h1 = max(dot(V[1] - P, N[1]) + h1, 0.0f);
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h2 = max(dot(V[2] - P, N[2]) + h2, 0.0f);
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h = max(min(min(h0, h1), h2), h * 0.5f);
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}
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else {
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float h0 = max(max(dot(V[0] - V[1], N[0]), dot(V[0] - V[2], N[0])), 0.0f);
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float h1 = max(max(dot(V[1] - V[0], N[1]), dot(V[1] - V[2], N[1])), 0.0f);
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float h2 = max(max(dot(V[2] - V[0], N[2]), dot(V[2] - V[1], N[2])), 0.0f);
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h0 = max(dot(P - V[0], N[0]) + h0, 0.0f);
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h1 = max(dot(P - V[1], N[1]) + h1, 0.0f);
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h2 = max(dot(P - V[2], N[2]) + h2, 0.0f);
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h = min(-min(min(h0, h1), h2), h * 0.5f);
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}
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return n * h;
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}
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/* Ray offset to avoid shadow terminator artifact. */
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ccl_device_inline float3 ray_offset_shadow(KernelGlobals *kg, ShaderData *sd, float3 L)
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{
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float NL = dot(sd->N, L);
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bool transmit = (NL < 0.0f);
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float3 Ng = (transmit ? -sd->Ng : sd->Ng);
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float3 P = ray_offset(sd->P, Ng);
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if ((sd->type & PRIMITIVE_ALL_TRIANGLE) && (sd->shader & SHADER_SMOOTH_NORMAL)) {
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const float offset_cutoff =
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kernel_tex_fetch(__objects, sd->object).shadow_terminator_geometry_offset;
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/* Do ray offset (heavy stuff) only for close to be terminated triangles:
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* offset_cutoff = 0.1f means that 10-20% of rays will be affected. Also
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* make a smooth transition near the threshold. */
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if (offset_cutoff > 0.0f) {
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float NgL = dot(Ng, L);
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float offset_amount = 0.0f;
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if (NL < offset_cutoff) {
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offset_amount = clamp(2.0f - (NgL + NL) / offset_cutoff, 0.0f, 1.0f);
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}
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else {
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offset_amount = clamp(1.0f - NgL / offset_cutoff, 0.0f, 1.0f);
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}
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if (offset_amount > 0.0f) {
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P += smooth_surface_offset(kg, sd, Ng) * offset_amount;
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}
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}
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}
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return P;
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}
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#if defined(__VOLUME_RECORD_ALL__) || (defined(__SHADOW_RECORD_ALL__) && defined(__KERNEL_CPU__))
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/* ToDo: Move to another file? */
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ccl_device int intersections_compare(const void *a, const void *b)
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@ -462,7 +462,7 @@ ccl_device_inline int bsdf_sample(KernelGlobals *kg,
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else {
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/* Shadow terminator offset. */
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const float frequency_multiplier =
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kernel_tex_fetch(__objects, sd->object).shadow_terminator_offset;
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kernel_tex_fetch(__objects, sd->object).shadow_terminator_shading_offset;
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if (frequency_multiplier > 1.0f) {
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*eval *= shift_cos_in(dot(*omega_in, sc->N), frequency_multiplier);
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}
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@ -488,12 +488,9 @@ ccl_device_inline
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const float3 omega_in,
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float *pdf)
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{
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/* For curves use the smooth normal, particularly for ribbons the geometric
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* normal gives too much darkening otherwise. */
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const float3 Ng = (sd->type & PRIMITIVE_ALL_CURVE) ? sd->N : sd->Ng;
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float3 eval;
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if (dot(Ng, omega_in) >= 0.0f) {
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if (dot(sd->N, omega_in) >= 0.0f) {
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switch (sc->type) {
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case CLOSURE_BSDF_DIFFUSE_ID:
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case CLOSURE_BSDF_BSSRDF_ID:
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@ -589,7 +586,7 @@ ccl_device_inline
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}
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/* Shadow terminator offset. */
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const float frequency_multiplier =
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kernel_tex_fetch(__objects, sd->object).shadow_terminator_offset;
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kernel_tex_fetch(__objects, sd->object).shadow_terminator_shading_offset;
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if (frequency_multiplier > 1.0f) {
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eval *= shift_cos_in(dot(omega_in, sc->N), frequency_multiplier);
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}
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@ -75,6 +75,19 @@ ccl_device_inline void triangle_vertices(KernelGlobals *kg, int prim, float3 P[3
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P[2] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 2));
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}
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/* Triangle vertex locations and vertex normals */
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ccl_device_inline void triangle_vertices_and_normals(KernelGlobals *kg, int prim, float3 P[3], float3 N[3])
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{
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const uint4 tri_vindex = kernel_tex_fetch(__tri_vindex, prim);
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P[0] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 0));
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P[1] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 1));
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P[2] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 2));
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N[0] = float4_to_float3(kernel_tex_fetch(__tri_vnormal, tri_vindex.x));
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N[1] = float4_to_float3(kernel_tex_fetch(__tri_vnormal, tri_vindex.y));
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N[2] = float4_to_float3(kernel_tex_fetch(__tri_vnormal, tri_vindex.z));
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}
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/* Interpolate smooth vertex normal from vertices */
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ccl_device_inline float3
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@ -176,8 +176,7 @@ ccl_device_noinline_cpu bool direct_emission(KernelGlobals *kg,
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if (ls->shader & SHADER_CAST_SHADOW) {
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/* setup ray */
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bool transmit = (dot(sd->Ng, ls->D) < 0.0f);
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ray->P = ray_offset(sd->P, (transmit) ? -sd->Ng : sd->Ng);
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ray->P = ray_offset_shadow(kg, sd, ls->D);
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if (ls->t == FLT_MAX) {
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/* distant light */
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@ -1479,7 +1479,8 @@ typedef struct KernelObject {
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float cryptomatte_object;
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float cryptomatte_asset;
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float shadow_terminator_offset;
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float shadow_terminator_shading_offset;
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float shadow_terminator_geometry_offset;
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float pad1, pad2, pad3;
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} KernelObject;
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static_assert_align(KernelObject, 16);
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@ -93,7 +93,8 @@ NODE_DEFINE(Object)
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SOCKET_POINT(dupli_generated, "Dupli Generated", zero_float3());
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SOCKET_POINT2(dupli_uv, "Dupli UV", zero_float2());
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SOCKET_TRANSFORM_ARRAY(motion, "Motion", array<Transform>());
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SOCKET_FLOAT(shadow_terminator_offset, "Terminator Offset", 0.0f);
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SOCKET_FLOAT(shadow_terminator_shading_offset, "Shadow Terminator Shading Offset", 0.0f);
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SOCKET_FLOAT(shadow_terminator_geometry_offset, "Shadow Terminator Geometry Offset", 0.1f);
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SOCKET_STRING(asset_name, "Asset Name", ustring());
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SOCKET_BOOLEAN(is_shadow_catcher, "Shadow Catcher", false);
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@ -507,7 +508,9 @@ void ObjectManager::device_update_object_transform(UpdateObjectTransformState *s
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kobject.cryptomatte_asset = util_hash_to_float(hash_asset);
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}
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kobject.shadow_terminator_offset = 1.0f / (1.0f - 0.5f * ob->shadow_terminator_offset);
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kobject.shadow_terminator_shading_offset = 1.0f /
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(1.0f - 0.5f * ob->shadow_terminator_shading_offset);
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kobject.shadow_terminator_geometry_offset = ob->shadow_terminator_geometry_offset;
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/* Object flag. */
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if (ob->use_holdout) {
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@ -64,7 +64,8 @@ class Object : public Node {
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NODE_SOCKET_API(bool, hide_on_missing_motion)
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NODE_SOCKET_API(bool, use_holdout)
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NODE_SOCKET_API(bool, is_shadow_catcher)
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NODE_SOCKET_API(float, shadow_terminator_offset)
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NODE_SOCKET_API(float, shadow_terminator_shading_offset)
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NODE_SOCKET_API(float, shadow_terminator_geometry_offset)
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NODE_SOCKET_API(float3, dupli_generated)
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NODE_SOCKET_API(float2, dupli_uv)
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