[Bf-blender-cvs] [9c6a382f954] master: Cycles: reduce shadow terminator artifacts
Mikhail Matrosov
noreply at git.blender.org
Mon Jun 28 14:34:34 CEST 2021
Commit: 9c6a382f9540c8e334a16b7740b5ba6bb294fca9
Author: Mikhail Matrosov
Date: Mon Jun 28 13:54:18 2021 +0200
Branches: master
https://developer.blender.org/rB9c6a382f9540c8e334a16b7740b5ba6bb294fca9
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
===================================================================
M intern/cycles/blender/addon/properties.py
M intern/cycles/blender/addon/ui.py
M intern/cycles/blender/blender_object.cpp
M intern/cycles/kernel/bvh/bvh_util.h
M intern/cycles/kernel/closure/bsdf.h
M intern/cycles/kernel/geom/geom_triangle.h
M intern/cycles/kernel/kernel_emission.h
M intern/cycles/kernel/kernel_types.h
M intern/cycles/render/object.cpp
M intern/cycles/render/object.h
===================================================================
diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index cda1355eb2d..71e2f9fc3a5 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -1254,12 +1254,19 @@ class CyclesObjectSettings(bpy.types.PropertyGroup):
)
shadow_terminator_offset: FloatProperty(
- name="Shadow Terminator Offset",
+ name="Shadow Terminator Shading Offset",
description="Push the shadow terminator towards the light to hide artifacts on low poly geometry",
min=0.0, max=1.0,
default=0.0,
)
+ shadow_terminator_geometry_offset: FloatProperty(
+ name="Shadow Terminator Geometry Offset",
+ description="Offset rays from the surface to reduce shadow terminator artifact on low poly geometry. Only affects triangles at grazing angles to light",
+ min=0.0, max=1.0,
+ default=0.1,
+ )
+
is_shadow_catcher: BoolProperty(
name="Shadow Catcher",
description="Only render shadows on this object, for compositing renders into real footage",
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 62a2fa7f036..3d990467f04 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1223,20 +1223,31 @@ class CYCLES_OBJECT_PT_shading(CyclesButtonsPanel, Panel):
@classmethod
def poll(cls, context):
- return CyclesButtonsPanel.poll(context) and (context.object)
+ if not CyclesButtonsPanel.poll(context):
+ return False
+
+ ob = context.object
+ return ob and has_geometry_visibility(ob)
+
+ def draw(self, context):
+ pass
+
+
+class CYCLES_OBJECT_PT_shading_shadow_terminator(CyclesButtonsPanel, Panel):
+ bl_label = "Shadow Terminator"
+ bl_parent_id = "CYCLES_OBJECT_PT_shading"
+ bl_context = "object"
def draw(self, context):
layout = self.layout
layout.use_property_split = True
- flow = layout.grid_flow(row_major=False, columns=0, even_columns=True, even_rows=False, align=False)
- layout = self.layout
+ flow = layout.grid_flow(row_major=False, columns=0, even_columns=True, even_rows=False, align=True)
+
ob = context.object
cob = ob.cycles
-
- if has_geometry_visibility(ob):
- col = flow.column()
- col.prop(cob, "shadow_terminator_offset")
+ flow.prop(cob, "shadow_terminator_geometry_offset", text="Geometry Offset")
+ flow.prop(cob, "shadow_terminator_offset", text="Shading Offset")
class CYCLES_OBJECT_PT_visibility(CyclesButtonsPanel, Panel):
@@ -2316,6 +2327,7 @@ classes = (
CYCLES_PT_context_material,
CYCLES_OBJECT_PT_motion_blur,
CYCLES_OBJECT_PT_shading,
+ CYCLES_OBJECT_PT_shading_shadow_terminator,
CYCLES_OBJECT_PT_visibility,
CYCLES_OBJECT_PT_visibility_ray_visibility,
CYCLES_OBJECT_PT_visibility_culling,
diff --git a/intern/cycles/blender/blender_object.cpp b/intern/cycles/blender/blender_object.cpp
index cb84013c551..635392fb3d4 100644
--- a/intern/cycles/blender/blender_object.cpp
+++ b/intern/cycles/blender/blender_object.cpp
@@ -290,8 +290,12 @@ Object *BlenderSync::sync_object(BL::Depsgraph &b_depsgraph,
bool is_shadow_catcher = get_boolean(cobject, "is_shadow_catcher");
object->set_is_shadow_catcher(is_shadow_catcher);
- float shadow_terminator_offset = get_float(cobject, "shadow_terminator_offset");
- object->set_shadow_terminator_offset(shadow_terminator_offset);
+ float shadow_terminator_shading_offset = get_float(cobject, "shadow_terminator_offset");
+ object->set_shadow_terminator_shading_offset(shadow_terminator_shading_offset);
+
+ float shadow_terminator_geometry_offset = get_float(cobject,
+ "shadow_terminator_geometry_offset");
+ object->set_shadow_terminator_geometry_offset(shadow_terminator_geometry_offset);
/* sync the asset name for Cryptomatte */
BL::Object parent = b_ob.parent();
diff --git a/intern/cycles/kernel/bvh/bvh_util.h b/intern/cycles/kernel/bvh/bvh_util.h
index a694e4dc259..168c2939136 100644
--- a/intern/cycles/kernel/bvh/bvh_util.h
+++ b/intern/cycles/kernel/bvh/bvh_util.h
@@ -71,6 +71,85 @@ ccl_device_inline float3 ray_offset(float3 P, float3 Ng)
#endif
}
+/* This function should be used to compute a modified ray start position for
+ * rays leaving from a surface. The algorithm slightly distorts flat surface
+ * of a triangle. Surface is lifted by amount h along normal n in the incident
+ * point. */
+
+ccl_device_inline float3 smooth_surface_offset(KernelGlobals *kg, ShaderData *sd, float3 Ng)
+{
+ float3 V[3], N[3];
+ triangle_vertices_and_normals(kg, sd->prim, V, N);
+
+ const float u = sd->u, v = sd->v;
+ const float w = 1 - u - v;
+ float3 P = V[0] * u + V[1] * v + V[2] * w; /* Local space */
+ float3 n = N[0] * u + N[1] * v + N[2] * w; /* We get away without normalization */
+ n = transform_direction(&(sd->ob_tfm), n); /* Normal x scale, world space */
+
+ /* Parabolic approximation */
+ float a = dot(N[2] - N[0], V[0] - V[2]);
+ float b = dot(N[2] - N[1], V[1] - V[2]);
+ float c = dot(N[1] - N[0], V[1] - V[0]);
+ float h = a * u * (u - 1) + (a + b + c) * u * v + b * v * (v - 1);
+
+ /* Check flipped normals */
+ if (dot(n, Ng) > 0) {
+ /* Local linear envelope */
+ float h0 = max(max(dot(V[1] - V[0], N[0]), dot(V[2] - V[0], N[0])), 0.0f);
+ float h1 = max(max(dot(V[0] - V[1], N[1]), dot(V[2] - V[1], N[1])), 0.0f);
+ float h2 = max(max(dot(V[0] - V[2], N[2]), dot(V[1] - V[2], N[2])), 0.0f);
+ h0 = max(dot(V[0] - P, N[0]) + h0, 0.0f);
+ h1 = max(dot(V[1] - P, N[1]) + h1, 0.0f);
+ h2 = max(dot(V[2] - P, N[2]) + h2, 0.0f);
+ h = max(min(min(h0, h1), h2), h * 0.5f);
+ }
+ else {
+ float h0 = max(max(dot(V[0] - V[1], N[0]), dot(V[0] - V[2], N[0])), 0.0f);
+ float h1 = max(max(dot(V[1] - V[0], N[1]), dot(V[1] - V[2], N[1])), 0.0f);
+ float h2 = max(max(dot(V[2] - V[0], N[2]), dot(V[2] - V[1], N[2])), 0.0f);
+ h0 = max(dot(P - V[0], N[0]) + h0, 0.0f);
+ h1 = max(dot(P - V[1], N[1]) + h1, 0.0f);
+ h2 = max(dot(P - V[2], N[2]) + h2, 0.0f);
+ h = min(-min(min(h0, h1), h2), h * 0.5f);
+ }
+
+ return n * h;
+}
+
+/* Ray offset to avoid shadow terminator artifact. */
+
+ccl_device_inline float3 ray_offset_shadow(KernelGlobals *kg, ShaderData *sd, float3 L)
+{
+ float NL = dot(sd->N, L);
+ bool transmit = (NL < 0.0f);
+ float3 Ng = (transmit ? -sd->Ng : sd->Ng);
+ float3 P = ray_offset(sd->P, Ng);
+
+ if ((sd->type & PRIMITIVE_ALL_TRIANGLE) && (sd->shader & SHADER_SMOOTH_NORMAL)) {
+ const float offset_cutoff =
+ kernel_tex_fetch(__objects, sd->object).shadow_terminator_geometry_offset;
+ /* Do ray offset (heavy stuff) only for close to be terminated triangles:
+ * offset_cutoff = 0.1f means that 10-20% of rays will be affected. Also
+ * make a smooth transition near the threshold. */
+ if (offset_cutoff > 0.0f) {
+ float NgL = dot(Ng, L);
+ float offset_amount = 0.0f;
+ if (NL < offset_cutoff) {
+ offset_amount = clamp(2.0f - (NgL + NL) / offset_cutoff, 0.0f, 1.0f);
+ }
+ else {
+ offset_amount = clamp(1.0f - NgL / offset_cutoff, 0.0f, 1.0f);
+ }
+ if (offset_amount > 0.0f) {
+ P += smooth_surface_offset(kg, sd, Ng) * offset_amount;
+ }
+ }
+ }
+
+ return P;
+}
+
#if defined(__VOLUME_RECORD_ALL__) || (defined(__SHADOW_RECORD_ALL__) && defined(__KERNEL_CPU__))
/* ToDo: Move to another file? */
ccl_device int intersections_compare(const void *a, const void *b)
diff --git a/intern/cycles/kernel/closure/bsdf.h b/intern/cycles/kernel/closure/bsdf.h
index 6070fd983f5..6f2f2ebb202 100644
--- a/intern/cycles/kernel/closure/bsdf.h
+++ b/intern/cycles/kernel/closure/bsdf.h
@@ -462,7 +462,7 @@ ccl_device_inline int bsdf_sample(KernelGlobals *kg,
else {
/* Shadow terminator offset. */
const float frequency_multiplier =
- kernel_tex_fetch(__objects, sd->object).shadow_terminator_offset;
+ kernel_tex_fetch(__objects, sd->object).shadow_terminator_shading_offset;
if (frequency_multiplier > 1.0f) {
*eval *= shift_cos_in(dot(*omega_in, sc->N), frequency_multiplier);
}
@@ -488,12 +488,9 @@ ccl_device_inline
const float3 omega_in,
float *pdf)
{
- /* For curves use the smooth normal, particularly for ribbons the geometric
- * normal gives too much darkening otherwise. */
- const float3 Ng = (sd->type & PRIMITIVE_ALL_CURVE) ? sd->N : sd->Ng;
float3 eval;
- if (dot(Ng, omega_in) >= 0.0f) {
+ if (dot(sd->N, omega_in) >= 0.0f) {
switch (sc->type) {
case CLOSURE_BSDF_DIFFUSE_ID:
case CLOSURE_BSDF_BSSRDF_ID:
@@ -589,7 +586,7 @@ ccl_device_inline
}
/* Shadow terminator offset. */
const float frequency_multiplier =
- kernel_tex_fetch(__objects, sd->object).shadow_terminator_offset;
+ kernel_tex_fetch(__objects, sd->object).shadow_terminator_shading_offset;
if (frequency_multiplier > 1.0f) {
eval *= shift_cos_in(dot(omega_in, sc->N), frequency_multiplier);
}
diff --git a/intern/cycles/kernel/geom/geom_triangle.h b/intern/cycles/kernel/geom/geom_triangle.h
index ebc5abc017a..0a9460aa166 100644
--- a/intern/cycles/kernel/geom/geom_triangle.h
+++ b/intern/cycles/kernel/geom/geom_triangle.h
@@ -75,6 +75,19 @@ ccl_device_inline void triangle_vertices(KernelGlobals *kg, int prim, float3 P[3
P[2] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 2));
}
+/* Triangle vertex locations and vertex normals */
+
+ccl_device_inline void triangle_vertices_and_normals(KernelGlobals *kg, int prim, float3 P[3], float3 N[3])
+{
+ const uint4 tri_vindex = kernel_tex_fetch(__tri_vindex, prim);
+ P[0] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 0));
+ P[1] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 1));
+ P[2] = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex.w + 2));
+ N[0] = float4_to_float3(kernel_tex_fetch(__tri_vnormal, tri_vindex.x));
+ N[1] = fl
@@ Diff output truncated at 10240 characters. @@
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