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/*
* 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.
*/
#pragma once
CCL_NAMESPACE_BEGIN
/* Ray offset to avoid self intersection.
*
* This function should be used to compute a modified ray start position for
* rays leaving from a surface. */
ccl_device_inline float3 ray_offset(float3 P, float3 Ng)
{
#ifdef __INTERSECTION_REFINE__
const float epsilon_f = 1e-5f;
/* ideally this should match epsilon_f, but instancing and motion blur
* precision makes it problematic */
const float epsilon_test = 1.0f;
const int epsilon_i = 32;
float3 res;
/* x component */
if (fabsf(P.x) < epsilon_test) {
res.x = P.x + Ng.x * epsilon_f;
}
else {
uint ix = __float_as_uint(P.x);
ix += ((ix ^ __float_as_uint(Ng.x)) >> 31) ? -epsilon_i : epsilon_i;
res.x = __uint_as_float(ix);
}
/* y component */
if (fabsf(P.y) < epsilon_test) {
res.y = P.y + Ng.y * epsilon_f;
}
else {
uint iy = __float_as_uint(P.y);
iy += ((iy ^ __float_as_uint(Ng.y)) >> 31) ? -epsilon_i : epsilon_i;
res.y = __uint_as_float(iy);
}
/* z component */
if (fabsf(P.z) < epsilon_test) {
res.z = P.z + Ng.z * epsilon_f;
}
else {
uint iz = __float_as_uint(P.z);
iz += ((iz ^ __float_as_uint(Ng.z)) >> 31) ? -epsilon_i : epsilon_i;
res.z = __uint_as_float(iz);
}
return res;
#else
const float epsilon_f = 1e-4f;
return P + epsilon_f * 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 */
object_normal_transform(kg, sd, &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)
{
const Intersection *isect_a = (const Intersection *)a;
const Intersection *isect_b = (const Intersection *)b;
if (isect_a->t < isect_b->t)
return -1;
else if (isect_a->t > isect_b->t)
return 1;
else
return 0;
}
#endif
#if defined(__SHADOW_RECORD_ALL__)
ccl_device_inline void sort_intersections(Intersection *hits, uint num_hits)
{
kernel_assert(num_hits > 0);
# ifdef __KERNEL_GPU__
/* Use bubble sort which has more friendly memory pattern on GPU. */
bool swapped;
do {
swapped = false;
for (int j = 0; j < num_hits - 1; ++j) {
if (hits[j].t > hits[j + 1].t) {
struct Intersection tmp = hits[j];
hits[j] = hits[j + 1];
hits[j + 1] = tmp;
swapped = true;
}
}
--num_hits;
} while (swapped);
# else
qsort(hits, num_hits, sizeof(Intersection), intersections_compare);
# endif
}
#endif /* __SHADOW_RECORD_ALL__ | __VOLUME_RECORD_ALL__ */
/* Utility to quickly get a shader flags from an intersection. */
ccl_device_forceinline int intersection_get_shader_flags(KernelGlobals *ccl_restrict kg,
const Intersection *isect)
{
const int prim = kernel_tex_fetch(__prim_index, isect->prim);
int shader = 0;
#ifdef __HAIR__
if (kernel_tex_fetch(__prim_type, isect->prim) & PRIMITIVE_ALL_TRIANGLE)
#endif
{
shader = kernel_tex_fetch(__tri_shader, prim);
}
#ifdef __HAIR__
else {
float4 str = kernel_tex_fetch(__curves, prim);
shader = __float_as_int(str.z);
}
#endif
return kernel_tex_fetch(__shaders, (shader & SHADER_MASK)).flags;
}
ccl_device_forceinline int intersection_get_shader(KernelGlobals *ccl_restrict kg,
const Intersection *isect)
{
const int prim = kernel_tex_fetch(__prim_index, isect->prim);
int shader = 0;
#ifdef __HAIR__
if (kernel_tex_fetch(__prim_type, isect->prim) & PRIMITIVE_ALL_TRIANGLE)
#endif
{
shader = kernel_tex_fetch(__tri_shader, prim);
}
#ifdef __HAIR__
else {
float4 str = kernel_tex_fetch(__curves, prim);
shader = __float_as_int(str.z);
}
#endif
return shader & SHADER_MASK;
}
CCL_NAMESPACE_END
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