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/*
* Copyright 2011-2016 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.
*/
/* Motion Triangle Primitive
*
* These are stored as regular triangles, plus extra positions and normals at
* times other than the frame center. Computing the triangle vertex positions
* or normals at a given ray time is a matter of interpolation of the two steps
* between which the ray time lies.
*
* The extra positions and normals are stored as ATTR_STD_MOTION_VERTEX_POSITION
* and ATTR_STD_MOTION_VERTEX_NORMAL mesh attributes.
*/
CCL_NAMESPACE_BEGIN
/* Refine triangle intersection to more precise hit point. For rays that travel
* far the precision is often not so good, this reintersects the primitive from
* a closer distance.
*/
ccl_device_inline float3 motion_triangle_refine(KernelGlobals *kg,
ShaderData *sd,
const Intersection *isect,
const Ray *ray,
float3 verts[3])
{
float3 P = ray->P;
float3 D = ray->D;
float t = isect->t;
#ifdef __INTERSECTION_REFINE__
if(isect->object != OBJECT_NONE) {
if(UNLIKELY(t == 0.0f)) {
return P;
}
# ifdef __OBJECT_MOTION__
Transform tfm = sd->ob_itfm;
# else
Transform tfm = object_fetch_transform(kg,
isect->object,
OBJECT_INVERSE_TRANSFORM);
# endif
P = transform_point(&tfm, P);
D = transform_direction(&tfm, D*t);
D = normalize_len(D, &t);
}
P = P + D*t;
/* Compute refined intersection distance. */
const float3 e1 = verts[0] - verts[2];
const float3 e2 = verts[1] - verts[2];
const float3 s1 = cross(D, e2);
const float invdivisor = 1.0f/dot(s1, e1);
const float3 d = P - verts[2];
const float3 s2 = cross(d, e1);
float rt = dot(e2, s2)*invdivisor;
/* Compute refined position. */
P = P + D*rt;
if(isect->object != OBJECT_NONE) {
# ifdef __OBJECT_MOTION__
Transform tfm = sd->ob_tfm;
# else
Transform tfm = object_fetch_transform(kg,
isect->object,
OBJECT_TRANSFORM);
# endif
P = transform_point(&tfm, P);
}
return P;
#else
return P + D*t;
#endif
}
/* Same as above, except that isect->t is assumed to be in object space
* for instancing.
*/
#ifdef __SUBSURFACE__
# if defined(__KERNEL_CUDA__) && (defined(i386) || defined(_M_IX86))
ccl_device_noinline
# else
ccl_device_inline
# endif
float3 motion_triangle_refine_subsurface(KernelGlobals *kg,
ShaderData *sd,
const Intersection *isect,
const Ray *ray,
float3 verts[3])
{
float3 P = ray->P;
float3 D = ray->D;
float t = isect->t;
# ifdef __INTERSECTION_REFINE__
if(isect->object != OBJECT_NONE) {
# ifdef __OBJECT_MOTION__
Transform tfm = sd->ob_itfm;
# else
Transform tfm = object_fetch_transform(kg,
isect->object,
OBJECT_INVERSE_TRANSFORM);
# endif
P = transform_point(&tfm, P);
D = transform_direction(&tfm, D);
D = normalize(D);
}
P = P + D*t;
/* compute refined intersection distance */
const float3 e1 = verts[0] - verts[2];
const float3 e2 = verts[1] - verts[2];
const float3 s1 = cross(D, e2);
const float invdivisor = 1.0f/dot(s1, e1);
const float3 d = P - verts[2];
const float3 s2 = cross(d, e1);
float rt = dot(e2, s2)*invdivisor;
P = P + D*rt;
if(isect->object != OBJECT_NONE) {
# ifdef __OBJECT_MOTION__
Transform tfm = sd->ob_tfm;
# else
Transform tfm = object_fetch_transform(kg,
isect->object,
OBJECT_TRANSFORM);
# endif
P = transform_point(&tfm, P);
}
return P;
# else /* __INTERSECTION_REFINE__ */
return P + D*t;
# endif /* __INTERSECTION_REFINE__ */
}
#endif /* __SUBSURFACE__ */
/* Ray intersection. We simply compute the vertex positions at the given ray
* time and do a ray intersection with the resulting triangle.
*/
ccl_device_inline bool motion_triangle_intersect(
KernelGlobals *kg,
Intersection *isect,
float3 P,
float3 dir,
float time,
uint visibility,
int object,
int prim_addr)
{
/* Primitive index for vertex location lookup. */
int prim = kernel_tex_fetch(__prim_index, prim_addr);
int fobject = (object == OBJECT_NONE)
? kernel_tex_fetch(__prim_object, prim_addr)
: object;
/* Get vertex locations for intersection. */
float3 verts[3];
motion_triangle_vertices(kg, fobject, prim, time, verts);
/* Ray-triangle intersection, unoptimized. */
float t, u, v;
if(ray_triangle_intersect(P,
dir,
isect->t,
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
(ssef*)verts,
#else
verts[0], verts[1], verts[2],
#endif
&u, &v, &t))
{
#ifdef __VISIBILITY_FLAG__
/* Visibility flag test. we do it here under the assumption
* that most triangles are culled by node flags.
*/
if(kernel_tex_fetch(__prim_visibility, prim_addr) & visibility)
#endif
{
isect->t = t;
isect->u = u;
isect->v = v;
isect->prim = prim_addr;
isect->object = object;
isect->type = PRIMITIVE_MOTION_TRIANGLE;
return true;
}
}
return false;
}
/* Special ray intersection routines for subsurface scattering. In that case we
* only want to intersect with primitives in the same object, and if case of
* multiple hits we pick a single random primitive as the intersection point.
*/
#ifdef __SUBSURFACE__
ccl_device_inline void motion_triangle_intersect_subsurface(
KernelGlobals *kg,
SubsurfaceIntersection *ss_isect,
float3 P,
float3 dir,
float time,
int object,
int prim_addr,
float tmax,
uint *lcg_state,
int max_hits)
{
/* Primitive index for vertex location lookup. */
int prim = kernel_tex_fetch(__prim_index, prim_addr);
int fobject = (object == OBJECT_NONE)
? kernel_tex_fetch(__prim_object, prim_addr)
: object;
/* Get vertex locations for intersection. */
float3 verts[3];
motion_triangle_vertices(kg, fobject, prim, time, verts);
/* Ray-triangle intersection, unoptimized. */
float t, u, v;
if(ray_triangle_intersect(P,
dir,
tmax,
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
(ssef*)verts,
#else
verts[0], verts[1], verts[2],
#endif
&u, &v, &t))
{
for(int i = min(max_hits, ss_isect->num_hits) - 1; i >= 0; --i) {
if(ss_isect->hits[i].t == t) {
return;
}
}
ss_isect->num_hits++;
int hit;
if(ss_isect->num_hits <= max_hits) {
hit = ss_isect->num_hits - 1;
}
else {
/* Reservoir sampling: if we are at the maximum number of
* hits, randomly replace element or skip it.
*/
hit = lcg_step_uint(lcg_state) % ss_isect->num_hits;
if(hit >= max_hits)
return;
}
/* Record intersection. */
Intersection *isect = &ss_isect->hits[hit];
isect->t = t;
isect->u = u;
isect->v = v;
isect->prim = prim_addr;
isect->object = object;
isect->type = PRIMITIVE_MOTION_TRIANGLE;
/* Record geometric normal. */
ss_isect->Ng[hit] = normalize(cross(verts[1] - verts[0],
verts[2] - verts[0]));
}
}
#endif /* __SUBSURFACE__ */
CCL_NAMESPACE_END
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