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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.
*/
#pragma once
CCL_NAMESPACE_BEGIN
/**
* Use the barycentric coordinates to get the intersection location
*/
ccl_device_inline float3 motion_triangle_point_from_uv(KernelGlobals kg,
ccl_private ShaderData *sd,
const int isect_object,
const int isect_prim,
const float u,
const float v,
float3 verts[3])
{
float w = 1.0f - u - v;
float3 P = u * verts[0] + v * verts[1] + w * verts[2];
if (!(sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
const Transform tfm = object_get_transform(kg, sd);
P = transform_point(&tfm, P);
}
return P;
}
/* 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,
ccl_private Intersection *isect,
float3 P,
float3 dir,
float tmax,
float time,
uint visibility,
int object,
int prim,
int prim_addr)
{
/* Get vertex locations for intersection. */
float3 verts[3];
motion_triangle_vertices(kg, object, prim, time, verts);
/* Ray-triangle intersection, unoptimized. */
float t, u, v;
if (ray_triangle_intersect(P, dir, tmax, verts[0], verts[1], verts[2], &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;
isect->object = object;
isect->type = PRIMITIVE_MOTION_TRIANGLE;
return true;
}
}
return false;
}
/* Special ray intersection routines for local intersections. 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.
* Returns whether traversal should be stopped.
*/
#ifdef __BVH_LOCAL__
ccl_device_inline bool motion_triangle_intersect_local(KernelGlobals kg,
ccl_private LocalIntersection *local_isect,
float3 P,
float3 dir,
float time,
int object,
int prim,
int prim_addr,
float tmax,
ccl_private uint *lcg_state,
int max_hits)
{
/* Get vertex locations for intersection. */
float3 verts[3];
motion_triangle_vertices(kg, object, prim, time, verts);
/* Ray-triangle intersection, unoptimized. */
float t, u, v;
if (!ray_triangle_intersect(P, dir, tmax, verts[0], verts[1], verts[2], &u, &v, &t)) {
return false;
}
/* If no actual hit information is requested, just return here. */
if (max_hits == 0) {
return true;
}
int hit;
if (lcg_state) {
/* Record up to max_hits intersections. */
for (int i = min(max_hits, local_isect->num_hits) - 1; i >= 0; --i) {
if (local_isect->hits[i].t == t) {
return false;
}
}
local_isect->num_hits++;
if (local_isect->num_hits <= max_hits) {
hit = local_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) % local_isect->num_hits;
if (hit >= max_hits)
return false;
}
}
else {
/* Record closest intersection only. */
if (local_isect->num_hits && t > local_isect->hits[0].t) {
return false;
}
hit = 0;
local_isect->num_hits = 1;
}
/* Record intersection. */
ccl_private Intersection *isect = &local_isect->hits[hit];
isect->t = t;
isect->u = u;
isect->v = v;
isect->prim = prim;
isect->object = object;
isect->type = PRIMITIVE_MOTION_TRIANGLE;
/* Record geometric normal. */
local_isect->Ng[hit] = normalize(cross(verts[1] - verts[0], verts[2] - verts[0]));
return false;
}
#endif /* __BVH_LOCAL__ */
CCL_NAMESPACE_END
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