4d10a46e63
Move some logic out of triangle intersection functions and into BVH traversal, so we can share logic between primitives. Ref D12954
267 lines
8.5 KiB
C
267 lines
8.5 KiB
C
/*
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* Copyright 2011-2016 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* Motion Triangle Primitive
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*
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* These are stored as regular triangles, plus extra positions and normals at
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* times other than the frame center. Computing the triangle vertex positions
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* or normals at a given ray time is a matter of interpolation of the two steps
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* between which the ray time lies.
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*
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* The extra positions and normals are stored as ATTR_STD_MOTION_VERTEX_POSITION
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* and ATTR_STD_MOTION_VERTEX_NORMAL mesh attributes.
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*/
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#pragma once
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CCL_NAMESPACE_BEGIN
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/* Refine triangle intersection to more precise hit point. For rays that travel
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* far the precision is often not so good, this reintersects the primitive from
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* a closer distance.
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*/
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ccl_device_inline float3 motion_triangle_refine(KernelGlobals kg,
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ccl_private ShaderData *sd,
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float3 P,
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float3 D,
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float t,
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const int isect_object,
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const int isect_prim,
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float3 verts[3])
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{
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#ifdef __INTERSECTION_REFINE__
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if (!(sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
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if (UNLIKELY(t == 0.0f)) {
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return P;
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}
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const Transform tfm = object_get_inverse_transform(kg, sd);
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P = transform_point(&tfm, P);
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D = transform_direction(&tfm, D * t);
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D = normalize_len(D, &t);
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}
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P = P + D * t;
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/* Compute refined intersection distance. */
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const float3 e1 = verts[0] - verts[2];
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const float3 e2 = verts[1] - verts[2];
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const float3 s1 = cross(D, e2);
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const float invdivisor = 1.0f / dot(s1, e1);
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const float3 d = P - verts[2];
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const float3 s2 = cross(d, e1);
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float rt = dot(e2, s2) * invdivisor;
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/* Compute refined position. */
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P = P + D * rt;
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if (!(sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
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const Transform tfm = object_get_transform(kg, sd);
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P = transform_point(&tfm, P);
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}
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return P;
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#else
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return P + D * t;
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#endif
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}
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/* Same as above, except that t is assumed to be in object space
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* for instancing.
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*/
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#ifdef __BVH_LOCAL__
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# if defined(__KERNEL_CUDA__) && (defined(i386) || defined(_M_IX86))
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ccl_device_noinline
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# else
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ccl_device_inline
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# endif
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float3
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motion_triangle_refine_local(KernelGlobals kg,
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ccl_private ShaderData *sd,
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float3 P,
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float3 D,
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float t,
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const int isect_object,
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const int isect_prim,
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float3 verts[3])
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{
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# if defined(__KERNEL_GPU_RAYTRACING__)
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/* t is always in world space with OptiX and MetalRT. */
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return motion_triangle_refine(kg, sd, P, D, t, isect_object, isect_prim, verts);
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# else
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# ifdef __INTERSECTION_REFINE__
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if (!(sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
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const Transform tfm = object_get_inverse_transform(kg, sd);
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P = transform_point(&tfm, P);
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D = transform_direction(&tfm, D);
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D = normalize(D);
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}
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P = P + D * t;
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/* compute refined intersection distance */
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const float3 e1 = verts[0] - verts[2];
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const float3 e2 = verts[1] - verts[2];
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const float3 s1 = cross(D, e2);
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const float invdivisor = 1.0f / dot(s1, e1);
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const float3 d = P - verts[2];
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const float3 s2 = cross(d, e1);
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float rt = dot(e2, s2) * invdivisor;
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P = P + D * rt;
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if (!(sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
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const Transform tfm = object_get_transform(kg, sd);
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P = transform_point(&tfm, P);
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}
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return P;
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# else /* __INTERSECTION_REFINE__ */
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return P + D * t;
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# endif /* __INTERSECTION_REFINE__ */
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# endif
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}
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#endif /* __BVH_LOCAL__ */
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/* Ray intersection. We simply compute the vertex positions at the given ray
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* time and do a ray intersection with the resulting triangle.
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*/
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ccl_device_inline bool motion_triangle_intersect(KernelGlobals kg,
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ccl_private Intersection *isect,
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float3 P,
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float3 dir,
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float tmax,
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float time,
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uint visibility,
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int object,
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int prim,
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int prim_addr)
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{
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/* Get vertex locations for intersection. */
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float3 verts[3];
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motion_triangle_vertices(kg, object, prim, time, verts);
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/* Ray-triangle intersection, unoptimized. */
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float t, u, v;
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if (ray_triangle_intersect(P, dir, tmax, verts[0], verts[1], verts[2], &u, &v, &t)) {
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#ifdef __VISIBILITY_FLAG__
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/* Visibility flag test. we do it here under the assumption
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* that most triangles are culled by node flags.
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*/
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if (kernel_tex_fetch(__prim_visibility, prim_addr) & visibility)
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#endif
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{
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isect->t = t;
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isect->u = u;
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isect->v = v;
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isect->prim = prim;
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isect->object = object;
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isect->type = PRIMITIVE_MOTION_TRIANGLE;
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return true;
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}
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}
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return false;
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}
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/* Special ray intersection routines for local intersections. In that case we
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* only want to intersect with primitives in the same object, and if case of
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* multiple hits we pick a single random primitive as the intersection point.
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* Returns whether traversal should be stopped.
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*/
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#ifdef __BVH_LOCAL__
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ccl_device_inline bool motion_triangle_intersect_local(KernelGlobals kg,
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ccl_private LocalIntersection *local_isect,
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float3 P,
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float3 dir,
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float time,
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int object,
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int prim,
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int prim_addr,
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float tmax,
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ccl_private uint *lcg_state,
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int max_hits)
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{
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/* Get vertex locations for intersection. */
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float3 verts[3];
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motion_triangle_vertices(kg, object, prim, time, verts);
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/* Ray-triangle intersection, unoptimized. */
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float t, u, v;
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if (!ray_triangle_intersect(P, dir, tmax, verts[0], verts[1], verts[2], &u, &v, &t)) {
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return false;
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}
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/* If no actual hit information is requested, just return here. */
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if (max_hits == 0) {
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return true;
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}
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int hit;
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if (lcg_state) {
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/* Record up to max_hits intersections. */
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for (int i = min(max_hits, local_isect->num_hits) - 1; i >= 0; --i) {
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if (local_isect->hits[i].t == t) {
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return false;
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}
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}
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local_isect->num_hits++;
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if (local_isect->num_hits <= max_hits) {
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hit = local_isect->num_hits - 1;
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}
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else {
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/* Reservoir sampling: if we are at the maximum number of
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* hits, randomly replace element or skip it.
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*/
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hit = lcg_step_uint(lcg_state) % local_isect->num_hits;
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if (hit >= max_hits)
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return false;
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}
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}
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else {
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/* Record closest intersection only. */
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if (local_isect->num_hits && t > local_isect->hits[0].t) {
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return false;
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}
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hit = 0;
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local_isect->num_hits = 1;
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}
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/* Record intersection. */
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ccl_private Intersection *isect = &local_isect->hits[hit];
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isect->t = t;
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isect->u = u;
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isect->v = v;
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isect->prim = prim;
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isect->object = object;
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isect->type = PRIMITIVE_MOTION_TRIANGLE;
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/* Record geometric normal. */
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local_isect->Ng[hit] = normalize(cross(verts[1] - verts[0], verts[2] - verts[0]));
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return false;
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}
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#endif /* __BVH_LOCAL__ */
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CCL_NAMESPACE_END
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