intern/cycles/kernel/kernel_bvh_traversal.h

   1 /*
   2  * Adapted from code Copyright 2009-2010 NVIDIA Corporation,
   3  * and code copyright 2009-2012 Intel Corporation
   4  *
   5  * Modifications Copyright 2011-2013, Blender Foundation.
   6  *
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  * http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19
  20 /* This is a template BVH traversal function, where various features can be
  21  * enabled/disabled. This way we can compile optimized versions for each case
  22  * without new features slowing things down.
  23  *
  24  * BVH_INSTANCING: object instancing
  25  * BVH_HAIR: hair curve rendering
  26  * BVH_HAIR_MINIMUM_WIDTH: hair curve rendering with minimum width
  27  * BVH_MOTION: motion blur rendering
  28  *
  29  */
  30
  31 #define FEATURE(f) (((BVH_FUNCTION_FEATURES) & (f)) != 0)
  32
  33 __device bool BVH_FUNCTION_NAME
  34 (KernelGlobals *kg, const Ray *ray, Intersection *isect, const uint visibility
  35 #if FEATURE(BVH_HAIR_MINIMUM_WIDTH)
  36 , uint *lcg_state, float difl, float extmax
  37 #endif
  38 )
  39 {
  40         /* todo:
  41          * - test if pushing distance on the stack helps (for non shadow rays)
  42          * - separate version for shadow rays
  43          * - likely and unlikely for if() statements
  44          * - SSE for hair
  45          * - test restrict attribute for pointers
  46          */
  47
  48         /* traversal stack in CUDA thread-local memory */
  49         int traversalStack[BVH_STACK_SIZE];
  50         traversalStack[0] = ENTRYPOINT_SENTINEL;
  51
  52         /* traversal variables in registers */
  53         int stackPtr = 0;
  54         int nodeAddr = kernel_data.bvh.root;
  55
  56         /* ray parameters in registers */
  57         const float tmax = ray->t;
  58         float3 P = ray->P;
  59         float3 idir = bvh_inverse_direction(ray->D);
  60         int object = ~0;
  61
  62 #if FEATURE(BVH_MOTION)
  63         Transform ob_tfm;
  64 #endif
  65
  66         isect->t = tmax;
  67         isect->object = ~0;
  68         isect->prim = ~0;
  69         isect->u = 0.0f;
  70         isect->v = 0.0f;
  71
  72 #if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
  73         const shuffle_swap_t shuf_identity = shuffle_swap_identity();
  74         const shuffle_swap_t shuf_swap = shuffle_swap_swap();
  75
  76         const __m128i pn = _mm_set_epi32(0x80000000, 0x80000000, 0x00000000, 0x00000000);
  77         __m128 Psplat[3], idirsplat[3];
  78
  79         Psplat[0] = _mm_set_ps1(P.x);
  80         Psplat[1] = _mm_set_ps1(P.y);
  81         Psplat[2] = _mm_set_ps1(P.z);
  82
  83         idirsplat[0] = _mm_xor_ps(_mm_set_ps1(idir.x), _mm_castsi128_ps(pn));
  84         idirsplat[1] = _mm_xor_ps(_mm_set_ps1(idir.y), _mm_castsi128_ps(pn));
  85         idirsplat[2] = _mm_xor_ps(_mm_set_ps1(idir.z), _mm_castsi128_ps(pn));
  86
  87         __m128 tsplat = _mm_set_ps(-isect->t, -isect->t, 0.0f, 0.0f);
  88
  89         shuffle_swap_t shufflex = (idir.x >= 0)? shuf_identity: shuf_swap;
  90         shuffle_swap_t shuffley = (idir.y >= 0)? shuf_identity: shuf_swap;
  91         shuffle_swap_t shufflez = (idir.z >= 0)? shuf_identity: shuf_swap;
  92 #endif
  93
  94         /* traversal loop */
  95         do {
  96                 do
  97                 {
  98                         /* traverse internal nodes */
  99                         while(nodeAddr >= 0 && nodeAddr != ENTRYPOINT_SENTINEL)
 100                         {
 101                                 bool traverseChild0, traverseChild1;
 102                                 int nodeAddrChild1;
 103
 104 #if !defined(__KERNEL_SSE2__) || FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 105                                 /* Intersect two child bounding boxes, non-SSE version */
 106                                 float t = isect->t;
 107
 108                                 /* fetch node data */
 109                                 float4 node0 = kernel_tex_fetch(__bvh_nodes, nodeAddr*BVH_NODE_SIZE+0);
 110                                 float4 node1 = kernel_tex_fetch(__bvh_nodes, nodeAddr*BVH_NODE_SIZE+1);
 111                                 float4 node2 = kernel_tex_fetch(__bvh_nodes, nodeAddr*BVH_NODE_SIZE+2);
 112                                 float4 cnodes = kernel_tex_fetch(__bvh_nodes, nodeAddr*BVH_NODE_SIZE+3);
 113
 114                                 /* intersect ray against child nodes */
 115                                 NO_EXTENDED_PRECISION float c0lox = (node0.x - P.x) * idir.x;
 116                                 NO_EXTENDED_PRECISION float c0hix = (node0.z - P.x) * idir.x;
 117                                 NO_EXTENDED_PRECISION float c0loy = (node1.x - P.y) * idir.y;
 118                                 NO_EXTENDED_PRECISION float c0hiy = (node1.z - P.y) * idir.y;
 119                                 NO_EXTENDED_PRECISION float c0loz = (node2.x - P.z) * idir.z;
 120                                 NO_EXTENDED_PRECISION float c0hiz = (node2.z - P.z) * idir.z;
 121                                 NO_EXTENDED_PRECISION float c0min = max4(min(c0lox, c0hix), min(c0loy, c0hiy), min(c0loz, c0hiz), 0.0f);
 122                                 NO_EXTENDED_PRECISION float c0max = min4(max(c0lox, c0hix), max(c0loy, c0hiy), max(c0loz, c0hiz), t);
 123
 124                                 NO_EXTENDED_PRECISION float c1lox = (node0.y - P.x) * idir.x;
 125                                 NO_EXTENDED_PRECISION float c1hix = (node0.w - P.x) * idir.x;
 126                                 NO_EXTENDED_PRECISION float c1loy = (node1.y - P.y) * idir.y;
 127                                 NO_EXTENDED_PRECISION float c1hiy = (node1.w - P.y) * idir.y;
 128                                 NO_EXTENDED_PRECISION float c1loz = (node2.y - P.z) * idir.z;
 129                                 NO_EXTENDED_PRECISION float c1hiz = (node2.w - P.z) * idir.z;
 130                                 NO_EXTENDED_PRECISION float c1min = max4(min(c1lox, c1hix), min(c1loy, c1hiy), min(c1loz, c1hiz), 0.0f);
 131                                 NO_EXTENDED_PRECISION float c1max = min4(max(c1lox, c1hix), max(c1loy, c1hiy), max(c1loz, c1hiz), t);
 132
 133 #if FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 134                                 if(difl != 0.0f) {
 135                                         float hdiff = 1.0f + difl;
 136                                         float ldiff = 1.0f - difl;
 137                                         if(__float_as_int(cnodes.z) & PATH_RAY_CURVE) {
 138                                                 c0min = max(ldiff * c0min, c0min - extmax);
 139                                                 c0max = min(hdiff * c0max, c0max + extmax);
 140                                         }
 141                                         if(__float_as_int(cnodes.w) & PATH_RAY_CURVE) {
 142                                                 c1min = max(ldiff * c1min, c1min - extmax);
 143                                                 c1max = min(hdiff * c1max, c1max + extmax);
 144                                         }
 145                                 }
 146 #endif
 147
 148                                 /* decide which nodes to traverse next */
 149 #ifdef __VISIBILITY_FLAG__
 150                                 /* this visibility test gives a 5% performance hit, how to solve? */
 151                                 traverseChild0 = (c0max >= c0min) && (__float_as_uint(cnodes.z) & visibility);
 152                                 traverseChild1 = (c1max >= c1min) && (__float_as_uint(cnodes.w) & visibility);
 153 #else
 154                                 traverseChild0 = (c0max >= c0min);
 155                                 traverseChild1 = (c1max >= c1min);
 156 #endif
 157
 158 #else // __KERNEL_SSE2__
 159                                 /* Intersect two child bounding boxes, SSE3 version adapted from Embree */
 160
 161                                 /* fetch node data */
 162                                 __m128 *bvh_nodes = (__m128*)kg->__bvh_nodes.data + nodeAddr*BVH_NODE_SIZE;
 163                                 float4 cnodes = ((float4*)bvh_nodes)[3];
 164
 165                                 /* intersect ray against child nodes */
 166                                 const __m128 tminmaxx = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[0], shufflex), Psplat[0]), idirsplat[0]);
 167                                 const __m128 tminmaxy = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[1], shuffley), Psplat[1]), idirsplat[1]);
 168                                 const __m128 tminmaxz = _mm_mul_ps(_mm_sub_ps(shuffle_swap(bvh_nodes[2], shufflez), Psplat[2]), idirsplat[2]);
 169
 170                                 const __m128 tminmax = _mm_xor_ps(_mm_max_ps(_mm_max_ps(tminmaxx, tminmaxy), _mm_max_ps(tminmaxz, tsplat)), _mm_castsi128_ps(pn));
 171                                 const __m128 lrhit = _mm_cmple_ps(tminmax, shuffle_swap(tminmax, shuf_swap));
 172
 173                                 /* decide which nodes to traverse next */
 174 #ifdef __VISIBILITY_FLAG__
 175                                 /* this visibility test gives a 5% performance hit, how to solve? */
 176                                 traverseChild0 = (_mm_movemask_ps(lrhit) & 1) && (__float_as_uint(cnodes.z) & visibility);
 177                                 traverseChild1 = (_mm_movemask_ps(lrhit) & 2) && (__float_as_uint(cnodes.w) & visibility);
 178 #else
 179                                 traverseChild0 = (_mm_movemask_ps(lrhit) & 1);
 180                                 traverseChild1 = (_mm_movemask_ps(lrhit) & 2);
 181 #endif
 182 #endif // __KERNEL_SSE2__
 183
 184                                 nodeAddr = __float_as_int(cnodes.x);
 185                                 nodeAddrChild1 = __float_as_int(cnodes.y);
 186
 187                                 if(traverseChild0 && traverseChild1) {
 188                                         /* both children were intersected, push the farther one */
 189 #if !defined(__KERNEL_SSE2__) || FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 190                                         bool closestChild1 = (c1min < c0min);
 191 #else
 192                                         union { __m128 m128; float v[4]; } uminmax;
 193                                         uminmax.m128 = tminmax;
 194                                         bool closestChild1 = uminmax.v[1] < uminmax.v[0];
 195 #endif
 196
 197                                         if(closestChild1) {
 198                                                 int tmp = nodeAddr;
 199                                                 nodeAddr = nodeAddrChild1;
 200                                                 nodeAddrChild1 = tmp;
 201                                         }
 202
 203                                         ++stackPtr;
 204                                         traversalStack[stackPtr] = nodeAddrChild1;
 205                                 }
 206                                 else {
 207                                         /* one child was intersected */
 208                                         if(traverseChild1) {
 209                                                 nodeAddr = nodeAddrChild1;
 210                                         }
 211                                         else if(!traverseChild0) {
 212                                                 /* neither child was intersected */
 213                                                 nodeAddr = traversalStack[stackPtr];
 214                                                 --stackPtr;
 215                                         }
 216                                 }
 217                         }
 218
 219                         /* if node is leaf, fetch triangle list */
 220                         if(nodeAddr < 0) {
 221                                 float4 leaf = kernel_tex_fetch(__bvh_nodes, (-nodeAddr-1)*BVH_NODE_SIZE+(BVH_NODE_SIZE-1));
 222                                 int primAddr = __float_as_int(leaf.x);
 223
 224 #if FEATURE(BVH_INSTANCING)
 225                                 if(primAddr >= 0) {
 226 #endif
 227                                         int primAddr2 = __float_as_int(leaf.y);
 228
 229                                         /* pop */
 230                                         nodeAddr = traversalStack[stackPtr];
 231                                         --stackPtr;
 232
 233                                         /* primitive intersection */
 234                                         while(primAddr < primAddr2) {
 235                                                 bool hit;
 236
 237                                                 /* intersect ray against primitive */
 238 #if FEATURE(BVH_HAIR)
 239                                                 uint segment = kernel_tex_fetch(__prim_segment, primAddr);
 240                                                 if(segment != ~0) {
 241
 242                                                         if(kernel_data.curve.curveflags & CURVE_KN_INTERPOLATE)
 243 #if FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 244                                                                 hit = bvh_cardinal_curve_intersect(kg, isect, P, idir, visibility, object, primAddr, segment, lcg_state, difl, extmax);
 245                                                         else
 246                                                                 hit = bvh_curve_intersect(kg, isect, P, idir, visibility, object, primAddr, segment, lcg_state, difl, extmax);
 247 #else
 248                                                                 hit = bvh_cardinal_curve_intersect(kg, isect, P, idir, visibility, object, primAddr, segment);
 249                                                         else
 250                                                                 hit = bvh_curve_intersect(kg, isect, P, idir, visibility, object, primAddr, segment);
 251 #endif
 252                                                 }
 253                                                 else
 254 #endif
 255                                                         hit = bvh_triangle_intersect(kg, isect, P, idir, visibility, object, primAddr);
 256
 257                                                 /* shadow ray early termination */
 258 #if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 259                                                 if(hit) {
 260                                                         if(visibility == PATH_RAY_SHADOW_OPAQUE)
 261                                                                 return true;
 262
 263                                                         tsplat = _mm_set_ps(-isect->t, -isect->t, 0.0f, 0.0f);
 264                                                 }
 265 #else
 266                                                 if(hit && visibility == PATH_RAY_SHADOW_OPAQUE)
 267                                                         return true;
 268 #endif
 269
 270                                                 primAddr++;
 271                                         }
 272                                 }
 273 #if FEATURE(BVH_INSTANCING)
 274                                 else {
 275                                         /* instance push */
 276                                         object = kernel_tex_fetch(__prim_object, -primAddr-1);
 277
 278 #if FEATURE(BVH_MOTION)
 279                                         bvh_instance_motion_push(kg, object, ray, &P, &idir, &isect->t, &ob_tfm, tmax);
 280 #else
 281                                         bvh_instance_push(kg, object, ray, &P, &idir, &isect->t, tmax);
 282 #endif
 283
 284 #if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 285                                         Psplat[0] = _mm_set_ps1(P.x);
 286                                         Psplat[1] = _mm_set_ps1(P.y);
 287                                         Psplat[2] = _mm_set_ps1(P.z);
 288
 289                                         idirsplat[0] = _mm_xor_ps(_mm_set_ps1(idir.x), _mm_castsi128_ps(pn));
 290                                         idirsplat[1] = _mm_xor_ps(_mm_set_ps1(idir.y), _mm_castsi128_ps(pn));
 291                                         idirsplat[2] = _mm_xor_ps(_mm_set_ps1(idir.z), _mm_castsi128_ps(pn));
 292
 293                                         tsplat = _mm_set_ps(-isect->t, -isect->t, 0.0f, 0.0f);
 294
 295                                         shufflex = (idir.x >= 0)? shuf_identity: shuf_swap;
 296                                         shuffley = (idir.y >= 0)? shuf_identity: shuf_swap;
 297                                         shufflez = (idir.z >= 0)? shuf_identity: shuf_swap;
 298 #endif
 299
 300                                         ++stackPtr;
 301                                         traversalStack[stackPtr] = ENTRYPOINT_SENTINEL;
 302
 303                                         nodeAddr = kernel_tex_fetch(__object_node, object);
 304                                 }
 305                         }
 306 #endif
 307                 } while(nodeAddr != ENTRYPOINT_SENTINEL);
 308
 309 #if FEATURE(BVH_INSTANCING)
 310                 if(stackPtr >= 0) {
 311                         kernel_assert(object != ~0);
 312
 313                         /* instance pop */
 314 #if FEATURE(BVH_MOTION)
 315                         bvh_instance_motion_pop(kg, object, ray, &P, &idir, &isect->t, &ob_tfm, tmax);
 316 #else
 317                         bvh_instance_pop(kg, object, ray, &P, &idir, &isect->t, tmax);
 318 #endif
 319
 320 #if defined(__KERNEL_SSE2__) && !FEATURE(BVH_HAIR_MINIMUM_WIDTH)
 321                         Psplat[0] = _mm_set_ps1(P.x);
 322                         Psplat[1] = _mm_set_ps1(P.y);
 323                         Psplat[2] = _mm_set_ps1(P.z);
 324
 325                         idirsplat[0] = _mm_xor_ps(_mm_set_ps1(idir.x), _mm_castsi128_ps(pn));
 326                         idirsplat[1] = _mm_xor_ps(_mm_set_ps1(idir.y), _mm_castsi128_ps(pn));
 327                         idirsplat[2] = _mm_xor_ps(_mm_set_ps1(idir.z), _mm_castsi128_ps(pn));
 328
 329                         tsplat = _mm_set_ps(-isect->t, -isect->t, 0.0f, 0.0f);
 330
 331                         shufflex = (idir.x >= 0)? shuf_identity: shuf_swap;
 332                         shuffley = (idir.y >= 0)? shuf_identity: shuf_swap;
 333                         shufflez = (idir.z >= 0)? shuf_identity: shuf_swap;
 334 #endif
 335
 336                         object = ~0;
 337                         nodeAddr = traversalStack[stackPtr];
 338                         --stackPtr;
 339                 }
 340 #endif
 341         } while(nodeAddr != ENTRYPOINT_SENTINEL);
 342
 343         return (isect->prim != ~0);
 344 }
 345
 346 #undef FEATURE
 347 #undef BVH_FUNCTION_NAME
 348 #undef BVH_FUNCTION_FEATURES
 349