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Add naive BVH_AFRA traversal.
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@jbikker
jbikker committed Nov 26, 2024
1 parent 1f5c066 commit ed5d196
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Showing 2 changed files with 32 additions and 21 deletions.
40 changes: 25 additions & 15 deletions tiny_bvh.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1378,7 +1378,7 @@ void BVH::Convert( const BVHLayout from, const BVHLayout to, const bool deleteOr
// Convert a 4-wide BVH to a format suitable for CPU traversal.
// See Faster Incoherent Ray Traversal Using 8-Wide AVX InstructionsLayout,
// Atilla T. Áfra, 2013.
unsigned spaceNeeded = usedBVH4Nodes * 4; // here, 'block' is 16 bytes.
unsigned spaceNeeded = usedBVH4Nodes;
if (allocatedAlt4bNodes < spaceNeeded)
{
FATAL_ERROR_IF( bvh4Node == 0, "BVH::Convert( BASIC_BVH4, BVH4_AFRA ), bvh4Node == 0." );
Expand All @@ -1400,19 +1400,25 @@ void BVH::Convert( const BVHLayout from, const BVHLayout to, const bool deleteOr
for (int cidx = 0, i = 0; i < 4; i++) if (orig.child[i])
{
const BVHNode4& child = bvh4Node[orig.child[i]];
((float*)&newNode.xmin4)[cidx] = child.aabbMin.x, ((float*)&newNode.ymin4)[cidx] = child.aabbMin.y;
((float*)&newNode.zmin4)[cidx] = child.aabbMin.z, ((float*)&newNode.xmax4)[cidx] = child.aabbMax.x;
((float*)&newNode.ymax4)[cidx] = child.aabbMax.y, ((float*)&newNode.zmax4)[cidx] = child.aabbMax.z;
((float*)&newNode.xmin4)[cidx] = child.aabbMin.x;
((float*)&newNode.ymin4)[cidx] = child.aabbMin.y;
((float*)&newNode.zmin4)[cidx] = child.aabbMin.z;
((float*)&newNode.xmax4)[cidx] = child.aabbMax.x;
((float*)&newNode.ymax4)[cidx] = child.aabbMax.y;
((float*)&newNode.zmax4)[cidx] = child.aabbMax.z;
if (child.isLeaf())
newNode.childFirst[cidx] = orig.firstTri, newNode.triCount[cidx] = orig.triCount;
newNode.childFirst[cidx] = child.firstTri,
newNode.triCount[cidx] = child.triCount;
else
stack[stackPtr++] = (unsigned)((float*)&newNode.childFirst[cidx] - (float*)bvh4Alt2),
stack[stackPtr++] = (unsigned)((unsigned*)&newNode.childFirst[cidx] - (unsigned*)bvh4Alt2),
stack[stackPtr++] = orig.child[i];
cidx++;
}
// pop next task
if (!stackPtr) break;
nodeIdx = stack[--stackPtr], ((unsigned*)bvh4Alt2)[stack[--stackPtr]] = newAlt4Ptr;
nodeIdx = stack[--stackPtr];
unsigned offset = stack[--stackPtr];
((unsigned*)bvh4Alt2)[offset] = newAlt4Ptr;
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
Expand Down Expand Up @@ -3172,30 +3178,31 @@ int BVH::Intersect_AltSoA( Ray& ray ) const

int BVH::Intersect_Afra( Ray& ray ) const
{
// SIMDVEC4 xmin4, ymin4, zmin4;
// SIMDVEC4 xmax4, ymax4, zmax4;
// unsigned childFirst[4];
// unsigned triCount[4];
#if 1
// quick-and-dirty intersect to verify data structure
unsigned nodeIdx = 0, stack[64], stackPtr = 0, steps = 0;
unsigned nodeIdx = 0, stack[1024], stackPtr = 0, steps = 0;
while (1)
{
steps++;
BVHNode4Alt2& node = bvh4Alt2[nodeIdx];
for( unsigned i = 0; i < 4; i++ )
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
for (unsigned i = 0; i < 4; i++) if (node.childFirst[i] + node.triCount[i] > 0)
{
bvhvec3 bmin, bmax;
bmin.x = ((float*)&node.xmin4)[i], bmax.x = ((float*)&node.xmax4)[i];
bmin.y = ((float*)&node.ymin4)[i], bmax.y = ((float*)&node.ymax4)[i];
bmin.z = ((float*)&node.zmin4)[i], bmax.z = ((float*)&node.zmax4)[i];
if (IntersectAABB( ray, bmin, bmax ))
float t = IntersectAABB( ray, bmin, bmax );
if (t < 1e30f)
{
if (node.triCount[i] > 0)
{
// process leaf
const unsigned first = node.childFirst[i], count = node.triCount[i];
for( unsigned j = 0; j < count; j++ ) IntersectTri( ray, triIdx[first + j] );
for (unsigned j = 0; j < count; j++) IntersectTri( ray, triIdx[first + j] );
}
else
{
Expand All @@ -3204,6 +3211,9 @@ int BVH::Intersect_Afra( Ray& ray ) const
}
}
}
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
if (stackPtr == 0) break; else nodeIdx = stack[--stackPtr];
}
#else
Expand Down
13 changes: 7 additions & 6 deletions tiny_bvh_fenster.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@

#define TINYBVH_IMPLEMENTATION
#include "tiny_bvh.h"
#include <fstream>

using namespace tinybvh;

Expand All @@ -21,8 +22,7 @@ BVH bvh;

#ifdef LOADSCENE
bvhvec4* triangles = 0;
const char scene[] = "happybuddha.bin";
#include <fstream>
const char scene[] = "cryteksponza.bin";
#else
ALIGNED( 16 ) bvhvec4 triangles[259 /* level 3 */ * 6 * 2 * 49 * 3]{};
#endif
Expand All @@ -35,7 +35,8 @@ int verts = 0;
static bvhvec3 eye( 0, 13, 30 ), p1, p2, p3;
static bvhvec3 view = normalize( bvhvec3( 0, 0.01f, -1 ) );
#else
static bvhvec3 eye( -3.5f, -1.5f, -6.5f ), view = normalize( bvhvec3( 3, 1.5f, 5 ) );
static bvhvec3 eye( -3.5f, -1.5f, -6.5f ), p1, p2, p3;
static bvhvec3 view = normalize( bvhvec3( 3, 1.5f, 5 ) );
#endif

void sphere_flake( float x, float y, float z, float s, int d = 0 )
Expand Down Expand Up @@ -109,8 +110,8 @@ void Init()
// build a BVH over the scene
#if defined(BVH_USEAVX)
bvh.BuildHQ( triangles, verts / 3 );
bvh.Convert( BVH::WALD_32BYTE, BVH::BASIC_BVH8 );
bvh.Convert( BVH::BASIC_BVH8, BVH::CWBVH );
bvh.Convert( BVH::WALD_32BYTE, BVH::BASIC_BVH4 );
bvh.Convert( BVH::BASIC_BVH4, BVH::BVH4_AFRA );
#elif defined(BVH_USENEON)
bvh.BuildNEON( triangles, verts / 3 );
#else
Expand Down Expand Up @@ -172,7 +173,7 @@ void Tick( uint32_t* buf )

// trace primary rays
#if !defined USE_EMBREE
for (int i = 0; i < N; i++) bvh.Intersect( rays[i], BVH::CWBVH );
for (int i = 0; i < N; i++) bvh.Intersect( rays[i], BVH::BVH4_AFRA );
#else
struct RTCRayHit rayhit;
for (int i = 0; i < N; i++)
Expand Down

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