d4708
/
source-engine
mirror of https://github.com/nillerusr/source-engine.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
198 Commits
25 Branches
6 Tags
221 MiB
 
 
 
 
 
 
Tree: 8334f8a378
Branches Tags
${ item.name }
Create tag ${ searchTerm }
Create branch ${ searchTerm }
from '8334f8a378'
${ noResults }
source-engine/raytrace/raytrace.cpp

901 lines
28 KiB
Raw Blame History

//========= Copyright Valve Corporation, All rights reserved. ============//
// $Id$
#include "raytrace.h"
#include <filesystem_tools.h>
#include <cmdlib.h>
#include <stdio.h>
static bool SameSign(float a, float b)
{
int32 aa=*((int *) &a);
int32 bb=*((int *) &b);
return ((aa^bb)&0x80000000)==0;
}
int FourRays::CalculateDirectionSignMask(void) const
{
// this code treats the floats as integers since all it cares about is the sign bit and
// floating point compares suck.
int ret;
int ormask;
int andmask;
int32 const *treat_as_int=((int32 const *) (&direction));
ormask=andmask=*(treat_as_int++);
ormask|=*treat_as_int;
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
if (ormask>=0)
ret=0;
else
{
if (andmask<0)
ret=1;
else return -1;
}
ormask=andmask=*(treat_as_int++);
ormask|=*treat_as_int;
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
if (ormask<0)
{
if (andmask<0)
ret|=2;
else return -1;
}
ormask=andmask=*(treat_as_int++);
ormask|=*treat_as_int;
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
ormask|=*(treat_as_int);
andmask&=*(treat_as_int++);
if (ormask<0)
{
if (andmask<0)
ret|=4;
else return -1;
}
return ret;
}
void RayTracingEnvironment::MakeRoomForTriangles( int ntris )
{
//OptimizedTriangleList.EnsureCapacity( ntris );
if (! (Flags & RTE_FLAGS_DONT_STORE_TRIANGLE_COLORS))
TriangleColors.EnsureCapacity( ntris );
}
void RayTracingEnvironment::AddTriangle(int32 id, const Vector &v1,
const Vector &v2, const Vector &v3,
const Vector &color)
{
AddTriangle( id, v1, v2, v3, color, 0, 0 );
}
void RayTracingEnvironment::AddTriangle(int32 id, const Vector &v1,
const Vector &v2, const Vector &v3,
const Vector &color, uint16 flags, int32 materialIndex)
{
CacheOptimizedTriangle tmptri;
tmptri.m_Data.m_GeometryData.m_nTriangleID = id;
tmptri.Vertex( 0 ) = v1;
tmptri.Vertex( 1 ) = v2;
tmptri.Vertex( 2 ) = v3;
tmptri.m_Data.m_GeometryData.m_nFlags = flags;
OptimizedTriangleList.AddToTail(tmptri);
if (! ( Flags & RTE_FLAGS_DONT_STORE_TRIANGLE_COLORS) )
TriangleColors.AddToTail(color);
if ( !( Flags & RTE_FLAGS_DONT_STORE_TRIANGLE_MATERIALS) )
TriangleMaterials.AddToTail(materialIndex);
// printf("add triange from (%f %f %f),(%f %f %f),(%f %f %f) id %d\n",
// XYZ(v1),XYZ(v2),XYZ(v3),id);
}
void RayTracingEnvironment::AddQuad(
int32 id, const Vector &v1, const Vector &v2, const Vector &v3,
const Vector &v4, // specify vertices in cw or ccw order
const Vector &color)
{
AddTriangle(id,v1,v2,v3,color);
AddTriangle(id+1,v1,v3,v4,color);
}
void RayTracingEnvironment::AddAxisAlignedRectangularSolid(int id,Vector minc, Vector maxc,
const Vector &color)
{
// "far" face
AddQuad(id,
Vector(minc.x,maxc.y,maxc.z),
Vector(maxc.x,maxc.y,maxc.z),Vector(maxc.x,minc.y,maxc.z),
Vector(minc.x,minc.y,maxc.z),color);
// "near" face
AddQuad(id,
Vector(minc.x,maxc.y,minc.z),
Vector(maxc.x,maxc.y,minc.z),Vector(maxc.x,minc.y,minc.z),
Vector(minc.x,minc.y,minc.z),color);
// "left" face
AddQuad(id,
Vector(minc.x,maxc.y,maxc.z),
Vector(minc.x,maxc.y,minc.z),
Vector(minc.x,minc.y,minc.z),
Vector(minc.x,minc.y,maxc.z),color);
// "right" face
AddQuad(id,
Vector(maxc.x,maxc.y,maxc.z),
Vector(maxc.x,maxc.y,minc.z),
Vector(maxc.x,minc.y,minc.z),
Vector(maxc.x,minc.y,maxc.z),color);
// "top" face
AddQuad(id,
Vector(minc.x,maxc.y,maxc.z),
Vector(maxc.x,maxc.y,maxc.z),
Vector(maxc.x,maxc.y,minc.z),
Vector(minc.x,maxc.y,minc.z),color);
// "bot" face
AddQuad(id,
Vector(minc.x,minc.y,maxc.z),
Vector(maxc.x,minc.y,maxc.z),
Vector(maxc.x,minc.y,minc.z),
Vector(minc.x,minc.y,minc.z),color);
}
static Vector GetEdgeEquation(Vector p1, Vector p2, int c1, int c2, Vector InsidePoint)
{
float nx=p1[c2]-p2[c2];
float ny=p2[c1]-p1[c1];
float d=-(nx*p1[c1]+ny*p1[c2]);
// assert(fabs(nx*p1[c1]+ny*p1[c2]+d)<0.01);
// assert(fabs(nx*p2[c1]+ny*p2[c2]+d)<0.01);
// use the convention that negative is "outside"
float trial_dist=InsidePoint[c1]*nx+InsidePoint[c2]*ny+d;
if (trial_dist<0)
{
nx = -nx;
ny = -ny;
d = -d;
trial_dist = -trial_dist;
}
nx /= trial_dist; // scale so that it will be =1.0 at the oppositve vertex
ny /= trial_dist;
d /= trial_dist;
return Vector(nx,ny,d);
}
void CacheOptimizedTriangle::ChangeIntoIntersectionFormat(void)
{
// lose the vertices and use edge equations instead
// grab the whole original triangle to we don't overwrite it
TriGeometryData_t srcTri = m_Data.m_GeometryData;
m_Data.m_IntersectData.m_nFlags = srcTri.m_nFlags;
m_Data.m_IntersectData.m_nTriangleID = srcTri.m_nTriangleID;
Vector p1 = srcTri.Vertex( 0 );
Vector p2 = srcTri.Vertex( 1 );
Vector p3 = srcTri.Vertex( 2 );
Vector e1 = p2 - p1;
Vector e2 = p3 - p1;
Vector N = e1.Cross( e2 );
N.NormalizeInPlace();
// now, determine which axis to drop
int drop_axis = 0;
for(int c=1 ; c<3 ; c++)
if ( fabs(N[c]) > fabs( N[drop_axis] ) )
drop_axis = c;
m_Data.m_IntersectData.m_flD = N.Dot( p1 );
m_Data.m_IntersectData.m_flNx = N.x;
m_Data.m_IntersectData.m_flNy = N.y;
m_Data.m_IntersectData.m_flNz = N.z;
// decide which axes to keep
int nCoordSelect0 = ( drop_axis + 1 ) % 3;
int nCoordSelect1 = ( drop_axis + 2 ) % 3;
m_Data.m_IntersectData.m_nCoordSelect0 = nCoordSelect0;
m_Data.m_IntersectData.m_nCoordSelect1 = nCoordSelect1;
Vector edge1 = GetEdgeEquation( p1, p2, nCoordSelect0, nCoordSelect1, p3 );
m_Data.m_IntersectData.m_ProjectedEdgeEquations[0] = edge1.x;
m_Data.m_IntersectData.m_ProjectedEdgeEquations[1] = edge1.y;
m_Data.m_IntersectData.m_ProjectedEdgeEquations[2] = edge1.z;
Vector edge2 = GetEdgeEquation( p2, p3, nCoordSelect0, nCoordSelect1, p1 );
m_Data.m_IntersectData.m_ProjectedEdgeEquations[3] = edge2.x;
m_Data.m_IntersectData.m_ProjectedEdgeEquations[4] = edge2.y;
m_Data.m_IntersectData.m_ProjectedEdgeEquations[5] = edge2.z;
}
int n_intersection_calculations=0;
int CacheOptimizedTriangle::ClassifyAgainstAxisSplit(int split_plane, float split_value)
{
// classify a triangle against an axis-aligned plane
float minc=Vertex(0)[split_plane];
float maxc=minc;
for(int v=1;v<3;v++)
{
minc=min(minc,Vertex(v)[split_plane]);
maxc=max(maxc,Vertex(v)[split_plane]);
}
if (minc>=split_value)
return PLANECHECK_POSITIVE;
if (maxc<=split_value)
return PLANECHECK_NEGATIVE;
if (minc==maxc)
return PLANECHECK_POSITIVE;
return PLANECHECK_STRADDLING;
}
#define MAILBOX_HASH_SIZE 256
#define MAX_TREE_DEPTH 21
#define MAX_NODE_STACK_LEN (40*MAX_TREE_DEPTH)
struct NodeToVisit {
CacheOptimizedKDNode const *node;
fltx4 TMin;
fltx4 TMax;
};
static fltx4 FourEpsilons={1.0e-10,1.0e-10,1.0e-10,1.0e-10};
static fltx4 FourZeros={1.0e-10,1.0e-10,1.0e-10,1.0e-10};
static fltx4 FourNegativeEpsilons={-1.0e-10,-1.0e-10,-1.0e-10,-1.0e-10};
static float BoxSurfaceArea(Vector const &boxmin, Vector const &boxmax)
{
Vector boxdim=boxmax-boxmin;
return 2.0*((boxdim[0]*boxdim[2])+(boxdim[0]*boxdim[1])+(boxdim[1]*boxdim[2]));
}
void RayTracingEnvironment::Trace4Rays(const FourRays &rays, fltx4 TMin, fltx4 TMax,
RayTracingResult *rslt_out,
int32 skip_id, ITransparentTriangleCallback *pCallback)
{
int msk=rays.CalculateDirectionSignMask();
if (msk!=-1)
Trace4Rays(rays,TMin,TMax,msk,rslt_out,skip_id, pCallback);
else
{
// sucky case - can't trace 4 rays at once. in the worst case, need to trace all 4
// separately, but usually we will still get 2x, Since our tracer only does 4 at a
// time, we will have to cover up the undesired rays with the desired ray
//!! speed!! there is room for some sse-ization here
FourRays tmprays;
tmprays.origin=rays.origin;
uint8 need_trace[4]={1,1,1,1};
for(int try_trace=0;try_trace<4;try_trace++)
{
if (need_trace[try_trace])
{
need_trace[try_trace]=2; // going to trace it
// replicate the ray being traced into all 4 rays
tmprays.direction.x=ReplicateX4(rays.direction.X(try_trace));
tmprays.direction.y=ReplicateX4(rays.direction.Y(try_trace));
tmprays.direction.z=ReplicateX4(rays.direction.Z(try_trace));
// now, see if any of the other remaining rays can be handled at the same time.
for(int try2=try_trace+1;try2<4;try2++)
if (need_trace[try2])
{
if (
SameSign(rays.direction.X(try2),
rays.direction.X(try_trace)) &&
SameSign(rays.direction.Y(try2),
rays.direction.Y(try_trace)) &&
SameSign(rays.direction.Z(try2),
rays.direction.Z(try_trace)))
{
need_trace[try2]=2;
tmprays.direction.X(try2) = rays.direction.X(try2);
tmprays.direction.Y(try2) = rays.direction.Y(try2);
tmprays.direction.Z(try2) = rays.direction.Z(try2);
}
}
// ok, now trace between 1 and 3 rays, and output the results
RayTracingResult tmpresults;
msk=tmprays.CalculateDirectionSignMask();
assert(msk!=-1);
Trace4Rays(tmprays,TMin,TMax,msk,&tmpresults,skip_id, pCallback);
// now, move results to proper place
for(int i=0;i<4;i++)
if (need_trace[i]==2)
{
need_trace[i]=0;
rslt_out->HitIds[i]=tmpresults.HitIds[i];
SubFloat(rslt_out->HitDistance, i) = SubFloat(tmpresults.HitDistance, i);
rslt_out->surface_normal.X(i) = tmpresults.surface_normal.X(i);
rslt_out->surface_normal.Y(i) = tmpresults.surface_normal.Y(i);
rslt_out->surface_normal.Z(i) = tmpresults.surface_normal.Z(i);
}
}
}
}
}
void RayTracingEnvironment::Trace4Rays(const FourRays &rays, fltx4 TMin, fltx4 TMax,
int DirectionSignMask, RayTracingResult *rslt_out,
int32 skip_id, ITransparentTriangleCallback *pCallback)
{
rays.Check();
memset(rslt_out->HitIds,0xff,sizeof(rslt_out->HitIds));
rslt_out->HitDistance=ReplicateX4(1.0e23);
rslt_out->surface_normal.DuplicateVector(Vector(0.,0.,0.));
FourVectors OneOverRayDir=rays.direction;
OneOverRayDir.MakeReciprocalSaturate();
// now, clip rays against bounding box
for(int c=0;c<3;c++)
{
fltx4 isect_min_t=
MulSIMD(SubSIMD(ReplicateX4(m_MinBound[c]),rays.origin[c]),OneOverRayDir[c]);
fltx4 isect_max_t=
MulSIMD(SubSIMD(ReplicateX4(m_MaxBound[c]),rays.origin[c]),OneOverRayDir[c]);
TMin=MaxSIMD(TMin,MinSIMD(isect_min_t,isect_max_t));
TMax=MinSIMD(TMax,MaxSIMD(isect_min_t,isect_max_t));
}
fltx4 active=CmpLeSIMD(TMin,TMax); // mask of which rays are active
if (! IsAnyNegative(active) )
return; // missed bounding box
int32 mailboxids[MAILBOX_HASH_SIZE]; // used to avoid redundant triangle tests
memset(mailboxids,0xff,sizeof(mailboxids)); // !!speed!! keep around?
int front_idx[3],back_idx[3]; // based on ray direction, whether to
// visit left or right node first
if (DirectionSignMask & 1)
{
back_idx[0]=0;
front_idx[0]=1;
}
else
{
back_idx[0]=1;
front_idx[0]=0;
}
if (DirectionSignMask & 2)
{
back_idx[1]=0;
front_idx[1]=1;
}
else
{
back_idx[1]=1;
front_idx[1]=0;
}
if (DirectionSignMask & 4)
{
back_idx[2]=0;
front_idx[2]=1;
}
else
{
back_idx[2]=1;
front_idx[2]=0;
}
NodeToVisit NodeQueue[MAX_NODE_STACK_LEN];
CacheOptimizedKDNode const *CurNode=&(OptimizedKDTree[0]);
NodeToVisit *stack_ptr=&NodeQueue[MAX_NODE_STACK_LEN];
while(1)
{
while (CurNode->NodeType() != KDNODE_STATE_LEAF) // traverse until next leaf
{
int split_plane_number=CurNode->NodeType();
CacheOptimizedKDNode const *FrontChild=&(OptimizedKDTree[CurNode->LeftChild()]);
fltx4 dist_to_sep_plane= // dist=(split-org)/dir
MulSIMD(
SubSIMD(ReplicateX4(CurNode->SplittingPlaneValue),
rays.origin[split_plane_number]),OneOverRayDir[split_plane_number]);
active=CmpLeSIMD(TMin,TMax); // mask of which rays are active
// now, decide how to traverse children. can either do front,back, or do front and push
// back.
fltx4 hits_front=AndSIMD(active,CmpGeSIMD(dist_to_sep_plane,TMin));
if (! IsAnyNegative(hits_front))
{
// missed the front. only traverse back
//printf("only visit back %d\n",CurNode->LeftChild()+back_idx[split_plane_number]);
CurNode=FrontChild+back_idx[split_plane_number];
TMin=MaxSIMD(TMin, dist_to_sep_plane);
}
else
{
fltx4 hits_back=AndSIMD(active,CmpLeSIMD(dist_to_sep_plane,TMax));
if (! IsAnyNegative(hits_back) )
{
// missed the back - only need to traverse front node
//printf("only visit front %d\n",CurNode->LeftChild()+front_idx[split_plane_number]);
CurNode=FrontChild+front_idx[split_plane_number];
TMax=MinSIMD(TMax, dist_to_sep_plane);
}
else
{
// at least some rays hit both nodes.
// must push far, traverse near
//printf("visit %d,%d\n",CurNode->LeftChild()+front_idx[split_plane_number],
// CurNode->LeftChild()+back_idx[split_plane_number]);
assert(stack_ptr>NodeQueue);
--stack_ptr;
stack_ptr->node=FrontChild+back_idx[split_plane_number];
stack_ptr->TMin=MaxSIMD(TMin,dist_to_sep_plane);
stack_ptr->TMax=TMax;
CurNode=FrontChild+front_idx[split_plane_number];
TMax=MinSIMD(TMax,dist_to_sep_plane);
}
}
}
// hit a leaf! must do intersection check
int ntris=CurNode->NumberOfTrianglesInLeaf();
if (ntris)
{
int32 const *tlist=&(TriangleIndexList[CurNode->TriangleIndexStart()]);
do
{
int tnum=*(tlist++);
//printf("try tri %d\n",tnum);
// check mailbox
int mbox_slot=tnum & (MAILBOX_HASH_SIZE-1);
TriIntersectData_t const *tri = &( OptimizedTriangleList[tnum].m_Data.m_IntersectData );
if ( ( mailboxids[mbox_slot] != tnum ) && ( tri->m_nTriangleID != skip_id ) )
{
n_intersection_calculations++;
mailboxids[mbox_slot] = tnum;
// compute plane intersection
FourVectors N;
N.x = ReplicateX4( tri->m_flNx );
N.y = ReplicateX4( tri->m_flNy );
N.z = ReplicateX4( tri->m_flNz );
fltx4 DDotN = rays.direction * N;
// mask off zero or near zero (ray parallel to surface)
fltx4 did_hit = OrSIMD( CmpGtSIMD( DDotN,FourEpsilons ),
CmpLtSIMD( DDotN, FourNegativeEpsilons ) );
fltx4 numerator=SubSIMD( ReplicateX4( tri->m_flD ), rays.origin * N );
fltx4 isect_t=DivSIMD( numerator,DDotN );
// now, we have the distance to the plane. lets update our mask
did_hit = AndSIMD( did_hit, CmpGtSIMD( isect_t, FourZeros ) );
//did_hit=AndSIMD(did_hit,CmpLtSIMD(isect_t,TMax));
did_hit = AndSIMD( did_hit, CmpLtSIMD( isect_t, rslt_out->HitDistance ) );
if ( ! IsAnyNegative( did_hit ) )
continue;
// now, check 3 edges
fltx4 hitc1 = AddSIMD( rays.origin[tri->m_nCoordSelect0],
MulSIMD( isect_t, rays.direction[ tri->m_nCoordSelect0] ) );
fltx4 hitc2 = AddSIMD( rays.origin[tri->m_nCoordSelect1],
MulSIMD( isect_t, rays.direction[tri->m_nCoordSelect1] ) );
// do barycentric coordinate check
fltx4 B0 = MulSIMD( ReplicateX4( tri->m_ProjectedEdgeEquations[0] ), hitc1 );
B0 = AddSIMD(
B0,
MulSIMD( ReplicateX4( tri->m_ProjectedEdgeEquations[1] ), hitc2 ) );
B0 = AddSIMD(
B0, ReplicateX4( tri->m_ProjectedEdgeEquations[2] ) );
did_hit = AndSIMD( did_hit, CmpGeSIMD( B0, FourZeros ) );
fltx4 B1 = MulSIMD( ReplicateX4( tri->m_ProjectedEdgeEquations[3] ), hitc1 );
B1 = AddSIMD(
B1,
MulSIMD( ReplicateX4( tri->m_ProjectedEdgeEquations[4]), hitc2 ) );
B1 = AddSIMD(
B1, ReplicateX4( tri->m_ProjectedEdgeEquations[5] ) );
did_hit = AndSIMD( did_hit, CmpGeSIMD( B1, FourZeros ) );
fltx4 B2 = AddSIMD( B1, B0 );
did_hit = AndSIMD( did_hit, CmpLeSIMD( B2, Four_Ones ) );
if ( ! IsAnyNegative( did_hit ) )
continue;
// if the triangle is transparent
if ( tri->m_nFlags & FCACHETRI_TRANSPARENT )
{
if ( pCallback )
{
// assuming a triangle indexed as v0, v1, v2
// the projected edge equations are set up such that the vert opposite the first
// equation is v2, and the vert opposite the second equation is v0
// Therefore we pass them back in 1, 2, 0 order
// Also B2 is currently B1 + B0 and needs to be 1 - (B1+B0) in order to be a real
// barycentric coordinate. Compute that now and pass it to the callback
fltx4 b2 = SubSIMD( Four_Ones, B2 );
if ( pCallback->VisitTriangle_ShouldContinue( *tri, rays, &did_hit, &B1, &b2, &B0, tnum ) )
{
did_hit = Four_Zeros;
}
}
}
// now, set the hit_id and closest_hit fields for any enabled rays
fltx4 replicated_n = ReplicateIX4(tnum);
StoreAlignedSIMD((float *) rslt_out->HitIds,
OrSIMD(AndSIMD(replicated_n,did_hit),
AndNotSIMD(did_hit,LoadAlignedSIMD(
(float *) rslt_out->HitIds))));
rslt_out->HitDistance=OrSIMD(AndSIMD(isect_t,did_hit),
AndNotSIMD(did_hit,rslt_out->HitDistance));
rslt_out->surface_normal.x=OrSIMD(
AndSIMD(N.x,did_hit),
AndNotSIMD(did_hit,rslt_out->surface_normal.x));
rslt_out->surface_normal.y=OrSIMD(
AndSIMD(N.y,did_hit),
AndNotSIMD(did_hit,rslt_out->surface_normal.y));
rslt_out->surface_normal.z=OrSIMD(
AndSIMD(N.z,did_hit),
AndNotSIMD(did_hit,rslt_out->surface_normal.z));
}
} while (--ntris);
// now, check if all rays have terminated
fltx4 raydone=CmpLeSIMD(TMax,rslt_out->HitDistance);
if (! IsAnyNegative(raydone))
{
return;
}
}
if (stack_ptr==&NodeQueue[MAX_NODE_STACK_LEN])
{
return;
}
// pop stack!
CurNode=stack_ptr->node;
TMin=stack_ptr->TMin;
TMax=stack_ptr->TMax;
stack_ptr++;
}
}
int RayTracingEnvironment::MakeLeafNode(int first_tri, int last_tri)
{
CacheOptimizedKDNode ret;
ret.Children=KDNODE_STATE_LEAF+(TriangleIndexList.Count()<<2);
ret.SetNumberOfTrianglesInLeafNode(1+(last_tri-first_tri));
for(int tnum=first_tri;tnum<=last_tri;tnum++)
TriangleIndexList.AddToTail(tnum);
OptimizedKDTree.AddToTail(ret);
return OptimizedKDTree.Count()-1;
}
void RayTracingEnvironment::CalculateTriangleListBounds(int32 const *tris,int ntris,
Vector &minout, Vector &maxout)
{
minout = Vector( 1.0e23, 1.0e23, 1.0e23);
maxout = Vector( -1.0e23, -1.0e23, -1.0e23);
for(int i=0; i<ntris; i++)
{
CacheOptimizedTriangle const &tri=OptimizedTriangleList[tris[i]];
for(int v=0; v<3; v++)
for(int c=0; c<3; c++)
{
minout[c]=min(minout[c],tri.Vertex(v)[c]);
maxout[c]=max(maxout[c],tri.Vertex(v)[c]);
}
}
}
// Both the "quick" and regular kd tree building algorithms here use the "surface area heuristic":
// the relative probability of hitting the "left" subvolume (Vl) from a split is equal to that
// subvolume's surface area divided by its parent's surface area (Vp) : P(Vl | V)=SA(Vl)/SA(Vp).
// The same holds for the right subvolume, Vp. Nl is the number of triangles in the left volume,
// and Nr in the right volume. if Ct is the cost of traversing one tree node, and Ci is the cost of
// intersection with the primitive, than the cost of splitting is estimated as:
//
// Ct+Ci*((SA(Vl)/SA(V))*Nl+(SA(Vr)/SA(V)*Nr)).
// and the cost of not splitting is
// Ci*N
//
// This both provides a metric to minimize when computing how and where to split, and also a
// termination criterion.
//
// the "quick" method just splits down the middle, while the slow method splits at the best
// discontinuity of the cost formula. The quick method splits along the longest axis ; the
// regular algorithm tries all 3 to find which one results in the minimum cost
//
// both methods use the additional optimization of "growing" empty nodes - if the split results in
// one side being devoid of triangles, the empty side is "grown" as much as possible.
//
#define COST_OF_TRAVERSAL 75 // approximate #operations
#define COST_OF_INTERSECTION 167 // approximate #operations
float RayTracingEnvironment::CalculateCostsOfSplit(
int split_plane,int32 const *tri_list,int ntris,
Vector MinBound,Vector MaxBound, float &split_value,
int &nleft, int &nright, int &nboth)
{
// determine the costs of splitting on a given axis, and label triangles with respect to
// that axis by storing the value in coordselect0. It will also return the number of
// tris in the left, right, and nboth groups, in order to facilitate memory
nleft=nboth=nright=0;
// now, label each triangle. Since we have not converted the triangles into
// intersection fromat yet, we can use the CoordSelect0 field of each as a temp.
nleft=0;
nright=0;
nboth=0;
float min_coord=1.0e23,max_coord=-1.0e23;
for(int t=0;t<ntris;t++)
{
CacheOptimizedTriangle &tri=OptimizedTriangleList[tri_list[t]];
// determine max and min coordinate values for later optimization
for(int v=0;v<3;v++)
{
min_coord = min( min_coord, tri.Vertex(v)[split_plane] );
max_coord = max( max_coord, tri.Vertex(v)[split_plane] );
}
switch(tri.ClassifyAgainstAxisSplit(split_plane,split_value))
{
case PLANECHECK_NEGATIVE:
nleft++;
tri.m_Data.m_GeometryData.m_nTmpData0 = PLANECHECK_NEGATIVE;
break;
case PLANECHECK_POSITIVE:
nright++;
tri.m_Data.m_GeometryData.m_nTmpData0 = PLANECHECK_POSITIVE;
break;
case PLANECHECK_STRADDLING:
nboth++;
tri.m_Data.m_GeometryData.m_nTmpData0 = PLANECHECK_STRADDLING;
break;
}
}
// now, if the split resulted in one half being empty, "grow" the empty half
if (nleft && (nboth==0) && (nright==0))
split_value=max_coord;
if (nright && (nboth==0) && (nleft==0))
split_value=min_coord;
// now, perform surface area/cost check to determine whether this split was worth it
Vector LeftMins=MinBound;
Vector LeftMaxes=MaxBound;
Vector RightMins=MinBound;
Vector RightMaxes=MaxBound;
LeftMaxes[split_plane]=split_value;
RightMins[split_plane]=split_value;
float SA_L=BoxSurfaceArea(LeftMins,LeftMaxes);
float SA_R=BoxSurfaceArea(RightMins,RightMaxes);
float ISA=1.0/BoxSurfaceArea(MinBound,MaxBound);
float cost_of_split=COST_OF_TRAVERSAL+COST_OF_INTERSECTION*(nboth+
(SA_L*ISA*(nleft))+(SA_R*ISA*(nright)));
return cost_of_split;
}
#define NEVER_SPLIT 0
void RayTracingEnvironment::RefineNode(int node_number,int32 const *tri_list,int ntris,
Vector MinBound,Vector MaxBound, int depth)
{
if (ntris<3) // never split empty lists
{
// no point in continuing
OptimizedKDTree[node_number].Children=KDNODE_STATE_LEAF+(TriangleIndexList.Count()<<2);
OptimizedKDTree[node_number].SetNumberOfTrianglesInLeafNode(ntris);
#ifdef DEBUG_RAYTRACE
OptimizedKDTree[node_number].vecMins = MinBound;
OptimizedKDTree[node_number].vecMaxs = MaxBound;
#endif
for(int t=0;t<ntris;t++)
TriangleIndexList.AddToTail(tri_list[t]);
return;
}
float best_cost=1.0e23;
int best_nleft=0,best_nright=0,best_nboth=0;
float best_splitvalue=0;
int split_plane=0;
int tri_skip=1+(ntris/10); // don't try all trinagles as split
// points when there are a lot of them
for(int axis=0;axis<3;axis++)
{
for(int ts=-1;ts<ntris;ts+=tri_skip)
{
for(int tv=0;tv<3;tv++)
{
int trial_nleft,trial_nright,trial_nboth;
float trial_splitvalue;
if (ts==-1)
trial_splitvalue=0.5*(MinBound[axis]+MaxBound[axis]);
else
{
// else, split at the triangle vertex if possible
CacheOptimizedTriangle &tri=OptimizedTriangleList[tri_list[ts]];
trial_splitvalue = tri.Vertex(tv)[axis];
if ((trial_splitvalue>MaxBound[axis]) || (trial_splitvalue<MinBound[axis]))
continue; // don't try this vertex - not inside
}
// printf("ts=%d tv=%d tp=%f\n",ts,tv,trial_splitvalue);
float trial_cost=
CalculateCostsOfSplit(axis,tri_list,ntris,MinBound,MaxBound,trial_splitvalue,
trial_nleft,trial_nright, trial_nboth);
// printf("try %d cost=%f nl=%d nr=%d nb=%d sp=%f\n",axis,trial_cost,trial_nleft,trial_nright, trial_nboth,
// trial_splitvalue);
if (trial_cost<best_cost)
{
split_plane=axis;
best_cost=trial_cost;
best_nleft=trial_nleft;
best_nright=trial_nright;
best_nboth=trial_nboth;
best_splitvalue=trial_splitvalue;
// save away the axis classification of each triangle
for(int t=0 ; t < ntris; t++)
{
CacheOptimizedTriangle &tri=OptimizedTriangleList[tri_list[t]];
tri.m_Data.m_GeometryData.m_nTmpData1 = tri.m_Data.m_GeometryData.m_nTmpData0;
}
}
if (ts==-1)
break;
}
}
}
float cost_of_no_split=COST_OF_INTERSECTION*ntris;
if ( (cost_of_no_split<=best_cost) || NEVER_SPLIT || (depth>MAX_TREE_DEPTH))
{
// no benefit to splitting. just make this a leaf node
OptimizedKDTree[node_number].Children=KDNODE_STATE_LEAF+(TriangleIndexList.Count()<<2);
OptimizedKDTree[node_number].SetNumberOfTrianglesInLeafNode(ntris);
#ifdef DEBUG_RAYTRACE
OptimizedKDTree[node_number].vecMins = MinBound;
OptimizedKDTree[node_number].vecMaxs = MaxBound;
#endif
for(int t=0;t<ntris;t++)
TriangleIndexList.AddToTail(tri_list[t]);
}
else
{
// printf("best split was %d at %f (mid=%f,n=%d, sk=%d)\n",split_plane,best_splitvalue,
// 0.5*(MinBound[split_plane]+MaxBound[split_plane]),ntris,tri_skip);
// its worth splitting!
// we will achieve the splitting without sorting by using a selection algorithm.
int32 *new_triangle_list;
new_triangle_list=new int32[ntris];
// now, perform surface area/cost check to determine whether this split was worth it
Vector LeftMins=MinBound;
Vector LeftMaxes=MaxBound;
Vector RightMins=MinBound;
Vector RightMaxes=MaxBound;
LeftMaxes[split_plane]=best_splitvalue;
RightMins[split_plane]=best_splitvalue;
int n_left_output=0;
int n_both_output=0;
int n_right_output=0;
for(int t=0;t<ntris;t++)
{
CacheOptimizedTriangle &tri=OptimizedTriangleList[tri_list[t]];
switch( tri.m_Data.m_GeometryData.m_nTmpData1 )
{
case PLANECHECK_NEGATIVE:
// printf("%d goes left\n",t);
new_triangle_list[n_left_output++]=tri_list[t];
break;
case PLANECHECK_POSITIVE:
n_right_output++;
// printf("%d goes right\n",t);
new_triangle_list[ntris-n_right_output]=tri_list[t];
break;
case PLANECHECK_STRADDLING:
// printf("%d goes both\n",t);
new_triangle_list[best_nleft+n_both_output]=tri_list[t];
n_both_output++;
break;
}
}
int left_child=OptimizedKDTree.Count();
int right_child=left_child+1;
// printf("node %d split on axis %d at %f, nl=%d nr=%d nb=%d lc=%d rc=%d\n",node_number,
// split_plane,best_splitvalue,best_nleft,best_nright,best_nboth,
// left_child,right_child);
OptimizedKDTree[node_number].Children=split_plane+(left_child<<2);
OptimizedKDTree[node_number].SplittingPlaneValue=best_splitvalue;
#ifdef DEBUG_RAYTRACE
OptimizedKDTree[node_number].vecMins = MinBound;
OptimizedKDTree[node_number].vecMaxs = MaxBound;
#endif
CacheOptimizedKDNode newnode;
OptimizedKDTree.AddToTail(newnode);
OptimizedKDTree.AddToTail(newnode);
// now, recurse!
if ( (ntris<20) && ((best_nleft==0) || (best_nright==0)) )
depth+=100;
RefineNode(left_child,new_triangle_list,best_nleft+best_nboth,LeftMins,LeftMaxes,depth+1);
RefineNode(right_child,new_triangle_list+best_nleft,best_nright+best_nboth,
RightMins,RightMaxes,depth+1);
delete[] new_triangle_list;
}
}
void RayTracingEnvironment::SetupAccelerationStructure(void)
{
CacheOptimizedKDNode root;
OptimizedKDTree.AddToTail(root);
int32 *root_triangle_list=new int32[OptimizedTriangleList.Count()];
for(int t=0;t<OptimizedTriangleList.Count();t++)
root_triangle_list[t]=t;
CalculateTriangleListBounds(root_triangle_list,OptimizedTriangleList.Count(),m_MinBound,
m_MaxBound);
RefineNode(0,root_triangle_list,OptimizedTriangleList.Count(),m_MinBound,m_MaxBound,0);
delete[] root_triangle_list;
// now, convert all triangles to "intersection format"
for(int i=0;i<OptimizedTriangleList.Count();i++)
OptimizedTriangleList[i].ChangeIntoIntersectionFormat();
}
void RayTracingEnvironment::AddInfinitePointLight(Vector position, Vector intensity)
{
LightDesc_t mylight(position,intensity);
LightList.AddToTail(mylight);
}