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//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of NVIDIA CORPORATION nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Copyright (c) 2008-2018 NVIDIA Corporation. All rights reserved.
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
#ifndef GU_INTERSECTION_RAY_TRIANGLE_H
#define GU_INTERSECTION_RAY_TRIANGLE_H
#include "foundation/PxVec3.h"
#include "PxPhysXCommonConfig.h"
#include "CmPhysXCommon.h"
namespace physx
{
namespace Gu
{
// PT: this is used for backface culling. It existed in Moller's original code already. Basically this is only to avoid dividing by zero.
// This should not depend on what units are used, and neither should it depend on the size of triangles. A large triangle with the same
// orientation as a small triangle should be backface culled the same way. A triangle whose orientation does not change should not suddenly
// become culled or visible when we scale it.
//
// An absolute epsilon is fine here. The computation will work fine for small triangles, and large triangles will simply make 'det' larger,
// more and more inaccurate, but it won't suddenly make it negative.
//
// Using FLT_EPSILON^2 ensures that triangles whose edges are smaller than FLT_EPSILON long are rejected. This epsilon makes the code work
// for very small triangles, while still preventing divisions by too small values.
#define GU_CULLING_EPSILON_RAY_TRIANGLE FLT_EPSILON*FLT_EPSILON
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
/**
* Computes a ray-triangle intersection test.
* From Tomas Moeller's "Fast Minimum Storage Ray-Triangle Intersection"
* Could be optimized and cut into 2 methods (culled or not). Should make a batch one too to avoid the call overhead, or make it inline.
*
* \param orig [in] ray origin
* \param dir [in] ray direction
* \param vert0 [in] triangle vertex
* \param vert1 [in] triangle vertex
* \param vert2 [in] triangle vertex
* \param at [out] distance
* \param au [out] impact barycentric coordinate
* \param av [out] impact barycentric coordinate
* \param cull [in] true to use backface culling
* \param enlarge [in] enlarge triangle by specified epsilon in UV space to avoid false near-edge rejections
* \return true on overlap
* \note u, v and t will remain unchanged if false is returned.
*/
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
PX_FORCE_INLINE bool intersectRayTriangle( const PxVec3& orig, const PxVec3& dir,
const PxVec3& vert0, const PxVec3& vert1, const PxVec3& vert2,
PxReal& at, PxReal& au, PxReal& av,
bool cull, float enlarge=0.0f)
{
// Find vectors for two edges sharing vert0
const PxVec3 edge1 = vert1 - vert0;
const PxVec3 edge2 = vert2 - vert0;
// Begin calculating determinant - also used to calculate U parameter
const PxVec3 pvec = dir.cross(edge2); // error ~ |v2-v0|
// If determinant is near zero, ray lies in plane of triangle
const PxReal det = edge1.dot(pvec); // error ~ |v2-v0|*|v1-v0|
if(cull)
{
if(det<GU_CULLING_EPSILON_RAY_TRIANGLE)
return false;
// Calculate distance from vert0 to ray origin
const PxVec3 tvec = orig - vert0;
// Calculate U parameter and test bounds
const PxReal u = tvec.dot(pvec);
const PxReal enlargeCoeff = enlarge*det;
const PxReal uvlimit = -enlargeCoeff;
const PxReal uvlimit2 = det + enlargeCoeff;
if(u<uvlimit || u>uvlimit2)
return false;
// Prepare to test V parameter
const PxVec3 qvec = tvec.cross(edge1);
// Calculate V parameter and test bounds
const PxReal v = dir.dot(qvec);
if(v<uvlimit || (u+v)>uvlimit2)
return false;
// Calculate t, scale parameters, ray intersects triangle
const PxReal t = edge2.dot(qvec);
const PxReal inv_det = 1.0f / det;
at = t*inv_det;
au = u*inv_det;
av = v*inv_det;
}
else
{
// the non-culling branch
if(PxAbs(det)<GU_CULLING_EPSILON_RAY_TRIANGLE)
return false;
const PxReal inv_det = 1.0f / det;
// Calculate distance from vert0 to ray origin
const PxVec3 tvec = orig - vert0; // error ~ |orig-v0|
// Calculate U parameter and test bounds
const PxReal u = tvec.dot(pvec) * inv_det;
if(u<-enlarge || u>1.0f+enlarge)
return false;
// prepare to test V parameter
const PxVec3 qvec = tvec.cross(edge1);
// Calculate V parameter and test bounds
const PxReal v = dir.dot(qvec) * inv_det;
if(v<-enlarge || (u+v)>1.0f+enlarge)
return false;
// Calculate t, ray intersects triangle
const PxReal t = edge2.dot(qvec) * inv_det;
at = t;
au = u;
av = v;
}
return true;
}
/* \note u, v and t will remain unchanged if false is returned. */
PX_FORCE_INLINE bool intersectRayTriangleCulling( const PxVec3& orig, const PxVec3& dir,
const PxVec3& vert0, const PxVec3& vert1, const PxVec3& vert2,
PxReal& t, PxReal& u, PxReal& v,
float enlarge=0.0f)
{
return intersectRayTriangle(orig, dir, vert0, vert1, vert2, t, u, v, true, enlarge);
}
/* \note u, v and t will remain unchanged if false is returned. */
PX_FORCE_INLINE bool intersectRayTriangleNoCulling( const PxVec3& orig, const PxVec3& dir,
const PxVec3& vert0, const PxVec3& vert1, const PxVec3& vert2,
PxReal& t, PxReal& u, PxReal& v,
float enlarge=0.0f)
{
return intersectRayTriangle(orig, dir, vert0, vert1, vert2, t, u, v, false, enlarge);
}
} // namespace Gu
}
#endif
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