OPCODE/OPC_RayTriOverlap.h

   1 #define LOCAL_EPSILON 0.000001f
   2
   3 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
   4 /**
   5  *      Computes a ray-triangle intersection test.
   6  *      Original code from Tomas Möller's "Fast Minimum Storage Ray-Triangle Intersection".
   7  *      It's been optimized a bit with integer code, and modified to return a non-intersection if distance from
   8  *      ray origin to triangle is negative.
   9  *
  10  *      \param          vert0   [in] triangle vertex
  11  *      \param          vert1   [in] triangle vertex
  12  *      \param          vert2   [in] triangle vertex
  13  *      \return         true on overlap. mStabbedFace is filled with relevant info.
  14  */
  15 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  16 inline_ BOOL RayCollider::RayTriOverlap(const Point& vert0, const Point& vert1, const Point& vert2)
  17 {
  18         // Stats
  19         mNbRayPrimTests++;
  20
  21         // Find vectors for two edges sharing vert0
  22         Point edge1 = vert1 - vert0;
  23         Point edge2 = vert2 - vert0;
  24
  25         // Begin calculating determinant - also used to calculate U parameter
  26         Point pvec = mDir^edge2;
  27
  28         // If determinant is near zero, ray lies in plane of triangle
  29         float det = edge1|pvec;
  30
  31         if(mCulling)
  32         {
  33                 if(det <= LOCAL_EPSILON * FCMin2(edge1.SquareMagnitude(), edge2.SquareMagnitude())) return FALSE;
  34                 // From here, det is > 0. So we can use integer cmp.
  35
  36                 // Calculate distance from vert0 to ray origin
  37                 Point tvec = mOrigin - vert0;
  38
  39                 // Calculate U parameter and test bounds
  40                 mStabbedFace.mU = tvec|pvec;
  41 //              if(IR(u)&0x80000000 || u>det)                                   return FALSE;
  42                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IR(det))           return FALSE;
  43
  44                 // Prepare to test V parameter
  45                 Point qvec = tvec^edge1;
  46
  47                 // Calculate V parameter and test bounds
  48                 mStabbedFace.mV = mDir|qvec;
  49                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>det)   return FALSE;
  50
  51                 // Calculate t, scale parameters, ray intersects triangle
  52                 mStabbedFace.mDistance = edge2|qvec;
  53                 // Det > 0 so we can early exit here
  54                 // Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
  55                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance))                                                           return FALSE;
  56                 // Else go on
  57                 float OneOverDet = 1.0f / det;
  58                 mStabbedFace.mDistance *= OneOverDet;
  59                 mStabbedFace.mU *= OneOverDet;
  60                 mStabbedFace.mV *= OneOverDet;
  61         }
  62         else
  63         {
  64                 // the non-culling branch
  65                 if(FastFabs(det) <= LOCAL_EPSILON * FCMin2(edge1.SquareMagnitude(), edge2.SquareMagnitude())) return FALSE;
  66                 float OneOverDet = 1.0f / det;
  67
  68                 // Calculate distance from vert0 to ray origin
  69                 Point tvec = mOrigin - vert0;
  70
  71                 // Calculate U parameter and test bounds
  72                 mStabbedFace.mU = (tvec|pvec) * OneOverDet;
  73 //              if(IR(u)&0x80000000 || u>1.0f)                                  return FALSE;
  74                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IEEE_1_0)          return FALSE;
  75
  76                 // prepare to test V parameter
  77                 Point qvec = tvec^edge1;
  78
  79                 // Calculate V parameter and test bounds
  80                 mStabbedFace.mV = (mDir|qvec) * OneOverDet;
  81                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>1.0f)  return FALSE;
  82
  83                 // Calculate t, ray intersects triangle
  84                 mStabbedFace.mDistance = (edge2|qvec) * OneOverDet;
  85                 // Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
  86                 if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance))                                                           return FALSE;
  87         }
  88         return TRUE;
  89 }