90 lines
3.4 KiB
C
90 lines
3.4 KiB
C
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#define LOCAL_EPSILON 0.000001f
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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* Computes a ray-triangle intersection test.
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* Original code from Tomas M<EFBFBD>ller's "Fast Minimum Storage Ray-Triangle Intersection".
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* It's been optimized a bit with integer code, and modified to return a non-intersection if distance from
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* ray origin to triangle is negative.
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*
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* \param vert0 [in] triangle vertex
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* \param vert1 [in] triangle vertex
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* \param vert2 [in] triangle vertex
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* \return true on overlap. mStabbedFace is filled with relevant info.
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*/
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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inline_ BOOL RayCollider::RayTriOverlap(const Point& vert0, const Point& vert1, const Point& vert2)
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{
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// Stats
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mNbRayPrimTests++;
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// Find vectors for two edges sharing vert0
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Point edge1 = vert1 - vert0;
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Point edge2 = vert2 - vert0;
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// Begin calculating determinant - also used to calculate U parameter
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Point pvec = mDir^edge2;
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// If determinant is near zero, ray lies in plane of triangle
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float det = edge1|pvec;
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if(mCulling)
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{
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if(det<LOCAL_EPSILON) return FALSE;
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// From here, det is > 0. So we can use integer cmp.
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// Calculate distance from vert0 to ray origin
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Point tvec = mOrigin - vert0;
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// Calculate U parameter and test bounds
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mStabbedFace.mU = tvec|pvec;
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// if(IR(u)&0x80000000 || u>det) return FALSE;
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IR(det)) return FALSE;
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// Prepare to test V parameter
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Point qvec = tvec^edge1;
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// Calculate V parameter and test bounds
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mStabbedFace.mV = mDir|qvec;
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>det) return FALSE;
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// Calculate t, scale parameters, ray intersects triangle
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mStabbedFace.mDistance = edge2|qvec;
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// Det > 0 so we can early exit here
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// Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance)) return FALSE;
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// Else go on
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float OneOverDet = 1.0f / det;
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mStabbedFace.mDistance *= OneOverDet;
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mStabbedFace.mU *= OneOverDet;
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mStabbedFace.mV *= OneOverDet;
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}
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else
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{
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// the non-culling branch
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if(det>-LOCAL_EPSILON && det<LOCAL_EPSILON) return FALSE;
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float OneOverDet = 1.0f / det;
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// Calculate distance from vert0 to ray origin
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Point tvec = mOrigin - vert0;
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// Calculate U parameter and test bounds
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mStabbedFace.mU = (tvec|pvec) * OneOverDet;
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// if(IR(u)&0x80000000 || u>1.0f) return FALSE;
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mU) || IR(mStabbedFace.mU)>IEEE_1_0) return FALSE;
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// prepare to test V parameter
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Point qvec = tvec^edge1;
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// Calculate V parameter and test bounds
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mStabbedFace.mV = (mDir|qvec) * OneOverDet;
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mV) || mStabbedFace.mU+mStabbedFace.mV>1.0f) return FALSE;
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// Calculate t, ray intersects triangle
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mStabbedFace.mDistance = (edge2|qvec) * OneOverDet;
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// Intersection point is valid if distance is positive (else it can just be a face behind the orig point)
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if(IS_NEGATIVE_FLOAT(mStabbedFace.mDistance)) return FALSE;
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}
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return TRUE;
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}
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