1 files changed, 81 insertions, 0 deletions
diff --git a/indra/newview/llvosurfacepatch.cpp b/indra/newview/llvosurfacepatch.cpp
index 968cc69d3a..e912a19f81 100644
--- a/indra/newview/llvosurfacepatch.cpp
+++ b/indra/newview/llvosurfacepatch.cpp
@@ -916,6 +916,87 @@ void LLVOSurfacePatch::getGeomSizesEast(const S32 stride, const S32 east_stride,
 	}
 }
 
+BOOL LLVOSurfacePatch::lineSegmentIntersect(const LLVector3& start, const LLVector3& end, S32 face, BOOL pick_transparent, S32 *face_hitp,
+									  LLVector3* intersection,LLVector2* tex_coord, LLVector3* normal, LLVector3* bi_normal)
+	
+{
+
+	if (!lineSegmentBoundingBox(start, end))
+	{
+		return FALSE;
+	}
+
+	LLVector3 delta = end-start;
+		
+	LLVector3 pdelta = delta;
+	pdelta.mV[2] = 0;
+
+	F32 plength = pdelta.length();
+	
+	F32 tdelta = 1.f/plength;
+
+	LLVector3 origin = start - mRegionp->getOriginAgent();
+
+	if (mRegionp->getLandHeightRegion(origin) > origin.mV[2])
+	{
+		//origin is under ground, treat as no intersection
+		return FALSE;
+	}
+
+	//step one meter at a time until intersection point found
+
+	F32 t = 0.f;
+	while ( t <= 1.f)
+	{
+		LLVector3 sample = origin + delta*t;
+		
+		F32 height = mRegionp->getLandHeightRegion(sample);
+		if (height > sample.mV[2])
+		{ //ray went below ground, positive intersection
+			//quick and dirty binary search to get impact point
+			tdelta = -tdelta*0.5f;
+			F32 err_dist = 0.001f;
+			F32 dist = fabsf(sample.mV[2] - height);
+
+			while (dist > err_dist && tdelta*tdelta > 0.0f)
+			{
+				t += tdelta;
+				sample = origin+delta*t;
+				height = mRegionp->getLandHeightRegion(sample);
+				if ((tdelta < 0 && height < sample.mV[2]) ||
+					(height > sample.mV[2] && tdelta > 0))
+				{ //jumped over intersection point, go back
+					tdelta = -tdelta;
+				}
+				tdelta *= 0.5f;
+				dist = fabsf(sample.mV[2] - height);
+			}
+
+			if (intersection)
+			{
+				sample.mV[2] = mRegionp->getLandHeightRegion(sample);
+				*intersection = sample + mRegionp->getOriginAgent();
+			}
+
+			if (normal)
+			{
+				*normal = mRegionp->getLand().resolveNormalGlobal(mRegionp->getPosGlobalFromRegion(sample));
+			}
+
+			return TRUE;
+		}
+
+		t += tdelta;
+		if (t > 1 && t < 1.f+tdelta*0.99f)
+		{ //make sure end point is checked (saves vertical lines coming up negative)
+			t = 1.f;
+		}
+	}
+
+
+	return FALSE;
+}
+
 void LLVOSurfacePatch::updateSpatialExtents(LLVector3& newMin, LLVector3 &newMax)
 {
 	LLVector3 posAgent = getPositionAgent();