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diff --git a/indra/llmath/llplane.h b/indra/llmath/llplane.h
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+++ b/indra/llmath/llplane.h
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+/** 
+ * @file llplane.h
+ *
+ * Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
+ * $License$
+ */
+
+#ifndef LL_LLPLANE_H
+#define LL_LLPLANE_H
+
+#include "v3math.h"
+#include "v4math.h"
+
+// A simple way to specify a plane is to give its normal,
+// and it's nearest approach to the origin.
+// 
+// Given the equation for a plane : A*x + B*y + C*z + D = 0
+// The plane normal = [A, B, C]
+// The closest approach = D / sqrt(A*A + B*B + C*C)
+
+class LLPlane : public LLVector4
+{
+public:
+	LLPlane() {}; // no default constructor
+	LLPlane(const LLVector3 &p0, F32 d) { setVec(p0, d); }
+	LLPlane(const LLVector3 &p0, const LLVector3 &n) { setVec(p0, n); }
+	void setVec(const LLVector3 &p0, F32 d) { LLVector4::setVec(p0[0], p0[1], p0[2], d); }
+	void setVec(const LLVector3 &p0, const LLVector3 &n)
+	{
+		F32 d = -(p0 * n);
+		setVec(n, d);
+	}
+	void setVec(const LLVector3 &p0, const LLVector3 &p1, const LLVector3 &p2)
+	{
+		LLVector3 u, v, w;
+		u = p1 - p0;
+		v = p2 - p0;
+		w = u % v;
+		w.normVec();
+		F32 d = -(w * p0);
+		setVec(w, d);
+	}
+	LLPlane& operator=(const LLVector4& v2) {  LLVector4::setVec(v2[0],v2[1],v2[2],v2[3]); return *this;}
+	F32 dist(const LLVector3 &v2) const { return mV[0]*v2[0] + mV[1]*v2[1] + mV[2]*v2[2] + mV[3]; }
+};
+
+
+
+#endif // LL_LLPLANE_H