3 files changed, 25 insertions, 1 deletions
diff --git a/indra/llmath/llcamera.cpp b/indra/llmath/llcamera.cpp
index 054afd3e95..6a1e3804be 100755
--- a/indra/llmath/llcamera.cpp
+++ b/indra/llmath/llcamera.cpp
@@ -161,6 +161,22 @@ size_t LLCamera::readFrustumFromBuffer(const char *buffer)
 
 // ---------------- test methods  ---------------- 
 
+bool LLCamera::isChanged()
+{
+	bool changed = false;
+	for (U32 i = 0; i < mPlaneCount; i++)
+	{
+		U8 mask = mPlaneMask[i];
+		if (mask != 0xff && !changed)
+		{
+			changed = !mAgentPlanes[i].equal(mLastAgentPlanes[i]);
+		}
+		mLastAgentPlanes[i].set(mAgentPlanes[i]);
+	}
+
+	return changed;
+}
+
 S32 LLCamera::AABBInFrustum(const LLVector4a &center, const LLVector4a& radius, const LLPlane* planes) 
 {
 	static const LLVector4a scaler[] = {
diff --git a/indra/llmath/llcamera.h b/indra/llmath/llcamera.h
index 898d73ed7e..a7cdcff4ac 100755
--- a/indra/llmath/llcamera.h
+++ b/indra/llmath/llcamera.h
@@ -110,6 +110,7 @@ public:
 private:
 	LL_ALIGN_16(LLPlane mAgentPlanes[7]);  //frustum planes in agent space a la gluUnproject (I'm a bastard, I know) - DaveP
 	LL_ALIGN_16(LLPlane mRegionPlanes[7]);  //frustum planes in a local region space, derived from mAgentPlanes
+	LL_ALIGN_16(LLPlane mLastAgentPlanes[7]);
 	U8 mPlaneMask[8];         // 8 for alignment	
 	
 	F32 mView;					// angle between top and bottom frustum planes in radians.
@@ -138,6 +139,7 @@ public:
 	LLCamera(F32 vertical_fov_rads, F32 aspect_ratio, S32 view_height_in_pixels, F32 near_plane, F32 far_plane);
 	virtual ~LLCamera();
 	
+	bool isChanged(); //check if mAgentPlanes changed since last frame.
 
 	void setUserClipPlane(LLPlane& plane);
 	void disableUserClipPlane();
diff --git a/indra/llmath/llplane.h b/indra/llmath/llplane.h
index 3c32441b11..64a3eed0e5 100755
--- a/indra/llmath/llplane.h
+++ b/indra/llmath/llplane.h
@@ -93,7 +93,13 @@ public:
 	{ 
 		return mV.greaterEqual(LLVector4a::getZero()).getGatheredBits() & LLVector4Logical::MASK_XYZ;
 	}
-		
+	
+	//check if two planes are nearly same
+	bool equal(const LLPlane& p) const
+	{
+		return mV.equals4(p.mV);
+	}
+
 private:
 	LLVector4a mV;
 } LL_ALIGN_POSTFIX(16);