From 0887bc12691e5622b6bf2173e6b6ab71be5f0579 Mon Sep 17 00:00:00 2001
From: cutealien <cutealien@dfc29bdd-3216-0410-991c-e03cc46cb475>
Date: Thu, 18 Sep 2014 21:57:30 +0000
Subject: [PATCH] Merge revision 4920:4921 from trunk to ogl-es: - Added sphere
 frustum culling support.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/branches/ogl-es@4935 dfc29bdd-3216-0410-991c-e03cc46cb475
---
 include/SViewFrustum.h               | 87 ++++++++++++++++++++++++++--
 source/Irrlicht/CCameraSceneNode.cpp |  3 +
 source/Irrlicht/CSceneManager.cpp    | 13 ++++-
 3 files changed, 97 insertions(+), 6 deletions(-)

diff --git a/include/SViewFrustum.h b/include/SViewFrustum.h
index 88d7e2e1..97e1a3d5 100644
--- a/include/SViewFrustum.h
+++ b/include/SViewFrustum.h
@@ -45,7 +45,7 @@ namespace scene
 
 
 		//! Default Constructor
-		SViewFrustum() {}
+		SViewFrustum() : BoundingRadius(0.f), FarNearDistance(0.f) {}
 
 		//! Copy Constructor
 		SViewFrustum(const SViewFrustum& other);
@@ -87,9 +87,18 @@ namespace scene
 		//! returns a bounding box enclosing the whole view frustum
 		const core::aabbox3d<f32> &getBoundingBox() const;
 
-		//! recalculates the bounding box member based on the planes
+		//! recalculates the bounding box and sphere based on the planes
 		inline void recalculateBoundingBox();
 
+		//! get the bounding sphere's radius (of an optimized sphere, not the AABB's)
+		float getBoundingRadius() const;
+
+		//! get the bounding sphere's radius (of an optimized sphere, not the AABB's)
+		core::vector3df getBoundingCenter() const;
+
+		//! the cam should tell the frustum the distance between far and near
+		void setFarNearDistance(float distance);
+
 		//! get the given state's matrix based on frustum E_TRANSFORMATION_STATE
 		core::matrix4& getTransform( video::E_TRANSFORMATION_STATE state);
 
@@ -118,8 +127,15 @@ namespace scene
 			ETS_COUNT_FRUSTUM
 		};
 
+		//! recalculates the bounding sphere based on the planes
+		inline void recalculateBoundingSphere();
+
 		//! Hold a copy of important transform matrices
 		core::matrix4 Matrices[ETS_COUNT_FRUSTUM];
+
+		float BoundingRadius;
+		float FarNearDistance;
+		core::vector3df BoundingCenter;
 	};
 
 
@@ -137,11 +153,15 @@ namespace scene
 
 		for (i=0; i<ETS_COUNT_FRUSTUM; ++i)
 			Matrices[i]=other.Matrices[i];
+
+		BoundingRadius = other.BoundingRadius;
+		FarNearDistance = other.FarNearDistance;
+		BoundingCenter = other.BoundingCenter;
 	}
 
 	inline SViewFrustum::SViewFrustum(const core::matrix4& mat)
 	{
-		setFrom ( mat );
+		setFrom(mat);
 	}
 
 
@@ -248,6 +268,24 @@ namespace scene
 		boundingBox.addInternalPoint(getFarRightUp());
 		boundingBox.addInternalPoint(getFarLeftDown());
 		boundingBox.addInternalPoint(getFarRightDown());
+
+		// Also recalculate the bounding sphere when the bbox changes
+		recalculateBoundingSphere();
+	}
+
+	inline float SViewFrustum::getBoundingRadius() const
+	{
+		return BoundingRadius;
+	}
+
+	inline core::vector3df SViewFrustum::getBoundingCenter() const
+	{
+		return BoundingCenter;
+	}
+
+	inline void SViewFrustum::setFarNearDistance(float distance)
+	{
+		FarNearDistance = distance;
 	}
 
 	//! This constructor creates a view frustum based on a projection
@@ -307,7 +345,7 @@ namespace scene
 	/*!
 		View Frustum depends on Projection & View Matrix
 	*/
-	inline core::matrix4& SViewFrustum::getTransform(video::E_TRANSFORMATION_STATE state )
+	inline core::matrix4& SViewFrustum::getTransform(video::E_TRANSFORMATION_STATE state)
 	{
 		u32 index = 0;
 		switch ( state )
@@ -325,7 +363,7 @@ namespace scene
 	/*!
 		View Frustum depends on Projection & View Matrix
 	*/
-	inline const core::matrix4& SViewFrustum::getTransform(video::E_TRANSFORMATION_STATE state ) const
+	inline const core::matrix4& SViewFrustum::getTransform(video::E_TRANSFORMATION_STATE state) const
 	{
 		u32 index = 0;
 		switch ( state )
@@ -362,6 +400,45 @@ namespace scene
 		return wasClipped;
 	}
 
+	inline void SViewFrustum::recalculateBoundingSphere()
+	{
+		// Find the center
+		const float shortlen = (getNearLeftUp() - getNearRightUp()).getLength();
+		const float longlen = (getFarLeftUp() - getFarRightUp()).getLength();
+
+		const float farlen = FarNearDistance;
+		const float fartocenter = (farlen + (shortlen - longlen) * (shortlen + longlen)/(4*farlen)) / 2;
+		const float neartocenter = farlen - fartocenter;
+
+		BoundingCenter = cameraPosition + -planes[VF_NEAR_PLANE].Normal * neartocenter;
+
+		// Find the radius
+		core::vector3df dir[8];
+		dir[0] = getFarLeftUp() - BoundingCenter;
+		dir[1] = getFarRightUp() - BoundingCenter;
+		dir[2] = getFarLeftDown() - BoundingCenter;
+		dir[3] = getFarRightDown() - BoundingCenter;
+		dir[4] = getNearRightDown() - BoundingCenter;
+		dir[5] = getNearLeftDown() - BoundingCenter;
+		dir[6] = getNearRightUp() - BoundingCenter;
+		dir[7] = getNearLeftUp() - BoundingCenter;
+
+		u32 i = 0;
+		float diam[8] = { 0.f };
+
+		for (i = 0; i < 8; ++i)
+			diam[i] = dir[i].getLengthSQ();
+
+		float longest = 0;
+
+		for (i = 0; i < 8; ++i)
+		{
+			if (diam[i] > longest)
+				longest = diam[i];
+		}
+
+		BoundingRadius = sqrtf(longest);
+	}
 
 } // end namespace scene
 } // end namespace irr
diff --git a/source/Irrlicht/CCameraSceneNode.cpp b/source/Irrlicht/CCameraSceneNode.cpp
index 760dda65..3f9bc891 100644
--- a/source/Irrlicht/CCameraSceneNode.cpp
+++ b/source/Irrlicht/CCameraSceneNode.cpp
@@ -36,6 +36,7 @@ CCameraSceneNode::CCameraSceneNode(ISceneNode* parent, ISceneManager* mgr, s32 i
 
 	recalculateProjectionMatrix();
 	recalculateViewArea();
+	ViewArea.setFarNearDistance(ZFar - ZNear);
 }
 
 
@@ -201,6 +202,7 @@ void CCameraSceneNode::setNearValue(f32 f)
 {
 	ZNear = f;
 	recalculateProjectionMatrix();
+	ViewArea.setFarNearDistance(ZFar - ZNear);
 }
 
 
@@ -208,6 +210,7 @@ void CCameraSceneNode::setFarValue(f32 f)
 {
 	ZFar = f;
 	recalculateProjectionMatrix();
+	ViewArea.setFarNearDistance(ZFar - ZNear);
 }
 
 
diff --git a/source/Irrlicht/CSceneManager.cpp b/source/Irrlicht/CSceneManager.cpp
index 1f326427..f1588a2a 100644
--- a/source/Irrlicht/CSceneManager.cpp
+++ b/source/Irrlicht/CSceneManager.cpp
@@ -1204,7 +1204,18 @@ bool CSceneManager::isCulled(const ISceneNode* node) const
 
 	// can be seen by a bounding sphere
 	if (!result && (node->getAutomaticCulling() & scene::EAC_FRUSTUM_SPHERE))
-	{ // requires bbox diameter
+	{
+		const core::aabbox3df nbox = node->getTransformedBoundingBox();
+		const float rad = nbox.getRadius();
+		const core::vector3df center = nbox.getCenter();
+
+		const float camrad = cam->getViewFrustum()->getBoundingRadius();
+		const core::vector3df camcenter = cam->getViewFrustum()->getBoundingCenter();
+
+		const float dist = (center - camcenter).getLengthSQ();
+		const float maxdist = (rad + camrad) * (rad + camrad);
+
+		result = dist > maxdist;
 	}
 
 	// can be seen by cam pyramid planes ?