Remove code duplication in templated projectors

1 files changed, 25 insertions, 618 deletions

diff --git a/include/astra/FanFlatBeamStripKernelProjector2D.inl b/include/astra/FanFlatBeamStripKernelProjector2D.inl
index e3f8b29..f95a065 100644
--- a/include/astra/FanFlatBeamStripKernelProjector2D.inl
+++ b/include/astra/FanFlatBeamStripKernelProjector2D.inl
@@ -29,11 +29,32 @@ $Id$
 
 using namespace astra;
 
-//----------------------------------------------------------------------------------------
-// PROJECT ALL 
 template <typename Policy>
 void CFanFlatBeamStripKernelProjector2D::project(Policy& p)
 {
+	projectBlock_internal(0, m_pProjectionGeometry->getProjectionAngleCount(),
+	                      0, m_pProjectionGeometry->getDetectorCount(), p);
+}
+
+template <typename Policy>
+void CFanFlatBeamStripKernelProjector2D::projectSingleProjection(int _iProjection, Policy& p)
+{
+	projectBlock_internal(_iProjection, _iProjection + 1,
+	                      0, m_pProjectionGeometry->getDetectorCount(), p);
+}
+
+template <typename Policy>
+void CFanFlatBeamStripKernelProjector2D::projectSingleRay(int _iProjection, int _iDetector, Policy& p)
+{
+	projectBlock_internal(_iProjection, _iProjection + 1,
+	                      _iDetector, _iDetector + 1, p);
+}
+
+//----------------------------------------------------------------------------------------
+// PROJECT BLOCK
+template <typename Policy>
+void CFanFlatBeamStripKernelProjector2D::projectBlock_internal(int _iProjFrom, int _iProjTo, int _iDetFrom, int _iDetTo, Policy& p)
+{
 	ASTRA_ASSERT(m_bIsInitialized);
 
 	// Some variables
@@ -65,7 +86,7 @@ void CFanFlatBeamStripKernelProjector2D::project(Policy& p)
 	}
 
 	// loop angles
-	for (iAngle = 0; iAngle < m_pProjectionGeometry->getProjectionAngleCount(); ++iAngle) {
+	for (iAngle = _iProjFrom; iAngle < _iProjTo; ++iAngle) {
 		
 		// get values
 		theta = m_pProjectionGeometry->getProjectionAngle(iAngle);
@@ -84,7 +105,7 @@ void CFanFlatBeamStripKernelProjector2D::project(Policy& p)
 		if (theta < PIdiv4) {
 
 			// loop detectors
-			for (iDetector = 0; iDetector < m_pProjectionGeometry->getDetectorCount(); ++iDetector) {
+			for (iDetector = _iDetFrom; iDetector < _iDetTo; ++iDetector) {
 
 				iRayIndex = iAngle * m_pProjectionGeometry->getDetectorCount() + iDetector;
 
@@ -345,617 +366,3 @@ void CFanFlatBeamStripKernelProjector2D::project(Policy& p)
 	delete[] sin_alpha;
 }
 
-
-//----------------------------------------------------------------------------------------
-// PROJECT SINGLE PROJECTION
-template <typename Policy>
-void CFanFlatBeamStripKernelProjector2D::projectSingleProjection(int _iProjection, Policy& p)
-{
-	ASTRA_ASSERT(m_bIsInitialized);
-
-	// Some variables
-	float32 theta;
-	int row, col;
-	int iDetector;
-	float32 res;
-	int x1L, x1R;
-	float32 x2L, x2R;
-	int iVolumeIndex, iRayIndex;
-	
-	CFanFlatProjectionGeometry2D* projgeom = static_cast<CFanFlatProjectionGeometry2D*>(m_pProjectionGeometry);
-
-	// Other precalculations
-	float32 PW = m_pVolumeGeometry->getPixelLengthX();
-	float32 PH = m_pVolumeGeometry->getPixelLengthY();
-	float32 DW = m_pProjectionGeometry->getDetectorWidth();
-	float32 inv_PW = 1.0f / PW;
-	float32 inv_PH = 1.0f / PH;
-
-	// calculate alpha's
-	float32 alpha;
-	float32* cos_alpha = new float32[m_pProjectionGeometry->getDetectorCount() + 1];
-	float32* sin_alpha = new float32[m_pProjectionGeometry->getDetectorCount() + 1];
-	for (int i = 0; i < m_pProjectionGeometry->getDetectorCount() + 1; ++i) {
-		alpha = -atan((i - m_pProjectionGeometry->getDetectorCount()*0.5f) * DW / projgeom->getSourceDetectorDistance());
-		cos_alpha[i] = cos(alpha);
-		sin_alpha[i] = sin(alpha);
-	}
-
-		
-	// get values
-	theta = m_pProjectionGeometry->getProjectionAngle(_iProjection);
-	bool switch_t = false;
-	if (theta >= 7*PIdiv4) theta -= 2*PI;
-	if (theta >= 3*PIdiv4) {
-		theta -= PI;
-		switch_t = true;
-	}
-
-	// Precalculate sin, cos, 1/cos
-	float32 sin_theta = sin(theta);
-	float32 cos_theta = cos(theta);
-
-	// [-45?,45?] and [135?,225?]
-	if (theta < PIdiv4) {
-
-		// loop detectors
-		for (iDetector = 0; iDetector < m_pProjectionGeometry->getDetectorCount(); ++iDetector) {
-
-			iRayIndex = _iProjection * m_pProjectionGeometry->getDetectorCount() + iDetector;
-
-			// POLICY: RAY PRIOR
-			if (!p.rayPrior(iRayIndex)) continue;
-
-			float32 sin_theta_left, cos_theta_left;
-			float32 sin_theta_right, cos_theta_right;
-
-			// get theta_l = alpha_left + theta and theta_r = alpha_right + theta
-			float32 t_l, t_r;
-			if (!switch_t) {
-				sin_theta_left = sin_theta * cos_alpha[iDetector+1] + cos_theta * sin_alpha[iDetector+1];
-				sin_theta_right = sin_theta * cos_alpha[iDetector] + cos_theta * sin_alpha[iDetector];
-
-				cos_theta_left = cos_theta * cos_alpha[iDetector+1] - sin_theta * sin_alpha[iDetector+1];
-				cos_theta_right = cos_theta * cos_alpha[iDetector] - sin_theta * sin_alpha[iDetector];
-
-				t_l = sin_alpha[iDetector+1] * projgeom->getOriginSourceDistance();
-				t_r = sin_alpha[iDetector] * projgeom->getOriginSourceDistance();
-
-			} else {
-				sin_theta_left = sin_theta * cos_alpha[iDetector] + cos_theta * sin_alpha[iDetector];
-				sin_theta_right = sin_theta * cos_alpha[iDetector+1] + cos_theta * sin_alpha[iDetector+1];
-
-				cos_theta_left = cos_theta * cos_alpha[iDetector] - sin_theta * sin_alpha[iDetector];
-				cos_theta_right = cos_theta * cos_alpha[iDetector+1] - sin_theta * sin_alpha[iDetector+1];
-
-				t_l = -sin_alpha[iDetector] * projgeom->getOriginSourceDistance();
-				t_r = -sin_alpha[iDetector+1] * projgeom->getOriginSourceDistance();	
-			}
-
-			float32 inv_cos_theta_left = 1.0f / cos_theta_left; 
-			float32 inv_cos_theta_right = 1.0f / cos_theta_right; 
-
-			float32 updateX_left = sin_theta_left * inv_cos_theta_left;
-			float32 updateX_right = sin_theta_right * inv_cos_theta_right;
-
-			// Precalculate kernel limits
-			float32 S_l = -0.5f * updateX_left;
-			if (S_l > 0) {S_l = -S_l;}
-			float32 T_l = -S_l;
-			float32 U_l = 1.0f + S_l;
-			float32 V_l = 1.0f - S_l;
-			float32 inv_4T_l = 0.25f / T_l;
-
-			float32 S_r = -0.5f * updateX_right;
-			if (S_r > 0) {S_r = -S_r;}
-			float32 T_r = -S_r;
-			float32 U_r = 1.0f + S_r;
-			float32 V_r = 1.0f - S_r;
-			float32 inv_4T_r = 0.25f / T_r;
-
-			// calculate strip extremes (volume coordinates)
-			float32 PL = (t_l - sin_theta_left * m_pVolumeGeometry->pixelRowToCenterY(0)) * inv_cos_theta_left;
-			float32 PR = (t_r - sin_theta_right * m_pVolumeGeometry->pixelRowToCenterY(0)) * inv_cos_theta_right;
-			float32 PLimitL = PL + S_l * PH;
-			float32 PLimitR = PR - S_r * PH;
-			
-			// calculate strip extremes (pixel coordinates)
-			float32 XLimitL = (PLimitL - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-			float32 XLimitR = (PLimitR - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-			float32 xL = (PL - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-			float32 xR = (PR - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-
-			// for each row
-			for (row = 0; row < m_pVolumeGeometry->getGridRowCount(); ++row) {
-			
-				// get strip extremes in column indices
-				x1L = int((XLimitL > 0.0f) ? XLimitL : XLimitL-1.0f);
-				x1R = int((XLimitR > 0.0f) ? XLimitR : XLimitR-1.0f);
-
-				// get coords w.r.t leftmost column hit by strip
-				x2L = xL - x1L; 
-				x2R = xR - x1L;
-				
-				// update strip extremes for the next row
-				XLimitL += updateX_left; 
-				XLimitR += updateX_right;
-				xL += updateX_left; 
-				xR += updateX_right; 
-
-				// for each affected col
-				for (col = x1L; col <= x1R; ++col) {
-
-					if (col < 0 || col >= m_pVolumeGeometry->getGridColCount()) { x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-					iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, col);
-					// POLICY: PIXEL PRIOR
-					if (!p.pixelPrior(iVolumeIndex)) { x2L -= 1.0f; x2R -= 1.0f; continue; }
-					
-					// right
-					if (x2R >= V_r)			res = 1.0f;
-					else if (x2R > U_r)		res = x2R - (x2R-U_r)*(x2R-U_r)*inv_4T_r;
-					else if (x2R >= T_r)	res = x2R;
-					else if (x2R > S_r)		res = (x2R-S_r)*(x2R-S_r) * inv_4T_r;
-					else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-							
-					// left
-					if (x2L <= S_l)			{}
-					else if (x2L < T_l)		res -= (x2L-S_l)*(x2L-S_l) * inv_4T_l;
-					else if (x2L <= U_l)	res -= x2L;
-					else if (x2L < V_l)		res -= x2L - (x2L-U_l)*(x2L-U_l)*inv_4T_l;
-					else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-					// POLICY: ADD
-					p.addWeight(iRayIndex, iVolumeIndex, PW*PH * res);
-
-					// POLICY: PIXEL POSTERIOR
-					p.pixelPosterior(iVolumeIndex);
-
-					x2L -= 1.0f;		
-					x2R -= 1.0f;
-
-				} // end col loop
-
-			} // end row loop
-
-			// POLICY: RAY POSTERIOR
-			p.rayPosterior(iRayIndex);
-
-		}	// end detector loop
-
-	// [45?,135?] and [225?,315?]
-	// horizontaly
-	} else {
-
-		// loop detectors
-		for (iDetector = 0; iDetector < m_pProjectionGeometry->getDetectorCount(); ++iDetector) {
-
-			iRayIndex = _iProjection * m_pProjectionGeometry->getDetectorCount() + iDetector;
-
-			// POLICY: RAY PRIOR
-			if (!p.rayPrior(iRayIndex)) continue;
-
-			// get theta_l = alpha_left + theta and theta_r = alpha_right + theta
-			float32 sin_theta_left, cos_theta_left;
-			float32 sin_theta_right, cos_theta_right;
-			float32 t_l, t_r;
-			if (!switch_t) {
-				sin_theta_left = sin_theta * cos_alpha[iDetector] + cos_theta * sin_alpha[iDetector];
-				sin_theta_right = sin_theta * cos_alpha[iDetector+1] + cos_theta * sin_alpha[iDetector+1];
-
-				cos_theta_left = cos_theta * cos_alpha[iDetector] - sin_theta * sin_alpha[iDetector];
-				cos_theta_right = cos_theta * cos_alpha[iDetector+1] - sin_theta * sin_alpha[iDetector+1];
-
-				t_l = sin_alpha[iDetector] * projgeom->getOriginSourceDistance();
-				t_r = sin_alpha[iDetector+1] * projgeom->getOriginSourceDistance();
-
-			} else {
-				sin_theta_left = sin_theta * cos_alpha[iDetector+1] + cos_theta * sin_alpha[iDetector+1];
-				sin_theta_right = sin_theta * cos_alpha[iDetector] + cos_theta * sin_alpha[iDetector];
-
-				cos_theta_left = cos_theta * cos_alpha[iDetector+1] - sin_theta * sin_alpha[iDetector+1];
-				cos_theta_right = cos_theta * cos_alpha[iDetector] - sin_theta * sin_alpha[iDetector];
-
-				t_l = -sin_alpha[iDetector+1] * projgeom->getOriginSourceDistance();
-				t_r = -sin_alpha[iDetector] * projgeom->getOriginSourceDistance();	
-			}
-
-			float32 inv_sin_theta_left = 1.0f / sin_theta_left;
-			float32 inv_sin_theta_right = 1.0f / sin_theta_right;
-
-			float32 updateX_left = cos_theta_left * inv_sin_theta_left;
-			float32 updateX_right = cos_theta_right * inv_sin_theta_right;
-
-			// Precalculate kernel limits
-			float32 S_l = -0.5f * updateX_left;
-			if (S_l > 0) { S_l = -S_l; }
-			float32 T_l = -S_l;
-			float32 U_l = 1.0f + S_l;
-			float32 V_l = 1.0f - S_l;
-			float32 inv_4T_l = 0.25f / T_l;
-
-			float32 S_r = -0.5f * updateX_right;
-			if (S_r > 0) { S_r = -S_r; }
-			float32 T_r = -S_r;
-			float32 U_r = 1.0f + S_r;
-			float32 V_r = 1.0f - S_r;
-			float32 inv_4T_r = 0.25f / T_r;
-
-			// calculate strip extremes (volume coordinates)
-			float32 PL = (t_l - cos_theta_left * m_pVolumeGeometry->pixelColToCenterX(0)) * inv_sin_theta_left;
-			float32 PR = (t_r - cos_theta_right * m_pVolumeGeometry->pixelColToCenterX(0)) * inv_sin_theta_right;
-			float32 PLimitL = PL - S_l * PW;
-			float32 PLimitR = PR + S_r * PW;
-			
-			// calculate strip extremes (pixel coordinates)
-			float32 XLimitL = (m_pVolumeGeometry->getWindowMaxY() - PLimitL) * inv_PH;
-			float32 XLimitR = (m_pVolumeGeometry->getWindowMaxY() - PLimitR) * inv_PH;
-			float32 xL = (m_pVolumeGeometry->getWindowMaxY() - PL) * inv_PH;
-			float32 xR = (m_pVolumeGeometry->getWindowMaxY() - PR) * inv_PH;
-
-			// for each col
-			for (col = 0; col < m_pVolumeGeometry->getGridColCount(); ++col) {
-
-				// get strip extremes in column indices
-				x1L = int((XLimitL > 0.0f) ? XLimitL : XLimitL-1.0f);
-				x1R = int((XLimitR > 0.0f) ? XLimitR : XLimitR-1.0f);
-
-				// get coords w.r.t leftmost column hit by strip
-				x2L = xL - x1L; 
-				x2R = xR - x1L;
-				
-				// update strip extremes for the next row
-				XLimitL += updateX_left; 
-				XLimitR += updateX_right;
-				xL += updateX_left; 
-				xR += updateX_right; 
-
-				// for each affected row
-				for (row = x1L; row <= x1R; ++row) {
-
-					if (row < 0 || row >= m_pVolumeGeometry->getGridRowCount()) { x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-					iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, col);
-
-					// POLICY: PIXEL PRIOR
-					if (!p.pixelPrior(iVolumeIndex)) { x2L -= 1.0f; x2R -= 1.0f; continue; }
-
-					// right
-					if (x2R >= V_r)			res = 1.0f;
-					else if (x2R > U_r)		res = x2R - (x2R-U_r)*(x2R-U_r)*inv_4T_r;
-					else if (x2R >= T_r)	res = x2R;
-					else if (x2R > S_r)		res = (x2R-S_r)*(x2R-S_r) * inv_4T_r;
-					else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-							
-					// left
-					if (x2L <= S_l)			{}
-					else if (x2L < T_l)		res -= (x2L-S_l)*(x2L-S_l) * inv_4T_l;
-					else if (x2L <= U_l)	res -= x2L;
-					else if (x2L < V_l)		res -= x2L - (x2L-U_l)*(x2L-U_l)*inv_4T_l;
-					else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-					// POLICY: ADD
-					p.addWeight(iRayIndex, iVolumeIndex, PW*PH * res);
-
-					// POLICY: PIXEL POSTERIOR
-					p.pixelPosterior(iVolumeIndex);
-
-					x2L -= 1.0f;		
-					x2R -= 1.0f;
-
-				} // end col loop
-
-			} // end row loop
-
-			// POLICY: RAY POSTERIOR
-			p.rayPosterior(iRayIndex);
-
-		}	// end detector loop
-
-	} // end theta switch
-
-	delete[] cos_alpha;
-	delete[] sin_alpha;
-}
-
-
-//----------------------------------------------------------------------------------------
-// PROJECT SINGLE RAY
-template <typename Policy>
-void CFanFlatBeamStripKernelProjector2D::projectSingleRay(int _iProjection, int _iDetector, Policy& p)
-{
-	ASTRA_ASSERT(m_bIsInitialized);
-
-	// Some variables
-	float32 theta;
-	int row, col;
-	float32 res;
-	int x1L, x1R;
-	float32 x2L, x2R;
-	int iVolumeIndex, iRayIndex;
-	
-	CFanFlatProjectionGeometry2D* projgeom = static_cast<CFanFlatProjectionGeometry2D*>(m_pProjectionGeometry);
-
-	// Other precalculations
-	float32 PW = m_pVolumeGeometry->getPixelLengthX();
-	float32 PH = m_pVolumeGeometry->getPixelLengthY();
-	float32 DW = m_pProjectionGeometry->getDetectorWidth();
-	float32 inv_PW = 1.0f / PW;
-	float32 inv_PH = 1.0f / PH;
-
-	// calculate alpha's
-	float32 alpha;
-	float32* cos_alpha = new float32[m_pProjectionGeometry->getDetectorCount() + 1];
-	float32* sin_alpha = new float32[m_pProjectionGeometry->getDetectorCount() + 1];
-	for (int i = 0; i < m_pProjectionGeometry->getDetectorCount() + 1; ++i) {
-		alpha = -atan((i - m_pProjectionGeometry->getDetectorCount()*0.5f) * DW / projgeom->getSourceDetectorDistance());
-		cos_alpha[i] = cos(alpha);
-		sin_alpha[i] = sin(alpha);
-	}
-
-		
-	// get values
-	theta = m_pProjectionGeometry->getProjectionAngle(_iProjection);
-	bool switch_t = false;
-	if (theta >= 7*PIdiv4) theta -= 2*PI;
-	if (theta >= 3*PIdiv4) {
-		theta -= PI;
-		switch_t = true;
-	}
-
-	// Precalculate sin, cos, 1/cos
-	float32 sin_theta = sin(theta);
-	float32 cos_theta = cos(theta);
-
-	// [-45?,45?] and [135?,225?]
-	if (theta < PIdiv4) {
-
-		iRayIndex = _iProjection * m_pProjectionGeometry->getDetectorCount() + _iDetector;
-
-		// POLICY: RAY PRIOR
-		if (!p.rayPrior(iRayIndex)) { delete[] cos_alpha; delete[] sin_alpha; return; }
-
-		float32 sin_theta_left, cos_theta_left;
-		float32 sin_theta_right, cos_theta_right;
-
-		// get theta_l = alpha_left + theta and theta_r = alpha_right + theta
-		float32 t_l, t_r;
-		if (!switch_t) {
-			sin_theta_left = sin_theta * cos_alpha[_iDetector+1] + cos_theta * sin_alpha[_iDetector+1];
-			sin_theta_right = sin_theta * cos_alpha[_iDetector] + cos_theta * sin_alpha[_iDetector];
-
-			cos_theta_left = cos_theta * cos_alpha[_iDetector+1] - sin_theta * sin_alpha[_iDetector+1];
-			cos_theta_right = cos_theta * cos_alpha[_iDetector] - sin_theta * sin_alpha[_iDetector];
-
-			t_l = sin_alpha[_iDetector+1] * projgeom->getOriginSourceDistance();
-			t_r = sin_alpha[_iDetector] * projgeom->getOriginSourceDistance();
-
-		} else {
-			sin_theta_left = sin_theta * cos_alpha[_iDetector] + cos_theta * sin_alpha[_iDetector];
-			sin_theta_right = sin_theta * cos_alpha[_iDetector+1] + cos_theta * sin_alpha[_iDetector+1];
-
-			cos_theta_left = cos_theta * cos_alpha[_iDetector] - sin_theta * sin_alpha[_iDetector];
-			cos_theta_right = cos_theta * cos_alpha[_iDetector+1] - sin_theta * sin_alpha[_iDetector+1];
-
-			t_l = -sin_alpha[_iDetector] * projgeom->getOriginSourceDistance();
-			t_r = -sin_alpha[_iDetector+1] * projgeom->getOriginSourceDistance();	
-		}
-
-		float32 inv_cos_theta_left = 1.0f / cos_theta_left; 
-		float32 inv_cos_theta_right = 1.0f / cos_theta_right; 
-
-		float32 updateX_left = sin_theta_left * inv_cos_theta_left;
-		float32 updateX_right = sin_theta_right * inv_cos_theta_right;
-
-		// Precalculate kernel limits
-		float32 S_l = -0.5f * updateX_left;
-		if (S_l > 0) {S_l = -S_l;}
-		float32 T_l = -S_l;
-		float32 U_l = 1.0f + S_l;
-		float32 V_l = 1.0f - S_l;
-		float32 inv_4T_l = 0.25f / T_l;
-
-		float32 S_r = -0.5f * updateX_right;
-		if (S_r > 0) {S_r = -S_r;}
-		float32 T_r = -S_r;
-		float32 U_r = 1.0f + S_r;
-		float32 V_r = 1.0f - S_r;
-		float32 inv_4T_r = 0.25f / T_r;
-
-		// calculate strip extremes (volume coordinates)
-		float32 PL = (t_l - sin_theta_left * m_pVolumeGeometry->pixelRowToCenterY(0)) * inv_cos_theta_left;
-		float32 PR = (t_r - sin_theta_right * m_pVolumeGeometry->pixelRowToCenterY(0)) * inv_cos_theta_right;
-		float32 PLimitL = PL + S_l * PH;
-		float32 PLimitR = PR - S_r * PH;
-		
-		// calculate strip extremes (pixel coordinates)
-		float32 XLimitL = (PLimitL - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-		float32 XLimitR = (PLimitR - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-		float32 xL = (PL - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-		float32 xR = (PR - m_pVolumeGeometry->getWindowMinX()) * inv_PW;
-
-		// for each row
-		for (row = 0; row < m_pVolumeGeometry->getGridRowCount(); ++row) {
-		
-			// get strip extremes in column indices
-			x1L = int((XLimitL > 0.0f) ? XLimitL : XLimitL-1.0f);
-			x1R = int((XLimitR > 0.0f) ? XLimitR : XLimitR-1.0f);
-
-			// get coords w.r.t leftmost column hit by strip
-			x2L = xL - x1L; 
-			x2R = xR - x1L;
-			
-			// update strip extremes for the next row
-			XLimitL += updateX_left; 
-			XLimitR += updateX_right;
-			xL += updateX_left; 
-			xR += updateX_right; 
-
-			// for each affected col
-			for (col = x1L; col <= x1R; ++col) {
-
-				if (col < 0 || col >= m_pVolumeGeometry->getGridColCount()) { x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-				iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, col);
-				// POLICY: PIXEL PRIOR
-				if (!p.pixelPrior(iVolumeIndex)) { x2L -= 1.0f; x2R -= 1.0f; continue; }
-				
-				// right
-				if (x2R >= V_r)			res = 1.0f;
-				else if (x2R > U_r)		res = x2R - (x2R-U_r)*(x2R-U_r)*inv_4T_r;
-				else if (x2R >= T_r)	res = x2R;
-				else if (x2R > S_r)		res = (x2R-S_r)*(x2R-S_r) * inv_4T_r;
-				else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-						
-				// left
-				if (x2L <= S_l)			{}
-				else if (x2L < T_l)		res -= (x2L-S_l)*(x2L-S_l) * inv_4T_l;
-				else if (x2L <= U_l)	res -= x2L;
-				else if (x2L < V_l)		res -= x2L - (x2L-U_l)*(x2L-U_l)*inv_4T_l;
-				else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-				// POLICY: ADD
-				p.addWeight(iRayIndex, iVolumeIndex, PW*PH * res);
-
-				// POLICY: PIXEL POSTERIOR
-				p.pixelPosterior(iVolumeIndex);
-
-				x2L -= 1.0f;		
-				x2R -= 1.0f;
-
-			} // end col loop
-
-		} // end row loop
-
-		// POLICY: RAY POSTERIOR
-		p.rayPosterior(iRayIndex);
-
-	// [45?,135?] and [225?,315?]
-	// horizontaly
-	} else {
-
-		iRayIndex = _iProjection * m_pProjectionGeometry->getDetectorCount() + _iDetector;
-
-		// POLICY: RAY PRIOR
-		if (!p.rayPrior(iRayIndex)) { delete[] cos_alpha; delete[] sin_alpha; return; }
-
-		// get theta_l = alpha_left + theta and theta_r = alpha_right + theta
-		float32 sin_theta_left, cos_theta_left;
-		float32 sin_theta_right, cos_theta_right;
-		float32 t_l, t_r;
-		if (!switch_t) {
-			sin_theta_left = sin_theta * cos_alpha[_iDetector] + cos_theta * sin_alpha[_iDetector];
-			sin_theta_right = sin_theta * cos_alpha[_iDetector+1] + cos_theta * sin_alpha[_iDetector+1];
-
-			cos_theta_left = cos_theta * cos_alpha[_iDetector] - sin_theta * sin_alpha[_iDetector];
-			cos_theta_right = cos_theta * cos_alpha[_iDetector+1] - sin_theta * sin_alpha[_iDetector+1];
-
-			t_l = sin_alpha[_iDetector] * projgeom->getOriginSourceDistance();
-			t_r = sin_alpha[_iDetector+1] * projgeom->getOriginSourceDistance();
-
-		} else {
-			sin_theta_left = sin_theta * cos_alpha[_iDetector+1] + cos_theta * sin_alpha[_iDetector+1];
-			sin_theta_right = sin_theta * cos_alpha[_iDetector] + cos_theta * sin_alpha[_iDetector];
-
-			cos_theta_left = cos_theta * cos_alpha[_iDetector+1] - sin_theta * sin_alpha[_iDetector+1];
-			cos_theta_right = cos_theta * cos_alpha[_iDetector] - sin_theta * sin_alpha[_iDetector];
-
-			t_l = -sin_alpha[_iDetector+1] * projgeom->getOriginSourceDistance();
-			t_r = -sin_alpha[_iDetector] * projgeom->getOriginSourceDistance();	
-		}
-
-		float32 inv_sin_theta_left = 1.0f / sin_theta_left;
-		float32 inv_sin_theta_right = 1.0f / sin_theta_right;
-
-		float32 updateX_left = cos_theta_left * inv_sin_theta_left;
-		float32 updateX_right = cos_theta_right * inv_sin_theta_right;
-
-		// Precalculate kernel limits
-		float32 S_l = -0.5f * updateX_left;
-		if (S_l > 0) { S_l = -S_l; }
-		float32 T_l = -S_l;
-		float32 U_l = 1.0f + S_l;
-		float32 V_l = 1.0f - S_l;
-		float32 inv_4T_l = 0.25f / T_l;
-
-		float32 S_r = -0.5f * updateX_right;
-		if (S_r > 0) { S_r = -S_r; }
-		float32 T_r = -S_r;
-		float32 U_r = 1.0f + S_r;
-		float32 V_r = 1.0f - S_r;
-		float32 inv_4T_r = 0.25f / T_r;
-
-		// calculate strip extremes (volume coordinates)
-		float32 PL = (t_l - cos_theta_left * m_pVolumeGeometry->pixelColToCenterX(0)) * inv_sin_theta_left;
-		float32 PR = (t_r - cos_theta_right * m_pVolumeGeometry->pixelColToCenterX(0)) * inv_sin_theta_right;
-		float32 PLimitL = PL - S_l * PW;
-		float32 PLimitR = PR + S_r * PW;
-		
-		// calculate strip extremes (pixel coordinates)
-		float32 XLimitL = (m_pVolumeGeometry->getWindowMaxY() - PLimitL) * inv_PH;
-		float32 XLimitR = (m_pVolumeGeometry->getWindowMaxY() - PLimitR) * inv_PH;
-		float32 xL = (m_pVolumeGeometry->getWindowMaxY() - PL) * inv_PH;
-		float32 xR = (m_pVolumeGeometry->getWindowMaxY() - PR) * inv_PH;
-
-		// for each col
-		for (col = 0; col < m_pVolumeGeometry->getGridColCount(); ++col) {
-
-			// get strip extremes in column indices
-			x1L = int((XLimitL > 0.0f) ? XLimitL : XLimitL-1.0f);
-			x1R = int((XLimitR > 0.0f) ? XLimitR : XLimitR-1.0f);
-
-			// get coords w.r.t leftmost column hit by strip
-			x2L = xL - x1L; 
-			x2R = xR - x1L;
-			
-			// update strip extremes for the next row
-			XLimitL += updateX_left; 
-			XLimitR += updateX_right;
-			xL += updateX_left; 
-			xR += updateX_right; 
-
-			// for each affected row
-			for (row = x1L; row <= x1R; ++row) {
-
-				if (row < 0 || row >= m_pVolumeGeometry->getGridRowCount()) { x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-				iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, col);
-
-				// POLICY: PIXEL PRIOR
-				if (!p.pixelPrior(iVolumeIndex)) { x2L -= 1.0f; x2R -= 1.0f; continue; }
-
-				// right
-				if (x2R >= V_r)			res = 1.0f;
-				else if (x2R > U_r)		res = x2R - (x2R-U_r)*(x2R-U_r)*inv_4T_r;
-				else if (x2R >= T_r)	res = x2R;
-				else if (x2R > S_r)		res = (x2R-S_r)*(x2R-S_r) * inv_4T_r;
-				else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-						
-				// left
-				if (x2L <= S_l)			{}
-				else if (x2L < T_l)		res -= (x2L-S_l)*(x2L-S_l) * inv_4T_l;
-				else if (x2L <= U_l)	res -= x2L;
-				else if (x2L < V_l)		res -= x2L - (x2L-U_l)*(x2L-U_l)*inv_4T_l;
-				else					{ x2L -= 1.0f; x2R -= 1.0f;	continue; }
-
-				// POLICY: ADD
-				p.addWeight(iRayIndex, iVolumeIndex, PW*PH * res);
-
-				// POLICY: PIXEL POSTERIOR
-				p.pixelPosterior(iVolumeIndex);
-
-				x2L -= 1.0f;		
-				x2R -= 1.0f;
-
-			} // end col loop
-
-		} // end row loop
-
-		// POLICY: RAY POSTERIOR
-		p.rayPosterior(iRayIndex);
-
-	} // end theta switch
-
-	delete[] cos_alpha;
-	delete[] sin_alpha;
-}