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183 lines
7.7 KiB
183 lines
7.7 KiB
/*=========================================================================
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Program: Visualization Toolkit
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Module: $RCSfile: vtkUnstructuredGridPreIntegration.h,v $
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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/*
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* Copyright 2004 Sandia Corporation.
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* Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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* license for use of this work by or on behalf of the
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* U.S. Government. Redistribution and use in source and binary forms, with
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* or without modification, are permitted provided that this Notice and any
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* statement of authorship are reproduced on all copies.
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*/
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// .NAME vtkUnstructuredGridPreIntegration - performs ray integration with pre-integration tables.
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//
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// .SECTION Description
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//
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// vtkUnstructuredGridPreIntegration performs ray integration by looking
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// into a precomputed table. The result should be equivalent to that
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// computed by vtkUnstructuredGridLinearRayIntegrator and
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// vtkUnstructuredGridPartialPreIntegration, but faster than either one.
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// The pre-integration algorithm was first introduced by Roettger, Kraus,
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// and Ertl in "Hardware-Accelerated Volume And Isosurface Rendering Based
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// On Cell-Projection."
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//
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// Due to table size limitations, a table can only be indexed by
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// independent scalars. Thus, dependent scalars are not supported.
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//
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#ifndef __vtkUnstructuredGridPreIntegration_h
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#define __vtkUnstructuredGridPreIntegration_h
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#include "vtkUnstructuredGridVolumeRayIntegrator.h"
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class vtkVolumeProperty;
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class VTK_VOLUMERENDERING_EXPORT vtkUnstructuredGridPreIntegration : public vtkUnstructuredGridVolumeRayIntegrator
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{
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public:
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vtkTypeRevisionMacro(vtkUnstructuredGridPreIntegration,
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vtkUnstructuredGridVolumeRayIntegrator);
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static vtkUnstructuredGridPreIntegration *New();
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virtual void PrintSelf(ostream &os, vtkIndent indent);
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virtual void Initialize(vtkVolume *volume, vtkDataArray *scalars);
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virtual void Integrate(vtkDoubleArray *intersectionLengths,
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vtkDataArray *nearIntersections,
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vtkDataArray *farIntersections,
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float color[4]);
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// Description:
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// The class used to fill the pre integration table. By default, a
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// vtkUnstructuredGridPartialPreIntegration is built.
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vtkGetObjectMacro(Integrator, vtkUnstructuredGridVolumeRayIntegrator);
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virtual void SetIntegrator(vtkUnstructuredGridVolumeRayIntegrator *);
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// Description:
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// Set/Get the size of the integration table built.
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vtkSetMacro(IntegrationTableScalarResolution, int);
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vtkGetMacro(IntegrationTableScalarResolution, int);
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vtkSetMacro(IntegrationTableLengthResolution, int);
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vtkGetMacro(IntegrationTableLengthResolution, int);
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// Description::
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// Get how an integration table is indexed.
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virtual double GetIntegrationTableScalarShift(int component = 0);
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virtual double GetIntegrationTableScalarScale(int component = 0);
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virtual double GetIntegrationTableLengthScale();
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// Description:
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// Get/set whether to use incremental pre-integration (by default it's
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// on). Incremental pre-integration is much faster but can introduce
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// error due to numerical imprecision. Under most circumstances, the
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// error is not noticable.
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vtkGetMacro(IncrementalPreIntegration, int);
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vtkSetMacro(IncrementalPreIntegration, int);
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vtkBooleanMacro(IncrementalPreIntegration, int);
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// Description:
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// Get the partial pre-integration table for the given scalar component.
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// The tables are built when Initialize is called. A segment of length d
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// with a front scalar of sf and a back scalar of sb is referenced in the
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// resulting table as 4 * ((l * \c IntegrationTableLengthScale) * \c
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// IntegrationTableScalarResolution * \c IntegrationTableScalarResolution
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// + (sb * \c IntegrationTableScalarScale + \c
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// IntegrationTableScalarShift) * \c IntegrationTableScalarResolution
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// + (sf * \c IntegrationTableScalarScale + \c
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// IntegrationTableScalarShift)).
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virtual float *GetPreIntegrationTable(int component = 0);
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// Description:
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// Get an entry (RGBA) in one of the pre-integration tables. The tables
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// are built when Intialize is called.
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float *GetTableEntry(double scalar_front, double scalar_back, double lenth,
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int component = 0);
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// Description:
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// Like GetTableEntry, except the inputs are scaled indices into the table
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// rather than than the actual scalar and length values. Use GetTableEntry
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// unless you are really sure you know what you are doing.
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float *GetIndexedTableEntry(int scalar_front_index, int scalar_back_index,
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int length_index, int component = 0);
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protected:
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vtkUnstructuredGridPreIntegration();
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~vtkUnstructuredGridPreIntegration();
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vtkUnstructuredGridVolumeRayIntegrator *Integrator;
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vtkVolume *Volume;
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vtkVolumeProperty *Property;
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double MaxLength;
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int NumComponents;
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float **IntegrationTable;
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double *IntegrationTableScalarShift;
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double *IntegrationTableScalarScale;
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double IntegrationTableLengthScale;
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vtkTimeStamp IntegrationTableBuilt;
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int IntegrationTableScalarResolution;
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int IntegrationTableLengthResolution;
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int IncrementalPreIntegration;
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virtual void BuildPreIntegrationTables(vtkDataArray *scalars);
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private:
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vtkUnstructuredGridPreIntegration(const vtkUnstructuredGridPreIntegration&); // Not implemented.
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void operator=(const vtkUnstructuredGridPreIntegration&); // Not implemented
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};
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inline float *vtkUnstructuredGridPreIntegration::GetIndexedTableEntry(
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int scalar_front_index,
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int scalar_back_index,
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int length_index,
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int component)
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{
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// Snap entries to bounds. I don't really want to spend cycles doing
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// this, but I've had the ray caster give me values that are noticeably
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// out of bounds.
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if (scalar_front_index < 0) scalar_front_index = 0;
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if (scalar_front_index >= this->IntegrationTableScalarResolution)
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scalar_front_index = this->IntegrationTableScalarResolution - 1;
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if (scalar_back_index < 0) scalar_back_index = 0;
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if (scalar_back_index >= this->IntegrationTableScalarResolution)
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scalar_back_index = this->IntegrationTableScalarResolution - 1;
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if (length_index < 0) length_index = 0;
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if (length_index >= this->IntegrationTableLengthResolution)
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length_index = this->IntegrationTableLengthResolution - 1;
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return ( this->IntegrationTable[component]
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+ 4*( ( ( length_index*this->IntegrationTableScalarResolution
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+ scalar_back_index)
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* this->IntegrationTableScalarResolution)
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+ scalar_front_index));
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}
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inline float *vtkUnstructuredGridPreIntegration::GetTableEntry(
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double scalar_front, double scalar_back, double length, int component)
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{
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int sfi = (int)( scalar_front
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*this->IntegrationTableScalarScale[component]
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+ this->IntegrationTableScalarShift[component] + 0.5);
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int sbi = (int)( scalar_back*this->IntegrationTableScalarScale[component]
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+ this->IntegrationTableScalarShift[component] + 0.5);
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int li = (int)(length*this->IntegrationTableLengthScale + 0.5);
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return this->GetIndexedTableEntry(sfi, sbi, li, component);
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}
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#endif //__vtkUnstructuredGridPreIntegration_h
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