vtkOpenGLInstanceCulling.h

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/*=========================================================================
 
  Program:   Visualization Toolkit
  Module:    vtkOpenGLInstanceCulling.h
 
  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
 
     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.
 
=========================================================================*/
 
#ifndef vtkOpenGLInstanceCulling_h
#define vtkOpenGLInstanceCulling_h
 
#include "vtkObject.h"
#include "vtkOpenGLHelper.h"           // For vtkOpenGLHelper
#include "vtkRenderingOpenGL2Module.h" // For export macro
#include "vtkSmartPointer.h"           // For smart pointer
 
#include <vector> // for std::vector
 
class vtkOpenGLIndexBufferObject;
class vtkOpenGLBufferObject;
class vtkPolyData;
class vtkOpenGLShaderCache;
 
class VTKRENDERINGOPENGL2_EXPORT vtkOpenGLInstanceCulling : public vtkObject
{
public:
  static vtkOpenGLInstanceCulling* New();
  vtkTypeMacro(vtkOpenGLInstanceCulling, vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent) override;
 
  struct InstanceLOD
  {
    float Distance;
    unsigned int Query;
    vtkOpenGLIndexBufferObject* IBO;
    vtkOpenGLBufferObject* PositionVBO;
    vtkOpenGLBufferObject* NormalVBO;
    int NumberOfInstances;
 
    // used for sorting
    bool operator<(const InstanceLOD& other) const { return this->Distance < other.Distance; }
  };
 
  void InitLOD(vtkPolyData* pd);
 
  void AddLOD(float distance, float targetReduction);
 
  void BuildCullingShaders(vtkOpenGLShaderCache* cache, vtkIdType numInstances, bool withNormals);
 
  vtkOpenGLHelper& GetHelper();
 
  InstanceLOD& GetLOD(vtkIdType index);
 
  vtkIdType GetNumberOfLOD();
 
  vtkOpenGLBufferObject* GetLODBuffer(vtkIdType index);
 
  void RunCullingShaders(vtkIdType numInstances, vtkOpenGLBufferObject* matrixBuffer,
    vtkOpenGLBufferObject* colorBuffer, vtkOpenGLBufferObject* normalBuffer);
 
 
  vtkSetMacro(ColorLOD, bool);
  vtkGetMacro(ColorLOD, bool);
 
protected:
  vtkOpenGLInstanceCulling() = default;
  ~vtkOpenGLInstanceCulling() override;
 
  void DeleteLODs();
  void UploadCurrentState(InstanceLOD& lod, vtkPolyData* pd);
 
private:
  vtkOpenGLInstanceCulling(const vtkOpenGLInstanceCulling&) = delete;
  void operator=(const vtkOpenGLInstanceCulling&) = delete;
 
  vtkOpenGLHelper CullingHelper;
  std::vector<InstanceLOD> LODList;
  vtkSmartPointer<vtkPolyData> PolyData;
  bool ColorLOD = false;
};
 
#endif // vtkOpenGLInstanceCulling_h