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>

class vtkOpenGLIndexBufferObject;
class vtkOpenGLBufferObject;
class vtkPolyData;
class vtkOpenGLShaderCache;

class VTKRENDERINGOPENGL2_EXPORT vtkOpenGLInstanceCulling : public vtkObject
{
public:
  static vtkOpenGLInstanceCulling *New();
  vtkTypeMacro(vtkOpenGLInstanceCulling, vtkObject)

  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

// VTK-HeaderTest-Exclude: vtkOpenGLInstanceCulling.h