vtkTransformFeedback.h

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/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkTransformFeedback.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 vtkTransformFeedback_h
#define vtkTransformFeedback_h

#include "vtkRenderingOpenGL2Module.h" // For export macro
#include "vtkObject.h"

#include <string> // For string
#include <vector> // For vector

class vtkShaderProgram;
class vtkWindow;
class vtkOpenGLBufferObject;

class VTKRENDERINGOPENGL2_EXPORT vtkTransformFeedback : public vtkObject
{
public:
  static vtkTransformFeedback *New();
  vtkTypeMacro(vtkTransformFeedback, vtkObject)
  void PrintSelf(ostream &os, vtkIndent indent) override;

  enum VaryingRole
  {
    Vertex_ClipCoordinate_F, // Projected XYZW
    Color_RGBA_F,
    Normal_F,
    Next_Buffer // Switch to next vertex stream (varying name must be "gl_NextBuffer")
  };

  struct VaryingMetaData
  {
    VaryingMetaData(VaryingRole role, const std::string &id)
      : Role(role), Identifier(id) {}
    VaryingRole Role;
    std::string Identifier;
  };

  void ClearVaryings();

  void AddVarying(VaryingRole role, const std::string &var);

  const std::vector<VaryingMetaData>& GetVaryings() const
  {
    return this->Varyings;
  }

  static size_t GetBytesPerVertex(VaryingRole role);

  size_t GetBytesPerVertex() const;


  vtkSetMacro(NumberOfVertices, size_t)
  void SetNumberOfVertices(int drawMode, size_t inputVerts);
  vtkGetMacro(NumberOfVertices, size_t)

  size_t GetBufferSize() const;

  void BindVaryings(vtkShaderProgram *prog);

  vtkOpenGLBufferObject* GetBuffer(int index);

  int GetBufferHandle(int index = 0);


  vtkSetMacro(PrimitiveMode, int)
  vtkGetMacro(PrimitiveMode, int)

  void Allocate(int nbBuffers, size_t size, unsigned int hint);

  void BindBuffer(bool allocateOneBuffer = true);

  void ReadBuffer(int index = 0);


  vtkGetMacro(BufferData, void*)

  void ReleaseGraphicsResources();

  void ReleaseBufferData(bool freeBuffer = true);

protected:
  vtkTransformFeedback();
  ~vtkTransformFeedback() override;

private:
  vtkTransformFeedback(const vtkTransformFeedback &) = delete;
  void operator=(const vtkTransformFeedback &) = delete;

  bool VaryingsBound;

  std::vector<VaryingMetaData> Varyings;
  size_t NumberOfVertices;
  int BufferMode;

  std::vector<vtkOpenGLBufferObject*> Buffers;
  int PrimitiveMode;

  unsigned char *BufferData;
};

//------------------------------------------------------------------------------
inline size_t vtkTransformFeedback::GetBytesPerVertex(
    vtkTransformFeedback::VaryingRole role)
{
  switch (role)
  {
    case Vertex_ClipCoordinate_F:
      return 4 * sizeof(float);
    case Color_RGBA_F:
      return 4 * sizeof(float);
    case Normal_F:
      return 3 * sizeof(float);
    case Next_Buffer:
      return 0;
  }

  vtkGenericWarningMacro("Unknown role enum value: " << role);
  return 0;
}

#endif // vtkTransformFeedback_h