vtkDepthPeelingPass.h

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

  Program:   Visualization Toolkit
  Module:    vtkDepthPeelingPass.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 vtkDepthPeelingPass_h
#define vtkDepthPeelingPass_h

#include "vtkRenderingOpenGL2Module.h" // For export macro
#include "vtkOpenGLRenderPass.h"
#include <vector>  // STL Header

class vtkOpenGLFramebufferObject;
class vtkTextureObject;
class vtkOpenGLRenderWindow;
class vtkOpenGLState;
class vtkOpenGLQuadHelper;

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

  void Render(const vtkRenderState *s) override;

  void ReleaseGraphicsResources(vtkWindow *w) override;


  vtkGetObjectMacro(TranslucentPass,vtkRenderPass);
  virtual void SetTranslucentPass(vtkRenderPass *translucentPass);


  vtkSetClampMacro(OcclusionRatio,double,0.0,0.5);
  vtkGetMacro(OcclusionRatio,double);


  vtkSetMacro(MaximumNumberOfPeels,int);
  vtkGetMacro(MaximumNumberOfPeels,int);

  // vtkOpenGLRenderPass virtuals:
  bool PostReplaceShaderValues(std::string &vertexShader,
                                   std::string &geometryShader,
                                   std::string &fragmentShader,
                                   vtkAbstractMapper *mapper,
                                   vtkProp *prop) override;
  bool SetShaderParameters(vtkShaderProgram *program,
                           vtkAbstractMapper *mapper, vtkProp *prop,
                           vtkOpenGLVertexArrayObject* VAO = nullptr) override;

  // Set Opaque Z texture, this must be set from the outer FO
  void SetOpaqueZTexture(vtkTextureObject *);

  // Set Opaque RGBA texture, this must be set from the outer FO
  void SetOpaqueRGBATexture(vtkTextureObject *);

  vtkSetMacro(DepthFormat, int);

 protected:
  vtkDepthPeelingPass();

  ~vtkDepthPeelingPass() override;

  vtkRenderPass *TranslucentPass;
  vtkTimeStamp CheckTime;


  int ViewportX;
  int ViewportY;
  int ViewportWidth;
  int ViewportHeight;

  double OcclusionRatio;

  int MaximumNumberOfPeels;

  vtkOpenGLFramebufferObject *Framebuffer;

  vtkOpenGLQuadHelper *FinalBlend;
  vtkOpenGLQuadHelper *IntermediateBlend;

  // obtained from the outer FO, we read from them
  vtkTextureObject *OpaqueZTexture;
  vtkTextureObject *OpaqueRGBATexture;
  bool OwnOpaqueZTexture;
  bool OwnOpaqueRGBATexture;

  // each peel merges two color buffers into one result
  vtkTextureObject *TranslucentRGBATexture[3];
  int ColorDrawCount;
  int PeelCount;

  // each peel compares a prior Z and writes to next
  vtkTextureObject *TranslucentZTexture[2];
  int DepthFormat;

  void BlendIntermediatePeels(vtkOpenGLRenderWindow *renWin, bool);
  void BlendFinalPeel(vtkOpenGLRenderWindow *renWin);

  // useful to store
  vtkOpenGLState *State;

 private:
  vtkDepthPeelingPass(const vtkDepthPeelingPass&) = delete;
  void operator=(const vtkDepthPeelingPass&) = delete;
};

#endif