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/*=========================================================================
Program: Visualization Toolkit
Module: vtkVolumeStateRAII.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 vtkVolumeStateRAII_h
#define vtkVolumeStateRAII_h
#include "vtkOpenGLRenderWindow.h"
#include "vtkOpenGLState.h"
// Only these states can be queries via glIsEnabled:
// http://www.khronos.org/opengles/sdk/docs/man/
VTK_ABI_NAMESPACE_BEGIN
class vtkVolumeStateRAII
{
public:
vtkVolumeStateRAII(vtkOpenGLState* ostate, bool noOp = false)
: NoOp(noOp)
{
this->State = ostate;
if (this->NoOp)
{
return;
}
this->DepthTestEnabled = ostate->GetEnumState(GL_DEPTH_TEST);
this->BlendEnabled = ostate->GetEnumState(GL_BLEND);
this->CullFaceEnabled = ostate->GetEnumState(GL_CULL_FACE);
ostate->vtkglGetIntegerv(GL_CULL_FACE_MODE, &this->CullFaceMode);
GLboolean depthMaskWrite = GL_TRUE;
ostate->vtkglGetBooleanv(GL_DEPTH_WRITEMASK, &depthMaskWrite);
this->DepthMaskEnabled = (depthMaskWrite == GL_TRUE);
// Enable depth_sampler test
ostate->vtkglEnable(GL_DEPTH_TEST);
// Set the over blending function
// NOTE: It is important to choose GL_ONE vs GL_SRC_ALPHA as our colors
// will be premultiplied by the alpha value (doing front to back blending)
ostate->vtkglBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
ostate->vtkglEnable(GL_BLEND);
// Enable cull face and set cull face mode
ostate->vtkglCullFace(GL_BACK);
ostate->vtkglEnable(GL_CULL_FACE);
// Disable depth mask writing
ostate->vtkglDepthMask(GL_FALSE);
}
~vtkVolumeStateRAII()
{
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
if (this->NoOp)
{
return;
}
this->State->vtkglCullFace(this->CullFaceMode);
this->State->SetEnumState(GL_CULL_FACE, this->CullFaceEnabled);
this->State->vtkglBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// this does not actually restore the state always
// but a test fails if I change it so either the original
// test was wrong or it is itended
if (!this->BlendEnabled)
{
this->State->vtkglDisable(GL_BLEND);
}
this->State->SetEnumState(GL_DEPTH_TEST, this->DepthTestEnabled);
if (this->DepthMaskEnabled)
{
this->State->vtkglDepthMask(GL_TRUE);
}
}
private:
bool NoOp;
bool DepthTestEnabled;
bool BlendEnabled;
bool CullFaceEnabled;
GLint CullFaceMode;
bool DepthMaskEnabled;
vtkOpenGLState* State;
};
VTK_ABI_NAMESPACE_END
#endif // vtkVolumeStateRAII_h
// VTK-HeaderTest-Exclude: vtkVolumeStateRAII.h
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