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/*=========================================================================
Program: Visualization Toolkit
Module: vtkOpenGLPropItem.cxx
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.
=========================================================================*/
#include "vtkOpenGLPropItem.h"
#include "vtkCamera.h"
#include "vtkContext2D.h"
#include "vtkContextScene.h"
#include "vtkMatrix4x4.h"
#include "vtkObjectFactory.h"
#include "vtkOpenGLContextDevice2D.h"
#include "vtkProp3D.h"
#include "vtkRenderer.h"
#include "vtkTransform.h"
VTK_ABI_NAMESPACE_BEGIN
vtkStandardNewMacro(vtkOpenGLPropItem);
void vtkOpenGLPropItem::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os, indent);
}
vtkOpenGLPropItem::vtkOpenGLPropItem() = default;
vtkOpenGLPropItem::~vtkOpenGLPropItem() = default;
void vtkOpenGLPropItem::UpdateTransforms()
{
vtkContextDevice2D* dev = this->Painter->GetDevice();
vtkOpenGLContextDevice2D* glDev = vtkOpenGLContextDevice2D::SafeDownCast(dev);
if (!glDev)
{
vtkErrorMacro(<< "Context device is not vtkOpenGLContextDevice2D.");
return;
}
// Get the active camera:
vtkRenderer* ren = this->Scene->GetRenderer();
vtkCamera* activeCamera = ren->GetActiveCamera();
// Cache the current state:
this->CameraCache->DeepCopy(activeCamera);
// Reset the info that computes the view:
vtkNew<vtkTransform> identity;
identity->Identity();
activeCamera->SetUserViewTransform(identity);
activeCamera->SetFocalPoint(0.0, 0.0, 0.0);
activeCamera->SetPosition(0.0, 0.0, 1.0);
activeCamera->SetViewUp(0.0, 1.0, 0.0);
// Update the camera model matrix with the current context2D modelview matrix:
double mv[16];
double* glMv = glDev->GetModelMatrix()->Element[0];
std::copy(glMv, glMv + 16, mv);
activeCamera->SetModelTransformMatrix(mv);
/* The perspective updates aren't nearly as straight-forward, and take a bit
* of code-spelunking and algebra. By inspecting the following methods, we
* see how the perspective matrix gets built at render-time:
*
* 1) vtkOpenGLCamera::Render() calls
* vtkCamera::GetProjectionTransformMatrix() with zRange = [-1, 1] and
* aspect = aspectModification * usize / vsize (see below).
* 2) vtkCamera::GetProjectionTransformMatrix() calls
* vtkCamera::ComputeProjectionTransform with the same arguments.
* 3) vtkCamera::ComputeProjectionTransform calls
* vtkPerspectiveTransform::Ortho with:
* xminGL = (vtkCamera::WindowCenter[0] - 1) * vtkCamera::ParallelScale * aspect
* xmaxGL = (vtkCamera::WindowCenter[0] + 1) * vtkCamera::ParallelScale * aspect
* yminGL = (vtkCamera::WindowCenter[1] - 1) * vtkCamera::ParallelScale
* ymaxGL = (vtkCamera::WindowCenter[1] + 1) * vtkCamera::ParallelScale
* zminGL = vtkCamera::ClippingRange[0]
* zmaxGL = vtkCamera::ClippingRange[1]
*
* In vtkOpenGLContext2D::Begin, glOrtho is called with:
* xminCTX = 0.5
* xmaxCTX = glViewport[0] - 0.5
* yminCTX = 0.5
* ymaxCTX = glViewport[1] - 0.5
* zminCTX = -2000
* zmaxCTX = 2000
*
* To set the camera parameters to reproduce the Context2D projective matrix,
* the following set of equations can be built:
*
* Using:
* Cx = vtkCamera::WindowCenter[0] (unknown)
* Cy = vtkCamera::WindowCenter[1] (unknown)
* P = vtkCamera::ParallelScale (unknown)
* a = aspect (known)
*
* The equations are:
* xminCTX = (Cx - 1)aP
* xmaxCTX = (Cx + 1)aP
* yminCTX = (Cy - 1)P
* ymaxCTX = (Cy + 1)P
*
* Solving simultaneously for the unknowns Cx, Cy, and P, we get:
* Cx = (xminCTX * a) / (xmaxCTX - xminCTX) + 1
* Cy = a * (yminCTX + ymaxCTX) / (xmaxCTX - xminCTX)
* P = (xmaxCTX - xminCTX) / (2 * a)
*/
// Collect the parameters to compute the projection matrix:
// (see vtkOpenGLCamera::Render)
int lowerLeft[2];
int usize, vsize;
double aspect1[2];
double aspect2[2];
vtkRecti vp = glDev->GetViewportRect();
ren->GetTiledSizeAndOrigin(&usize, &vsize, lowerLeft, lowerLeft + 1);
ren->ComputeAspect();
ren->GetAspect(aspect1);
ren->vtkViewport::ComputeAspect();
ren->vtkViewport::GetAspect(aspect2);
double aspectModification = (aspect1[0] * aspect2[1]) / (aspect1[1] * aspect2[0]);
// Set the variables for the equations:
double a = aspectModification * usize / vsize;
double xminCTX = 0.5;
double xmaxCTX = vp[2] - 0.5;
double yminCTX = 0.5;
double ymaxCTX = vp[3] - 0.5;
double zminCTX = -2000;
double zmaxCTX = 2000;
double Cx = (xminCTX * a) / (xmaxCTX - xminCTX) + 1.;
double Cy = a * (yminCTX + ymaxCTX) / (xmaxCTX - xminCTX);
double P = (xmaxCTX - xminCTX) / (2 * a);
// Set the camera state
activeCamera->SetParallelProjection(1);
activeCamera->SetParallelScale(P);
activeCamera->SetWindowCenter(Cx, Cy);
activeCamera->SetClippingRange(zminCTX, zmaxCTX);
}
void vtkOpenGLPropItem::ResetTransforms()
{
// Reset the active camera:
vtkCamera* activeCamera = this->Scene->GetRenderer()->GetActiveCamera();
activeCamera->DeepCopy(this->CameraCache);
}
bool vtkOpenGLPropItem::Paint(vtkContext2D* painter)
{
this->Painter = painter;
bool result = this->Superclass::Paint(painter);
this->Painter = nullptr;
return result;
}
VTK_ABI_NAMESPACE_END
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