vtkSobelGradientMagnitudePass Class Reference

#include <vtkSobelGradientMagnitudePass.h>

Inheritance diagram for vtkSobelGradientMagnitudePass:

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Collaboration diagram for vtkSobelGradientMagnitudePass:

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List of all members.


Detailed Description

Implement a post-processing edge detection with a Sobel gradient magnitude render pass.

Detect the edges of the image renderered by its delegate. Edge-detection uses a Sobel high-pass filter (3x3 kernel).

This pass expects an initialized depth buffer and color buffer. Initialized buffers means they have been cleared with farest z-value and background color/gradient/transparent color. An opaque pass may have been performed right after the initialization.

The delegate is used once.

Its delegate is usually set to a vtkCameraPass or to a post-processing pass.

This pass requires a OpenGL context that supports texture objects (TO), framebuffer objects (FBO) and GLSL. If not, it will emit an error message and will render its delegate and return.

Implementation:
To compute the gradient magnitude, the x and y components of the gradient (Gx and Gy) have to be computed first. Each computation of Gx and Gy uses a separable filter. The first pass takes the image from the delegate as the single input texture. The first pass has two outputs, one for the first part of Gx, Gx1, result of a convolution with (-1 0 1), one for the first part of Gy, Gy1, result of a convolution with (1 2 1). The second pass has two inputs, Gx1 and Gy1. Kernel (1 2 1)^T is applied to Gx1 and kernel (-1 0 1)^T is applied to Gx2. It gives the values for Gx and Gy. Thoses values are then used to compute the magnitude of the gradient which is stored in the render target. The gradient computation happens per component (R,G,B). A is arbitrarly set to 1 (full opacity).
Implementation:
vtkSobelGradientMagnitudePassFigure.png
See also:
vtkRenderPass
Tests:
vtkSobelGradientMagnitudePass (Tests)

Definition at line 74 of file vtkSobelGradientMagnitudePass.h.


Public Types

typedef vtkRenderPass Superclass

Public Member Functions

virtual const char * GetClassName ()
virtual int IsA (const char *type)
void PrintSelf (ostream &os, vtkIndent indent)
virtual void Render (const vtkRenderState *s)
void ReleaseGraphicsResources (vtkWindow *w)
virtual vtkRenderPassGetDelegatePass ()
virtual void SetDelegatePass (vtkRenderPass *delegatePass)

Static Public Member Functions

static
vtkSobelGradientMagnitudePass
New ()
static int IsTypeOf (const char *type)
static
vtkSobelGradientMagnitudePass
SafeDownCast (vtkObject *o)

Protected Member Functions

 vtkSobelGradientMagnitudePass ()
virtual ~vtkSobelGradientMagnitudePass ()

Protected Attributes

vtkRenderPassDelegatePass
vtkFrameBufferObjectFrameBufferObject
vtkTextureObjectPass1
vtkTextureObjectGx1
vtkTextureObjectGy1
vtkShaderProgram2Program1
vtkShaderProgram2Program2

Member Typedef Documentation

Reimplemented from vtkRenderPass.

Definition at line 78 of file vtkSobelGradientMagnitudePass.h.


Constructor & Destructor Documentation

vtkSobelGradientMagnitudePass::vtkSobelGradientMagnitudePass (  )  [protected]

Default constructor. DelegatePass is set to NULL.

virtual vtkSobelGradientMagnitudePass::~vtkSobelGradientMagnitudePass (  )  [protected, virtual]

Destructor.


Member Function Documentation

static vtkSobelGradientMagnitudePass* vtkSobelGradientMagnitudePass::New (  )  [static]

Create an object with Debug turned off, modified time initialized to zero, and reference counting on.

Reimplemented from vtkObject.

virtual const char* vtkSobelGradientMagnitudePass::GetClassName (  )  [virtual]

Reimplemented from vtkRenderPass.

static int vtkSobelGradientMagnitudePass::IsTypeOf ( const char *  name  )  [static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkRenderPass.

virtual int vtkSobelGradientMagnitudePass::IsA ( const char *  name  )  [virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.

Reimplemented from vtkRenderPass.

static vtkSobelGradientMagnitudePass* vtkSobelGradientMagnitudePass::SafeDownCast ( vtkObject o  )  [static]

Reimplemented from vtkRenderPass.

void vtkSobelGradientMagnitudePass::PrintSelf ( ostream &  os,
vtkIndent  indent 
) [virtual]

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkRenderPass.

virtual void vtkSobelGradientMagnitudePass::Render ( const vtkRenderState s  )  [virtual]

Perform rendering according to a render state s.

Precondition:
s_exists: s!=0

Implements vtkRenderPass.

void vtkSobelGradientMagnitudePass::ReleaseGraphicsResources ( vtkWindow w  )  [virtual]

Release graphics resources and ask components to release their own resources.

Precondition:
w_exists: w!=0

Reimplemented from vtkRenderPass.

virtual vtkRenderPass* vtkSobelGradientMagnitudePass::GetDelegatePass (  )  [virtual]

Delegate for rendering the image to be blurred. If it is NULL, nothing will be rendered and a warning will be emitted. It is usually set to a vtkCameraPass or to a post-processing pass. Initial value is a NULL pointer.

virtual void vtkSobelGradientMagnitudePass::SetDelegatePass ( vtkRenderPass delegatePass  )  [virtual]

Delegate for rendering the image to be blurred. If it is NULL, nothing will be rendered and a warning will be emitted. It is usually set to a vtkCameraPass or to a post-processing pass. Initial value is a NULL pointer.


Member Data Documentation

Definition at line 105 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 109 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 110 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 111 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 112 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 113 of file vtkSobelGradientMagnitudePass.h.

Graphics resources.

Definition at line 114 of file vtkSobelGradientMagnitudePass.h.


The documentation for this class was generated from the following file:

Generated on Wed Jun 3 19:34:56 2009 for VTK by  doxygen 1.5.6