GlView Class Reference

#include <ImFusion/GL/GlView.h>

Base class for implementing OpenGL views. More...

Inheritance diagram for GlView:

Detailed Description

Base class for implementing OpenGL views.

A GlView represents an OpenGL Viewport, i.e. a rectangular drawing area on the screen. Each GlView contains a matrix that converts view coordinates to world coordinates (camera located in the origin, looking down the negative z-axis). In order to map the 3D view coordinates to the 2D screen, each view internally uses a projection matrix converting view coordinates to clip coordinates (visible objects will be in a cube of -1 to 1 side length). You can access view and projection matrices through the GL::ViewState object that is updated during every render call.

The view is aware of the width and height of the viewport but it will not set glViewport. Thus, the actual glViewport must be set before calling render().

Derived classes shall draw all GlObjects of the view with the current view- and projection matrix in the current viewport on render(). Furthermore, they must set the GL::ViewState correctly.

Usually a GlView is wrapped by an InteractiveView to allow for handling user input events and for putting it into a DisplayWidget.

Examples

MyCustomGlObject.cpp, and MyCustomGlObject.h.

Classes
class	ViewStateGuard
	Temporarily changes the GL::ViewState of a GlView and resetting to the original value on destruction. More...

Public Types
enum	Type { SLICE2D = 0 , SLICE3D = 1 , SPACE3D = 2 , OTHER = 3 }
	Type of the view. More...

Public Member Functions
virtual bool	render ()=0
	Render scene. glViewport must be set before. Called with valid OpenGL context.
virtual Type	type () const =0
	Return the type of this view.
virtual void	setMatrix (const mat4 &mat)
	Sets the view matrix (view coordinates to world coordinates).
virtual const mat4 &	matrix () const
	Returns the current view matrix (view coordinates to world coordinates).
virtual void	resize (int width, int height)
	Set a new viewport size for this view.
virtual const GL::OrderIndependentTransparency *	orderIndependentTransparency () const
	Returns the optional OIT manager instance of the view if the feature is supported and enabled.
int	height () const
	Current viewport height of the view.
int	width () const
	Current viewport width of the view.
void	addObject (GlObject *object)
	Add a reference to a GlObject to be drawn by this view.
void	removeObject (GlObject *object)
	Remove a reference to a GlObject drawn by this view.
const std::vector< GlObject * > &	objects () const
	Return the set of GlObjects that are drawn by this view.
const GL::ViewState &	state () const
	Return the view state that was set during the last render() call.

Protected Member Functions
GL::OrderIndependentTransparency *	sharedOitInstance () const
	Offers support for GlViews sharing GL::OrderIndependentTransparency instances to reduce GPU memory consumption.

Protected Attributes
std::vector< GlObject * >	m_objects
	Other objects to consider during rendering.
mat4	m_matrix = mat4::Identity()
	Matrix converting view coordinates to world coords (inverse of a traditional OpenGL view matrix)
GL::ViewState	m_state
	OpenGL state describing viewport, projection and model-view matrix of last render call.
int	m_width = 0
int	m_height = 0

Member Enumeration Documentation

Type

enum Type

Type of the view.

Enumerator
SLICE2D	2D slice view
SLICE3D	3D MPR slice view
SPACE3D	3D volume view
OTHER	Other/unknown kind of view.

Member Function Documentation

render()

virtual bool render ( )

pure virtual

Render scene. glViewport must be set before. Called with valid OpenGL context.

Implemented in GlGeometryView, GlCurvedView, GlPlotView, GlSliceView, and GlVolumeView.

type()

virtual Type type ( ) const

pure virtual

Return the type of this view.

Implemented in GlGeometryView, GlCurvedView, GlPlotView, GlSliceView, and GlVolumeView.

setMatrix()

virtual void setMatrix ( const mat4 & mat )

inlinevirtual

Sets the view matrix (view coordinates to world coordinates).

Reimplemented in GlSliceView, and GlVolumeView.

matrix()

virtual const mat4 & matrix ( ) const

inlinevirtual

Returns the current view matrix (view coordinates to world coordinates).

Reimplemented in GlVolumeView.

resize()

virtual void resize ( int width, int height )

virtual

Set a new viewport size for this view.

Updates the width and height properties but does not change the glViewport. Depending on the view type, this may also update the view matrix.

Reimplemented in GlSliceView.

orderIndependentTransparency()

virtual const GL::OrderIndependentTransparency * orderIndependentTransparency ( ) const

inlinevirtual

Returns the optional OIT manager instance of the view if the feature is supported and enabled.

A GlView may choose to support correct order-independent blending of semi-transparent surfaces of scene objects. In this case it should override this function to return its corresponding GL::OrderIndependentTransparency instance. Draw calls of GlObjects can query OIT support through this function and use the pointer to setup their shaders so that it writes semi-transparent fragments to the OIT buffer which the view will ultimately resolve at the end of the render pass.

Reimplemented in GlSliceView, and GlVolumeView.

sharedOitInstance()

GL::OrderIndependentTransparency * sharedOitInstance ( ) const

protected

Offers support for GlViews sharing GL::OrderIndependentTransparency instances to reduce GPU memory consumption.

Internally, this function will use the GL::InstanceManager interface to manage the internal caching. Usage of this class must be limited to a single GlView::render() call in order to ensure that multiple views sharing the same instance do not compromise each other. This function will return nullptr if OIT is not supported.

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

• ImFusion/GL/GlView.h