vcl::CanvasOpenGL2< DerivedRenderApp > Class Template Reference

The Canvas class describes a canvas on which opengl2 can draw. More...

#include <vclib/opengl2/canvas.h>

Public Types
using	CallbackReadBuffer = ReadBufferTypes::CallbackReadBuffer

Public Member Functions
	CanvasOpenGL2 (void *winId, uint width, uint height, void *displayId=nullptr)
void	onInit ()
	Automatically called by the DerivedRenderApp when the window initializes. Initialization is requires in some backends+window manager combinations, and therefore it must be implemented (also if empty) in every Canvas class.
void	onPaint ()
	Automatically called by the DerivedRenderApp when the window asks to repaint.
bool	onReadDepth (const Point2i &point, CallbackReadBuffer callback=nullptr)
	Automatically called by the DerivedRenderApp when a drawer asks to read the depth buffer at a specific point.
bool	onReadId (const Point2i &point, CallbackReadBuffer callback=nullptr)
	Automatically called by the DerivedRenderApp when a drawer asks to read the ID at a specific point.
void	onResize (uint width, uint height)
	Automatically called by the DerivedRenderApp when the window is resized.
bool	onScreenshot (const std::string &filename, uint multiplier=1)
	Automatically called by the DerivedRenderApp when a drawer asks for a screenshot.
bool	screenshot (const std::string &filename, uint multiplier=1)
	Request a screenshot of the canvas. The screenshot will be saved asynchronously.
void	setDefaultClearColor (const Color &color)
Point2< uint >	size () const
uint	viewId () const

Protected Types
using	ByteData = ReadBufferTypes::ByteData
using	FloatData = ReadBufferTypes::FloatData
using	ReadData = ReadBufferTypes::ReadData

Private Member Functions
auto *	derived ()
const auto *	derived () const
void	readDepthData ()

Private Attributes
vcl::Color	mDefaultClearColor = vcl::Color::Black
CallbackReadBuffer	mReadBufferCallback = nullptr
Point2i	mReadDepthPoint = Point2i(-1, -1)
Point2< uint >	mSize = {0, 0}
void *	mWinId = nullptr

Detailed Description

template<typename DerivedRenderApp>
class vcl::CanvasOpenGL2< DerivedRenderApp >

The Canvas class describes a canvas on which opengl2 can draw.

Its usage requires to have a window object that can be used to initialize the canvas. The window object is not managed by the Canvas class, and can be managed by any of the windowing systems or libraries that allow to retrieve the native window handle (e.g. Qt, GLFW...).

You can create your custom bgfx canvas class by inheriting from this class and passing to the constructor the native window handle and the window size. Alternatively to the constructor, you can also use the init() method to initialize the canvas (if the required parameters are not available at construction time).

This class does not provide a render loop, that must be implemented in one of the derived classes. The render loop must call the frame() member function at the end of each frame, after all the bgfx rendering commands have been issued.

The opengl2 rendering code should be implemented in the virtual member function draw(), that must be reimplemented in the derived classes. This method is called by the frame() method (that must be called in the render loop).

The class provides two important member functions:

• frame(): this function must be called by the derived classes at the end of each frame, after all the opengl2 rendering commands have been issued;

Member Function Documentation

onReadDepth()

template<typename DerivedRenderApp >

bool vcl::CanvasOpenGL2< DerivedRenderApp >::onReadDepth ( const Point2i &  point, CallbackReadBuffer  callback = nullptr  )

inline

Automatically called by the DerivedRenderApp when a drawer asks to read the depth buffer at a specific point.

Parameters

point
callback

Returns

onReadId()

template<typename DerivedRenderApp >

bool vcl::CanvasOpenGL2< DerivedRenderApp >::onReadId ( const Point2i &  point, CallbackReadBuffer  callback = nullptr  )

inline

Automatically called by the DerivedRenderApp when a drawer asks to read the ID at a specific point.

Parameters

point	The point where the ID must be read.
callback	The callback function that will be called when the ID is read.

Returns

always false

Note

this function is not supported in opengl2

onResize()

template<typename DerivedRenderApp >

void vcl::CanvasOpenGL2< DerivedRenderApp >::onResize ( uint  width, uint  height  )

inline

Automatically called by the DerivedRenderApp when the window is resized.

Parameters

width
height

onScreenshot()

template<typename DerivedRenderApp >

bool vcl::CanvasOpenGL2< DerivedRenderApp >::onScreenshot ( const std::string &  filename, uint  multiplier = 1  )

inline

Automatically called by the DerivedRenderApp when a drawer asks for a screenshot.

Parameters

filename
width
height

Returns

screenshot()

template<typename DerivedRenderApp >

bool vcl::CanvasOpenGL2< DerivedRenderApp >::screenshot ( const std::string &  filename, uint  multiplier = 1  )

inline

Request a screenshot of the canvas. The screenshot will be saved asynchronously.

Parameters

filename	The filename where the screenshot will be saved.
multiplier	The multiplier applied to the canvas image.

Returns

true if the screenshot is requested, false otherwise.

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

• vclib/render/include/vclib/opengl2/canvas.h