# wx.glcanvas.GLCanvas¶

wx.glcanvas.GLCanvas is a class for displaying OpenGL graphics.

It is always used in conjunction with wx.glcanvas.GLContext as the context can only be made current (i.e. active for the OpenGL commands) when it is associated to a wx.glcanvas.GLCanvas.

More precisely, you first need to create a wx.glcanvas.GLCanvas window and then create an instance of a wx.glcanvas.GLContext that is initialized with this wx.glcanvas.GLCanvas and then later use either SetCurrent with the instance of the wx.glcanvas.GLContext or wx.glcanvas.GLContext.SetCurrent with the instance of the wx.glcanvas.GLCanvas (which might be not the same as was used for the creation of the context) to bind the OpenGL state that is represented by the rendering context to the canvas, and then finally call SwapBuffers to swap the buffers of the OpenGL canvas and thus show your current output.

Please note that wx.glcanvas.GLContext always uses physical pixels, even on the platforms where wx.Window uses logical pixels, affected by the coordinate scaling, on high DPI displays. Thus, if you want to set the OpenGL view port to the size of entire window, you must multiply the result returned by wx.Window.GetClientSize by wx.glcanvas.GLCanvas.GetContentScaleFactor before passing it to glViewport() . Same considerations apply to other OpenGL functions and other coordinates, notably those retrieved from wx.MouseEvent in the event handlers.

Notice that versions of wxWidgets previous to 2.9 used to implicitly create a wx.glcanvas.GLContext inside wx.glcanvas.GLCanvas itself. This is still supported in the current version but is deprecated now and will be removed in the future, please update your code to create the rendering contexts explicitly.

To set up the attributes for the canvas (number of bits for the depth buffer, number of bits for the stencil buffer and so on) you pass them in the constructor using a wx.glcanvas.GLAttributes instance. You can still use the way before 3.1.0 (setting up the correct values of the attribList parameter) but it’s discouraged.

Note

On those platforms which use a configure script (e.g. Linux and macOS) OpenGL support is automatically enabled if the relative headers and libraries are found. To switch it on under the other platforms (e.g. Windows), you need to edit the setup.h file and set USE_GLCANVAS to 1 and then also pass USE_OPENGL=1 to the make utility. You may also need to add opengl32.lib (and glu32.lib for old OpenGL versions) to the list of the libraries your program is linked with.

## Class Hierarchy¶

Inheritance diagram for class GLCanvas:

## Methods Summary¶

 __init__ Creates a window with the given parameters. GetClassDefaultAttributes IsDisplaySupported Determines if a canvas having the specified attributes is available. IsExtensionSupported Returns True if the extension with given name is supported. SetColour Sets the current colour for this window (using glcolor3f() ), using the wxWidgets colour database to find a named colour. SetCurrent Makes the OpenGL state that is represented by the OpenGL rendering context context current, i.e. SwapBuffers Swaps the double-buffer of this window, making the back-buffer the front-buffer and vice versa, so that the output of the previous OpenGL commands is displayed on the window.

## Class API¶

class wx.glcanvas.GLCanvas(Window)

Possible constructors:

GLCanvas(parent, dispAttrs, id=ID_ANY, pos=DefaultPosition,
size=DefaultSize, style=0, name=GLCanvasName, palette=NullPalette)

GLCanvas(parent, id=ID_ANY, attribList=None, pos=DefaultPosition,
size=DefaultSize, style=0, name='GLCanvas', palette=NullPalette)


GLCanvas is a class for displaying OpenGL graphics.

### Methods¶

__init__(self, *args, **kw)

__init__ (self, parent, dispAttrs, id=ID_ANY, pos=DefaultPosition, size=DefaultSize, style=0, name=GLCanvasName, palette=NullPalette)

Creates a window with the given parameters.

Notice that you need to create and use a wx.glcanvas.GLContext to output to this window.

Parameters
• parent (wx.Window) – Pointer to a parent window.

• dispAttrs (wx.glcanvas.GLAttributes) – The wx.glcanvas.GLAttributes used for setting display attributes (not for rendering context attributes).

• id (wx.WindowID) – Window identifier. If -1, will automatically create an identifier.

• pos (wx.Point) – Window position. DefaultPosition is (-1, -1) which indicates that wxWidgets should generate a default position for the window.

• size (wx.Size) – Window size. DefaultSize is (-1, -1) which indicates that wxWidgets should generate a default size for the window. If no suitable size can be found, the window will be sized to 20x20 pixels so that the window is visible but obviously not correctly sized.

• style (long) – Window style.

• name (string) – Window name.

• palette (wx.Palette) – Palette for indexed colour (i.e. non wx.glcanvas.WX_GL_RGBA) mode. Ignored under most platforms.

New in version 4.1/wxWidgets-3.1.0.

__init__ (self, parent, id=ID_ANY, attribList=None, pos=DefaultPosition, size=DefaultSize, style=0, name=’GLCanvas’, palette=NullPalette)

static GetClassDefaultAttributes(variant=WINDOW_VARIANT_NORMAL)
Parameters

variant (WindowVariant) –

Return type

wx.VisualAttributes

static IsDisplaySupported(*args, **kw)

IsDisplaySupported (dispAttrs)

Determines if a canvas having the specified attributes is available.

This only applies for visual attributes, not rendering context attributes.

Parameters

dispAttrs (wx.glcanvas.GLAttributes) – The requested attributes.

Return type

bool

Returns

True if attributes are supported.

New in version 4.1/wxWidgets-3.1.0.

IsDisplaySupported (attribList)

Determines if a canvas having the specified attributes is available.

This only applies for visual attributes, not rendering context attributes. Please, use the new form of this method, using wx.glcanvas.GLAttributes.

Parameters

attribList (list of integers) – See attribList for wx.glcanvas.GLCanvas.

Return type

bool

Returns

True if attributes are supported.

static IsExtensionSupported(extension)

Returns True if the extension with given name is supported.

Notice that while this function is implemented for all of GLX, WGL and NSOpenGL the extensions names are usually not the same for different platforms and so the code using it still usually uses conditional compilation.

Parameters

extension (int) –

Return type

bool

SetColour(self, colour)

Sets the current colour for this window (using glcolor3f() ), using the wxWidgets colour database to find a named colour.

Parameters

colour (string) –

Return type

bool

SetCurrent(self, context)

Makes the OpenGL state that is represented by the OpenGL rendering context context current, i.e.

it will be used by all subsequent OpenGL calls.

This is equivalent to wx.glcanvas.GLContext.SetCurrent called with this window as parameter.

Parameters

context (wx.glcanvas.GLContext) –

Return type

bool

Returns

False if an error occurred.

Note

This function may only be called when the window is shown on screen, in particular it can’t usually be called from the constructor as the window isn’t yet shown at this moment.

SwapBuffers(self)

Swaps the double-buffer of this window, making the back-buffer the front-buffer and vice versa, so that the output of the previous OpenGL commands is displayed on the window.

Return type

bool

Returns

False if an error occurred.