3D Graphics Programming with QuickDraw 3D 1.5.4

Creating a Draw Context

A draw context contains information that is specific to a particular type of window system, such as the extent of the pane to draw into and the method of clearing the window. You need to create a draw context and add it to a view in order to render a model. Listing 7 illustrates how to create a draw context for drawing into Macintosh windows.

Listing 7 Creating a Macintosh draw context



 
TQ3DrawContextObject MyNewDrawContext (WindowPtr theWindow)

{

    TQ3DrawContextObject            myDrawContext;

    TQ3DrawContextData              myDrawContextData;

    TQ3MacDrawContextData           myMacDrawContextData;

    TQ3ColorARGB                    myClearColor;

    

    /*Set the background color.*/

    Q3ColorARGB_Set(&myClearColor, 1.0, 0.6, 0.9, 0.9);

    

    /*Fill in draw context data.*/

    myDrawContextData.clearImageMethod = kQ3ClearMethodWithColor;

    myDrawContextData.clearImageColor = myClearColor;

    myDrawContextData.paneState = kQ3False;

    myDrawContextData.maskState = kQ3False;

    myDrawContextData.doubleBufferState = kQ3True;



    /*Fill in Macintosh-specific draw context data.*/

    myMacDrawContextData.drawContextData = myDrawContextData;

    myMacDrawContextData.window = (CWindowPtr) theWindow;

    myMacDrawContextData.library = kQ3Mac2DLibraryNone;

    myMacDrawContextData.viewPort = NULL;

    myMacDrawContextData.grafPort = NULL;



    /*Create draw context.*/

    myDrawContext = Q3MacDrawContext_New(&myMacDrawContextData);

    

    return (myDrawContext);

}

Essentially, MyNewDrawContext just fills in the fields of a TQ3MacDrawContextData structure and calls Q3MacDrawContext_New to create a new Macintosh draw context.