CSE 591 Project 1: Impressionist (hints)

Impressionist Hints

After the first class, you should be able to implement all the new brush shapes. Calculating image gradient and alpha compositing should be covered in the second class (but alpha compositing can probably be done on your own).
The class CImpBrush provides an abstract brush interface. You should subclass this and override the virtual methods to create your own brushes. There are seven important methods: BrushBegin, BrushMove, and BrushEnd are called when the left mouse button is pressed, dragged, and released, respectively. These should do the actual drawing. SelectBegin, SelectMove, and SelectEnd are similar, but use the right mouse button. BrushSelect is called whenever the brush is "picked up"; that is, whenever it is selected from the brushes dialog.
One instance of each brush type is created in CImpressionistDoc::OnNewDocument. When you add new brush types, you should modify this function to create the new brush object.
If some feature of OpenGL appears not to be working, make sure that it is enabled! OpenGL can use much faster rendering algorithms with some particular features turned off, so you must explcitly tell it when you want to use something with the glEnable and glDisable functions.
Adding new sliders to the dialog box can be tricky, since they must be tied to static text items to display their values, and there is a special MFC message for handling dragging the slider. Look at the one slider that is already implemented, and duplicate its code in the CBrushDialog class.
Other controls (such as checkboxes) are easier to add to the dialog box. Check out the Visual C++ documentation on CWnd::GetDlgItem for information on getting a pointer to the control's associated data structure.

problems or comments to dougz@cs.washington.edu

Tuesday, 31 March 1998 15:42:58