Assignment 1: Write a Paint Program

Requirements

• Interactive painting on color raster images
• Use the mouse or other 2-D input device to control where brushes paint. When the left mouse button is down it paints; when button is up it doesn't.
• Set brush color interactively from a wide range of choices.
• Paint with a solid color brush of variable size (say 1x1 to 40x40 pixels or so). You could choose to do square brushes (easier) or circular brushes (nicer looking).
• Brushes with transparency. User should be able to vary the transparency from completely transparent to completely opaque.
• draw 2-D polygons by specifying their vertices by mouse
• use a simple primitive object library to draw rectangles, circles, etc. (use mouse to select among them as in MS-DRAW)
• seed fill the 2-D polygons or primitives you draw (you can use OpenGL to fill out the primitives)
• Read in an image file and write out an image file, so that you can paint on an existing picture and save the results. You can also do this by saving the coordinates of the drawn primitives and commands that you applied to draw the picture to a text file and while loading read from this text file apply the commands again.

Important: Always comment your code. The code will also be checked during the demos.

Grading Criteria

• Does your program meet the requirements listed above? Your programs will be graded with respect to the number of the requirements they satisfy.
• You should construct a instructive user interface for your Paint program. The user interface should be easy to use. There should not be any menus without any information. In other words, an empty window without any information but when you click on a mouse button a menu appears is not a good user interface. The functionality of the user interface is a part of the grade criteria.

Tips

Please make sure your program runs in preparation for the demos. You might want to pre-compile and test your program on a PC to prepare for your demo. Do not forget to copy any dynamic libraries(DLLs) and shader files to the same location where your executable file is.

You should use dragging appropriately to draw lines, rectangles, circles. For example, you can draw a line by pressing the mouse button to specify the initial point, drag the mouse until you give the final point. When you release the mouse, the final line could be drawn. While the mouse is pressed, intermediate lines are also displayed.

For the circle, press the mouse to specify the center, then while dragged draw intermediate circles, finally when you release the mouse the final circle is drawn.

You should be able to input line size, type (solid, dotted, dashed lines), color, brush size, type (circular, rectangular), color to draw shapes and painting.

To change the brush color, you could use three sliders (easiest), or pick from a few colored patches, or (if you're feeling ambitious) display a color chart and let the user point and pick. Optionally, you could let the user pick up a color from the image (maybe use left button for painting, middle button for picking a color?).

OpenGL Support