Computer Graphics -- N3

This is a college assignment for Computer Graphics. It's a simple drawing application in which the user can draw some simple polygons and apply linear transforms to them.

It uses OpenGL 1, so it should run on any PC.

Dependencies

This project uses OpenGL, GLU and GLUT.

Documentation depends on Doxygen and LaTeX (for PDF doc only).

Build instructions

This project uses a simple Makefile. You can:

make: compiles the project;
make clean: removes compilation files;
make cleandoc: removes documentation files and;
make doc: generates documentation using Doxygen.

Keyboard commands

This application is mostly keyboard driven. Here are the valid commands:

A: Enters addition mode.
C: Changes current polygon color (picks a random color).
E: Enters edition mode.
+, =: Zooms In.
-: Zooms Out.
Space bar: Alternates between open or closed polygon.

In addition to the global keyboard commands, the application has two modes. They have unique keybindings, documented below.

Addition mode

LMB: Adds a new point to the current polygon. If no polygon is active, creates a new one.
RMB: Finishes the current polygon.

Edition mode

LMB: Selects a polygon (and possibly one of its points).
RMB: If a point is selected, saves its current position.
D: If a point is selected, deletes it.
R: Starts applying rotation transform (use the arrow keys to control).
S: Starts applying scale transform (use the arrow keys to control).
T: Starts applying translation transform (use the arrow keys to control).
Backspace: Deletes selected polygon.
Esc: Cancels selection.
Home: Resets a polygon transform.

Lessons learned

Having a render method on ars::Object and on ars::World was probably a bad idea. It “stains” two classes with OpenGL details instead of containing it on a single renderer object.

It may be not so apparent because this is a simple project, but if we had more object types and were to replace OpenGL immediate mode with modern OpenGL, DirectX or any other graphical tool, it would become a problem.