CS559 Fall 2002: Project 3

An Amusement Park

Due Date: 5pm Monday Dec 9

Project Source Code

The Basic Task

Like project 1, this project defines a set of sub-goals with points awarded for each goal. Unlike project 1, the goals are far more loosely defined, so there is scope to try interesting things to get all the points available. In fact, there are arbitrary numbers of points available because you can just keep modeling more objects and getting more points.

You may work in pairs. If you choose to work in a pair, then each member of the pair will get half of the earned points. Once again the maximum number of points, per person, is 100, but there are well over 200 points available.

The Tasks

Each task requires modeling some objects using one of the techniques described in class. You will score 25 points for the first object of each type, and 5 additional points for each additional object of that type, up to a maximum of 45 points for any one type. For instance, if you create a texture mapped polygonal ticket booth, and a texture-mapped polygonal roller-coaster carriage, and extrude the roller-coaster tracks, then you get 25 + 5 + 25 = 55 points. If an object involves more than one thing, such as a texture mapped Bezier surface, then you can score points for both texture mapping and Bezier surfaces.

The individual tasks are:

Texture Mapped Polygons

Add texture mapped polygon objects to the environment. Each "object" for grading purposes consists of at least 5 polygons all texture mapped. Different objects require different maps.

Hierarchical Animated Model

Add a hierarchical, animated model. Something like a ferris wheel is a good choice, but there are lots of rides that would do.

Parametric Instancing

Create a class of parametric objects and instantiate multiple instances with different parameters. The objects must differ by more than a transformation.

Sweep Objects

Add an extruded object or a surface of revolution. The natural choice is extruded tracks for the roller coaster.

Bezier Surfaces

Add something made of Bezier patches to the environment. A good possibility is the roller-coaster carriage. You are not allowed to cheat and use the OpenGL Bezier functions, and you must have multiple patches joined with C1 continuity.

Subdivision surfaces

Add some hills, or something else (a garbage heap) modeled as a subdivision surface. Fractal terrain counts as a subdivision scheme. Terrain must be texture mapped to get all the points. To help, the code for the subdivision sphere is available here.

Change the Navigation System

The navigation system now is not great. Change it to something better. To get all the points, you must have a mode where the viewer rides the roller-coaster.

Multiple objects modeled using the same technique must be significantly different in order to gain the additional points. Objects that differ only by a sequence of transformations are not different, nor are parameterized objects that only differ by the parameter. Hierarchical objects with the same hierarchy and animation are not different.

Make models that truly display the underlying technique. For instance, make bezier surfaces that really are curvy.

The Program Skeleton

• Back-face culling is turned on, so faces with normals that point away from the viewer will not be drawn. Polygon vertex order is used to determine that normal, so you must always order polygon vertices counter-clockwise about the outward-pointing normal.
• One light is defined and turned on. It is a directional light source with no specular component, so do not define specular components for your models. The light is coming in at an angle, so all the faces of an upright box have different shades. With lighting turned on, you must specify normal vectors for all your objects. (Actually, you could locally turn lighting off, but it would look weird).
• Texture mapping is used for the ground plane. In particular, it uses mipmapping and a targa image. You do not have to use either of these features with your own texture mapping, but for anything other than the simplest textures, it is probably sensible (and you can copy the code).

The Interface

Hints and Suggestions

• Have fun and be inventive.
• A key thing to consider is polygon count. Graphics hardware can only display so many polygons in a second, and if you try to display too many the frame rate will collapse. Texture maps also use memory, so too many textures can even more dramatically affect performance. To keep polygon counts down, allow larger errors in curve subdivisions, and avoid lots of complex terrain.
• The way the train alignment is set up, it is simplest to do just a single carriage, and a short one at that. Doing lots of cars makes it harder to keep then on the track, although it is possible.
• Make use of the OpenGL error checking mechanism. It is described in the red book.
• Start simple - just try to get a polygon to appear in the center of the world.
• The way the current carriage transformations are set up, the origin for the train is assumed to be at the bottom (at track level).
• It is OK to have multiple modeling techniques in one object. For instance, you could have a carriage made up of some texture mapped polygons with some Bezier patches. You get all the points if you do a sufficient amount of each technique.
• It is OK to borrow code from other sources - but not other students. You will probably learn as much trying to figure out how someone else's code works as you would doing it yourself.
• Texture images abound on the web, so feel free to use them. Or you can use a program like Photoshop to create your own. You might even find a use for the first project.