Introduction • Up until now all of your work in this course has been two-dimensional. • Images on a screen have been flat with only the width and height to be considered. • Now you must consider the depth and the placement in space.
Fixed 3D • Fixed 3D refers to a three-dimensional representation of the game world where foreground objects (i.e. game characters) are typically rendered in real time against a static background. The principal advantage of this technique is the ability to display high level detail on minimal hardware. • The main disadvantage is that the player’s frame of reference remains fixed at all times, preventing players from examining or moving about the environment from multiple viewpoints.
Fixed 3D Backgrounds • Tend to be pre-rendered two dimensional images, but are sometimes rendered in real time. For example the developers of SimCity 4 took advantage of fixed perspective by not texturing the reverse sides of objects. • Used to “fake” areas which are inaccessible to players. For instance the Legend of Zelda is nearly completely 3D but uses fixed 3D to represent many of the building interiors as well as one entire town.
Modeling • Modeling is the process of building images. • Creating figures and images that populate the world. • Most images are created with a series of cubes, although other shapes are also possible. • Images can be viewed as solid or in the form of a wire frame. • Wire frame image is invisible with only an outline defining the shape. A wire frame allows you to see the interior of an image.
Skeleton • After you have the frame, you must place a skeleton inside in order for an image to have motion. • The skeleton is a framework that can be manipulated much like the bones on a person.
Vertices and Mesh Modeling • One way that images are modeled is by using a series of points called vertices (a vertex is a single point.) The vertices location is defined in terms of X, Y and Z coordinate axis.
Vertices and Mesh Modeling • Two vertices connected in a line create an edge. • Three or more vertices create a face or a triangle. A polygon is a square shaped-plane that consists of two or more triangles. • This is called mesh modeling.
Mesh Modeling • The viewable surface of the mesh usually has a texture applied to it. • Textures are also known as materials in some 3D modeling packages. • A mesh can then be animated by rigging the model. This involves placing the skeleton comprised of jointed bones, and connecting areas of the mesh to a specific bone.
3D Model Categories • Solid models define the volume and are more realistic but more difficult to create. • They are mostly used for non-visual simulations such as medical and engineering simulations. • Shell/boundary models represent the surface or boundary of the object, not its volume. They are easier to work with. Almost all visual models used in games and films are shell models
Modeling in 3D software • There are four popular ways to represent a model in a 3D software package; • Polygonal modeling • NURBS modeling • Splines and patches • Primitive
Polygonal modeling • This uses points in 3D space called vertices, which are connected by line segments to form polygonal mesh. • Most 3D models today are built as textured polygonal models because they are extremely flexible and because computers can render them quickly.
NURBS modeling • A second way to create a figure is to use NURBS modeling. • NURBS stands for non-uniform rational B-spline • This form of modeling is similar to vector graphics in that the image is created with a series of curves. http://en.wikipedia.org/wiki/Non-uniform_rational_B-spline
NURBS Modeling • NURBS stands for ‘Non-uniform rational B-spline’. programs like Maya use this method to create perfectly smooth, curved surfaces. This modeling method is both accurate and flexible and can be transferred between various animation and rendering programs.
Splines and Patches • Like NURBS, Splines and Patches used curved lines to define the visible surface of a 3D object. Patches fall between NURBS and polygons in terms of flexibility and ease of use.
Primitive Modeling • Uses geometric primitives like spheres, cylinders, cones or cubes as building blocks for more complex models. • 3D construction with this type of modeling is quick easy and extremely precise. • Better suited for technical applications and less for organic shapes.
Box Modeling (subdivision modeling) • Similar to the Polygonal method, box modeling designs the 3D model by using lines to create a ‘mesh’ too. This method works by beginning with a simple box shape and gradually adding boxes before smoothing the surfaces. It is a faster way to work but allows less freedom, detail and versatility to polygonal.
Extruding • Most models begin with a basic shape. • Faces on the shape are them selected and extruded. • Extruding is the process of pulling a shape to a new size or to a new angle.
Platform • Models are created on grids that can be set to represent whatever dimensions you want. • A grid might represent one-inch, one-foot, or even one mile. • A single plane creates a floor for an image. • A plane has no depth, only length and width. • When working with models you need to be able to perform two separate actions. Object mode and Edit mode. • Object mode allows you to move an object around on the grid. • Edit mode allows you to modify the object.