• A wireframe object is simply rendered using the lines (straight, and curved) in a geometric model, then it is converted to screen coordinates using the Perspective Transformation.


• The process is as pictured below,



• If the geometric model is in some other form, such as CSG (Constructive Solids Geometry), it may have to be converted to lines before it may be used.


• Advantages,

- Very fast, allows real time manipulation

- Easy to see features normally hidden

- Supported by almost all computer technology

- This display method works with most displays


• Disadvantages,

- Drawings can become very crowded, very fast

- Hard to visualize solid properties


• Almost all computer graphics packages offer a wireframe display option.



1.2.1 Hidden Lines


• While the results seem similar, this method requires more sophisticated algorithms.


• Polygons must be used for surface representation.


• The diagram below shows the basic steps in the method of rendering

• Advantages,

- similar advantages of wireframe

- overcomes the drawing crowding

- can be simplified if polygons do not overlap


• Disadvantages,

- Consumes more computer time

- Does not support simple elemental geometric models


• Clipping algorithms may be difficult, and often use tricks like subdividing polygons into triangles. (There are only 5 cases to consider with overlapping triangles)




[an error occurred while processing this directive]