Page 119 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Unit 7: Implementation of Hidden Surface in 2D

BSP Tree Display Notes
showBSP( v: Viewer, T: BSPtree )
{
if T is empty then return
P := root of T
if viewer is in front of P
{
showBSP( back subtree of T )
draw P
showBSP( front subtree of T )
} else {
showBSP( front subtree of T )
draw P
showBSP( back subtree of T )
}
}

BSP Tree Analysis
Categorization:
• Easy to implement
• Hardware implementation

• Incremental drawing calculations (uses coherence)
• Pre-processing required
• On-line (does not need all objects before drawing begins)

• Memory intensive
• Handles transparency
• Handles refraction

• Polygon-based
• Extra work for moving objects
• Extra work for moving viewer

• Efficient shading
• Handles cycles and self-intersections
Binary Space Partition Trees (or BSP trees for short) where introduced by
Fuchs, Kedem, and Naylor around 1980.
7.2.4 Ray Tracing

Ray tracing is, in many ways, a standardized technique. Almost all ray tracing programs
(known as “ray tracers”) use the same basic algorithm in one way or the other. This algorithm
is presented below.

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