Vector drawing algorithm with "unrelated to graphics structure"
Xu Qingrong, this article (Wuhan University)
1. What is a graphic structure?
Here is a combination of figures (geometric patterns) and mutual combination of symbol patterns. The symbol pattern is a repeating unit in line symbols (such as roads, realms, rivers, etc.) or surface symbols (such as soil, geology, vegetation, water, etc.). Typically, both line symbols or surface symbols are formed by continuously engage or splicing such patterns, so the graphics structure is the line type or surface symbol of the linear symbol.
2. Vector drawing algorithm based on graphic structure
So far, the vector drawing algorithms of various mapping software are based on graphic structures, namely, respectively, vector drawing functions must be respectively prepared for different graphics structures (linear or filling). Therefore, some commodity vector pattern software does not have a function of drawing any line or arbitrary fill. The graphic structure is a variable, there are countless forms and combinations thereof, and the new month can vary. In the vector drawing algorithm based on graphic structure, the relationship between the graphics structure and the drawing function is N: N, that is, the n graphic structure must correspond to N draw functions, and n may have any more, the uncertainty. It can be seen that the amount of programming and maintenance engineering of vector drawing function cannot be estimated.
3. "Regardless of the graphic structure" algorithm and its basic principles
In the vector plot algorithm of "unrelated to graphics structure", the relationship between the graphics structure and the drawing function is N: 1, that is, the n type graphics structure only one draw function, regardless of graphics structure (any line or arbitrary fill type " ) Always use this same drawing function, saving huge programming amounts and maintenance engineering. This algorithm is incapable and broad prospects are self-evident.
The object of the "independent of the graphic structure" algorithm is a point instead of the entire graphic structure. Discard the symbol pattern into a range point (including color and associated markers, etc.), the drawing output process is the process of patterning space to the drawing space points-to-point topology map (before and after mapping, the topology between graphics points remains unchanged). Because the object of the algorithm is a point rather than the entire graphic structure, the same draw function can accommodate any line or any fill type.
4. Drawing example of "independent of graphic structure" algorithm
The following figure is purely fictitious, containing a variety of complex symbol graphics (dotted, linear, surface-shaped), all of which are output with the same drawing function, time consuming for 5 seconds.
5. UGS (General Draw Software) uses "independent of graphics structure" algorithm
UGS contains vector drawings and drawings two parts, where the drawing module uses "independent of graphic structure" algorithm.
UGS is a graphics tool class software, vector graphics software developers, suitable for drawing various images, especially map drawing.
UGS is posted on 9CBS (graphics and multimedia, graphics processing small class), download:
http://www.9cbs.net/cnshare/shtm/18.shtm
Contact: Short information can be sent to XQR at the 9CBS forum.
