If problems: First on a map, talking about how to achieve
FIG achieve the effect, there are the following three ways:
1. Draw the screen coordinates of a point feature, conversion is about latitude and longitude coordinates into screen coordinates plotted ways, most GIS systems are this way;
Advantages: simple implementation, better
Disadvantages: Because the orthogonal projection drawing, no depth information, unobstructed relationship model;
2. Using billboard draft mode, text is about to draw the image, generating textures to draw mode, using the billboard;
A little: simple implementation, better, and is a three-dimensional coordinates
Disadvantages: will generate a lot of texture, namely a text label generates a texture, to manage more complex, take up less memory, such as "China", will generate a picture, "China" will generate a picture, "" Can not shared memory
3. Using Billboard-ex embodiment, it is also a way billboard, but the data can be shared, to concentrate all the character data on a macro-textured management, data sharing manner index
Advantages: effective, three-dimensional coordinates
Cons: algorithm complexity
If the screen coordinates is not obstructed
However, in the three-dimensional coordinates, it may be blocked;
