mapnik/mapnik — Issue #1116: Support on-the-fly geometry clipping
Author: springmeyer
Created: 2012-03-06 20:01:23+00:00
State: open
Labels: clipping, performance

We can support geometry clipping.

It can potentially be:

* pre rendering, a new `VertexSource` in ctrans.hpp
* work in floating point (geo) coordinates.
* clip both lines and polygons while maintaining topology (good enough for rendering)

This can enable:

1) Faster rendering times for maps with a density of complex, large, and/or multi-part features, particularly at >= z10.

2) Cool cartography effects - e.g. allowing labels centroids to be sensitive to the clipped polygon region (#25)

3) Infinite zooming - currently >= z18-20 maps that intersect with very large polygons can cause overflows in AGG (#1076, #1075)

4) Complementing AGG's `clip_box()` functionality, which works in screen coords.

This ticket replaces #708, #876, #25, #1076, and #1075