Qt Location: fix for low quality of MapPolyline (track, route) rendering due to overlapping triangles

This suggestion relates to bug [1].

The current MapPolyline implementation produces very low quality track lines due to overlapping triangles and bad looking joints. They are probably not useable in production applications.

First, the triangulation mechanism has to be fixed to solve the problem of overlapping triangles (see [2]). Then I recommend to add an option for a line texture (in conjunction with the existing color and line width properties) as described in [2]. This gives much more freedom for line styling (for instance direction indicators).

[1] https://bugreports.qt.io/browse/QTBUG-38459
[2] http://gamedevelopment.tutsplus.com/tutorials/create-a-glowing-flowing-lava-river-using-bezier-curves-and-shaders--gamedev-919

Here is also some literature about how to improve the line properties:

• http://mattdesl.svbtle.com/drawing-lines-is-hard
• http://www.codeproject.com/Articles/226569/Drawing-polylines-by-tessellation
• http://jcgt.org/published/0002/02/08/paper.pdf