unify track style for various tracktypes

[zdila]

Current style for tracktype makes it difficult to determine grade visually. I've tuned the style for #tracks-notunnel-nobridge to feel the difference. Improvemets:

• all tracktypes differs only by b/line-dasharray and line-width, but later is only to make outline look equally for all traktypes
• grade1 has more clear outline so it is better visible in the forests
• higher the grade is, the line has shorter dashes and longer spaces. It is evenly visually distributed from grade2 to grade5.
• track without tracktype is the only composed of two different-long dashed what should represent "unknown grade - maybe lower, maybe higher"
• if track of tracktype > grade1 is joining track of tracktype=grade1 it is not interrupted by outline of the first track (using comp-op magic)

Please check it and tell mie if you like it or if you have even better idea for improvements. But IMHO current tracktype visual representation is confusing and should be improved.

If accepted, the style should be distributed to all other related layers.

#tracks-notunnel-nobridge {
  comp-op: src-over; // to force flattering first
  [zoom >= 14] {
    line-width: 3;
    line-color: white;
    line-opacity: 0.4;
    line-join: round;
    line-cap: round;
    line-comp-op: dst-over; // to not to draw over "b/" lines of other tracks
    b/line-width: 1.5;
    b/line-color: #996600;
    b/line-dasharray: 5,4,2,4;
    b/line-cap: round;
    b/line-join: round;
    b/line-opacity: 0.8;
    [tracktype = 'grade1'] {
      b/line-dasharray: 100,0; /* i.e. none, see https://github.com/mapbox/carto/issues/214 */
    line-width: 4;
    }
    [tracktype = 'grade2'] {
      line-width: 3.5;
      b/line-dasharray: 5,3;
    }
    [tracktype = 'grade3'] {
      b/line-dasharray: 4,4;
    }
    [tracktype = 'grade4'] {
      b/line-dasharray: 3,5;
    }
    [tracktype = 'grade5'] {
      b/line-dasharray: 2,6;
    }
  }
}

[tyrasd]

This sounds really promising. Do you have a quick example showcasing your proposal – maybe a comparison to the current tracktype rendering?

[zdila]

Attaching the showcase:
Current:

Proposed:

[gravitystorm]

refs #14

[gravitystorm]

My apologies for not responding to this properly!

I created a side-by-side comparison for my SotM talk on openstreetmap-carto:

I think the general approach is the correct one, but I think you can make more of a distinction between the grades e.g. grade 2 and 3 are very similar.

There has been some refactoring to the track rendering since you first worked on this, but I'd be happy to review a pull request based on v2.5.0 or later.

[matthijsmelissen]

See also https://trac.openstreetmap.org/ticket/2679 and https://trac.openstreetmap.org/ticket/3640.