postclip with polygon path maybe...

[saifulazfar]

im trying making a composite projection map as shown here

https://observablehq.com/@saifulazfar/composite-projection-with-d3-geoclippolygon

the map was originally design with avenza mappublisher to get the initial composition..i understand the sphere coordinate cause the issue of rounded with geoClip.polygon...but is there a way postclip with path/polygon? not just with rectangle...

im trying recreating this natgeo pacific map
\ picture remove due to copyright concern

[Fil]

We can define the spherical pre-clip shapes with more intermediate points—it still won't be a perfect line, but the issue will not be visible. On top of that, it's difficult to clip a shape with itself, so we need to take extra-care when we draw the outlines. I've sent you a suggestion. This is going to be a beautiful map!

[Fil]

PS: There might be a way to do the correct planar clipping, but it will be for another time :)

[saifulazfar]

thank u for your help...looks great...

[saifulazfar]

sory another one question @Fil ... is there any plan support postclip with polygon path...while currently the map clip was define with coordinates interpolate planar...definitely works great with any projection...but its still hard-code coordinate...maybe i want like just draw mask/clip with svg/canvas so there is flexibilty to define margin/gap between composition map or such...like mbostock postclip example looks great define margin/padding but still lmit to rectangle...just wonder how with custom polygon with postclip

[Fil]

d3-geo doesn't include a generic planar clipping algorithm (see d3/d3-polygon#4). It would be neat to have a generic clipping function (polygon postclip), but I don't think there is an easy solution.

[saifulazfar]

hi @Fil ..sory for reopen this issue just...since interpolate planar works great to counter clip with spehere coordinate...i assume there is no way to have rounded clip right?...like shown image below

[Fil]

The "rounded path" needs to be a polygon with as many vertices as necessary to give a good enough precision?

[saifulazfar]

need help https://observablehq.com/d/63fa416fb7f91e82 ... how to use d3.geoClipAntimeridian to clip d3.geoInterruptedHomolosine()

[Fil]

you could try this:

<clipPath id="popsdensityclip"><path d="${pops_density(outline)}" /></clipPath>
<path stroke="#333333" fill="white" stroke-width="0.4" d="${pops_density(land)}" clip-path="url(#popsdensityclip)" />
<path stroke="#333333" fill="none" stroke-width="1" d="${pops_density(outline)}"  />

(and remove the antimeridian clip)

[saifulazfar]

yeah...i tought originally there are like d3.geo.polygon way of clip the sphere of Interrupt Goode Homolosine projection...after looks at more example it seems just use svg and canvas clip only...i prefer to use d3.geo.polygon way of clipping (either clipAngle or d3.clipPolygon) since its more code literate and cleaner code output...