Fix pole geometry elevation sampling #12133
Merged
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Pole geometry in globe view is rendered by extrapolating vertex, elevation and color data from the bordering tiles. A triangle fan expanding towards either of the geographic poles is created for each tile without top or bottom neighbour
y == 0 || y == tiles - 1
.A bug was found where elevation of the pole geometry seems to be off when an exaggerated terrain is used with the
Terrain-DEM v1
source. After some investigation I found out that the metric elevation applied to pole vertices is in incorrect coordinate space.Terrain-RGB v1
source works fine as the elevation is always (observed to be) 0 for bordering tiles which is not the case with DEM v1.This PR fixes the following issues:
Two new render tests are added to validate the fix.
Partly fixes #12037.
Launch Checklist
@mapbox/map-design-team
@mapbox/static-apis
if this PR includes style spec API or visual changes@mapbox/gl-native
if this PR includes shader changes or needs a native portmapbox-gl-js
changelog:<changelog>Fix elevation of pole geometry when exaggerated terrain is used</changelog>