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[MAPS3D-425] introduce skirts for globe rendering #12523

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merged 1 commit into from
Jan 23, 2023
Merged

[MAPS3D-425] introduce skirts for globe rendering #12523

merged 1 commit into from
Jan 23, 2023

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alexey-romanov
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@alexey-romanov alexey-romanov commented Jan 17, 2023 •
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Absent skirts lead to holes for hight exaggerated terrain in globe mode.

Launch Checklist

  • briefly describe the changes in this PR
  • include before/after visuals or gifs if this PR includes visual changes
  • write tests for all new functionality
  • document any changes to public APIs
  • post benchmark scores
  • manually test the debug page
  • tagged @mapbox/map-design-team @mapbox/static-apis if this PR includes style spec API or visual changes
  • tagged @mapbox/gl-native if this PR includes shader changes or needs a native port
  • apply changelog label ('bug', 'feature', 'docs', etc) or use the label 'skip changelog'
  • add an entry inside this element for inclusion in the mapbox-gl-js changelog: <changelog>introduce skirts for terrain globe mode</changelog>

@alexey-romanov alexey-romanov requested a review from a team as a code owner January 17, 2023 12:43
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alexey-romanov commented Jan 17, 2023 •
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Introduce strips for terrain globe rendering. Absent strips lead to holes for high exaggerations.

Before:
before_no_strips
After:
after_with_strips

@alexey-romanov alexey-romanov added bug 🐞 GL native → GL JS For feature parity with Mapbox Maps SDK on a native platform labels Jan 17, 2023
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Case with transparent textures not handled -> update with moving skirts to be rendered last will be made

mourner
mourner reviewed Jan 17, 2023
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src/geo/projection/globe_util.js Outdated
// gridIndices: TriangleIndexArray,
// gridSegments: Array<SegmentVector>
// };
_fillGridMeshWithLods(longitudinalCellsCount: number, latitudinalLods: number[], hasStrip: boolean): GridWithLods {
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Nit: should we eliminate the hasStrip flag since it's always true? (I guess this a debugging leftover?)

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I have removed the flag from the interface, but kept it internal for potential debug uses

src/geo/projection/globe_util.js Outdated Show resolved Hide resolved
@alexey-romanov alexey-romanov force-pushed the ar5/terrain_globe_strips branch 3 times, most recently from f3694e9 to 7c8e08d Compare January 18, 2023 09:39
@alexey-romanov alexey-romanov changed the title [MAPS3D-425] introduce strips for globe rendering [MAPS3D-425] introduce skirts for globe rendering Jan 18, 2023
@alexey-romanov alexey-romanov force-pushed the ar5/terrain_globe_strips branch 5 times, most recently from 7a6ac35 to 3c97bdd Compare January 19, 2023 06:17
mpulkki-mapbox
mpulkki-mapbox reviewed Jan 19, 2023
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I noticed some areas where the skirt might be missing.

pole_skirts_missing.mov

src/terrain/draw_terrain_raster.js Outdated
const skirtHeightValue = Math.min(skirtHeight(tr.zoom) * terrain.exaggeration(), 20000);

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How was the value "20000" chosen?

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heuristically, without the limiting factor on certain zoom levels, e.g. 1.5 +- there can be seen triangles penetrating the earth surface. It was revealed by the globe anti-aliasing test with extreme exaggerations

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on the opposite side of the globe? What are the implications of triangles penetrating the surface?

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Fixed

src/terrain/draw_terrain_raster.js Outdated Show resolved Hide resolved
src/geo/projection/globe_util.js Outdated
indices.emplaceBack(idx + offsetToNextRow, idx + offsetToNextRow + 1, idx + 1);
}
}
segments.push(SegmentVector.simpleSegment(0, indexOffset, vertices.length, indices.length - indexOffset));
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@mpulkki-mapbox mpulkki-mapbox Jan 19, 2023 •
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Are you including skirt triangles into the same segment as the main grid triangles? We could have two different segments: one with skirts and one without skirts. This way we can skip rendering of skirts if the terrain is not enabled (or exaggeration is 0) in globe view.

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If I understood correctly this change will always render skirts?

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would it be possible to construct index buffer so that skirt triangles are immediately after terrain triangles? This wouldn't increase draw count as the only difference would be the number of rendered indices?

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currently, always, but yeah two segments (one with skirt and one without) can be used depending on terrain exaggeration. I'll do that modification

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Done

src/shaders/_prelude_terrain.vertex.glsl Show resolved Hide resolved
src/terrain/draw_terrain_raster.js Show resolved Hide resolved
@alexey-romanov alexey-romanov force-pushed the ar5/terrain_globe_strips branch 4 times, most recently from 5e568a5 to e785d9f Compare January 20, 2023 10:44
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Thanks for addressing the review comments @alexey-romanov! Code changes looks good to me but unfortunately there are still some scenarios where the skirt geometry is missing. It is also possible to see gaps when zooming in and out rapidly as I wrote previously.

image

I would suggest fixing remaining issues where gaps are visible even when camera is not moving. We can defer rest of the cases to a follow-up PR.

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Thanks for addressing the review comments @alexey-romanov! Code changes looks good to me but unfortunately there are still some scenarios where the skirt geometry is missing. It is also possible to see gaps when zooming in and out rapidly as I wrote previously.

image

I would suggest fixing remaining issues where gaps are visible even when camera is not moving. We can defer rest of the cases to a follow-up PR.

I was able to repro it locally. It is related to the case of transition between globe and mercator

@alexey-romanov
[MAPS3D-425] introduce skirts for globe rendering
77757cf 
Absent skirts lead to holes for hight exaggerated terrain in globe mode.
@alexey-romanov
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Thanks for addressing the review comments @alexey-romanov! Code changes looks good to me but unfortunately there are still some scenarios where the skirt geometry is missing. It is also possible to see gaps when zooming in and out rapidly as I wrote previously.

image

I would suggest fixing remaining issues where gaps are visible even when camera is not moving. We can defer rest of the cases to a follow-up PR.

Should be fixed now

@alexey-romanov alexey-romanov merged commit 9e8e044 into main Jan 23, 2023
@alexey-romanov alexey-romanov deleted the ar5/terrain_globe_strips branch January 23, 2023 07:23
@kallyas kallyas mentioned this pull request Jul 17, 2024
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@mpulkki-mapbox mpulkki-mapbox mpulkki-mapbox approved these changes

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