explorer: fix halo cutoff over terrain (disableDepthTestDistance)#181
Merged
rdhyee merged 1 commit intoisamplesorg:mainfrom May 9, 2026
Merged
explorer: fix halo cutoff over terrain (disableDepthTestDistance)#181rdhyee merged 1 commit intoisamplesorg:mainfrom
rdhyee merged 1 commit intoisamplesorg:mainfrom
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The white halos added in isamplesorg#180 made a pre-existing terrain depth-test artifact visible: dots positioned at altitude=0 get partly (or entirely) occluded by Cesium World Terrain wherever land elevation rises. Without halos, the truncation read as a smaller dot. With halos, the white ring exposes the cut as a crescent — and over higher terrain, the whole sprite disappears. Fix: add `disableDepthTestDistance: Number.POSITIVE_INFINITY` to all three PointPrimitive add() sites (h3Points x2 + samplePoints), matching the existing pattern used by `pointLabel` (line 843) — points render always-on-top regardless of intervening terrain. Reported view: explorer.html#v=1&lat=33.27&lng=-86.24&alt=311435 (Birmingham AL hill country). Verified locally — dots render as full circles; previously- missing dots over higher terrain are visible again. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Hotfix for the halo regression introduced in #180.
The white halos exposed a pre-existing Cesium terrain depth-test artifact: PointPrimitives are positioned at altitude=0, so wherever Cesium World Terrain has elevation, the front face of the terrain mesh occludes part of the sprite. Without halos, that truncation read as a slightly smaller dot. With halos, the white ring made the cut glaringly obvious — appearing as crescents — and over higher terrain the sprite vanishes entirely.
Reported view:
explorer.html#v=1&lat=33.2706&lng=-86.2375&alt=311435(Birmingham, AL hill country) — many dots showed only as half-moon halos or were entirely missing.Fix
Add
disableDepthTestDistance: Number.POSITIVE_INFINITYto all threePointPrimitive.add()sites (h3Points x2 cluster-mode + samplePoints x1). This matches the existing pattern already used bypointLabelat line 843 — points render always-on-top regardless of intervening terrain.Trade-off
With depth test off, points on the far side of the globe could in principle bleed through. In practice at the zoom levels users hit (regional → world), the cluster aggregation hides this, and Cesium's frustum culling still removes truly back-facing primitives. Standard fix per Cesium docs.
Verified locally
quarto render+ Playwright at the reported camera (lat=33.27, lng=-86.24, alt=311km):Test plan
https://isamples.org/explorer.html#v=1&lat=33.2706&lng=-86.2375&alt=311435&heading=360.0and confirm full-circle dots replace the previous crescents🤖 Generated with Claude Code