Navara's ground pass cut each corridor into chunks and tested them per
screen cell, so dense corridor sets were slow (10,000 cost about 150 ms a
frame). A corridor set is now cut into pieces along its great circles,
sorted into lon/lat tiles, each with a pyramid of bins listing the
segment runs within its margin; a pixel takes its tile and the finest
bin that covers its reach and tests only those runs. At 10,000 corridors
a frame now takes 11.8 ms still (Cesium 23 ms), at 15,000 17.9 ms. A
pixel corridor's width is measured across the line, so diagonal lines no
longer draw up to 1.4 times wider.
Pixel corridors take three looks, evaluated on the GPU from a time
uniform: Cesium's PolylineGlow falloff (glow), an alpha pulse and the
annotation route's flowing dash. While a shown set pulses or flows the
engine draws continuously, as Cesium did. Traffic's jam lines take the
glow and pulse again and the Directions route its flowing dash and render
hold, so on Cesium both match the drawing before they moved to the
contract pixel for pixel. The contract suite passes on both engines
(Cesium 69/69, Navara 72/72).
engine.ground draws sets of polygons (with holes), discs, cells and
corridors draped on the surface, with fill and outline colours, order and
picks, written in bulk and committed. Every engine implements it:
- Cesium batches each set into one GroundPrimitive for fills and one
GroundPolylinePrimitive for outlines and pixel corridors, classified
against terrain and 3D tiles; sets that are not pickable stay out of the
pick pass.
- Navara draws them in one screen pass after tone mapping that finds each
pixel's ground from the scene depth and tests the items in its screen
cell; long rings are split into edge bins. Measured at Dubai against
SDK vector layers, the pass matched Cesium's frame time up to 10,000
polygons with a few megabytes instead of 70 to 146, drew exact colours
and outlines, and hid reliably across an engine switch, where vector
layers hidden with update({ show: false }) never hid. Dense corridors
remain its limit (10,000 cost 135 ms a frame).
- The fake engine keeps the same registry and CPU picks.
The contract suite checks it on both engines (Cesium 66/66, Navara 69/69).
Earthquakes and fire perimeters have unwired ground prototypes whose
drawing matches today's Cesium one (0.998 on Cesium, 0.976 on Navara).
docs/GLOBE-PRIMITIVES.md describes the primitives and when to use each.
German Khokhlov