Replace static ground.jpg with a dynamic tile-based system that
fetches new tiles from ESRI World Imagery as the camera moves
through the world.
- GROUND_TILE_Z = 11 (~13 km per tile)
- GROUND_MOSAIC_SIZE = 9 (9x9 = 81 tiles, 2304x2304 canvas)
- GROUND_BUFFER_TILES = 2 (refetch when within 2 tiles of edge)
- Passau tile at zoom 11: x=1102, y=710
Shader:
- Two new uniforms: uGroundCenter (mosaic centre in world units),
uGroundSize (mosaic side length = 9)
- gUv = (hitPoint - uGroundCenter) / uGroundSize + 0.5 so the
mosaic centre stays at UV (0.5, 0.5) as the camera drifts
Runtime:
- maybeRefetchGround() called every 1.5s with current camera
position; if camera is in the buffer zone, mosaic centre is
shifted and missing tiles re-fetched in parallel
- Canvas re-uploaded to GPU after each rebuild
Camera can now roam indefinitely — every time we approach the
mosaic edge, a fresh 9x9 of tiles is fetched.
Richard Zink
979134102d