KBE3D / KBCore / Cesium / TILE_SIZE

变量: TILE_SIZE

const TILE_SIZE: 256 = 256

Creates a spatial hash key for the given longitude, latitude, and tile level. The precision is adjusted based on the tile level and extent to achieve finer precision at higher levels.

This function calculates the spatial hash key by first determining the precision at the given tile for the current maximum screenspace error (MAX_ERROR_PX), and then rounding the longitude and latitude to that precision for consistency.

The steps for computing the level precision are as follows:

1. Compute the resolution (meters per pixel) at the given level: level_resolution_m = (2 * PI * RADIUS) / (2^level * TILE_SIZE)

2. Compute the target precision in meters: level_precision_m = level_resolution_m * MAX_ERROR_PX

3. Compute the target precision to radians: level_precision_rad = level_precision_m / BODY_RADIUS

This simplifies to: level_precision_rad = (2 * PI * MAX_ERROR_PX) / (2^level * TILE_SIZE) which can also be written as: level_precision_rad = (PI * MAX_ERROR_PX) / (2level-1 * TILE_SIZE)

The computed level_precision_rad is then used to round the input longitude and latitude, ensuring that positions that fall within the same spatial bin produce the same hash key.

The constants below are computed once since they are fixed for the given configuration.