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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,132 @@ | ||
| import {CullingVolume, Plane, AxisAlignedBoundingBox} from '@math.gl/culling'; | ||
|
|
||
| const TILE_SIZE = 512; | ||
| // number of world copies to check | ||
| const MAX_MAPS = 3; | ||
|
|
||
| class OSMNode { | ||
| constructor(x, y, z) { | ||
| this.x = x; | ||
| this.y = y; | ||
| this.z = z; | ||
| } | ||
|
|
||
| get children() { | ||
| if (!this._children) { | ||
| const x = this.x * 2; | ||
| const y = this.y * 2; | ||
| const z = this.z + 1; | ||
| this._children = [ | ||
| new OSMNode(x, y, z), | ||
| new OSMNode(x, y + 1, z), | ||
| new OSMNode(x + 1, y, z), | ||
| new OSMNode(x + 1, y + 1, z) | ||
| ]; | ||
| } | ||
| return this._children; | ||
| } | ||
|
|
||
| update(params) { | ||
| const {viewport, cullingVolume, elevationBounds, minZ, maxZ, offset} = params; | ||
| const boundingVolume = this.getBoundingVolume(elevationBounds, offset); | ||
|
|
||
| // First, check if this tile is visible | ||
| const isInside = cullingVolume.computeVisibility(boundingVolume); | ||
| if (isInside < 0) { | ||
| return false; | ||
| } | ||
|
|
||
| // Avoid loading overlapping tiles - if a descendant is requested, do not request the ancester | ||
| if (!this.childVisible) { | ||
| let {z} = this; | ||
| if (z < maxZ && z >= minZ) { | ||
| // Adjust LOD by distance to camera | ||
| const distance = | ||
| (boundingVolume.distanceTo(viewport.cameraPosition) * viewport.scale) / viewport.height; | ||
| z += Math.floor(Math.log2(distance)); | ||
| } | ||
| if (z >= maxZ) { | ||
| // LOD is acceptable | ||
| this.selected = true; | ||
| return true; | ||
| } | ||
| } | ||
|
|
||
| // LOD is not enough, recursively test child tiles | ||
| this.selected = false; | ||
| this.childVisible = true; | ||
| for (const child of this.children) { | ||
| child.update(params); | ||
| } | ||
| return true; | ||
| } | ||
|
|
||
| getSelected(result = []) { | ||
| if (this.selected) { | ||
| result.push(this); | ||
| } | ||
| if (this._children) { | ||
| for (const node of this._children) { | ||
| node.getSelected(result); | ||
| } | ||
| } | ||
| return result; | ||
| } | ||
|
|
||
| getBoundingVolume(zRange, worldOffset) { | ||
| const scale = Math.pow(2, this.z); | ||
| const extent = TILE_SIZE / scale; | ||
| const originX = this.x * extent + worldOffset * TILE_SIZE; | ||
| // deck's common space is y-flipped | ||
| const originY = TILE_SIZE - (this.y + 1) * extent; | ||
|
|
||
| return new AxisAlignedBoundingBox( | ||
| [originX, originY, zRange[0]], | ||
| [originX + extent, originY + extent, zRange[1]] | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| export function getOSMTileIndices(viewport, maxZ, zRange) { | ||
| // Get the culling volume of the current camera | ||
| const planes = Object.values(viewport.getFrustumPlanes()).map( | ||
| ({normal, distance}) => new Plane(normal.clone().negate(), distance) | ||
| ); | ||
| const cullingVolume = new CullingVolume(planes); | ||
|
|
||
| // Project zRange from meters to common space | ||
| const unitsPerMeter = viewport.distanceScales.unitsPerMeter[2]; | ||
| const elevationMin = (zRange && zRange[0] * unitsPerMeter) || 0; | ||
| const elevationMax = (zRange && zRange[1] * unitsPerMeter) || 0; | ||
|
|
||
| // Always load at the current zoom level if pitch is small | ||
| const minZ = viewport.pitch <= 60 ? maxZ : 0; | ||
|
|
||
| const root = new OSMNode(0, 0, 0); | ||
| const traversalParams = { | ||
| viewport, | ||
| cullingVolume, | ||
| elevationBounds: [elevationMin, elevationMax], | ||
| minZ, | ||
| maxZ, | ||
| offset: 0 | ||
| }; | ||
|
|
||
| root.update(traversalParams); | ||
|
|
||
| // Check worlds in repeated maps | ||
| traversalParams.offset = -1; | ||
| while (root.update(traversalParams)) { | ||
| if (--traversalParams.offset < -MAX_MAPS) { | ||
| break; | ||
| } | ||
| } | ||
| traversalParams.offset = 1; | ||
| while (root.update(traversalParams)) { | ||
| if (++traversalParams.offset > -MAX_MAPS) { | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| return root.getSelected(); | ||
| } |
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