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[MAPS3D-869, 870] Refactor conflation and add support for new footpri…
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…nt format (#588)

* Add TriangleGridIndex

* Replace grid with triangle grid

* Add support for new footprint format

* Update and enable render tests

* Lint fixes

* flow fixes
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@mpulkki-mapbox
mpulkki-mapbox authored Jun 8, 2023
1 parent e2b6df8 commit 0342d1c
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Showing 12 changed files with 627 additions and 157 deletions.
4 changes: 2 additions & 2 deletions 3d-style/data/model.js
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ import MercatorCoordinate, {getMetersPerPixelAtLatitude, getLatitudeScale, merca
import Transform from '../../src/geo/transform.js';
import {rotationScaleYZFlipMatrix, getBoxBottomFace, rotationFor3Points, convertModelMatrixForGlobe} from '../util/model_util.js';
import type Point from '@mapbox/point-geometry';
import type GridIndex from 'grid-index';
import type TriangleGridIndex from '../../src/util/triangle_grid_index.js';

export type Sampler = {
minFilter: TextureFilter;
Expand Down Expand Up @@ -81,7 +81,7 @@ export type Mesh = {
export type Footprint = {
vertices: Array<Point>;
indices: Array<number>;
grid: GridIndex;
grid: TriangleGridIndex;
min: Point;
max: Point;
}
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204 changes: 160 additions & 44 deletions 3d-style/source/model_loader.js
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ import earcut from 'earcut';
import window from '../../src/util/window.js';
import {warnOnce, base64DecToArr} from '../../src/util/util.js';
import assert from 'assert';
import GridIndex from 'grid-index';
import TriangleGridIndex from '../../src/util/triangle_grid_index.js';

// From https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#accessor-data-types

Expand Down Expand Up @@ -301,9 +301,6 @@ function convertNode(nodeDesc: Object, gltf: Object, meshes: Array<Array<Mesh>>)
node.meshes = meshes[nodeDesc.mesh];
}
if (nodeDesc.extras) {
if (nodeDesc.extras.ground) {
node.footprint = convertFootprint(nodeDesc.extras.ground);
}
if (nodeDesc.extras.id) {
node.id = nodeDesc.extras.id;
}
Expand Down Expand Up @@ -336,9 +333,48 @@ function convertNode(nodeDesc: Object, gltf: Object, meshes: Array<Array<Mesh>>)
return node;
}

function convertFootprint(groundObject: Object): ?Footprint {
type FootprintMesh = {
vertices: Array<Point>;
indices: Array<number>;
};

function convertFootprint(mesh: FootprintMesh): ?Footprint {
if (mesh.vertices.length === 0 || mesh.indices.length === 0) {
return null;
}

const [min, max] = [mesh.vertices[0].clone(), mesh.vertices[0].clone()];

for (let i = 1; i < mesh.vertices.length; ++i) {
const v = mesh.vertices[i];
min.x = Math.min(min.x, v.x);
min.y = Math.min(min.y, v.y);
max.x = Math.max(max.x, v.x);
max.y = Math.max(max.y, v.y);
}

// Use a fixed size triangle grid (8x8 cells) for acceleration intersection queries
// with an exception that the cell size should never be larger than 256 tile units
// (equals to 32x32 subdivision).
const optimalCellCount = Math.ceil(Math.max(max.x - min.x, max.y - min.y) / 256);
const cellCount = Math.max(8, optimalCellCount);
const grid = new TriangleGridIndex(mesh.vertices, mesh.indices, cellCount);

return {
vertices: mesh.vertices,
indices: mesh.indices,
grid,
min,
max
};
}

function parseLegacyFootprintMesh(gltfNode: Object): ?FootprintMesh {
if (!gltfNode.extras || !gltfNode.extras.ground) {
return null;
}

const groundContainer = groundObject;
const groundContainer = gltfNode.extras.ground;
if (!groundContainer || !Array.isArray(groundContainer) || groundContainer.length === 0) {
return null;
}
Expand Down Expand Up @@ -366,37 +402,23 @@ function convertFootprint(groundObject: Object): ?Footprint {
vertices.push(new Point(x, y));
}

if (vertices.length > 1 && vertices[vertices.length - 1].equals(vertices[0])) {
vertices.pop();
}

if (vertices.length < 3) {
return null;
}

if (vertices.length > 1 && vertices[vertices.length - 1].equals(vertices[0])) {
vertices.pop();
}

// Ensure that the vertex list is defined in CW order
let cross = 0;

const getTriangleBounds = (out: Array<number>, a: Point, b: Point, c: Point) => {
out[0] = Math.min(a.x, b.x, c.x);
out[1] = Math.min(a.y, b.y, c.y);
out[2] = Math.max(a.x, b.x, c.x);
out[3] = Math.max(a.y, b.y, c.y);
};

const minmax = [Number.MAX_VALUE, Number.MAX_VALUE, -Number.MAX_VALUE, -Number.MAX_VALUE];

for (let i = 0; i < vertices.length; i++) {
const a = vertices[i];
const b = vertices[(i + 1) % vertices.length];
const c = vertices[(i + 2) % vertices.length];

cross += (a.x - b.x) * (c.y - b.y) - (c.x - b.x) * (a.y - b.y);

minmax[0] = Math.min(minmax[0], a.x, b.x, c.x);
minmax[1] = Math.min(minmax[1], a.y, b.y, c.y);
minmax[2] = Math.max(minmax[2], a.x, b.x, c.x);
minmax[3] = Math.max(minmax[3], a.y, b.y, c.y);
}

if (cross > 0) {
Expand All @@ -407,32 +429,125 @@ function convertFootprint(groundObject: Object): ?Footprint {
// more performant intersection queries.
const indices = earcut(vertices.flatMap(v => [v.x, v.y]), []);

const min = new Point(minmax[0], minmax[1]);
const max = new Point(minmax[2], minmax[3]);
let gridExtent = Math.max(max.x - min.x, max.y - min.y);
if (indices.length === 0) {
return null;
}

return {vertices, indices};
}

function parseNodeFootprintMesh(meshes: Array<Mesh>): ?FootprintMesh {
const vertices: Array<Point> = [];
const indices: Array<number> = [];

let baseVertex = 0;

if (gridExtent === 0)
gridExtent = 1;
for (const mesh of meshes) {
baseVertex = vertices.length;

const grid = new GridIndex(gridExtent, 8, 0);
const bounds = [];
const vArray = mesh.vertexArray.float32;
const iArray = mesh.indexArray.uint16;

for (let i = 0, idx = 0; i < indices.length; i += 3) {
const v0 = vertices[indices[i + 0]];
const v1 = vertices[indices[i + 1]];
const v2 = vertices[indices[i + 2]];
for (let i = 0; i < mesh.vertexArray.length; i++) {
vertices.push(new Point(vArray[i * 3 + 0], vArray[i * 3 + 1]));
}

getTriangleBounds(bounds, v0, v1, v2);
grid.insert(idx++, bounds[0] - min.x, bounds[1] - min.y, bounds[2] - min.x, bounds[3] - min.y);
for (let i = 0; i < mesh.indexArray.length * 3; i++) {
indices.push(iArray[i] + baseVertex);
}
}

return {
vertices,
indices,
grid,
min,
max
};
if (indices.length % 3 !== 0) {
return null;
}

for (let i = 0; i < indices.length; i += 3) {
const a = vertices[indices[i + 0]];
const b = vertices[indices[i + 1]];
const c = vertices[indices[i + 2]];

if ((a.x - b.x) * (c.y - b.y) - (c.x - b.x) * (a.y - b.y) > 0) {
// $FlowIssue[unsupported-syntax]
[indices[i + 1], indices[i + 2]] = [indices[i + 2], indices[i + 1]];
}
}

return {vertices, indices};
}

function convertFootprints(convertedNodes: Array<Node>, sceneNodes: any, modelNodes: any) {
// modelNodes == a list of nodes in the gltf file
// sceneNodes == an index array pointing to modelNodes being parsed
assert(convertedNodes.length === sceneNodes.length);

// Two different footprint formats are supported:
// 1) Legacy format where footprints are defined as a linestring json
// inside extras-section of the node.
// 2) Version "1" where footprints are included as regular gltf meshes and
// connected to correct models via matching ids.

// Find footprint-only nodes from the list.
const nodeFootprintLookup = {};
const footprintNodeIndices = new Set();

for (let i = 0; i < convertedNodes.length; i++) {
const gltfNode = modelNodes[sceneNodes[i]];

if (!gltfNode.extras) {
continue;
}

const fpVersion = gltfNode.extras["mapbox:footprint:version"];
const fpId = gltfNode.extras["mapbox:footprint:id"];

if (fpVersion || fpId) {
footprintNodeIndices.add(i);
}

if (fpVersion !== "1.0.0" || !fpId) {
continue;
}

nodeFootprintLookup[fpId] = i;
}

// Go through nodes and see if either of the supported footprint formats are defined
for (let i = 0; i < convertedNodes.length; i++) {
if (footprintNodeIndices.has(i)) {
continue;
}

const node = convertedNodes[i];
const gltfNode = modelNodes[sceneNodes[i]];

if (!gltfNode.extras) {
continue;
}

// Prefer footprint nodes over the legacy format
let fpMesh: ?FootprintMesh = null;

if (node.id in nodeFootprintLookup) {
fpMesh = parseNodeFootprintMesh(convertedNodes[nodeFootprintLookup[node.id]].meshes);
}

if (!fpMesh) {
fpMesh = parseLegacyFootprintMesh(gltfNode);
}

if (fpMesh) {
node.footprint = convertFootprint(fpMesh);
}
}

// Remove footprint nodes as they serve no other purpose
if (footprintNodeIndices.size > 0) {
const nodesToRemove = Array.from(footprintNodeIndices.values()).sort((a, b) => a - b);

for (let i = nodesToRemove.length - 1; i >= 0; i--) {
convertedNodes.splice(nodesToRemove[i], 1);
}
}
}

export default function convertModel(gltf: Object): Array<Node> {
Expand All @@ -449,6 +564,7 @@ export default function convertModel(gltf: Object): Array<Node> {
const nodeDesc = gltf.json.nodes[nodeIdx];
nodes.push(convertNode(nodeDesc, gltf, meshes));
}
convertFootprints(nodes, gltfNodes, gltf.json.nodes);
return nodes;
}

Expand Down
54 changes: 23 additions & 31 deletions 3d-style/source/replacement_source.js
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Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ class ReplacementSource {
}

for (const fp of footprints) {
if ((fp.footprint.grid: any).keys.length === 0) {
if (!fp.footprint) {
continue;
}

Expand Down Expand Up @@ -307,39 +307,31 @@ function transformAabbToTile(min: Point, max: Point, id: UnwrappedTileID): {min:
};
}

function footprintTrianglesIntersect(footprint: Footprint, vertices: Array<Point>, indices: Array<number>): boolean {
function footprintTrianglesIntersect(footprint: Footprint, vertices: Array<Point>, indices: Array<number> | Uint16Array, indexOffset: number, indexCount: number, baseVertex: number, padding: number): boolean {
const fpIndices = footprint.indices;
const fpVertices = footprint.vertices;
const candidateTriangles = [];

for (let i = 0; i < indices.length; i += 3) {
const v0 = vertices[indices[i + 0]];
const v1 = vertices[indices[i + 1]];
const v2 = vertices[indices[i + 2]];

// Compute vertices relative to the minimum coordinate of the grid
const gridV0 = new Point(v0.x - footprint.min.x, v0.y - footprint.min.y);
const gridV1 = new Point(v1.x - footprint.min.x, v1.y - footprint.min.y);
const gridV2 = new Point(v2.x - footprint.min.x, v2.y - footprint.min.y);

const mnx = Math.min(gridV0.x, gridV1.x, gridV2.x);
const mxx = Math.max(gridV0.x, gridV1.x, gridV2.x);
const mny = Math.min(gridV0.y, gridV1.y, gridV2.y);
const mxy = Math.max(gridV0.y, gridV1.y, gridV2.y);

const matching = footprint.grid.query(mnx, mny, mxx, mxy, (bx1, by1, bx2, by2) => {
if (mxx < bx1 || mnx > bx2)
return false;
if (mxy < by1 || mny > by2)
return false;
return true;
});
for (let i = indexOffset; i < indexOffset + indexCount; i += 3) {
const a = vertices[indices[i + 0] + baseVertex];
const b = vertices[indices[i + 1] + baseVertex];
const c = vertices[indices[i + 2] + baseVertex];

const mnx = Math.min(a.x, b.x, c.x);
const mxx = Math.max(a.x, b.x, c.x);
const mny = Math.min(a.y, b.y, c.y);
const mxy = Math.max(a.y, b.y, c.y);

candidateTriangles.length = 0;
footprint.grid.query(new Point(mnx, mny), new Point(mxx, mxy), candidateTriangles);

for (const triIdx of matching) {
const a = fpVertices[fpIndices[triIdx * 3 + 0]];
const b = fpVertices[fpIndices[triIdx * 3 + 1]];
const c = fpVertices[fpIndices[triIdx * 3 + 2]];
for (let j = 0; j < candidateTriangles.length; j++) {
const triIdx = candidateTriangles[j];
const v0 = fpVertices[fpIndices[triIdx * 3 + 0]];
const v1 = fpVertices[fpIndices[triIdx * 3 + 1]];
const v2 = fpVertices[fpIndices[triIdx * 3 + 2]];

if (triangleIntersectsTriangle(a, b, c, v0, v1, v2)) {
if (triangleIntersectsTriangle(v0, v1, v2, a, b, c, padding)) {
return true;
}
}
Expand All @@ -349,7 +341,7 @@ function footprintTrianglesIntersect(footprint: Footprint, vertices: Array<Point
}

function footprintsIntersect(a: Footprint, aTile: UnwrappedTileID, b: Footprint, bTile: UnwrappedTileID): boolean {
if ((a.grid: any).keys.length === 0 || (b.grid: any).keys.length === 0) {
if (!a || !b) {
return false;
}

Expand All @@ -373,7 +365,7 @@ function footprintsIntersect(a: Footprint, aTile: UnwrappedTileID, b: Footprint,
});
}

return footprintTrianglesIntersect(b, queryVertices, a.indices);
return footprintTrianglesIntersect(b, queryVertices, a.indices, 0, a.indices.length, 0, 0);
}

export type {TileFootprint, FootprintSource, Region};
Expand Down
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