[extra] add an example using babylon.js

[orion3dgames]

It would be great to have other examples of integration, for example babylon.js :)

It's rather difficult to understand how to modify getPositionsAndIndices() to provide the right data to generateSoloNavMesh();

[orion3dgames]

for anyone looking on how to do this, I got it to work.

getPositionsAndIndices = (meshes: Mesh[]): [positions: Float32Array, indices: Uint32Array] => {
        const toMerge: {
            positions: ArrayLike<number>;
            indices: ArrayLike<number>;
        }[] = [];

        for (const mesh of meshes) {
            const positions = mesh.getVerticesData(VertexBuffer.PositionKind);
            const indices = mesh.getIndices();
            indices.reverse();

            toMerge.push({
                positions,
                indices,
            });
        }
        return this.mergePositionsAndIndices(toMerge);
    };

    mergePositionsAndIndices = (
        meshes: Array<{
            positions: ArrayLike<number>;
            indices: ArrayLike<number>;
        }>
    ): [Float32Array, Uint32Array] => {
        const mergedPositions: number[] = [];
        const mergedIndices: number[] = [];

        const positionToIndex: { [hash: string]: number } = {};
        let indexCounter = 0;

        for (const { positions, indices } of meshes) {
            for (let i = 0; i < indices.length; i++) {
                const pt = indices[i] * 3;

                const x = positions[pt];
                const y = positions[pt + 1];
                const z = positions[pt + 2];

                const key = `${x}_${y}_${z}`;
                let idx = positionToIndex[key];

                if (!idx) {
                    positionToIndex[key] = idx = indexCounter;
                    mergedPositions.push(x, y, z);
                    indexCounter++;
                }

                mergedIndices.push(idx);
            }
        }

        return [Float32Array.from(mergedPositions), Uint32Array.from(mergedIndices)];
    };