unable to snap bounding box

[abhijitpatil181171]

i have created bounding box and gltf graphic . i also have enable the snap but when i hover my cursor on both gltf as well as bounding box i am unable to snap points out of them .any suggestion to enable snap on them

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• LINK: AccuSnap---core-frontend-link-to-docs
• TAG: imodeljs-docs-question
• SOURCE: https://www.itwinjs.org/reference/core-frontend/locatingelements/accusnap/

[pmconne]

You need to make a pickable graphic and tell AccuSnap what its snappable geometry looks like. https://www.itwinjs.org/reference/core-frontend/views/decorator/getdecorationgeometry/ If problems persist, show your code.

[YashodipD]

Hi @abhijitpatil181171 , below are my assumptions while answering to this question,

• You are using readGltf function which returns GltfGraphic.
• Before you move onto snapping gltf, you have already figured out snapping logic using solid primitives and it is working.

My answer starts here - GltfGraphic returned by readGltf() contains 2 bounding boxes. The type of bounding box is [Range3d] (https://www.itwinjs.org/reference/core-geometry/cartesiangeometry/range3d/). Range3d is an Axis Aligned Bounding Box (AABB) which does not have additional information which Mesh provides for solid primitives. For snapping purpose, you would want to use Oriented Bounding Box (OBB). In iTwin.js closest possible OBB is solid primitive Box . Solid Primitives are snappable also we can transform them in any direction you want.

In snapping - when testDecorationHit() returns true, you can return OBB using getDecorationGeometry(). Here is my example -

  public testDecorationHit(id: Id64String): boolean {
    return this._placedGraphics.has(id); // using Map to store id, RenderGraphic + Solid Bounding Box (Not Axis Aligned)
  }
  public getDecorationGeometry(hit: HitDetail): GeometryStreamProps | undefined {
    if (0 === this._placedGraphics.size) return; // Here I am assuming we are using Map data structure
    if (!this._placedGraphics.has(hit.sourceId)) return undefined; // checking if we have graphics with hit details
    const geometryStream: GeometryStreamProps = []; 
    const gltfGraphic = this._placedGraphics.get(hit.sourceId);
    geometryStream.push(IModelJson.Writer.toIModelJson(gltfGraphic?.OBB));
    return geometryStream;
  }

If still it does not help, please add more details here. Soon we will be releasing official sample for similar glTF snapping, stay tuned!

[abhijitpatil181171]

thanks