yet-another-cad-viewer/frontend/tools/selection.ts

// Model management from the graphics side

import type {MObject3D} from "./Selection.vue";
import type {Intersection} from "three";
import {Box3} from "three";

/** Information about a single item in the selection */
export class SelectionInfo {
    /** The object which was (partially) selected */
    object: MObject3D
    /** The type of the selection */
    kind: 'face' | 'edge' | 'vertex'
    /** Start and end indices of the primitives in the geometry */
    indices: [number, number]

    constructor(object: MObject3D, kind: 'face' | 'edge' | 'vertex', indices: [number, number]) {
        this.object = object;
        this.kind = kind;
        this.indices = indices;
    }

    public getKey() {
        return this.object.uuid + this.kind + this.indices[0].toFixed() + this.indices[1].toFixed();
    }

    public getBox(): Box3 {
        let index = this.object.geometry.index || {getX: (i: number) => i};
        let pos = this.object.geometry.getAttribute('position');
        let min = [Infinity, Infinity, Infinity];
        let max = [-Infinity, -Infinity, -Infinity];
        for (let i = this.indices[0]; i < this.indices[1]; i++) {
            let vertIndex = index!.getX(i);
            let x = pos.getX(vertIndex);
            let y = pos.getY(vertIndex);
            let z = pos.getZ(vertIndex);
            min[0] = Math.min(min[0], x);
            min[1] = Math.min(min[1], y);
            min[2] = Math.min(min[2], z);
            max[0] = Math.max(max[0], x);
            max[1] = Math.max(max[1], y);
            max[2] = Math.max(max[2], z);
        }
        return new Box3().setFromArray([...min, ...max]);
    }
}

export function hitToSelectionInfo(hit: Intersection<MObject3D>): SelectionInfo | null {
    let kind = hit.object.type;
    if (kind == 'Mesh' || kind == 'SkinnedMesh') {
        let indices = hitFaceTriangleIndices(hit);
        if (indices === null) return null;
        return new SelectionInfo(hit.object, 'face', indices);
    } else if (kind == 'Line' || kind == 'LineSegments') {
        // Select raw lines, not the wide meshes representing them
        // This is because the indices refer to the raw lines, not the wide meshes
        // Furthermore, this allows better "fuzzy" raycasting logic
        let indices = hitEdgePointIndices(hit);
        if (indices === null) return null;
        return new SelectionInfo(hit.object, 'edge', indices);
    } else if (kind == 'Points') {
        if (hit.index === undefined) return null;
        return new SelectionInfo(hit.object, 'vertex', [hit.index, hit.index + 1]);
    }
    return null;
}

function hitFaceTriangleIndices(hit: Intersection<MObject3D>): [number, number] | null {
    let faceTrianglesEnd = hit?.object?.geometry?.userData?.face_triangles_end;
    if (hit.faceIndex === undefined) return null;
    if (!faceTrianglesEnd) { // Fallback to selecting the whole imported mesh
        //console.log("No face_triangles_end found, selecting the whole mesh");
        return [0, (hit.object.geometry.index ?? hit.object.geometry.attributes.position).count];
    } else { // Normal CAD model
        let rawIndex = hit.faceIndex * 3; // Faces are triangles with 3 indices
        for (let i = 0; i < faceTrianglesEnd.length; i++) {
            let faceSwapIndex = faceTrianglesEnd[i]
            if (rawIndex < faceSwapIndex) {
                let start = i === 0 ? 0 : faceTrianglesEnd[i - 1];
                return [start, faceTrianglesEnd[i]];
            }
        }
    }
    return null;
}

function hitEdgePointIndices(hit: Intersection<MObject3D>): [number, number] | null {
    let edgePointsEnd = hit?.object?.geometry?.userData?.edge_points_end;
    if (!edgePointsEnd || hit.index === undefined) return null;
    let rawIndex = hit.index; // Faces are triangles with 3 indices
    for (let i = 0; i < edgePointsEnd.length; i++) {
        let edgeSwapIndex = edgePointsEnd[i]
        if (rawIndex < edgeSwapIndex) {
            let start = i === 0 ? 0 : edgePointsEnd[i - 1];
            return [start, edgePointsEnd[i]];
        }
    }
    return null;
}

function applyColor(selInfo: SelectionInfo, colorAttribute: any, color: [number, number, number, number]): [number, number, number, number] {
    let index = selInfo.object.geometry.index
    let prevColor: [number, number, number, number] | null = null;
    if (colorAttribute !== undefined) {
        for (let i = selInfo.indices[0]; i < selInfo.indices[1]; i++) {
            let vertIndex = index!.getX(i);
            if (prevColor === null) prevColor = [colorAttribute.getX(vertIndex), colorAttribute.getY(vertIndex), colorAttribute.getZ(vertIndex), colorAttribute.getW(vertIndex)];
            colorAttribute.setXYZW(vertIndex, color[0], color[1], color[2], color[3]);
        }
        colorAttribute.needsUpdate = true;
        if (selInfo.object.userData.niceLine !== undefined) {
            // Need to update the color of the nice line as well
            let indexAttribute = selInfo.object.geometry.index!!;
            let allNewColors = [];
            for (let i = 0; i < indexAttribute.count; i++) {
                if (indexAttribute.getX(i) >= selInfo.indices[0] && indexAttribute.getX(i) < selInfo.indices[1]) {
                    allNewColors.push(color[0], color[1], color[2]);
                } else {
                    allNewColors.push(colorAttribute.getX(indexAttribute.getX(i)), colorAttribute.getY(indexAttribute.getX(i)), colorAttribute.getZ(indexAttribute.getX(i)));
                }
            }
            selInfo.object.userData.niceLine.geometry.setColors(allNewColors);
            for (let attribute of Object.values(selInfo.object.userData.niceLine.geometry.attributes)) {
                (attribute as any).needsUpdate = true;
            }
        }
    } else { // Fallback to tinting the whole mesh for imported models
        //console.log("No color attribute found, tinting the whole mesh")
        let tmpPrevColor = selInfo.object.material.color;
        prevColor = [tmpPrevColor.r, tmpPrevColor.g, tmpPrevColor.b, 1];
        selInfo.object.material.color.setRGB(color[0], color[1], color[2]);
        selInfo.object.material.needsUpdate = true;
    }
    return prevColor!;
}

export function highlight(selInfo: SelectionInfo): void {
    // Update the color of all the triangles in the face
    let geometry = selInfo.object.geometry;
    let colorAttr = selInfo.object.geometry.getAttribute('color');
    geometry.userData.savedColor = geometry.userData.savedColor || {};
    geometry.userData.savedColor[selInfo.getKey()] = applyColor(selInfo, colorAttr, [1.0, 0.0, 0.0, 1.0]);
}

export function highlightUndo(selInfo: SelectionInfo): void {
    // Update the color of all the triangles in the face
    let geometry = selInfo.object.geometry;
    let colorAttr = selInfo.object.geometry.getAttribute('color');
    let savedColor = geometry.userData.savedColor[selInfo.getKey()];
    applyColor(selInfo, colorAttr, savedColor);
    delete geometry.userData.savedColor[selInfo.getKey()];
}