Method applyLabelCulling

ui/src/components/pixi/PixiRenderer.ts:1281–1368

* Show labels for the given nodes, culling any that overlap a previously * placed label. Nodes are processed largest-first so important nodes win. * * This method ONLY controls visibility. Scale and position are handled by * the update paths (update3D, updatePositionsFromBuffer, applyCou

(candidates: PixiNode[], invScale: number)

   * to avoid jitter from competing writes.
   */
  private applyLabelCulling(candidates: PixiNode[], invScale: number): void {
    // Sort by size descending — largest (highest degree) nodes get labels first
    candidates.sort((a, b) => b.size - a.size);

    const boxes: { x: number; y: number; w: number; h: number }[] = [];
    const lm = this.labelScaleMultiplier;
    const screenLabelScale = invScale * lm * this.vp.scale;
    const labelH = (LABEL_SIZE + 4) * screenLabelScale;

    // Viewport bounds in screen pixels with a small margin so a label
    // partially clipped at the edge still gets a slot — avoids
    // labels popping in/out as you pan across the boundary (Fix #49).
    const VIEWPORT_MARGIN = 80;
    const vpLeft = -VIEWPORT_MARGIN;
    const vpRight = this.width + VIEWPORT_MARGIN;
    const vpTop = -VIEWPORT_MARGIN;
    const vpBottom = this.height + VIEWPORT_MARGIN;

    // Skip labels for nodes whose sprite is too small on screen
    // (Fix #49). At zoom-out the entire graph compresses into a tiny
    // area; without this gate, every node still tries for a label
    // slot and the screen fills with text. Sprite on-screen radius =
    // node.size × vp.scale^(1-zoomSizeExponent). 2.5 px is the
    // current threshold — was 4, lowered so larger anchor nodes get
    // labels at lower zoom levels (overlap cull still keeps the
    // screen from filling with text at extreme zoom-out).
    const MIN_SPRITE_SCREEN_RADIUS = 2.5;
    const spriteRadiusFactor = Math.pow(
      this.vp.scale,
      Math.max(0, 1 - this.zoomSizeExponent),
    );

    for (const node of candidates) {
      // Screen position of the sprite — used for the viewport
      // pre-filter (skip cull work for off-screen labels).
      const cx = node.sprite.position.x * this.vp.scale + this.vp.x;
      const cy = node.sprite.position.y * this.vp.scale + this.vp.y;
      if (cx < vpLeft || cx > vpRight || cy < vpTop || cy > vpBottom) {
        if (node.label) node.label.visible = false;
        continue;
      }

      // Size gate — sprites too small to read don't get labels.
      const spriteScreenRadius = node.size * spriteRadiusFactor;
      if (spriteScreenRadius < MIN_SPRITE_SCREEN_RADIUS) {
        if (node.label) node.label.visible = false;
        continue;
      }

      // World-space gap that lands the label just outside the sprite
      // edge (Fix #27 — the only piece of my label rework that
      // survived the revert; without it the label slides inside the
      // sprite at deep zoom because the sprite is in world coords
      // while the label is screen-pixel-constant).
      const gap = this.labelGap(node);
      const nx = node.sprite.position.x;
      const ny = node.sprite.position.y;