src/engine/RenderLoop.js

import * as THREE from 'three';
import { STATE } from '../core/State.js';
import { updateNavigation } from './Navigation.js';
import { raycaster } from './Interaction.js';
import { getActiveReliefObjects } from '../visualizer/ReliefRenderer.js';
import { updateHUD } from '../ui/HUD.js';
import { renderAxisGizmo } from './AxisGizmo.js';

let rafId = null;

/**
 * Starts the main requestAnimationFrame loop: navigation, raycast selection,
 * relief HUD per-frame updates, HUD refresh, and scene render.
 *
 * Relief index/HUD helpers are injected so H11.2 can relocate them to
 * ReliefHUDController without touching the loop wiring again.
 */
export function startRenderLoop({
  scene,
  camera,
  renderer,
  controls,
  computeReliefIndices,
  fillReliefHUD,
}) {
  stopRenderLoop();

  const clock = new THREE.Clock();
  const lastCamPos = new THREE.Vector3();
  const lastCamRot = new THREE.Euler();
  let lastIntersects = [];

  function frame() {
    rafId = requestAnimationFrame(frame);
    if (!STATE.isReady) return;

    const delta = Math.min(clock.getDelta(), 0.1);

    if (STATE.engineMode === 'MICRO') {
      STATE.threads.forEach(t => {
        if (t.uniforms) t.uniforms.highlightIndex.value = STATE.currentSelectedIndex;
      });
    }

    const isRelief = (STATE.layoutMode === 'BLANKET' || STATE.layoutMode === 'COMPARE');
    const isReliefInteractive = isRelief && STATE.comparisonMode !== 'C';

    if (controls.isLocked) {
      updateNavigation(camera, controls, delta);

      const crosshair = document.getElementById('hud-crosshair');

      const positionChanged = lastCamPos.distanceToSquared(camera.position) > 0.0001;
      const rotationChanged = Math.abs(lastCamRot.x - camera.rotation.x) +
                             Math.abs(lastCamRot.y - camera.rotation.y) +
                             Math.abs(lastCamRot.z - camera.rotation.z) > 0.0001;

      let intersects = lastIntersects;

      if (positionChanged || rotationChanged) {
        raycaster.setFromCamera(new THREE.Vector2(0, 0), camera);

        if (isRelief) {
          const reliefObjects = getActiveReliefObjects();
          intersects = raycaster.intersectObjects(reliefObjects, false);
        } else if (STATE.engineMode === 'MACRO') {
          if (STATE.macroMeshes && STATE.macroMeshes.points) {
            intersects = raycaster.intersectObject(STATE.macroMeshes.points);
          } else {
            intersects = [];
          }
        } else {
          const meshes = [];
          STATE.threads.forEach(t => {
            if (t.pointsMesh && t.pointsMesh.visible) meshes.push(t.pointsMesh);
          });
          intersects = raycaster.intersectObjects(meshes, false);
        }

        lastCamPos.copy(camera.position);
        lastCamRot.copy(camera.rotation);
        lastIntersects = intersects;
      }

      if (STATE.isTargetLocked) {
        if (crosshair) {
          crosshair.style.borderColor = 'var(--color-semantic-error)';
          const dot = crosshair.querySelector('div');
          if (dot) dot.style.background = 'var(--color-semantic-error)';
        }
        if (isReliefInteractive && STATE.reliefPinned) {
          fillReliefHUD(STATE.reliefPinned.chunkIndex, STATE.reliefPinned.dimIndex, true, STATE.reliefPinned.source);
        }
      } else if (intersects.length > 0) {
        if (crosshair) {
          crosshair.style.borderColor = 'var(--color-semantic-warning)';
          const dot = crosshair.querySelector('div');
          if (dot) dot.style.background = 'var(--color-semantic-warning)';
        }

        const hit = intersects[0];

        if (isReliefInteractive) {
          const indices = computeReliefIndices(hit);
          if (indices) {
            STATE.reliefHover = indices;
            if (!STATE.reliefPinned) {
              STATE.currentSelectedIndex = indices.dimIndex;
              fillReliefHUD(indices.chunkIndex, indices.dimIndex, false);
            } else {
              fillReliefHUD(STATE.reliefPinned.chunkIndex, STATE.reliefPinned.dimIndex, true, STATE.reliefPinned.source);
            }
          }
        } else if (STATE.engineMode === 'MACRO') {
          if (hit.index !== undefined) {
            const firstThread = STATE.threads[0];
            const len = firstThread && firstThread.embedding ? firstThread.embedding.length : 0;
            if (len > 0) STATE.currentSelectedIndex = hit.index % len;
          }
        } else if (hit.index !== undefined) {
          STATE.currentSelectedIndex = hit.index;
        }
      } else {
        if (crosshair) {
          crosshair.style.borderColor = 'var(--color-semantic-success)';
          const dot = crosshair.querySelector('div');
          if (dot) dot.style.background = 'var(--color-semantic-success)';
        }

        if (isReliefInteractive && STATE.reliefPinned) {
          fillReliefHUD(STATE.reliefPinned.chunkIndex, STATE.reliefPinned.dimIndex, true, STATE.reliefPinned.source);
        } else {
          const hudEl = document.getElementById('relief-hud');
          if (hudEl && isRelief) hudEl.style.display = 'none';
          const coordsEl = document.getElementById('relief-coords');
          if (coordsEl) coordsEl.style.display = 'none';
        }
      }
    } else {
      if (isReliefInteractive && STATE.reliefPinned) {
        fillReliefHUD(STATE.reliefPinned.chunkIndex, STATE.reliefPinned.dimIndex, true, STATE.reliefPinned.source);
        const coordsEl = document.getElementById('relief-coords');
        if (coordsEl) coordsEl.style.display = 'none';
      } else {
        const hudEl = document.getElementById('relief-hud');
        if (hudEl) hudEl.style.display = 'none';
        const coordsEl = document.getElementById('relief-coords');
        if (coordsEl) coordsEl.style.display = 'none';
      }
    }

    updateHUD(camera);
    renderer.render(scene, camera);
    renderAxisGizmo(renderer, camera);
  }

  rafId = requestAnimationFrame(frame);
}

/** Cancels the active animation frame loop, if any. */
export function stopRenderLoop() {
  if (rafId !== null) {
    cancelAnimationFrame(rafId);
    rafId = null;
  }
}