AWS-Dem-Downloader/terrain_viewer.html at main · orcunkok/AWS-Dem-Downloader · GitHub

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Manual Tile Viewer</title>
    <style>
      html,
      body {
        height: 100%;
        margin: 0;
        padding: 0;
        overflow: hidden; /* Prevent body scrollbars */
        font-family: sans-serif;
        background-color: #eee; /* Background for area outside map */
      }
      #map-container {
        position: relative; /* Context for absolute positioning inside */
        width: 100%;
        height: 100%;
        overflow: hidden; /* Crucial: Clips the tile-grid */
        cursor: grab; /* Indicate draggable */
        background-color: #ccc; /* Fallback if tiles don't load */
      }
      #map-container.dragging {
        cursor: grabbing;
      }
      #tile-grid {
        position: absolute;
        top: 0;
        left: 0;
        width: 1px; /* Will be effectively infinite */
        height: 1px;
        will-change: transform; /* Hint for performance */
        user-select: none; /* Prevent text selection during drag */
        -webkit-user-select: none;
        -ms-user-select: none;
        transform: translate3d(0, 0, 0); /* Force GPU acceleration */
      }
      .tile-image {
        position: absolute;
        width: 256px; /* Standard tile size */
        height: 256px;
        user-select: none; /* Prevent image selection */
        -webkit-user-select: none;
        -ms-user-select: none;
        pointer-events: none; /* Prevent image interference with dragging */
        background-color: #0a1a33; /* Slightly lighter shade of the main color */
        backface-visibility: hidden; /* Performance boost */
        border: 0.1px solid rgba(255, 255, 255, 0.8); /* Add white border with transparency */
        box-sizing: border-box; /* Make sure border is included in the width/height */
      }
      .tile-coords {
        position: absolute;
        top: 2px;
        right: 2px;
        color: #f7c1cc;
        font-size: 12px;
        font-weight: bold;
        padding: 1px 3px;
        border-radius: 2px;
        pointer-events: none;
        z-index: 1; /* Above tile image */
        white-space: nowrap;
      }
      /* Custom zoom controls (same as before) */
      .custom-zoom {
        position: absolute;
        top: 10px;
        left: 10px;
        z-index: 1000;
        background: white;
        border: 1px solid #ccc;
        border-radius: 4px;
        box-shadow: 0 1px 5px rgba(0, 0, 0, 0.65);
      }
      .custom-zoom button {
        display: block;
        width: 30px;
        height: 30px;
        font-size: 18px;
        font-weight: bold;
        border: none;
        background-color: white;
        cursor: pointer;
        line-height: 30px;
        text-align: center;
      }
      .custom-zoom button:first-child {
        border-bottom: 1px solid #ccc;
        border-radius: 4px 4px 0 0;
      }
      .custom-zoom button:last-child {
        border-radius: 0 0 4px 4px;
      }
      .custom-zoom button:hover {
        background-color: #f4f4f4;
      }
      .custom-zoom button:disabled {
        cursor: default;
        background-color: #eee;
        color: #aaa;
      }

      #loading-indicator {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        background-color: rgba(255, 255, 255, 0.8);
        padding: 10px 20px;
        border-radius: 5px;
        z-index: 2000;
        display: none; /* Hidden by default */
      }

      /* Stats card */
      #stats-card {
        position: absolute;
        bottom: 10px;
        right: 10px;
        background-color: rgba(255, 255, 255, 0.8);
        padding: 8px 12px;
        border-radius: 4px;
        font-size: 12px;
        box-shadow: 0 1px 5px rgba(0, 0, 0, 0.4);
        z-index: 1000;
        max-width: 250px;
        line-height: 1.4;
      }
      #stats-card table {
        margin: 0;
        border-collapse: collapse;
      }
      #stats-card td {
        padding: 2px 5px;
      }
      #stats-card td:first-child {
        font-weight: bold;
        padding-right: 10px;
      }
    </style>
  </head>
  <body>
    <div id="map-container">
      <div id="tile-grid"></div>
    </div>

    <div class="custom-zoom">
      <button id="zoom-in" title="Zoom in">+</button>
      <button id="zoom-out" title="Zoom out">-</button>
    </div>

    <div id="loading-indicator">Loading...</div>

    <div id="stats-card">
      <table>
        <tr>
          <td>FPS:</td>
          <td id="fps-value">0</td>
        </tr>
        <tr>
          <td>Center:</td>
          <td id="center-value">0.000, 0.000</td>
        </tr>
        <tr>
          <td>Zoom:</td>
          <td id="zoom-value">0</td>
        </tr>
        <tr>
          <td>Tiles:</td>
          <td id="tiles-value">0</td>
        </tr>
        <tr>
          <td>Memory:</td>
          <td id="memory-value">0 MB</td>
        </tr>
      </table>
    </div>

    <script>
      // --- Configuration ---
      const tilesJsonPath = "./terrain_tiles/tiles.json"; // Adjust if needed
      const tilePath = "./terrain_tiles/{z}/{x}/{y}.png"; // Adjust if needed
      const TILE_SIZE = 256; // Pixel dimensions of a tile
      const TILE_BUFFER = 1; // Buffer of tiles to load around viewport
      const TILE_MEMORY_ESTIMATE = 0.25; // Estimated MB per tile

      // --- DOM Elements ---
      const mapContainer = document.getElementById("map-container");
      const tileGrid = document.getElementById("tile-grid");
      const zoomInButton = document.getElementById("zoom-in");
      const zoomOutButton = document.getElementById("zoom-out");
      const loadingIndicator = document.getElementById("loading-indicator");

      // Stats elements
      const fpsValue = document.getElementById("fps-value");
      const centerValue = document.getElementById("center-value");
      const zoomValue = document.getElementById("zoom-value");
      const tilesValue = document.getElementById("tiles-value");
      const memoryValue = document.getElementById("memory-value");

      // --- State Variables ---
      let config = null; // To store loaded tiles.json data
      let currentZoom = 10; // Initial default zoom
      let minZoom = 0;
      let maxZoom = 15;
      // Offset of the tile grid's top-left corner relative to the container's top-left
      let gridOffsetX = 0;
      let gridOffsetY = 0;
      let viewportWidth = mapContainer.clientWidth;
      let viewportHeight = mapContainer.clientHeight;
      let isDragging = false;
      let startDragX = 0;
      let startDragY = 0;
      let startGridX = 0;
      let startGridY = 0;
      let tileLoadCounter = 0; // To track async tile loading
      let visibleTiles = 0; // Number of tiles currently visible
      let lastFrameTime = 0; // For FPS calculation
      let frameCount = 0; // For FPS calculation
      let fps = 0; // Current FPS
      let tileCache = new Map(); // Cache for tile elements
      let loadVisibleTilesDebounced = null; // For debouncing tile loading
      let animationFrameId = null; // For animation frame

      // --- Utility Functions ---

      // Convert lat/lon to tile coordinates (from your utils)
      function deg2num(lat_deg, lon_deg, zoom) {
        const lat_rad = (lat_deg * Math.PI) / 180;
        const n = Math.pow(2, zoom);
        const xtile = Math.floor(((lon_deg + 180.0) / 360.0) * n);
        const ytile = Math.floor(
          ((1.0 - Math.asinh(Math.tan(lat_rad)) / Math.PI) / 2.0) * n
        );
        return { x: xtile, y: ytile };
      }

      // Convert tile coordinates to lat/lon
      function num2deg(xtile, ytile, zoom) {
        const n = Math.pow(2, zoom);
        const lon_deg = (xtile / n) * 360.0 - 180.0;
        const lat_rad = Math.atan(Math.sinh(Math.PI * (1 - (2 * ytile) / n)));
        const lat_deg = (lat_rad * 180.0) / Math.PI;
        return { lat: lat_deg, lon: lon_deg };
      }

      // Debounce function to limit how often a function is called
      function debounce(func, wait) {
        let timeout;
        return function (...args) {
          clearTimeout(timeout);
          timeout = setTimeout(() => func.apply(this, args), wait);
        };
      }

      // --- Core Logic ---

      function updateGridTransform() {
        // Use translate3d for hardware acceleration
        tileGrid.style.transform = `translate3d(${gridOffsetX}px, ${gridOffsetY}px, 0)`;

        // Update center coordinates in stats
        updateCenterCoordinates();
      }

      function updateCenterCoordinates() {
        // Calculate the center point in tile coordinates
        const centerGridX = -gridOffsetX + viewportWidth / 2;
        const centerGridY = -gridOffsetY + viewportHeight / 2;

        // Convert to tile indices
        const tileX = centerGridX / TILE_SIZE;
        const tileY = centerGridY / TILE_SIZE;

        // Convert to geographic coordinates
        const geoCoords = num2deg(tileX, tileY, currentZoom);

        // Update the display
        centerValue.textContent = `${geoCoords.lat.toFixed(
          5
        )}, ${geoCoords.lon.toFixed(5)}`;
        zoomValue.textContent = currentZoom;
      }

      function showLoading(show) {
        loadingIndicator.style.display = show ? "block" : "none";
      }

      function loadVisibleTiles() {
        if (!config) return; // Need config first
        showLoading(true);
        tileLoadCounter = 0; // Reset counter

        // Calculate the pixel bounds of the visible area in the grid's coordinate system
        const viewMinX = -gridOffsetX;
        const viewMinY = -gridOffsetY;
        const viewMaxX = viewMinX + viewportWidth;
        const viewMaxY = viewMinY + viewportHeight;

        // Calculate the range of tile indices needed
        // Add a buffer of tiles around the viewport for smoother panning
        const minTileX = Math.floor(viewMinX / TILE_SIZE) - TILE_BUFFER;
        const maxTileX = Math.ceil(viewMaxX / TILE_SIZE) + TILE_BUFFER;
        const minTileY = Math.floor(viewMinY / TILE_SIZE) - TILE_BUFFER;
        const maxTileY = Math.ceil(viewMaxY / TILE_SIZE) + TILE_BUFFER;

        const maxTileIndexAtZoom = Math.pow(2, currentZoom);
        let tilesToLoad = 0;
        let newTiles = new Set(); // Track tiles we're about to create

        // First pass: identify tiles we need
        for (let x = minTileX; x <= maxTileX; x++) {
          for (let y = minTileY; y <= maxTileY; y++) {
            // Wrap tile indices if necessary
            const wrappedX =
              ((x % maxTileIndexAtZoom) + maxTileIndexAtZoom) %
              maxTileIndexAtZoom;
            // Clamp Y coordinate
            if (y < 0 || y >= maxTileIndexAtZoom) {
              continue;
            }

            const tileKey = `${currentZoom}/${wrappedX}/${y}`;
            newTiles.add(tileKey);

            // Skip if this tile is already in the DOM
            if (tileCache.has(tileKey)) {
              continue;
            }

            tilesToLoad++;
            const tileUrl = tilePath
              .replace("{z}", currentZoom)
              .replace("{x}", wrappedX)
              .replace("{y}", y);

            const tile = document.createElement("img");
            tile.className = "tile-image";
            tile.src = tileUrl;
            tile.style.left = `${x * TILE_SIZE}px`; // Use original x for positioning
            tile.style.top = `${y * TILE_SIZE}px`;
            tile.dataset.z = currentZoom;
            tile.dataset.x = wrappedX; // Store wrapped coords
            tile.dataset.y = y;
            tile.loading = "lazy"; // Basic browser optimization
            tile.decoding = "async"; // Use async decoding for better performance

            // Add coordinate label
            const coordsLabel = document.createElement("div");
            coordsLabel.className = "tile-coords";
            coordsLabel.textContent = tileKey;
            coordsLabel.style.left = `${x * TILE_SIZE}px`; // Position label with tile
            coordsLabel.style.top = `${y * TILE_SIZE}px`;

            // Handle tile loading completion/error
            const onTileLoadOrError = () => {
              tileLoadCounter++;
              if (tileLoadCounter >= tilesToLoad) {
                showLoading(false);
              }
            };
            tile.onload = onTileLoadOrError;
            tile.onerror = () => {
              tile.style.backgroundColor = "#080929"; // Indicate error visually
              console.warn(`Failed to load tile: ${tileUrl}`);
              onTileLoadOrError(); // Still count it as "processed"
            };

            tileGrid.appendChild(tile);
            tileGrid.appendChild(coordsLabel);

            // Store in cache
            tileCache.set(tileKey, { tile, label: coordsLabel });
          }
        }

        // Second pass: remove tiles that are no longer visible
        for (const [tileKey, elements] of tileCache.entries()) {
          if (!newTiles.has(tileKey)) {
            // Remove from DOM and cache
            tileGrid.removeChild(elements.tile);
            tileGrid.removeChild(elements.label);
            tileCache.delete(tileKey);
          }
        }

        // Update stats
        visibleTiles = tileCache.size;
        tilesValue.textContent = visibleTiles;
        memoryValue.textContent = `~${Math.round(
          visibleTiles * TILE_MEMORY_ESTIMATE
        )} MB`;

        if (tilesToLoad === 0) {
          showLoading(false); // Hide if no tiles were even attempted
        }
      }

      function handleZoom(zoomIn) {
        const newZoom = zoomIn ? currentZoom + 1 : currentZoom - 1;

        if (newZoom < minZoom || newZoom > maxZoom) {
          return; // Zoom level out of bounds
        }

        // 1. Calculate the pixel coordinates of the viewport center relative to the current grid
        const centerGridX = -gridOffsetX + viewportWidth / 2;
        const centerGridY = -gridOffsetY + viewportHeight / 2;

        // 2. Calculate the scaling factor between zoom levels
        const scaleFactor = Math.pow(2, newZoom - currentZoom);

        // 3. Calculate the equivalent pixel coordinates in the new zoom level's grid
        const newCenterGridX = centerGridX * scaleFactor;
        const newCenterGridY = centerGridY * scaleFactor;

        // 4. Calculate the new grid offset to keep the new center point aligned with the viewport center
        gridOffsetX = viewportWidth / 2 - newCenterGridX;
        gridOffsetY = viewportHeight / 2 - newCenterGridY;

        // 5. Update state and reload
        currentZoom = newZoom;

        // Clear tile cache when zoom changes
        tileCache.clear();
        tileGrid.innerHTML = "";

        updateGridTransform();
        loadVisibleTiles();
        updateZoomButtons();
      }

      function updateZoomButtons() {
        zoomInButton.disabled = currentZoom >= maxZoom;
        zoomOutButton.disabled = currentZoom <= minZoom;
      }

      function updateFPS(timestamp) {
        if (!lastFrameTime) {
          lastFrameTime = timestamp;
          frameCount = 0;
        }

        frameCount++;

        // Update FPS every second
        if (timestamp - lastFrameTime >= 1000) {
          fps = Math.round((frameCount * 1000) / (timestamp - lastFrameTime));
          fpsValue.textContent = fps;
          frameCount = 0;
          lastFrameTime = timestamp;
        }

        animationFrameId = requestAnimationFrame(updateFPS);
      }

      // --- Event Handlers ---

      function onMouseDown(event) {
        // Prevent default image dragging behavior
        if (event.target.tagName === "IMG") {
          event.preventDefault();
        }
        isDragging = true;
        startDragX = event.clientX;
        startDragY = event.clientY;
        startGridX = gridOffsetX;
        startGridY = gridOffsetY;
        mapContainer.classList.add("dragging");
        // Add listeners to the window to catch mouse movements/mouseup outside the container
        window.addEventListener("mousemove", onMouseMove, { passive: true });
        window.addEventListener("mouseup", onMouseUp);
      }

      function onMouseMove(event) {
        if (!isDragging) return;
        const dx = event.clientX - startDragX;
        const dy = event.clientY - startDragY;
        gridOffsetX = startGridX + dx;
        gridOffsetY = startGridY + dy;
        updateGridTransform();
        // Use debounced version for better performance during drag
        loadVisibleTilesDebounced();
      }

      function onMouseUp(event) {
        if (!isDragging) return;
        isDragging = false;
        mapContainer.classList.remove("dragging");
        window.removeEventListener("mousemove", onMouseMove);
        window.removeEventListener("mouseup", onMouseUp);
        // Reload tiles now that dragging stopped
        loadVisibleTiles();
      }

      function onResize() {
        viewportWidth = mapContainer.clientWidth;
        viewportHeight = mapContainer.clientHeight;
        loadVisibleTiles();
      }

      // Touch event handlers for mobile support
      function onTouchStart(event) {
        if (event.touches.length !== 1) return;
        event.preventDefault();
        isDragging = true;
        startDragX = event.touches[0].clientX;
        startDragY = event.touches[0].clientY;
        startGridX = gridOffsetX;
        startGridY = gridOffsetY;
        mapContainer.classList.add("dragging");
      }

      function onTouchMove(event) {
        if (!isDragging || event.touches.length !== 1) return;
        const dx = event.touches[0].clientX - startDragX;
        const dy = event.touches[0].clientY - startDragY;
        gridOffsetX = startGridX + dx;
        gridOffsetY = startGridY + dy;
        updateGridTransform();
        loadVisibleTilesDebounced();
      }

      function onTouchEnd(event) {
        if (!isDragging) return;
        isDragging = false;
        mapContainer.classList.remove("dragging");
        loadVisibleTiles();
      }

      // --- Initialization ---
      function initializeMap() {
        showLoading(true);

        // Create debounced version of loadVisibleTiles
        loadVisibleTilesDebounced = debounce(loadVisibleTiles, 100);

        // Start FPS counter
        animationFrameId = requestAnimationFrame(updateFPS);

        fetch(tilesJsonPath)
          .then((response) => {
            if (!response.ok)
              throw new Error(
                `HTTP ${response.status} fetching ${tilesJsonPath}`
              );
            return response.json();
          })
          .then((jsonConfig) => {
            config = jsonConfig;
            minZoom = config.minzoom ?? 0;
            maxZoom = config.maxzoom ?? 15;
            currentZoom = config.center
              ? Math.max(
                  minZoom,
                  Math.min(maxZoom, Math.round(config.center[2]))
                )
              : minZoom;

            // Calculate initial center tile and pixel offset
            const centerLon = config.center ? config.center[0] : 0;
            const centerLat = config.center ? config.center[1] : 0;
            const centerTile = deg2num(centerLat, centerLon, currentZoom);

            // Calculate offset to place the *center* of the center tile at the viewport center
            gridOffsetX =
              viewportWidth / 2 - centerTile.x * TILE_SIZE - TILE_SIZE / 2;
            gridOffsetY =
              viewportHeight / 2 - centerTile.y * TILE_SIZE - TILE_SIZE / 2;

            console.log(
              `Initial Zoom: ${currentZoom}, Center Tile: ${centerTile.x},${
                centerTile.y
              }, Offset: ${gridOffsetX.toFixed(1)},${gridOffsetY.toFixed(1)}`
            );

            updateGridTransform();
            loadVisibleTiles();
            updateZoomButtons();

            // Setup event listeners
            mapContainer.addEventListener("mousedown", onMouseDown);
            mapContainer.addEventListener("touchstart", onTouchStart, {
              passive: false,
            });
            mapContainer.addEventListener("touchmove", onTouchMove, {
              passive: true,
            });
            mapContainer.addEventListener("touchend", onTouchEnd);
            zoomInButton.addEventListener("click", () => handleZoom(true));
            zoomOutButton.addEventListener("click", () => handleZoom(false));

            // Use passive event listener for better scroll performance
            window.addEventListener("resize", onResize, { passive: true });

            // Add wheel zoom support
            mapContainer.addEventListener(
              "wheel",
              (e) => {
                e.preventDefault();
                handleZoom(e.deltaY < 0);
              },
              { passive: false }
            );
          })
          .catch((error) => {
            console.error("Initialization failed:", error);
            mapContainer.innerHTML = `<p style="color: red; padding: 20px;">Error loading map configuration: ${error.message}. Check console and ensure '${tilesJsonPath}' is accessible.</p>`;
            showLoading(false);
          });
      }

      // Start initialization when the DOM is ready
      document.addEventListener("DOMContentLoaded", initializeMap);

      // Clean up on page unload
      window.addEventListener("beforeunload", () => {
        if (animationFrameId) {
          cancelAnimationFrame(animationFrameId);
        }
        tileCache.clear();
      });
    </script>
  </body>
</html>