dartterm/lib/game/sitemode/camera.dart

part of 'sitemode.dart';

// We render each thing as a 2x2 block.
// We want the player's cell to be
// _actually centered_, and the terminal is an even number of cells across
// So, shifting the camera an extra cell to the north and then
// drawing one extra tile offscreen? That should accomplish it!
const cameraViewWidth = Terminal.width ~/ 2 + 1;
const cameraViewHeight = Terminal.height ~/ 2 + 1;
const cameraMargin =
    4; // how far the camera is from the ideal position before it pans
const cameraTileOffset = geo.Offset(-1, -1);

extension CameraParts on SiteMode {
  void cameraInit() {
    camera = _cameraIdeal();
  }

  void cameraMaintain() {
    var ideal = _cameraIdeal();
    while (camera.x < ideal.x - cameraMargin) {
      camera = geo.Offset(camera.x + 1, camera.y);
    }
    while (camera.x > ideal.x + cameraMargin) {
      camera = geo.Offset(camera.x - 1, camera.y);
    }
    while (camera.y < ideal.y - cameraMargin) {
      camera = geo.Offset(camera.x, camera.y + 1);
    }
    while (camera.y > ideal.y + cameraMargin) {
      camera = geo.Offset(camera.x, camera.y - 1);
    }
  }

  geo.Offset _cameraIdeal() {
    return geo.Offset(playerPosition.x - cameraViewWidth ~/ 2 - 1,
        playerPosition.y - cameraViewHeight ~/ 2 - 1);
  }

  void cameraDraw() {
    // Draw the world!
    // Work in columns, top to bottom, which should facilitate our fake 3D effects
    for (var cx = 0; cx < cameraViewWidth; cx++) {
      for (var cy = 0; cy < cameraViewHeight; cy++) {
        var tx = cameraTileOffset.x + cx * 2;
        var ty = cameraTileOffset.y + cy * 2;
        cameraDrawFloor(tx, ty, camera.x + cx, camera.y + cy);
      }
    }
    for (var cx = 0; cx < cameraViewWidth; cx++) {
      for (var cy = 0; cy < cameraViewHeight; cy++) {
        var tx = cameraTileOffset.x + cx * 2;
        var ty = cameraTileOffset.y + cy * 2;
        cameraDrawCell(tx, ty, camera.x + cx, camera.y + cy);
      }
    }
  }

  void cameraDrawFloor(int tx, int ty, int cx, int cy) {
    var cxy = geo.Offset(cx, cy);
    if (!fovVisible.contains(cxy)) {
      return;
    }

    var tile = level.tiles.get(cx, cy);
    at(tx, ty).bg(Palette.sitemodeSeenFloor).puts("  ");
  }

  void cameraDrawCell(int tx, int ty, int cx, int cy) {
    var cursorAbove = at(tx, ty);
    var cursorBelow = at(tx, ty + 2);

    LevelTile? tile;
    // TODO: Fade tiles when loaded from memory
    // TODO: Darken live floors
    bool seenLive;

    var cxy = geo.Offset(cx, cy);
    if (fovVisible.contains(cxy)) {
      tile = level.tiles.get(cx, cy);
      seenLive = true;
    } else if (fovMemory.contains(cxy)) {
      tile = level.tiles.get(cx, cy);
      seenLive = false;
    } else {
      return;
    }

    if (fovMovable.contains(geo.Offset(cx, cy))) {
      cursorAbove
          .highlight()
          .act(Act(label: "Move", callback: () => playerMoveTo(cx, cy)));
    }

    var colorWall = Palette.sitemodeSeenWall;
    var colorWallInner = Palette.sitemodeSeenWall;
    var colorExit = Palette.sitemodeSeenExit;
    var colorDoor = Palette.sitemodeSeenDoor;
    if (cy >= playerPosition.y) {
      colorWallInner = Palette.sitemodeUnseenWall; // we wouldn't see it anyway
    }
    if (!seenLive) {
      colorWallInner = colorWall = Palette.sitemodeUnseenWall;
      colorExit = Palette.sitemodeUnseenExit;
      colorDoor = Palette.sitemodeUnseenDoor;
    }

    switch (tile) {
      case null:
      case LevelTile.floor:
      case LevelTile.openDoor:
        cursorAbove.touch(2);
      case LevelTile.exit:
        cursorAbove.big().fg(colorExit).puts("X");
      case LevelTile.wall:
        cursorAbove.fg(colorWall).puts("██");
        cursorBelow.small().fg(colorWallInner).puts("░░");
      case LevelTile.closedDoor:
        cursorAbove.big().fg(colorDoor).puts("+");
    }

    var cursorContent = at(tx, ty);
    if (geo.Offset(cx, cy) == playerPosition) {
      cursorContent.fg(Palette.sitemodePlayer).big().putc(0xff);
    }
  }
}