Negative depth in the Tutorial

The pause screen lists the level, the player's depth in feet, his money, kills, time and saves. In the Tutorial it calls the level TUTORIAL CAVE, but works out the depth as it does on any level, and there the sum comes out below zero everywhere: -147.60 feet where the player starts, and still -82.32 on the floor of the lower cave. Nothing else uses the depth, so it changes nothing in play.

The player enters the Tutorial and pauses: the screen gives his depth as -147.60 feet. He walks on, drops into the lower cave and pauses again on its floor, the lowest he can stand, and the depth is still below zero, -82.32 feet ^[1].

The pause screen's code writes the depth from the level's number and the player's height, py, his y when the game paused ^[2]:

    if (isLevel())
    {
        n = 128-24;
        if (global.currLevel < 1) draw_text(40, n-24, "TUTORIAL CAVE");
        else if (isRoom("rLoadLevel")) draw_text(40, n-24, "LEVEL: " + global.customLevelName + " BY " + global.customLevelAuthor);
        else draw_text(40, n-24, "LEVEL " + string(global.currLevel));
        draw_text(40, n-16, "DEPTH: " + string(174.8*(global.currLevel-1)+(py+8)*0.34) + " FEET");

That's 174.8 feet for each level before this one, and 0.34 feet a pixel down the level. isLevel() counts the Tutorial's room as a level ^[3], and both ways into the Tutorial, the START door on a first game and the TUTORIAL door, set the level to 0 ^[4]. So the depth starts at 174.8 * (0 - 1), -174.8 feet, and the cave, 304 pixels tall, is too shallow for the 0.34 feet a pixel to bring it back above zero ^[5]. The code gives the Tutorial its own name a line above, but not its own depth.

Pause anywhere in the Tutorial. Where the player starts, py is 72, so the depth is -174.8 + 80 * 0.34, shown as -147.60. The replay of the clip pauses there (frame 568) and again on the lower cave's floor (980), at py 264, -82.32 feet ^[6]. Another replay pauses where the player starts, on the way back to the title ^[7].

The spelunky.ai port reproduces it exactly: it's in docs/quirks.md's list of the 1.1 source's bugs ^[5], and the oracle's fingerprint of the replay pins the level and the player's height the depth is worked out from. No option turns it off.