flipperino.lua

--[[

    flipperino.lua

    Written by Zeus guy
    A few lines of code taken from MrDoubleA's One-Way Walls and maybe from the default libraries.

    Known issues:
    -In vertical sections, dropped items move wildly while jumping. Not much I can do there, at least it still works.
    -When interacting with an NPC, the icon appears under the npc instead of above it. Again, not much I can do there.
    -Effects aren't flipped.
]]

local cb = Graphics.CaptureBuffer(800, 600);
local blockmanager = require("blockmanager");
local blockutils = require("blocks/blockutils");
local cp = require("blocks/ai/clearpipe");

local flipperino = {}

function flipperino.onInitAPI()
    registerEvent(flipperino, "onStart", "onStart", false);
    registerEvent(flipperino, "onTick", "onTick", false);
    registerEvent(flipperino, "onDraw", "onDraw", false);
    registerEvent(flipperino, "onEvent", "onEvent", false);
    registerEvent(flipperino, "onCameraUpdate", "onCameraUpdate", false);
end

--Init stuff
flipperino.flipped = false;      --If the level is flipped or not.
flipperino.flipNpcs = {};        --Used for when an NPC should turn into another when the level is flipped. Values can be added in your level file if needed.
flipperino.parallaxFlipBgs = {}; --Used for storing the background layers that will be shown when the level is flipped.
flipperino.showMirrored = true;  --If set to false, the camera doesn't flip while the level is upside-down.
flipperino.flipBgos = {};        --When the player touches one of these BGOs, the level will turn upside-down.
flipperino.unflipBgos = {};      --When the player touches one of these BGOS, the level will return to normal.
flipperino.flipSound = 13;       --The sound that plays when the level flips.

function flipperino.onStart()

    --Stretch and Ceiling Stretch. There's no situation where you wouldn't want these to turn into each other. Mainly because they'd break.
    flipperino.flipNpcs[323] = 324;
    flipperino.flipNpcs[324] = 323;

    --Background layer "FLIP" should only appear when the level is flipped. You can add more layers on your luna.lua file.
    flipperino.parallaxFlipBgs["FLIP"] = true;

    --Search for all blocks in the level and store their flipped graphic, if it exists.
    flipperino.flippedBlocks = {};
    for k,v in ipairs(Block.get()) do
        if (flipperino.flippedBlocks[v.id] == nil) then
            flipperino.flippedBlocks[v.id] = Graphics.loadImage("flipped/block-"..v.id..".png") ;
        end
        --In order to make upside-down sizeables work, all sizeables now have bottom collision as well as top collision.
        if (Block.config[v.id].sizeable) then
            blockmanager.registerEvent(v.id, flipperino, "onTickEndBlock");
        end
    end

    --Search for all npcs in the level and store their flipped graphic, if it exists.
    flipperino.flippedNpcs = {};
    for k,v in ipairs(NPC.get()) do
        if (flipperino.flippedNpcs[v.id] == nil) then
            flipperino.flippedNpcs[v.id] = Graphics.loadImage("flipped/npc-"..v.id..".png");
        end
    end

    --Search for all bgos in the level and, of course, store their flipped graphic, if it exists.
    flipperino.flippedBgos = {};
    for k,v in ipairs(BGO.get()) do
        if (flipperino.flippedBgos[v.id] == nil) then
            flipperino.flippedBgos[v.id] = Graphics.loadImage("flipped/background-"..v.id..".png");
        end
    end

end

function flipperino.onCameraUpdate(camIdx)
    --Horizontal splitscreen fix
    if (flipperino.flipped and flipperino.showMirrored and camera2 ~= nil and camera2.isSplit and camera.height == 300) then
        if (Player(1).y > Player(2).y) then
            camera.renderY = -0.5;
            camera2.renderY = 301;
        else
            camera2.renderY = -0.5;
            camera.renderY = 301;
        end
    end
end

function drawFlipped()

    --If the level is flipped and showMirrored is true, then draw the camera upside-down.
    if (flipperino.flipped and flipperino.showMirrored) then
        cb:captureAt(-5);

        if (camera2 ~= nil  and camera2.isSplit and camera.height == 300) then
            Graphics.glDraw {
                vertexCoords = {
                    0,   -300,
                    800, -300,
                    0,   300,
                    0,   300,
                    800, 300,
                    800, -300
                },
                texture = cb,
                textureCoords = {0,1, 1,1, 0,0, 0,0, 1,0, 1,1},
                primitive = Graphics.GL_TRIANGLE,
                priority = -5
            };
        else
            Graphics.glDraw {
                vertexCoords = {
                    0,   0,
                    800, 0,
                    0,   600,
                    0,   600,
                    800, 600,
                    800, 0
                },
                texture = cb,
                textureCoords = {0,1, 1,1, 0,0, 0,0, 1,0, 1,1},
                primitive = Graphics.GL_TRIANGLE,
                priority = -5
            };
        end
    end
end

function flipperino.onDraw()
    drawFlipped();
end

function flipperino.onTick()

    itemCaught = false; --Without this, only the last player can pick up items from the item box.
    fSections = {}; --There is some code that shouldn't run twice if both players are on the same section.

    for _,p in ipairs(Player.get()) do

        if (Camera(p.idx).isSplit) then
            bounds = Camera(p.idx).bounds;
        else
            bounds = camera.bounds;
        end

        for k,n in ipairs(NPC.getIntersecting(bounds.left, bounds.top, bounds.right, bounds.bottom)) do

            --This code handles the item box while upside-down.
            --The item is set to friendly until it visually reaches the point where the player should be, and then teleports to the appropriate position.
            --Way easier than trying to modify the item's actual position, trust me.
            if (flipperino.flipped and n:mem(0x138, FIELD_WORD) == 2 and not itemCaught) then

                midpoint = (bounds.top+bounds.bottom)/2 - 16;
                py = midpoint + (midpoint - (p.y + hOffset));

                n.friendly = true;

                pBox = Colliders.Box(p.x, py - p.height / 2, p.width, p.height);
                nBox = Colliders.Box(n.x, n.y, n.width, n.height);

                Text.print("PY:  "..py, 20, 20);
                Text.print("APY: "..py - p.height / 2, 20, 40);
                Text.print("IY:  "..n.y, 20, 60);

                if (Colliders.collide(pBox, nBox)) then
                    n:mem(0x13C,FIELD_DFLOAT, 2);
                    n.y = p.y;
                    n.friendly = false;
                    itemCaught = true;
                end

            elseif (n.friendly and n:mem(0x138, FIELD_WORD) == 2) then
                n.friendly = false; --You should still be able to collect the item properly if you flip the level while the item is on its way.
            end

            --Items affected by gravity should stick to the ground when the level is flipped.
            --Some vanilla NPCs, like Rippers, have nogravity set to false, so this makes them drop to the floor.
            --This also happens to coins, shockingly. That's why the isCoin check is there.
            if (flipperino.flipped and not NPC.config[n.id].isCoin and not NPC.config[n.id].nogravity and not fSections[p.section] and n.despawnTimer > 0) then
                n.speedY = n.speedY - 0.26;

                if (n.collidesBlockUp) then
                    n:mem(0x136, FIELD_BOOL, false); --This makes thrown items believe they are touching the ground, when they are in fact touching the ceiling.
                end
            end
        end

        for _,b in ipairs(BGO.getIntersecting(p.x, p.y, p.x+p.width, p.y+p.height)) do
            if (flipperino.flipBgos[b.id] and not flipperino.flipped) then
                flipperino.performFlip();
            elseif (flipperino.unflipBgos[b.id] and flipperino.flipped) then
                flipperino.performFlip();
            end
        end

        fSections[p.section] = true;
    end
end

function flipperino.performFlip()

    --Play sound effect.
    SFX.play(flipperino.flipSound);

    --Flip the screen and change npc gravity.
    flipperino.flipped = not flipperino.flipped;
    Defines.npc_grav = flipperino.flipped and 0 or 0.26;

    --Iterate through all sections and flip them. I'm sure this won't be a problem on huge levels.
    for i=0,20,1 do

        sec = Section(i);

        --Switch backgrounds
        for v in pairs(flipperino.parallaxFlipBgs) do
            if (sec.background ~= nil and sec.background:get(v) ~= nil) then
                sec.background:get(v).opacity = flipperino.flipped and 1 or 0;
            end
        end

        bounds = sec.boundary;
        midpoint = (bounds.top+bounds.bottom)/2 - 16;

        --Change block positions.
        for k,v in ipairs(Block.getIntersecting(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            hOffset = v.height - 32;
            v.y = midpoint + (midpoint - (v.y + hOffset));
        end

        --Change block sprites.
        for v in pairs(flipperino.flippedBlocks) do
            if (flipperino.flipped) then
                Graphics.sprites.block[v].img = flipperino.flippedBlocks[v];
            else
                Graphics.sprites.block[v].img = nil;
            end

            --Slopes are flipped here, too.
            temp = -Block.config[v].floorslope;
            Block.config[v].floorslope = -Block.config[v].ceilingslope;
            Block.config[v].ceilingslope = temp;
        end

        --Flip clearpipes.
        for k, v in pairs(cp.PIPES) do
            cp.PIPES[k] = {v[2], v[1], v[3], v[4]};
        end

        for k,v in pairs(cp.JUNCS) do
            if (v == 1 or v == 6) then
                cp.JUNCS[k] = v + 1;
            elseif (v == 2 or v == 7) then
                cp.JUNCS[k] = v - 1;
            end
        end

        for k,v in pairs(cp.ELBS) do
            cp.ELBS[k] = -v;
        end

        --Change NPC sprites.
        for _,v in pairs(flipperino.flippedNpcs) do
            if (flipperino.flipped) then
                Graphics.sprites.npc[v].img = flipperino.flippedNpcs[v];
            else
                Graphics.sprites.npc[v].img = nil;
            end
        end

        --Change BGO positions.
        for k,v in ipairs(BGO.getIntersecting(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            hOffset = v.height - 32;
            v.y = midpoint + (midpoint - (v.y + hOffset));
        end

        --Change BGO sprites.
        for v in pairs(flipperino.flippedBgos) do
            if (flipperino.flipped) then
                Graphics.sprites.background[v].img = flipperino.flippedBgos[v];
            else
                Graphics.sprites.background[v].img = nil;
            end
        end

        --Hide interaction hardcoded icon when flipped
        if (flipperino.flipped) then
            Graphics.sprites.hardcoded[43].img = Graphics.loadImage("flipped/hardcoded-43.png");
        else
            Graphics.sprites.hardcoded[43].img = nil;
        end

        --Change liquid positions.
        for k,v in ipairs(Liquid.getIntersecting(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            hOffset = v.height - 32;
            v.y = midpoint + (midpoint - (v.y + hOffset));
        end

        --Change warp positions.
        for k,v in ipairs(Warp.getIntersectingEntrance(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            hOffset = v.entranceHeight - 32;
            v.entranceY = midpoint + (midpoint - (v.entranceY + hOffset)) + (32 * ((v.warpType == 2 or (v.entranceDirection == 2 or v.entranceDirection == 4)) and 1 or 0));

            if (v.warpType ~= 2) then
                if     (v.entranceDirection == 1) then v.entranceDirection = 3;
                elseif (v.entranceDirection == 3) then v.entranceDirection = 1;
                end
            end
        end

        for k,v in ipairs(Warp.getIntersectingExit(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            hOffset = v.exitHeight - 32;
            v.exitY = midpoint + (midpoint - (v.exitY + hOffset)) + (32 * ((v.warpType == 2 or (v.exitDirection == 2 or v.exitDirection == 4)) and 1 or 0));

            if (v.warpType ~= 2) then
                if     (v.exitDirection == 1) then v.exitDirection = 3;
                elseif (v.exitDirection == 3) then v.exitDirection = 1;
                end
            end
        end

        --Change player position
        for _,p in ipairs(Player.get()) do
            if (p.section == i) then
                hOffset = p.height - 32;
                p.y = midpoint + (midpoint - (p.y + hOffset));
                p.speedY = -p.speedY;
            end
        end

        --Change NPC position.
        for k,v in ipairs(NPC.getIntersecting(bounds.left, bounds.top, bounds.right, bounds.bottom)) do
            if (v:mem(0x138, FIELD_WORD) ~= 2) then

                hOffset = v.height - 32;
                v.y = midpoint + (midpoint - (v.y + hOffset));
                v.speedY = -v.speedY;

                if (flipperino.flipNpcs[v.id] ~= nil) then
                    v.id = flipperino.flipNpcs[v.id];
                    v.spawnId = v.id; --Really important, or else npcs would revert when they respawned.
                end

                spawnY = midpoint + (midpoint - (v.spawnY + hOffset));
                --v:mem(0xB0, FIELD_DFLOAT, spawnY); --Pretty sure this is just v.spawnY? I'll leave this here just in case it's not and something breaks.
                v.spawnY = spawnY;

                --Thwomps.
                if (v.id == 432 or v.id == 435 or v.id == 437) then

                    v.data._basegame.direction = -v.data._basegame.direction;
                    v.data._basegame.previous.speedY = -v.data._basegame.previous.speedY;

                    if (v.data._basegame.state == 3) then v.data._basegame.state = 6;
                    elseif (v.data._basegame.state == 6) then v.data._basegame.state = 3; end

                    if (v.data._basegame.state == 2) then v.data._basegame.state = 5;
                    elseif (v.data._basegame.state == 5) then v.data._basegame.state = 2; end

                    if (v.data._basegame.state == 1) then v.data._basegame.state = 4;
                    elseif (v.data._basegame.state == 4) then v.data._basegame.state = 1; end

                --Wall crawlers. They kinda work but sometimes they don't. Mainly when colliding when quicksand. Or water. Or sizeables. Or slopes.
                elseif ( v.id == 205 or v.id == 206 or v.id == 207) then

                    if (v.ai1 == 1) then v.ai1 = 3;
                    elseif (v.ai1 == 2) then v.ai1 = 4;
                    elseif (v.ai1 == 3) then v.ai1 = 1;
                    elseif (v.ai1 == 4) then v.ai1 = 2;
                    end

                end
            end
        end

    end

end

--In order to flip the level, you call an event with the name "flip". That's it.
function flipperino.onEvent(eventName)
    if (eventName == "flip") then
        flipperino.performFlip();
    elseif (eventName == "flipUpsideDown" and not flipperino.flipped) then
        flipperino.performFlip();
    elseif (eventName == "flipNormal" and flipperino.flipped) then
        flipperino.performFlip();
    end
end

--The following functions have been "borrowed" from MrDoubleA's One-Way Walls. Wanted to rewrite it but I ran out of time, so I'll do that later.

local function objectHasCollision(v) -- Get whether a player/NPC has collision. Obviously not perfect, but I guess it does the job
    if type(v) == "Player" then
        return ((v.forcedState == 0 and v.deathTimer == 0 and not v:mem(0x13C,FIELD_BOOL)) and not Defines.cheat_shadowmario)
    elseif type(v) == "NPC" then
        local config = NPC.config[v.id]
        return ((v.despawnTimer > 0 and not v.isGenerator and not v.isHidden) and not v.noblockcollision and (not config or not config.noblockcollision) and v.id ~= 266 and v:mem(0x12C,FIELD_WORD) == 0 and v:mem(0x138,FIELD_WORD) == 0)
    end
end

local function pushObjectOut(v, w)
    if (w.y-w.speedY) >= (v.y+v.height-v.speedY) and (w.speedY < 0) then
        w.y = v.y+v.height
        w.speedY = 0

        if type(w) == "Player" then
            w:mem(0x11C,FIELD_WORD,0) -- Jump force
            w:mem(0x14A,FIELD_WORD,2)
        elseif type(w) == "NPC" then
            w.collidesBlockUp = true
        end
    end
end

function flipperino.onTickEndBlock(v)
    if v.isHidden or v:mem(0x5A, FIELD_BOOL) then return end

    -- Players
    for _,w in ipairs(Player.get()) do
        if objectHasCollision(w) and v:collidesWith(w) > 0 then
            pushObjectOut(v,w)
        end
    end
    -- NPCs
    local hitbox = blockutils.getHitbox(v,0.3)

    for _,w in ipairs(Colliders.getColliding{a = hitbox,btype = Colliders.NPC,filter = objectHasCollision}) do
        pushObjectOut(v,w)
    end

end

return flipperino;