Java Community | Help. Code. Learn.•2y ago

Java game slopes tile collision

I'm trying to figure out how I can make my player move on sloped tiles. My tiles all represent RGB values, and this is how I currently handle collisions and whether the player can move there or not:

// Go through all pixels in the level and add all data related to the level
for (int y = 0; y < img.getHeight(); y++)
    for (int x = 0; x < img.getWidth(); x++) {
    Color color     = new Color(img.getRGB(x, y));
    int red     = color.getRed();
    levelData[y][x] = red;

int tileValue = level.getLevelData()[tileY][tileX];
return switch (tileValue) {
    case TRANSPARENT_TILE, SLOPED_TILE -> false;
    default -> true;
    };

// Go through all pixels in the level and add all data related to the level
for (int y = 0; y < img.getHeight(); y++)
    for (int x = 0; x < img.getWidth(); x++) {
    Color color     = new Color(img.getRGB(x, y));
    int red     = color.getRed();
    levelData[y][x] = red;

int tileValue = level.getLevelData()[tileY][tileX];
return switch (tileValue) {
    case TRANSPARENT_TILE, SLOPED_TILE -> false;
    default -> true;
    };

And here I check if the tile is solid, and if so, the player can move to position and I update his hitbox.x (which is the top left position of the hitbox).

boolean isTopLeftSolid = isSolid(x, y, level);
boolean isTopRightSolid = isSolid(x + width, y, level);
boolean isBottomLeftSolid = isSolid(x, y+height, level);
boolean isBottomRightSolid = isSolid(x+width, y+height, level);

if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
    hitbox.x += xDirection;

boolean isTopLeftSolid = isSolid(x, y, level);
boolean isTopRightSolid = isSolid(x + width, y, level);
boolean isBottomLeftSolid = isSolid(x, y+height, level);
boolean isBottomRightSolid = isSolid(x+width, y+height, level);

if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
    hitbox.x += xDirection;

My question is, how can I adjust the player hitbox y position based on what section of a sloped tile he is standing on? I have the section of the tile he is standing on but I don't know how to update the "solidity" of a sloped tile.

boolean isTileSloped(int tileX, int tileY, Level level) {
    int tileValue = level.getLevelData()[tileY][tileX];

    if (tileValue != SLOPED_TILE)
        return false;

    float bottomLeft = hitbox.x / TILES_SIZE;
    int bottomLeftFloor = (int) Math.floor(bottomLeft);
    float difference = bottomLeft - bottomLeftFloor;
    int section = (int) (difference * 4) + 1;

    if (tileX == bottomLeftFloor) {
        System.out.println("Section " + section);
        if (section == 1) {
        // Need help here with setting the hitbox y position
        }
    }
    return true;
}

boolean isTileSloped(int tileX, int tileY, Level level) {
    int tileValue = level.getLevelData()[tileY][tileX];

    if (tileValue != SLOPED_TILE)
        return false;

    float bottomLeft = hitbox.x / TILES_SIZE;
    int bottomLeftFloor = (int) Math.floor(bottomLeft);
    float difference = bottomLeft - bottomLeftFloor;
    int section = (int) (difference * 4) + 1;

    if (tileX == bottomLeftFloor) {
        System.out.println("Section " + section);
        if (section == 1) {
        // Need help here with setting the hitbox y position
        }
    }
    return true;
}

68 Replies

JavaBot•2y ago

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Unknown User•2y ago

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ErkyOP•2y ago

@Fischstaebchen im trying to focus on simply setting the hitbox to be at the appropriate height when passing a sector, i can calculate slope angles when i first get this to work. just having trouble with the overall code approach, like how can i update the hitbox.y position to be at the right height? because when setting it like this, he just keeps bouncing because he thinks he is in the air. i have a method isEntityOnGround that checks if the bottom left and bottom right of the hitbox is on the ground, and if so, moves the hitbox down to the ground. so i need to add a checker before that somehow so if i disable falling mechanics, it looks decent when moving fast, but when moving slow i slowly float up to the top tile for some reason?

protected boolean isEntityInAir(Rectangle2D.Float hitbox, Level level) {
    // check the bottom left and bottom right corner of the hitbox
    boolean isBottomLeftSolid     = isSolid(hitbox.x, hitbox.y + hitbox.height + 1, level);
    boolean isBottomRightSolid     = isSolid(hitbox.x + hitbox.width, hitbox.y + hitbox.height + 1, level);

    // returns false if either hitbox for bottom left and bottom right corner is colliding with a solid tile
    if (isBottomLeftSolid || isBottomRightSolid)
        return false;
    else
        return true;
    }

protected boolean isEntityInAir(Rectangle2D.Float hitbox, Level level) {
    // check the bottom left and bottom right corner of the hitbox
    boolean isBottomLeftSolid     = isSolid(hitbox.x, hitbox.y + hitbox.height + 1, level);
    boolean isBottomRightSolid     = isSolid(hitbox.x + hitbox.width, hitbox.y + hitbox.height + 1, level);

    // returns false if either hitbox for bottom left and bottom right corner is colliding with a solid tile
    if (isBottomLeftSolid || isBottomRightSolid)
        return false;
    else
        return true;
    }

so this one checks if im in the air or not

ErkyOP•2y ago

Unknown User•2y ago

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ErkyOP•2y ago

I mean, In my game I only have two types of slopes which is diagonal from top left to top right or vice versa the slope is just an image, which i have defined as non-solid so i can walk through it

Unknown User•2y ago

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ErkyOP•2y ago

walk through the slope from the right side

Unknown User•2y ago

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ErkyOP•2y ago

public class Entity

protected boolean canMoveToPosition(float x, float y, float width, float height, Level level) {
    // Get x, y, width and height position for player and see if he can move to the next position or not
    boolean isTopLeftSolid = isSolid(x, y, level);
    boolean isTopRightSolid = isSolid(x + width, y, level);
    boolean isBottomLeftSolid = isSolid(x, y + height, level);
    boolean isBottomRightSolid = isSolid(x + width, y + height, level);

    // If neither corner is solid, the entity can move here
    if (!isTopLeftSolid && !isTopRightSolid && !isBottomLeftSolid && !isBottomRightSolid)
        return true;

    // Returns false by default, meaning cannot move to the position
    return false;
    }

    protected boolean isSolid(float x, float y, Level level) {
    int tileX = (int) (x / TILES_SIZE);
    int tileY = (int) (y / TILES_SIZE);

    if (isTileSolid(tileX, tileY, level))
        return true;
    else
        return false;
    }

    protected boolean isTileSolid(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    return switch (tileValue) {
        case TRANSPARENT_TILE, SLOPED_TILE -> false;
        default -> true;
    };
    }

// These are in the Player class and are called every tick of the game
public class Player

protected void updateXDirection() {
    xDirection = 0;
    if (direction == LEFT)
        xDirection = -xSpeed;
    if (direction == RIGHT)
        xDirection = xSpeed;
    }

protected void startMovingWithDirection(float xDirection, Level level) {
    if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
        hitbox.x += xDirection; // HERE WE ARE SETTING THE POSITION OF THE HITBOX
    }

public class Entity

protected boolean canMoveToPosition(float x, float y, float width, float height, Level level) {
    // Get x, y, width and height position for player and see if he can move to the next position or not
    boolean isTopLeftSolid = isSolid(x, y, level);
    boolean isTopRightSolid = isSolid(x + width, y, level);
    boolean isBottomLeftSolid = isSolid(x, y + height, level);
    boolean isBottomRightSolid = isSolid(x + width, y + height, level);

    // If neither corner is solid, the entity can move here
    if (!isTopLeftSolid && !isTopRightSolid && !isBottomLeftSolid && !isBottomRightSolid)
        return true;

    // Returns false by default, meaning cannot move to the position
    return false;
    }

    protected boolean isSolid(float x, float y, Level level) {
    int tileX = (int) (x / TILES_SIZE);
    int tileY = (int) (y / TILES_SIZE);

    if (isTileSolid(tileX, tileY, level))
        return true;
    else
        return false;
    }

    protected boolean isTileSolid(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    return switch (tileValue) {
        case TRANSPARENT_TILE, SLOPED_TILE -> false;
        default -> true;
    };
    }

// These are in the Player class and are called every tick of the game
public class Player

protected void updateXDirection() {
    xDirection = 0;
    if (direction == LEFT)
        xDirection = -xSpeed;
    if (direction == RIGHT)
        xDirection = xSpeed;
    }

protected void startMovingWithDirection(float xDirection, Level level) {
    if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
        hitbox.x += xDirection; // HERE WE ARE SETTING THE POSITION OF THE HITBOX
    }

Unknown User•2y ago

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ErkyOP•2y ago

private boolean isTileSloped(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    if (tileValue != SLOPED_TILE)
        return false;

    float bottomLeft = hitbox.x / TILES_SIZE;
    int bottomLeftFloor = (int) Math.floor(bottomLeft);
    float difference = bottomLeft - bottomLeftFloor;
    int section = (int) (difference * 4) + 1;

    if (tileX > bottomLeftFloor) {
        section = 1;
    }

    System.out.println("Section " + section);
    if (section == 1)
        hitbox.y -= 1;
    if (section == 2)
        hitbox.y -= 0.75f;
    if (section == 3)
        hitbox.y -= 0.5f;
    if (section == 4)
        hitbox.y -= 0.25f;

    return true;
    }

private boolean isTileSloped(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    if (tileValue != SLOPED_TILE)
        return false;

    float bottomLeft = hitbox.x / TILES_SIZE;
    int bottomLeftFloor = (int) Math.floor(bottomLeft);
    float difference = bottomLeft - bottomLeftFloor;
    int section = (int) (difference * 4) + 1;

    if (tileX > bottomLeftFloor) {
        section = 1;
    }

    System.out.println("Section " + section);
    if (section == 1)
        hitbox.y -= 1;
    if (section == 2)
        hitbox.y -= 0.75f;
    if (section == 3)
        hitbox.y -= 0.5f;
    if (section == 4)
        hitbox.y -= 0.25f;

    return true;
    }

if (isTileSloped(tileX,tileY,level)) {
        System.out.println("sloped");
    }

if (isTileSloped(tileX,tileY,level)) {
        System.out.println("sloped");
    }

so I try to adjust the hitbox according to what section of the tile its standing on. if in section 4 (the leftmost) the tile is almost solid at the top, so make a small change to the hitbox, if in section 1, the tile is nearly transparent and hitbox should almost be on the floor

ErkyOP•2y ago

Unknown User•2y ago

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ErkyOP•2y ago

yeah thats the problem, this isnt a good solution i dont think. thats why it clashes with the falling mechanics which also sets the hitbox.y

Unknown User•2y ago

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ErkyOP•2y ago

what do you mean define the slope as a hitbox? how would i do that?

Unknown User•2y ago

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ErkyOP•2y ago

https://discord.com/channels/648956210850299986/1092511181215899779/1092543191405822032 so i draw the map with rgb values and I define if they are solid or not in the

isTileSolid

isTileSolid

public static final int TRANSPARENT_TILE     = 99;
public static final int SLOPED_TILE             = 40;

public static final int TRANSPARENT_TILE     = 99;
public static final int SLOPED_TILE             = 40;

this is their RGB value which is how i can check a specific tile on the map

Unknown User•2y ago

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ErkyOP•2y ago

no, the map is loaded via a png

ErkyOP•2y ago

each pixel represents a tile

ErkyOP•2y ago

Unknown User•2y ago

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ErkyOP•2y ago

yeah so how should i approach this

Unknown User•2y ago

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ErkyOP•2y ago

yeah , so how can I adjust the player hitbox then based on the coordinates inside the tile? should I send over the github?

Unknown User•2y ago

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ErkyOP•2y ago

https://github.com/emyhrberg/2d-platformer-game entity file is here https://github.com/emyhrberg/2d-platformer-game/blob/main/src/entities/Entity.java

Unknown User•2y ago

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ErkyOP•2y ago

thanks

JavaBot•2y ago

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ErkyOP•2y ago

just really wanna get these sloped tiles working it would be really awesome 😄

Unknown User•2y ago

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ErkyOP•2y ago

40 public static final int TILES_SIZE_DEFAULT = 40; public static final float SCALE = 1.5f; public static final int TILES_SIZE = (int) (TILES_SIZE_DEFAULT * SCALE); put then i scale it a little bit, but TILES_SIZE is the value I use to get the tile position

Unknown User•2y ago

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ErkyOP•2y ago

yes

Unknown User•2y ago

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ErkyOP•2y ago

yeahh i guess

Unknown User•2y ago

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ErkyOP•2y ago

what do you mean make sure that its correct?

protected boolean isTileSolid(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    // sloped tile
    if (tileValue == SLOPED_TILE) {
        updateSlopePosition(tileX, tileY, level);
        return true;
    }

    return switch (tileValue) {
        case TRANSPARENT_TILE -> false;
        default -> true;
    };
    }

    private void updateSlopePosition(int tileX, int tileY, Level level) {
    // Calculate the section based on the player's x position relative to the sloped tile
    float topLeftPosition = hitbox.x / TILES_SIZE;

    System.out.println(topLeftPosition);
    }

protected boolean isTileSolid(int tileX, int tileY, Level level) {
    // Get every tile value from the level
    int tileValue = level.getLevelData()[tileY][tileX];

    // sloped tile
    if (tileValue == SLOPED_TILE) {
        updateSlopePosition(tileX, tileY, level);
        return true;
    }

    return switch (tileValue) {
        case TRANSPARENT_TILE -> false;
        default -> true;
    };
    }

    private void updateSlopePosition(int tileX, int tileY, Level level) {
    // Calculate the section based on the player's x position relative to the sloped tile
    float topLeftPosition = hitbox.x / TILES_SIZE;

    System.out.println(topLeftPosition);
    }

where do i go from here

Unknown User•2y ago

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ErkyOP•2y ago

i think the most logical step would be to update the slope position directly in here, so i check if the tile is sloped and in that case i can determine the behavior in updateslopeposition. because here i can access the hitbox all corners and then i can define how the slope looks and whatnot and then i return that the tile is solid after that, so i should be able to fall through it if coming from the top or the right side

ErkyOP•2y ago

so if im coming from the top and falling down through it, i want to keep falling through and then depending on the position of the slope, set the hitbox.y

Unknown User•2y ago

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ErkyOP•2y ago

yes thats true, can i add a checker there, so that it exits and doesnt go further if im in a SLOPED_TILE like this: if tileValue == SLOPED_TILE return only problem is i dont know how to get the tileValue inside my entityInAir method, been stuck on that for a while feels like i have everything i need with my section solution where i divide it into 4 sections, later i can optimize this surely, but i just want to set the hitbox.y inside here but i dont know why it isnt working as expected

Unknown User•2y ago

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ErkyOP•2y ago

https://gyazo.com/8db5bdbd645188477b0814ba775a22ee

Gyazo

Unknown User•2y ago

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ErkyOP•2y ago

wait whaat x == y? i feel like continuing with my solution, just need to set hitbox.y here somehow , thats my main question

Unknown User•2y ago

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ErkyOP•2y ago

do you know how to set hitbox.y correctly and avoid making the player fall? i have this variable falling that i could adjust also

Unknown User•2y ago

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ErkyOP•2y ago

protected void startMovingWithDirection(float xDirection, Level level) {
    // Update the player hitbox if not colliding with a solid block on the next X position
    if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
        hitbox.x += xDirection;
    }

protected void startMovingWithDirection(float xDirection, Level level) {
    // Update the player hitbox if not colliding with a solid block on the next X position
    if (canMoveToPosition(hitbox.x + xDirection, hitbox.y, hitbox.width, hitbox.height, level))
        hitbox.x += xDirection;
    }

moveToPosition

Unknown User•2y ago

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ErkyOP•2y ago

protected void startFalling(Level level) {
    if(canMoveToPosition(hitbox.x, hitbox.y + ySpeed, hitbox.width, hitbox.height, level)) {
        // Start falling, move Y downwards
        hitbox.y += ySpeed;
        ySpeed += GRAVITY;
    } else {
        // Stop falling, reset jump
        if (ySpeed > 0) {
        ySpeed = 0;
        jumping = false;
        falling = false;
        } else {
        // Hit roof, start falling downwards fast!
        ySpeed = GRAVITY * 10;
        }
    }
    }

protected void startFalling(Level level) {
    if(canMoveToPosition(hitbox.x, hitbox.y + ySpeed, hitbox.width, hitbox.height, level)) {
        // Start falling, move Y downwards
        hitbox.y += ySpeed;
        ySpeed += GRAVITY;
    } else {
        // Stop falling, reset jump
        if (ySpeed > 0) {
        ySpeed = 0;
        jumping = false;
        falling = false;
        } else {
        // Hit roof, start falling downwards fast!
        ySpeed = GRAVITY * 10;
        }
    }
    }

Unknown User•2y ago

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ErkyOP•2y ago

because in the arguments, i check if they can move to the next x position, or the next y position

Unknown User•2y ago

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ErkyOP•2y ago

ok 👍 appreciate your help 🙂

Unknown User•2y ago

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ErkyOP•2y ago

oh ok thanks! will keep looking myself, good night 🙂

JavaBot•2y ago

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ErkyOP•2y ago

still working on this

JavaBot•2y ago

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JavaBot•2y ago

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Java game slopes tile collision

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