CODEWITHSUNDEEP
javagraphicslibgdx
Ben Beri
Ben Beri

Reputation: 1201

LibGdx - Make sprite follow a line path

I have an isometric map drawn.

I take the current position of my sprite and the target position of where my sprite should be at after the move:

    // region is my TextureRegion.
    int x1 = getIsometricX(1,1,region);
    int x2 = getIsometricX(1,2,region);

    int y1= getIsometricY(1,1,region);
    int y2 = getIsometricY(1,2,region);

And then I draw a simple line using ShapeRenderer to see if the local/target points are correctly set, and the rectangle so you can see where the sprite rendering starts.

    renderer.setProjectionMatrix(camera.combined);
    renderer.begin(ShapeRenderer.ShapeType.Line);
    renderer.setColor(Color.RED);
    renderer.line(x1 + location.getOffsetx(), y1 + location.getOffsety(), x2 + location.getOffsetx(), y2 + location.getOffsety());
    renderer.rect(x1 + location.getOffsetx(), y1 + location.getOffsety(), region.getRegionWidth(), region.getRegionHeight());
    renderer.end();

Every sprite of mine has set offsetX and offsetY to adjust its location on the isometric tile, because every sprite is different.

Output looks like this:

img

what you can see here, is the starting point of where the sprite starts to draw (you see that offsets adjusted it so the sprite looks like its on the 1,1 tile.

and you can see the line which starts at the starting draw point of the sprite, and ends at the target draw point of the sprite.

Now my question is, how can I make that sprite move on that line's path, so it will look like the ship is moving forward?

So the main concept of the question is.. How can you make a sprite move in a straight line, from local point to target point?

Some functions you might need to see:

public int getIsometricX(int x, int y, TextureRegion region) {
    return (x * GameTile.TILE_WIDTH / 2) - (y * GameTile.TILE_WIDTH / 2) - (region.getRegionWidth() / 2);
}

public int getIsometricY(int x, int y, TextureRegion region) {
    return (x * GameTile.TILE_HEIGHT / 2) + (y * GameTile.TILE_HEIGHT / 2) - (region.getRegionHeight() / 2);
}

Tiles are drawn using the same method, just with Tile's texture.

Upvotes: 1

Views: 825

Answers (2)

Ben Beri
Ben Beri

Reputation: 1201

I would like to answer myself this question, because other people might have the same issue and just over-complicate it like me.

If you want to perform any move on your isometric map, do not follow my misunderstandings and calculate it on the isometric coordinates.

You have to calculate it on your flat screen matrix coordinates, and then convert it to isometric coordinates.

For example, I want to move up like this line, all I need to do is this:

ship.y += 0.1f // when it reaches 1, then it will be at 0, 1

So you know that you want to be at 0,1 on your non-isometric map.

So you do this increment, and then for last, you have to convert it to isometric coordinates before drawing:

float x = (ship.x * GameTile.TILE_WIDTH / 2) - (ship.y * GameTile.TILE_WIDTH / 2) - (textyure.getWidth() / 2);

float y = (ship.x * GameTile.TILE_HEIGHT / 2) + (ship.y * GameTile.TILE_HEIGHT / 2) - (texture.getHeight() / 2);

And that will draw it on the isometric map, exactly like on your screen-coordinates, but on an isometric format.

Upvotes: 1

Lucas B
Lucas B

Reputation: 348

for(float x : new float[targetx - currentx]) {ship.setPosition(ship.getX + x, ship.getY); }

And you would do the same for y.

Edit:

I guess this is wrong since you're calling this every frame I assume.

Instead you would keep track of your distance traveled between target and ship and you would increment sip position by 1 each time to x and y until it reached the distance.

Upvotes: 0

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