The size of the square is calculated incorrectly | Java libgdx

Question

I am creating a game in which there is a 10x10 map and I need to calculate the size of these squares so that they all fit on the screen.

rect_x_end, rect_y_end The size of the square by x and y

screen_x, screen_y Screen Size

len_map_x, len_map_y Map width and length = 10

I calculated the size of the square like this:

rect_x_end = screen_x / len_map_x
rect_y_end = screen_y / len_map_y

example:

64 = 640 / 10
48 = 480 / 10

In this example, everything works correctly, but as soon as I start resizing the screen, this method gives an incorrect result.

I was doing something similar to python (pygame) and everything worked there.

kucer0043.java

package com.kucer0043.game;

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
import com.badlogic.gdx.utils.ScreenUtils;

public class kucer0043 extends ApplicationAdapter {
    private ShapeRenderer shapeRenderer;
    private int map_size;

    @Override
    public void create () {
        shapeRenderer = new ShapeRenderer();
        map_size = 10; // square map size
    }

    @Override
    public void render () {
        ScreenUtils.clear(0.5f, 0.5f, 0.5f, 1);
        int rect_x_end = Gdx.graphics.getWidth() / map_size;
        int rect_y_end = Gdx.graphics.getHeight() / map_size;
        int map_x = Gdx.input.getX() / rect_x_end;
        int map_y = Gdx.input.getY() / rect_y_end;
        int x = map_x * rect_x_end;
        int y = Gdx.graphics.getHeight() - (map_y + 1) * rect_y_end;
        shapeRenderer.begin(ShapeRenderer.ShapeType.Filled);
        shapeRenderer.setColor(0f,1f,0f,0f);
        shapeRenderer.rect(x,y, rect_x_end, rect_y_end);
        shapeRenderer.end();

    }
    
    @Override
    public void dispose () {
    }
}

Answer 1

The projection matrix of your ShapeRenderer is calculated on initialization,you need to re-calculate it whenever the window changes size.

There are a few ways of achieving this, the simplest might be to just create a new ShapeRenderer when the window resizes:

@Override
public void resize(int width, int height) {
    shapeRenderer = new ShapeRenderer();
}