activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:background="@drawable/caida_del_mundo"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/derecha"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.95" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/izquierda"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.05" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/arriba"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.025" />
    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/abajo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.975" />

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="350dp"
        android:layout_height="300dp"
        app:layout_constraintBottom_toTopOf="@+id/abajo"
        app:layout_constraintEnd_toStartOf="@+id/derecha"
        app:layout_constraintHorizontal_bias="0.45"
        app:layout_constraintStart_toStartOf="@+id/izquierda"
        app:layout_constraintTop_toTopOf="@+id/arriba">

        <EditText
            android:id="@+id/usuario"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="30dp"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="Name"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <EditText
            android:id="@+id/contraseña"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:ems="10"
            android:inputType="textPassword"
            android:hint="Contraseña"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/usuario" />

        <Button
            android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="44dp"
            android:text="Iniciar Secion"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/contraseña" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Registrar"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.373"
            app:layout_constraintStart_toEndOf="@+id/button"
            app:layout_constraintTop_toBottomOf="@+id/contraseña" />
    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.constraintlayout.widget.ConstraintLayout>