Player.cs

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;

namespace EngineTest
{
    public class Player : Entity
    {
        public Player(Texture2D texture)
            : base(texture)
        {

        }

        private Vector2 move;
        private float grav = 0.3f;
        private Int32 input_left;
        private Int32 input_right;
        private bool input_up;
        public Vector2 speed  = new Vector2(2f, -4f);



        public override void Update(GameTime gameTime, List<Entity> entities)
        {

            input_left = Convert.ToInt32(Keyboard.GetState().IsKeyDown(Keys.A));
            input_right = Convert.ToInt32(Keyboard.GetState().IsKeyDown(Keys.D));
            input_up = Keyboard.GetState().IsKeyDown(Keys.Space);

            Move();
            foreach (var entity in entities) //Looks at all entities created
            {
                if (entity == this) //If it is player, don't check collision
                    continue;

                //Horizontal Collision
                if (PlaceMeeting(new Vector2(Position.X + Velocity.X, Position.Y), entity))
                {
                    while (!PlaceMeeting(new Vector2(Position.X + Math.Sign(Velocity.X), Position.Y), entity))
                    {
                        Position.X += Math.Sign(Velocity.X);
                    }
                    Velocity.X = 0;
                }
                //Vertical Collision
                if (PlaceMeeting(new Vector2(Position.X, Position.Y + Velocity.Y), entity)) // checking if it's going to collide in 1 step
                {
                    while (!PlaceMeeting(new Vector2(Position.X, Position.Y + Math.Sign(Velocity.Y)), entity))// checking if it's not going to collide in 1 pixel
                    {
                        Position.Y += Math.Sign(Velocity.Y); // incrementing pixel By pixel until it's going to collide in 1 pixel
                    }
                    Velocity.Y = 0; //stoping the player
                }
            }
            Position += Velocity;
        }
        private void Move()
        {
            move.X = (input_right - input_left);
            Velocity.X = move.X * speed.X;
            Velocity.Y += grav;
            if (input_up)
                Velocity.Y = speed.Y;


        }


    }
}