Texture Atlases lesson

Summary:

Breaking down the method of grabbing frames

Texture Atlases lesson

Kronack (guest) 07 Apr 2015 20:35

So im trying to wrap my head around this.

public class AnimatedSprite
    {
        public Texture2D Texture { get; set; }
        public int Rows { get; set; }
        public int Columns { get; set; }
        private int currentFrame;
        private int totalFrames;
 
        public AnimatedSprite(Texture2D texture, int rows, int columns)
        {
            Texture = texture;
            Rows = rows;
            Columns = columns;
            currentFrame = 0;
            totalFrames = Rows * Columns;
        }
 
        public void Update()
        {
            currentFrame++;
            if (currentFrame == totalFrames)
                currentFrame = 0;
        }
 
        public void Draw(SpriteBatch spriteBatch, Vector2 location)
        {
            int width = Texture.Width / Columns;
            int height = Texture.Height / Rows;
            int row = (int)((float)currentFrame / (float)Columns);
            int column = currentFrame % Columns;
 
            Rectangle sourceRectangle = new Rectangle(width * column, height * row, width, height);
            Rectangle destinationRectangle = new Rectangle((int)location.X, (int)location.Y, width, height);
 
            spriteBatch.Begin();
            spriteBatch.Draw(Texture, destinationRectangle, sourceRectangle, Color.White);
            spriteBatch.End();
        }
    }
}

Can anyone help me break this down. the part where im stuck is if currentFrames = 0, then when you divide by the columns, won't you always get zero? I'm apologize if this is a dumb question. I did try just copypasting the code, and it works, but I am trying to figure out WHY it works.

Last edited on 08 Apr 2015 03:43 by rbwhitaker Show more

Kronack (guest) 07 Apr 2015 21:33

Wow, a few minutes after I posted it I had the "Ahah!" moment and it clicked. I was just being dumb.

It's okay if current / columns is cast to zero, because it allows us to stay on the correct row, until the amount of current frame / columns reaches 1, which we will then be on the next row.

Also for the record, just wanted to say Mr. Whitaker, I've been learning on this site for months and I bought your book. You should be proud of how well you explain things. You are a natural born teacher. You really should do online lectures or something, I would pay for them in a heartbeat.

rbwhitaker 08 Apr 2015 03:48

Hi Kronack! I'm glad you got it figured out. That code for wrapping frames has been confusing to quite a few people. I probably ought to replace it with something simpler, or maybe put in a little paragraph or two that explains it better. So even though you got yourself unconfused, I'm glad you posted your question anyway.

Thanks for the compliments about the book and the site. While on most days, I don't feel like teaching comes naturally to me (it's a ton of planning and editing and reworking, and usually the first couple of iterations are more harmful than helpful…) there's probably something to be said about the fact that my dad was a math teacher, my mom was an English/Spanish/German teacher, and even both of my sisters have spent at least part of their professional careers as teachers. There must be something genetic about it, right? :D