• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
black_darkness

How do I center a game character on the screen?

4 posts in this topic

I would like my character to be the center of the screen at all times. I am using allegro and C++. Right now I am rendering the full 30x30 map at all times. But my end goal is to have only 9x9 rendering at once. I don't know if I should do this by changing the displays variables. (tried this but it just changed the windows size.) Or change the which part of the map is displayed. ( I tried this but the character wasnt centered and the map did change but character moved left, and the map followed. So I stayed in the same spot indefinitely. )

 

 

I achieved this result with this code.

 

 

            for(int col=0;col<height;col++) {                 for(int row=0;row<width;row++) {                     al_draw_bitmap_region(tileset, mv[col][row].sx * 16, mv[col][row].sy * 16, 16, 16, (row*16 + hero.wloc*16), col*16, 0);                 }             }  
 

 

 

And it looks like this (Before and after 7 movements. Notice how the character isnt centered and the map isnt being drawn around him.)

 

example.png

 

 

 

 

 

Here is something I am curious about. Should I draw the whole map or only the part I am currently on?

 

 

            for(int col=0;col<height;col++) {                 for(int row=0;row<width;row++) {                     al_draw_bitmap_region(tileset, mv[col][row].sx * 16, mv[col][row].sy * 16, 16, 16, row*16, col*16, 0);                 }             }  

 

 

For reference here is a screenshot of my character. Notice how he is in the bottom right corner.

 

Okay. I deleted the previous attempt at centering and this is how my character is displayed. Every time he moves the screen stays stationary. (notice how he is at bottom right of screen instead of centered.)

 

Untitled.png

 

 

The following video is an example of how I want my character to behave.

http://www.youtube.com/watch?v=YkVvRZdnCi4

 

 

A release of my game.

https://www.dropbox.com/s/pxnnfmvwgslkxcs/negfaron.rar

 

Source code

main.cpp - http://pastie.org/5565697

make_map.h - http://pastie.org/5565698

main.h - http://pastie.org/5565699

 

 

Display initialization

 

ALLEGRO_DISPLAY* display = NULL;
Edited by black_darkness
0

Share this post


Link to post
Share on other sites

Draw only the onscreen tiles and a 1 tile margin around the screen edges to make smooth scrolling easier. In other words, if your display is 15x15 tiles then draw 17x17 tiles.

 

As for centering the map around the character;

 

Start by getting your map x/y (which tile are you on) to use as the point to center on.

Subtract half the screen width (in tiles) from x and half the height from y.

This should give you the x/y of the tile to be placed in the upper-left corner.

 

I haven't looked at your code but I think you could probably take it from there.

 

If you want to the screen to not scroll its edges past the map edge then you'll need to do some bounds checking. For instance, run the above calculations and if x or y is negative then set them to 0. If they're greater than the map dims minus the screen dims then set them to map dims minus screen dims, etc.

1

Share this post


Link to post
Share on other sites
Draw only the onscreen tiles and a 1 tile margin around the screen edges to make smooth scrolling easier. In other words, if your display is 15x15 tiles then draw 17x17 tiles.

 

As for centering the map around the character;

 

Start by getting your map x/y (which tile are you on) to use as the point to center on.

Subtract half the screen width (in tiles) from x and half the height from y.

This should give you the x/y of the tile to be placed in the upper-left corner.

 

I haven't looked at your code but I think you could probably take it from there.

 

If you want to the screen to not scroll its edges past the map edge then you'll need to do some bounds checking. For instance, run the above calculations and if x or y is negative then set them to 0. If they're greater than the map dims minus the screen dims then set them to map dims minus screen dims, etc.

 

 

Okay, I will try to always render the hero at the center of the map first. brb.

 

 

Edit: Alright the game is centered properly.  Thank you for the answer.

Edited by black_darkness
0

Share this post


Link to post
Share on other sites
if your display is 15x15 tiles then draw 17x17 tiles.

Shouldn't he/she draw only 16x16 if 15x15 from 0x, 0y fill whole screen?!

0

Share this post


Link to post
Share on other sites

The player may move in either direction. You can do one additional and then just throw the margin onto the side that you're moving toward when you start scrolling, but it's easier to just do it on both sides and tile-based engines are pretty lightweight in the rendering department.

 

I think the first time I did it I actually had a 1-tile margin that I would just move around to the other side of the screen, like using logs to roll a boulder on, lol. I'd scroll the tile sprites and then when a row/column passed out of the screen I'd move those tiles to the other side of the tileset. It got pretty crazy for a while until I refactored it and did it right.

 

Edit - I guess I should be more clear about what I'm talking about.

 

If you use a single-tile margin then when scrolling triggers to the left you should 'snap' the tile sprites such that the current extreme-right tile is on the rightmost edge and the 'margin' (offscreen) column is on the leftmost edge, then move all the tile sprites smoothly to the right for the length of one tile. Then you 'snap' again and repeat as needed. However, if you scroll to the right you have to snap oppositely - such that the leftmost visible tiles are placed in the leftmost edge of your tile sprites and the margin column is offscreen to the right, etc.

 

Using a double-width margin means that you can have a margin in all 4 directions. This way you can skip the first step (the snapping to one side or the other) and just start smooth motion of the sprites, then just reset the sprite positions and snap the tiles to center when you finish scrolling by 1 tile.

 

It sounds trivial, and it kind of is, but in practice it makes the process less complicated by removing that first snap.

Edited by Khatharr
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0