Image Treatment For Games

General Discussion Other

pedroglp

in General Discussion • Other • 4 months ago

Hi everybody,
I'm developing a plataform game such as mario. For this, I've been using pBox2d and all the fisics are almost done, so I began to create all the sprites/animations. But at the moment, my real problem is how to properly treat images to use then as sprites/background.

First I tryed to use background fuction to load my background, but the image that've created for it was bigger than the screen, so I failed. After this I used loadImage before I draw any sprites, but it make my game start "laging" and too slow.
Then I thought if I could "cut" the background image, set as background and when my character moves I cut it again and set as Background? But I didn't find any library to do that :/.
Can someone help or tell how properly do that?

Thank everyboy and sorry about my english.

Replies(6)

quarks

Re: Image Treatment For Games

4 months ago

How big is your background image?

Are you using loadImage from inside draw() or any function called from draw()?

pedroglp

Re: Re: Image Treatment For Games

4 months ago

Its about 2x screen size(2*height,2*width), but it needs to be bigger as the cenary I want for the game.
And yes I was calling loadImage inside draw().

You can find the code here: http://github.com/Pedroglp/jogoDev But, all the comments/some variables are written in Portuguese pt-br, I'll change the language as soon as possible to help the understanding.

quarks

Re: Image Treatment For Games

4 months ago

And yes I was calling loadImage inside draw().

This is what causing the slow down - the draw() method is executed ~60 times a second which means it is loading the images every frame.

Load all your imapges in setup() use the PImages(s) created in draw().

pedroglp

Re: Image Treatment For Games

4 months ago

Thank you, quarks :). I'll check as soon as I arrive home.
Btw are the guy who made this: www.lagers.org.uk/s4p/ ? I'm thinking to use on my game, but as I see it already have a own physic engine inside and I don't know if will hard to adapt to pBox2d.
Also, do you any library that can cut a sprite sheet and then load with box2d? And don't you think that doing that with the background would reduce the computer memory used by the program?

quarks

Re: Image Treatment For Games

4 months ago

Btw are the guy who made this: www.lagers.org.uk/s4p/ ?

Yes - all the libraries and tools on that website are mine.

Also, do you any library that can cut a sprite sheet and then load with box2d?

No - BUT the code below might help.

To use the code create a new tab in the processing IDE and name it Textures.java (it is important that you use the exact name including the uppercase T)

Assuming you have declared a PImage variable e.g.

PImage img;

Then to load an image use

img = Textures.loadImage("filename");

The Textures class will remember every filename loaded so if you do something like

img = Textures.loadImage("mypic.png");
img = Textures.loadImage("mypic.png");

Line 1 will load mypic.png and create a PImage - both are remembered
Line 2 will return the PImage remebered in 1 - it will not load it from disk again

Once you have an image you can create a 2D array of images e.g.

PImage[][] tiles = Textures.makeTiles(img, nbrColums, nmrRows);

Textures.java

import java.util.HashMap;
import processing.core.PApplet;
import processing.core.PImage;
/**
* This class is used to load bitmap files and create images. <br>
*
* Although there maybe multiple requests for a particular bitmap file only
* one PImage is created for each file.
*
* @author Peter Lager
*
*/
public class Textures {
private static HashMap<String, PImage> textures = new HashMap<String, PImage>();
/**
* Load an bitmap file return a reference to the PImage created.
*
* @param app
* @param filename
* @return null if the file does not exist else the PImage object
*/
public static PImage loadImage(PApplet app, String filename){
if(textures.containsKey(filename)){
return textures.get(filename);
}
PImage image = app.loadImage(filename);
if(image != null){
textures.put(filename, image);
}
else
PApplet.println("Unable to load image from file '" + filename+"'");
return image;
}
/**
* Load images from multiple files
* @param app
* @param filename an array of filenames
* @return an array of images
*/
public static PImage[] loadImage(PApplet app, String[] filename){
PImage[] images = new PImage[filename.length];
for(int i = 0; i < images.length; i++)
images[i] = loadImage(app, filename[i]);
return images;
}
/**
* Make multiple images from a given image.
*
* @param app
* @param img the tiled image
* @param nCols number of tiles across
* @param nRows number of tiles down
* @return an array of images (tiles)
*/
public static PImage[][] makeTiles(PApplet app, PImage img, int nCols, int nRows){
PImage[][] imageTiles = new PImage[nCols][nRows];
int tileW = img.width / nCols;
int tileH = img.height / nRows;
for(int y = 0; y < nRows; y++){
for(int x = 0; x < nCols; x++){
imageTiles[x][y] = app.createImage(tileW, tileH, PApplet.ARGB);
imageTiles[x][y].copy(img, x * tileW, y * tileH, tileW, tileH, 0, 0, tileW, tileH);
}
}
return imageTiles;
}
}

pedroglp

Re: Re: Image Treatment For Games

4 months ago

Sorry for the delay on answering the topic, I am not having too much time for programming (things on Brazil its going crazy + college). Nvm got it, i'm going to try something like it.
Thank you so much for your help :)

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