DaniWeb IT Discussion Community

Game programming - allocating actions based on surroundings

llemes4011 — Sun, 22 Nov 2009 19:35:55 GMT

I'm working on an rpg game, and one of the big issues that I had (have), is having the players actions change around other objects.

For example, normally the "a" key would attack, but when next to a person, it would trigger a dialog sequence, and when next to a rock, allow you to push/pull it around.

At first I thought to do something like this:

if(nextToPerson()) aCommand = talk;

else if(nextToRock()) aCommand = pushPull;

else aCommand = attack;

I then realized that this would be very inefficient in the long run, and cause the player class to be much larger than need-be.

I then came up with the idea of the surrounding objects controlling the players available actions.

example:

public interface ACommand{

    int aRange(); // how far does the action effect?

    void callACommand(/*args*/);

}



//========================



public class Person implements ACommand{

    // Player's a command changes within 1 meter of a person

    int aRange(){ return 1; } 

    void callACommand(/*args*/){ Player.talk(this); }

}



//========================



public class Player implements ACommand{ // default command

    int aRange(){ return 150; } // default value (may be something else)

    void callACommand(/*args*/){ Player.attack(); }

    void keyPressed(KeyEvent e){

        if(e.getKeyChar()=='a'){

            Object closestActionChange = null;

            if(closestActionChange = findClosestAction()){

                if(closestActionChange instanceof Player) 

                    this.callACommand();

                if(closestActionChange instanceof Person) 

                    ((Person)(closestActionChange)).callACommand();

            }

        }

   }

}

This is the solution that I came up with. It allows the Player class to remain somewhat simpler, and allows objects to govern themselves. findClosestAction() talks to the game engine to see what is around that can influence the Player's available actions. This is just something that I came up with, trying to make a game work a bit smoother. Most times, the interface would be implemented by the abstract super class of the object, and be overridden as necessary.

If you have any comments/suggestions, please let me know. I'm hoping that this is a good way to do this, and if not, I would like to know why, and where it could be improved. (This isn't really a question, rather a discussion about pros and cons of this way of doing things.)

Also, this is just a rough outline. The interfaces would be more structured, and things would fit together better than in the example. The keyPressed method in the player class would be better structured as well.

Edit:
Now, I'm thinking that the keyPressed method should go in the GameEngine class, which would hold the window, rather than in the player class

Thoughts about Qt

llemes4011 — Sat, 21 Nov 2009 15:13:10 GMT

The company that I work for just bought a Qt License, so we've been messing around with it. So far, it's really nice. I'm more of a Java guy, and it's made the transition from Java to C++ much easier. The only real problem I have with it now, is that you pretty much have to use their IDE to develop applications with it.

So, my question is, what do you think of Qt?
Qt Libraries

Writing a Graphics Library

llemes4011 — Mon, 16 Nov 2009 03:37:58 GMT

Hi everyone, I decided that I wanted to try to write a graphics library. Yes, I know Java already has one, I just thought that it would be fun to try. I looked around, but couldn't find anything on the subject. I want it to be for Java, but I'm pretty sure that it will have to include some C/C++ as well. Does anyone know where to find a good tutorial or have any advise (other than "don't")?

Thanks =D

System Mouse Click

llemes4011 — Thu, 22 Oct 2009 21:48:05 GMT

Hello. I'm trying to write a program that registers Mouse Clicks that occur on the System, not just in a JFrame. Does java6's desktop integration allow this sort of thing? or would I have to use JNI to listen for Mouse clicks and Key Pressed?

Code Snippet Generating a basic Fractal.

llemes4011 — Thu, 15 Oct 2009 01:08:54 GMT

This is a very basic implementation of a Julia Set Fractal Generator. All of the variables are coded in, so feel free to change them to experiment with different results. I give an explanation of Complex Numbers and the Complex Plane, but you should look it up for your self, as I only go a little but into detail.

There are other formulas that you can use inplace of f(z+1) = z^2 + c, and some of them give pretty cool results. Have fun =)

Fractal Color Generation

llemes4011 — Wed, 14 Oct 2009 23:43:20 GMT

Hello! I'm writing a fractal generation application. I have the fractal part down, but I can't seem to get the coloring right.

What I want to do is, as the number gets closer to infinity, the pixel it relates to's color should get darker (Black relating to infinity, The other color relating to 0).

Currently, I'm doing the following to compute the colors:

        minMagnitude = 100.0;

        maxMagnitude = 0.0;



        System.out.println("MAXMAG = "+maxMagnitude+"\nMINMAG = "+minMagnitude);



        // Find the lowest & highest magnitudes

        for(int i=0;i
            for(int j=0;j
                if(doubles[i][j]>maxMagnitude){

                    maxMagnitude = doubles[i][j];

                }



                if(doubles[i][j]
                    minMagnitude = doubles[i][j];

                }

            }

        }



        System.out.println("MAXMAG = "+maxMagnitude+"\nMINMAG = "+minMagnitude);



        double value = maxMagnitude-minMagnitude;

        double ratio = 1.0/value;



        // Calculate color values

        for(int i=0;i
            for(int j=0;j
                colors[i][j] = Color.HSBtoRGB((float)(doubles[i][j]*ratio), .3f, .7f);

            }

        }

From the printlns, I know that the number range from almost Zero, to Infinity:

MAXMAG = 0.0

MINMAG = 100.0

MAXMAG = Infinity

MINMAG = 1.4797537555783645E-5

The MAG (Magnitude) variables are calculated like so:
(Where a & b are variables in a Complex Number (a+bi) )

public class ComplexNumber{

    //... Other methods

    public double magnitude(){

        return this.a*this.a+this.b*this.b;

    }

The coloring should be a smooth gradient, but instead it is much more contrasted (Sorry, if that's the wrong word, I'm not an artsy guy...).

If anyone knows of a solution, it would be great if you could point me in the right direction =).

Also, I've included a picture of what is happening when it runs.

Attached Images

FractalColorMishap.bmp (739.3 KB)

GUI Component Dragging

llemes4011 — Mon, 12 Oct 2009 01:54:41 GMT

Hello. I've been using NetBeans for quite a while, and I really like the Draggable components that it uses. In both the GUI Builder & the GUI itself. So, my question is, How do you drag components around in the UI like that? I've looked into the java.awt.dnd package, and the tutorials don't really cover component dragging, just text dragging. If anyone has any tips or links to good tutorials, those would be awesome =).

Beginning MySQL with Java

llemes4011 — Mon, 05 Oct 2009 01:39:06 GMT

Hello everyone =) I'm a Java programmer who wants to do work with databases. MySQL seems to be a popular choice, but I don't know where to start. I messed around with Derby, but I didn't really understand what was going on. If anyone could point me in the direction of a good tutorial for MySQL through Java, that would be awesome =)

Thank you!

Business Apps

llemes4011 — Thu, 01 Oct 2009 23:19:27 GMT

Hi everyone. I know that asking for project ideas is generally frowned upon, but I wish to ask anyways. This isn't for school, it's just because I want to. I want to start writing applications that would be used in a business or workplace environment. I don't have a lot of expertise in this specific area, and it isn't something that my programing class goes over. So, I guess my question is: Does anyone have any ideas? I don't want to do something really basic, it needs to be challenging. If anyone has any ideas, that would be great =)

also, would this be something to do with JavaEE instead of JavaSE?

-Neil

Derby Connection Issues

llemes4011 — Mon, 28 Sep 2009 21:15:07 GMT

Hello, I'm using NetBeans 6.7.1, and Derby 10.5.3.0. I'm trying to learn how to write Database applications, and I'm having trouble connecting to my Database. It loads the Derby Driver (EmbeddedDriver), but won't connect to the the Database named test. I looked at tests Properties in NetBeans, and it said that it was using the org.apache.jdbc.derby.ClientDriver. I did create the Database, and give it no username or password. Below is the code that I have. If anybody could help, that would be great =D

package jdb.test;

import java.sql.*;



public class DatabaseTest {



    public static void main(String[] args){

        try{

            // Load the EmbeddedDriver class

            Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();

            System.out.println("Loaded Derby Driver");

        }catch(Exception e){

            e.printStackTrace();

            System.out.println("Error loading Derby Driver.  Shutting down.");

            System.exit(-1);

        }



        // The database located on my computer

        String database = "jdbc:derby://localhost:1527/test";

        try{

            // Connect without a username and password

            Connection conn = DriverManager.getConnection(database);

            System.out.println("Connected to "+database);

        }catch(SQLException e){

            e.printStackTrace();

            System.out.println("Could not connect to "+database);

            System.exit(-1);

        }

        System.out.println("You have connect to the selected database.");

    }

}

This is the error that I get:

java.sql.SQLException: No suitable driver found for jdbc:derby://localhost:1527/test

        at java.sql.DriverManager.getConnection(DriverManager.java:602)

        at java.sql.DriverManager.getConnection(DriverManager.java:207)

        at jdb.test.DatabaseTest.main(DatabaseTest.java:22)

Intersects Arc

llemes4011 — Mon, 07 Sep 2009 02:50:03 GMT

Hi everyone. I have a quick question: Is there anyway that you can check to see if a point lays on an Arc2D object? I'm trying to write a Physics library (or at least part of one), and I noticed that there is no method that does it. You can check to see if the point is inside the curve, but that's not what I need. Is there a class that does that kind of math for you, or will I have to figure it out myself. Which brings me to: Can you retrieve an Array the points that are on an Arc?

Any help in this matter would be greatly appreciated! =)

User Libraries

llemes4011 — Thu, 03 Sep 2009 01:11:50 GMT

I need a diversion, and I was wondering. What would be a good library to write? It's somethings that I've wanted to do for a while, just never gotten around to. I was thinking about a lib for some of the methods that I often use, just much more generalized in some cases. Does anyone have any ideas for useful classes/methods to put in there?