XNA 2d animation

Added animation to pieces. They now glide from one square to another smoothly. At the start of the animation I make a note of the game time, so I know when the animation started. I add a second to calculate when it should end. Then I get the x and y coordinates of the start and end positions.

Then later on, in the display function, work out how far the piece should have moved between the start and end points given the current game time and display a piece at that location.

When the animation starts I make the call to move the piece so I have to display over the destination square with a sprite to show one fewer pieces than are actually there until the animation ends, when the moving piece arrives at it's destination.

The animation takes the same length of time no matter how far the piece is going to move, and the movement is linear, there is no easing into and out of the move. I am developing on a netbook, and I think the animation would be smoother on a desktop, but it looks pretty good.

XNA, the fun bit

I worked on improving the graphics, creating help screens, realising that twiddling with images could extend indefinitely, so have made a list of things to change and will stop when it looks good enough. Also decided that I really must add some animation of pieces so that they glide from one position to another rather than teleporting.

Changing the rules

I played a few games and realised I wanted to change the rules. Instead of capturing the opponents pieces you can send them back to their start square. This improves the game play enormously, but does mean that the weightings I generated earlier are all invalid.

XNA game

I hooked up the existing code to generate the computer's move and make it.

There are still no delays yet, so after your turn the dice get rolled and the move is made instantly, then the dice are rolled again instantly and it's your turn. I need to think of a way to introduce a delay, possibly even an animation to move the pieces smoothly and give the human player a chance to appreciate what is happening.

Highlighting moves

I added highlighting to show the square you are hovering over and the square the piece would move to with the current dice. To do this I am using PNG files with transparent backgrounds as follows

Background



Piece



Highlight

Put it all together



and for the destination cell

Background + Highlight

These only show up if there is a legal move for the piece hovered over using the current dice.

To display them I am adding them to a spriteBatch:

// start collecting sprites
spriteBatch.Begin();
...// where to display the sprite
Vector2 tempVector = new Vector2(x, y);
// display piece (a Texture2D)
spriteBatch.Draw(piece, tempVector, Color.White);
...
// finished collecting sprites
spriteBatch.End();

That's all it takes to display a 2D board game, lots of sprites displayed in the right place. Not too difficult.

Moving pieces

I captured the mouse position and added the ability to select a piece to move, checking, of course, that it was a legal move.

This was easy to add as all the game logic for deciding legality of moves already existed in the console app. This was partly why I wanted to get the game play sorted out in a console app before trying to tackle XNA.

Searching the rainforests

If you have been using Bing or Yahoo for search, consider using Ecosia instead.

It's a search engine created by the WWF in conjunction with Yahoo and Bing. It has the advantage that most of the money taken from advertising goes to protect the rainforest. According to the search page they have already managed to protect 108,000 square yards. The more people use the search engine the faster that figure will grow.

Obviously, it isn't enough and what is really needed is for Governments to act. I know small changes are not enough, but it is time to do whatever we can.

XNA Conference

Tomorrow is the first XBLIGUK conference in Birmingham, for XNA developers. I am not going to be there, but I hope it is a success and that it is the first of many. The agenda looks very promising.

Putting the code into XNA, part 2

I added a GameMode class to handle the succession of different modes that happen within the game, starting with the following :-

Player 1 rolls the dice,
Player 1 enters a move,
Make player 1's first move,
Player 1 enters second move,
Make player 1's second move,
Player 2 rolls the dice,
Player 2 generates 2 moves,
Make player 2's 1st move,
Make player 2's 2nd move

After player 2 has moved the game loops back to player 1's turn.

I found it best to keep to keep the Draw method just for displaying the board and all the changes to the gamemode in the Update method of the game loop.

So the game Update method contains a switch statement similar to this...

switch (GameMode.State)
{
case GameMode.Player0RollingDice:
{
Dice.Roll();
GameMode.State = GameMode.Player0Input1;
break;
}
case...

Putting the code into XNA

I started by getting XNA to display the board, this is easy
as it is just a static background so I used the spriteBatch.

Vector2 tempVector = new Vector2(0, 0);

spriteBatch.Draw(background, tempVector, Color.White);

I also needed to resize the window in the Initialize() method...

this.graphics.PreferredBackBufferWidth = 224;

this.graphics.PreferredBackBufferHeight = 471;

this.graphics.ApplyChanges();

Then display the pieces on the board in their starting positions and finally the dice. It is only a 2d game but this seems really easy.
I needed to get mouse input. I used Mouse.GetState().

If the game was ever going to run on the XBox then this wouldn't be enough. Apparently they forgot to add a mouse when they designed the XBox. What were they thinking? I'd need to add support for a GamePad. I don't own an XBox so I am not too bothered about this.

KeyboardState keyboard = Keyboard.GetState();

MouseState mouse = Mouse.GetState();

Now, I can use mouse.X, mouse.Y and compare mouse.LeftButton with ButtonState.Pressed.

Alpha beta tree pruning

A method where you can limit the number of nodes that the computer looks ahead in a game by stopping if you can prove that a particular move would be worse than one you have already evaluated. I think.

The wikipedia article leads me to conclude that some people
have spent a lot of time thinking about games.

Maybe next time I write a game I'll use it.

XNA game

I tried to improve the genetic programming approach.

Player One uses a set of weightings giving different importance to various ways of evaluating a position. Then generate ten random sets of weightings around Player One's settings for Player Two to use. Get Player One to play twenty games against each of the sets of ten mutated values. If there was a clear winner then let Player One adopt those weightings and continue with ten new mutated sets based around them. If there was no clear winner then increase the variability slightly and try again with new mutations.

I left it running over night to see if it would improve dramatically.

It seems to have varied the weightings a lot but not really in one direction. Looking at the logs I can see one particular value would go up then down, repeatedly. This could mean there are different approaches to playing and that some of them have slight advantages over others, but not a significant advantage.

Or it could be like stone - paper - scissors played as if there was a best choice. Playing stone all the time leads your opponent to play paper, but if you adopt paper as the winning solution then they play scissors. When you play scissors they play stone and together you proceed around and around.

Not sure what to do about this, but I've added "Read a book on genetic algorithms" to my ever increasing to-do list along with "find out about alpha-beta pruning next time" (as recommended by El Walrus).

XBLIG-UK conference

There is an XBLIG-UK conference in Birmingham on Saturday 5th December. It is organised, I think, by nxtgenug.

This looks like it will be a jolly good event, lots of interesting sessions from people who are experienced with XNA.

Sadly, I shall not be there as I have other commitments that day. So, I hope there will be another.

Is it improving?

Checking the game to see if the computer player improved Switched back to human vs computer mode and played a game. I was pleased that it actually won a game. I wasn't trying hard to win, but this is progress.

So far the approach seems to have worked well. The moves it makes are occasionally sensible ones that I would make myself.

Sometimes it makes moves that I wouldn't.

XNA game. Evolving a better player

I've changed the code so the computer can play against itself. I gave each of the two computer players different weights for the evaluation. This is like having two human players with different playing styles.

Changed the game loop so that they play matches of twenty games against each other using their current weightings. The loser of a match changes their weightings by some small random amount. Then they play another match to see who wins.

I left it to play 5,000 matches to see if it improves. Over time, it ought to evolve into a better player.

XNA game development

Trying to improve the computer's game:
I gave the software a way of evaluating a position. So some moves will result in a position that achieves a high score, such as capturing pieces, and some a low score, such as having pieces taken or leaving them exposed.

I am working out what to evaluate by noticing what I think is a good position when I am playing.

I gave random weights to each of the methods of evaluating the position, since I can't really say what priority I actually give to the things I consider.

The approach is to sum the results from each of the weighted methods for each possible position and use those to pick the best move.

The computer still loses every time.

XNA game progress

I have been working on getting the computer to play. The simplest approach is to have it pick random pieces to move, and keep trying till it finds a legal move. This isn't a good approach, it loses every time, I just want to get the flow of the game going.

The game I am writing involves two players taking turns to roll two dice and move one or two of their pieces. Unfortunately, the computer move is instantaneous so it makes it difficult to see what is happening. I need to add some delays. I might leave this until I put the code into
XNA.

Notes on Open University Course T206_2 An introduction to

4 Renewable Energy Sources
Most renewables originate from the sunTidal from gravityGeothermal from heat trapped in the earth Solar-thermal-PV
Indirect solar-Wind-WaveThese will be renewed naturally, won't run out.
Presently more expensive than fossil fuels but attractive
due to lower environmental impacts
5 Energy Services and Efficiency Improvement
Efficiency : 2 thirds of the energy ends up as waste heat
Energy has been reducing in price so little incentive to
attempt to improve efficiency.
Supply side: generation efficiency can be improved...Combined Cycle Gas Turbine (CCGT) uses hot exhaust gases
from gas turbine generator to power a steam generator.CHP Combine Heat and Power, uses waste heat from power
stations to heat buildings8% of energy lost through transmission/distribution
Demand side:More efficient appliances (must be wary of embedded carbon,
co2 produced in the creation of a new appliance can outweigh
any benefit from energy saved in use) Social changes (walking cycling to work, public transport)
Four sectors: Domestic (draught proofing, insulation) Commercial & Institutional Industrial (reuse waste heat, product design, thinner
materials) Transport
6 Energy in a Sustainable Future
How to improve sustainability:Carbon sequestration (storing carbon so it cannot get back
into atmosphere)Fuels switching - to less polluting fuelsSwitching to renewablesDemand side efficiency improvements
Royal Commission on Environmental Pollution (RCEP) proposed
four scenarios for the UK which consider the options
available for balancing supply with demand given the need to
reduce CO2 emissions by 60%.
World Energy Council has come up with six scenarios
incorporating different assumptions about rates of economic
growth in rich and poor countries; choices of technology and
its development; and the priority given to ecological issues
A number of paths to sustainability, but, since they rely on
different mixes of technology, they are likely to have
different social, environmental and political implications.

Writing an XNA Game

I'm writing a board game in C# with the intention of getting it to run in XNA.

I don't want to get distracted with xna and graphics just yet. I want to have a working game first. The approach I am taking is:-

1. Create a console app.


2. Get it to initialise and display the board as text. Each of the 24 squares on the board is numbered (0 - 23) and the pieces are represented by red or green non-zero values. An empty square is shown as a white zero. Start squares and home squares are in blue

3. I have added code to capture how the pieces move from square to square.

4. Also added rules, for checking when the game is over and who won, and preventing any illegal moves.

5. I have added a game loop so you can play a game human vs human.

This is working well so far, but the display is not easy to read in a console app.

Notes on Open University Course T206_2 An introduction to sustainable energy

A free course from the Open University

1 Why sustainable energy matters
Current use of fossil fuels not sustainable.
Finite supply(but not about to run out immediately)

Location of 2 thirds of oil in Middle East or N. Africa - has led to conflict.
Price rises led to protests. (Renewables need to enable the same level of affluence that fossil fuels have enabled, else acceptance will be low)
Accidents during extraction, distribution and use.
Pollutants from use. And CO2 leading to climate change affecting ecosystems, agriculture, sea levels
Nuclear is source of 7 percent of primary energy
No green house gases, but...Supply of uranium also limited (decades or possibly centuries at current rate of use), proliferation of weapons, problems of disposal and cleanup.
Efficiency of systems is an important factor in mitigating the effects of energy use.

Renewables - Replenished by natural processes.
Solar energy, bioenergy, hydroelectricity, wind and wave power
Current costs can be higher than conventional sources, slows take up.
Need:-

• To reduce impact of fossil and nuclear
• To develop and deploy renewables
• To improve efficiency of conversion, distribution and use
  

2 Definitions: Energy, Sustainability and the Future

Energy is the capacity to do work.
Power is the rate of doing work.
Energy = power x time
Sustainable development is ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs ’ (United Nations, 1987).

3 Present Energy Sources and Sustainability

80% of energy comes from fossil fuel at present
At current rate-200 years of coal, 60 years gas, 40 years oil

Hydrocarbons release co2 on combustion, a greenhouse gas.

Nuclear:Energy released by splitting uranium atoms (fission)
Major concerns are safety and disposal of waste
Biofuel:Combustion of straw and forestry waste. Incomplete combustion can release pollutants. Only sustainable if trees replanted ( also only sustainable if biodiversity of resource is maintained.)
Hydroelectricity 17% of electricity produced in 2000 came from hydroelectric.
- indirectly solar power from evaporation of water to rain

Bee pictures

Here is a view inside the hive. The bees are mostly on five frames:-

Rachel with some of the bees on a new frame:-

Me, posing with the hive:-