This is an in-progress work with the aim to model the combat system of a collectible card game like Magic: the Gathering.
Currently, I am still experimenting with the UI, and few game mechanics have been implemented. There are creatures on the battlefield with default images and stats that can be declared to attack, and turns go through each step, but full combat and other game actions have not been implemented.
At this point, this is best viewed as a showcase of my experimenting with RxJava, Dagger 2, and Data Binding.
The bottom row represents the hand, the row above land resource cards, and the row above creature cards. Above that is your opponent's creatures (not implemented), then a game log and a button to progress through the turn, then finally the turn counter, life tracker for each player, and a button to switch what player you are viewing as.
Touching the creature cards will produce no action most of the time, but during the "declare attackers" step, if you are viewing the game as the current player, this will add or remove a sword icon that designiates it as an attacking creature. When you press the button labeled "Confirm Attack", and don't cancel, the creatures will be rotated 90 degrees (tapped). The sword icon will disappear after the "end of combat" step, and the creatures will untap at the start of the current player's next turn.
During the "combat damage" step, attacking creatures will deal damage to the other player. Creature-to-creature combat has not been implemented yet, nor has game loss.
Touching the "next step" button will progress through the steps in a turn, indicated in the game log. After the end step, it will switch to the other player's turn. The current player is indicated in the turn counter, both in name and color.
Touching the "switch" button will switch which player you are viewing the board as, but will not change whose turn it is. In the future, this will allow players to cast spells during another player's turn, and this will be used to set up blockers when the other player attacks.
In the future, the game will follow a simplified version of the rules of Magic: the Gathering. On your turn, you draw a card from your library, then you can move land cards from your hand to the battlefield, and use them to cast spells. Creature spells will be put on the battlefield, while sorceries will have an effect but then go to the graveyard. You can have creatures attack during the combat step of your turn. Once you go through all steps and phases on your turn, it switches to your opponent's turn. At any time, you can switch perspective to the other player and cast spells on your opponent's turn, if that spell allows you to.
- Add tests for recent changes.
- Implement attacking, life point loss, and game loss.
- Implement full combat, with blocking and creature destruction, although limited to default creatures.
- Implement creatures with different power and toughness.
- Specify creatures in XML instead of programmatically.
- Implement lands and casting creature spells.
- Implement card drawing and the library.
- Have fully functioning card game, albeit with only creatures that have no abilities.
- Add static creature abilities, which can be specified in XML.
- Add sorcery spells, programmatically and then in XML.
- Implement "enter the battlefield" effects on creatures, which can be specified in XML.
- Add instant spells that can be cast on the opponent's turn.
- Add more complex abilities on creatures.
- Add other card types.
While working on this project, I had discovered problems with Data Binding. One feature is that switching players (the SWITCH button in the top right) will change the background color of every view in the main Fragment, which I planned to handle by using Data Binding to set the background of each view in the Fragment's XML with a function in the Fragment's View Model. However, when Data Binding is used to set the background of views in a PercentRelativeLayout, the background isn't properly sized. If Data Binding is not used and a static background is set in the layout, it loads properly, but even if Data Binding will always specify the same background resource, it doesn't load properly. My guess is that it always uses the dimensions of whatever view is loaded first, which in my case, was the bottom RecyclerView that takes up the width of the screen, but I have not experimented with this. I switched to setting the background programmatically, and it works properly.
Another feature is that clicking a creature (third row from the bottom) will cause the image to rotate 90 degrees (tap) or return to normal (untap), but after switching players a few times, some views would not properly do this. The data models were updating properly, but I found that the function to load the image, called from a Data Binding BindingAdapter function, was not being called. Instead of using Data Binding, I switched to just loading the image in onBindViewHolder() for the containing RecyclerView, and it works properly now.
At this point, I have mostly abandoned using Data Binding, with the exception of in fragment_board.xml, following the recommendations for how to use RecyclerViews with Model - View - View Model design at this link (https://medium.com/@hiBrianLee/writing-testable-android-mvvm-app-part-2-fd291290af83). Currently, I am also using Data Binding to set the power/toughness indicator for creatures, but that is a static value, and I expect issues to crop up when it starts changing.