B4J Tutorial [B4X] [BitmapCreator] Creating a cross platform Tetris game

This example shows how BitmapCreator can be used to create a cross platform Tetris game.
The code is an evolution of the code introduced in the "walking character" example.

There are three types of modules in these projects:

• Main module which is mostly empty and is different in each of the projects.
• The game framework classes, shared by all three projects, and not specific to this game.
  The following classes are included:
  • GameUtils - Manages the main loop and also includes various utility methods.
  • Sprite - Each custom sprite object holds a Sprite object. The Sprite object implements all the sprite common features.
  • DummySprite - Useful for simple sprites that do not need special implementation.
  • ScoreLabel - A custom view that shows the score
• Game specific classes, shared by all three projects:
  • Game - The main game class. GameUtils calls all kinds of methods of this class.
  • Background - The background sprite. Note that the moving pieces start as sprites and once they stop moving they are drawn onto the background sprite.
  • Piece - Represents a moving piece

If you are interested in cross platform development then it is most important to understand how to add modules as linked modules:



This way, changes in one project will be updated automatically in other projects.

I will not go over all the code. If you are interested then download it, play with it and feel free to ask any question you have.

Some interesting points:

- The pieces structure is loaded from a text file. It defines all the pieces. For example:
P1.Color=FF0000
P1.Pattern=(0,0)-(0,-1)-(0,1)-(0,2)
P1.Orientations=2
P1.Center=(1,1)
P2.Color=1400FF
P2.Pattern=(0,0)-(-1,1)-(0,1)-(1,1)
P2.Orientations=4
P2.Center=(1,1)

Each piece is defined with a 4x4 grid. The Pattern field defines the blocks in this grid where block (0,0) position is defined by the Center field.

- The Rows list stores the state of all blocks. There are 20 rows and 10 blocks in each row. Each item in the Rows list is an array of booleans. Each boolean represents the state of the column in that row.
- When a piece stops moving we check for full rows. Full rows are removed from the list and new empty rows are inserted at position 0.
- When one or more rows are removed, the existing graphical rows are copied to a temporary BC and after the moving animation completes, back to the background bc.
- The B4A game uses Immersive Mode: https://www.b4x.com/android/forum/threads/90882/#content
- The B4i game uses full screen: https://www.b4x.com/android/forum/threads/full-screen-apps.47866/#content
- The clickable labels in B4A and B4i provide haptic feedback. It is done with NativeObject / JavaObject.
- The blocks graphics are made from this greyscale image:

- GameUtils.GreyscaleToColor sub is used to create copies of this image with different colors.
- All the layout handling is done with two layout files. The first sets the main layout and the second uses designer script to set the ImageView width/height ratio:

Code:

GameRatio = 2
ScreenRatio = 100%y / 100%x
If ScreenRatio > GameRatio Then
 Pane1.SetLeftAndRight(0, 100%x)
 Pane1.Height = Pane1.Width * GameRatio
 Pane1.VerticalCenter = 50%y
Else
 Pane1.SetTopAndBottom(0, 100%y)
 Pane1.Width = Pane1.Height / GameRatio
 Pane1.HorizontalCenter = 50%x
End If
ImageView1.SetLeftAndRight(2dip, Pane1.Width - 2dip)
ImageView1.SetTopAndBottom(2dip, Pane1.Height - 2dip)

The ImageView is inside a Panel named Pane1.
- All the game logic was developed and tested with B4J. Once the main things worked I ported it to B4A and B4i.

Credits: Font and inspiration: https://github.com/spypunk/tetris
- Tetris itself is a trademark of The Tetris Company. It is used here for educational purposes only.

Depends on BitmapCreator v3.6+
It is included in B4A v8.3
B4i: https://www.b4x.com/android/forum/threads/updates-to-internal-libraries.48179/#post-596138
B4J: https://www.b4x.com/android/forum/threads/updates-to-internal-libaries.48274/#post-596139

 

Note that there is a bug that causes the game to crash if you rotate some of the pieces when they are at the top position. Will be fixed.

You should use iXUI v1.70+. It was included in B4i v5.00.

 

Just noticed it as well while playing on my phone

Will be fixed.

 

See the dependencies section at the end of the first post.

 

An updated version was uploaded. It fixes the crash discussed above.

 

I'm not sure that it is a problem. There are some edge cases where it is not possible to rotate the piece.

If you do want to allow it then the best solution is to allow blocks to be located in negative rows. It will require a few changes.