CS306 Processing Systems and Structures Spring 2002 Final Project

Snood Clone

Due Date	Demo on April 22
Purpose	Assembly-implemented Snood Clone

Introduction

The project will involve the assembly implementation of Snood, a highly addictive game involving the launching of specified pieces from a fixed location at varying angles (see www.snood.com). Using video mode 13h, graphics will be somewhat limited in resolution, but gameplay will be similar to the original. Implementation will include graphics input, video output, user input, and gameplay/scoring. Rather than standard snoods, initially, simple blocks of colors will be used.

Screen capture from www.snood.com

Implementation

The game will be implemented in a similar fashion as MP3 and MP4. An internal representation of the board will be maintained as an array of pieces, with separate graphics routines used to draw pieces in mode 13h, and update positions. Calculations for landing positions and collision resolution of pieces shot at different angles will be carried out using a lookup table with preset values. Modified ISRs will provide user input through the mouse and keyboard.

The GameBoard array will contain predefined constants, much like the maze in MP3. It will represent the entire visible screen, including walls, background, and game pieces. There is also a fixed width for every piece and wall. Background pieces are 1/2 the width so that columns can be staggered.

Procedures

GenerateGameBoard
- Purpose: Creates internal array of the game board.
- Input: none
- Output: GameBoard
- Description: Fills array with predefined constants. When two walls pieces are next to each other, then a new row has begun. Uses RandomPiece to fill in pieces.
- Owner: Jacob Perkins
Move
- Purpose: Moves given game piece from one location to another
- Input: SI is old pos, DI is new pos
- Outputs: GameBoard
- Description: Moves piece at old pos to new pos. Error checking should be done in the function that calls Move
- Owner: Jacob Perkins
DropRow
- Purpose: Drops an entire row down one row
- Inputs: SI is the start of the row
- Output: GameBoard
- Description: The row starting at SI is moved down one row, probably calling Move on each piece.
- Owner: Jacob Perkins
DropAll
- Purpose: Drops every row of block down 1.
- Inputs: none
- Output: GameBoard
- Description: Every row is moved down one and any space above the top row is filled in with 'bricks'. Uses DropRow and then fills top row with 'bricks'.
- Owner: Jacob Perkins
DeleteBlocks
- Purpose: If needed, a set of blocks is deleted
- Inputs: SI is the location of the new block
- Output: GameBoard
- Description: Checks around current block for any blocks of the same type then recursively deletes those blocks (if there are more than 2).
- Owner: Jacob Perkins
RandomPiece
- Purpose: Generate a random piece
- Inputs: none
- Output: DX holds value of piece
- Description: Generates random piece and returns that value in DX.
- Owner: Jacob Perkins
DrawBoard
- Purpose: Draws initial board
- Inputs: Game Board
- Output: Screen
- Description:draws pieces that are represented by the constants in Game Board array
- Owner: Graphics
UpdateBoard
- Purpose: Changes board during gameplay
- Inputs: TBD
- Output: screen
- Description: this method by only drawing what has changed will help us avoid having to redraw the entire board
- Owner: Graphics
RotateShooter
- Purpose: Rotates Shooter to aim, based on mouse position
- Inputs: BL, the position of the mouse ranging from 0-10
- Output: Graphical representation of the shooter on screen
- Description: Uses BL to access lookup table, and DisplayPicture to display shooter image on screen
- Owner: Nathan Gosse
LaunchPiece
- Purpose: Sets up variables for shooting; Begins animation of launched piece
- Inputs: Angle
- Output: none
- Description: sets initial X Position, calls animation and math routines
- Owner: Jon Agnich
GetParametrics
- Purpose: Sets coefficients for piece movement determination.
- Inputs: Angle
- Output: AVar and BVar are set
- Description: Uses lookup table to find x and y coefficients
- Owner: Jon Agnich
Bounce
- Purpose: Determines new angle and X intercept after collision with wall
- Inputs: old Angle, old X_Shift
- Output: new Angle, new X_Shift, GetParametrics called
- Description: finds new linear parametric equations for position
- Owner: Jon Agnich
GetRealPosition
- Purpose: return expected next position, rounded to integer
- Inputs: Angle, X_Shift, and Time
- Output: ah contains rounded X coordinate; al contains rounded Y coordinate
- Description: executes parametric equations and rounds results
- Owner: Jon Agnich
MainLoop
- Purpose:Establish continuous loop, polling mouse and keyboard status
- Inputs: Mouse position, button status, keyboard status
- Output: CX = integer between 0 and 638 (incremented by 8), representing the x-axis position of the mouse
  BX = mouse button status. 1 = button released (clicked), 0 = button not clicked.
- Description: Infinite loop with mouse (int 33h) and keyboard (int 16h) polling, with other program calls being made following user input.
  This procedure also includes the subroutines PauseGame, QuitGame and NewGame, which are activated by specific keystrokes, and will pause, quit, or begin a new game, respectively. Each of these three functions will employ the DisplayPicture routine that displays a dialog box in the upper righthand of the screen. Verification of intent to start a new game or quit the program will then make calls to the proper graphics and internal implementation routines.
- Owner: Nathan Gosse
EndGame
- Purpose:End current game, display game over image, start new game
- Inputs: GameBoard data
- Output: Screen, GameBoard
- Description: Based on piece positions in the GameBoard, EndGame is called to end current game.
- Owner: Jacob Perkins
StartNewGame
- Purpose: Generate and draw new board, display commands window, get next piece
- Inputs: None
- Output: GameBoard, screen
- Owner: Nathan Gosse
GetNextPiece
- Purpose: Update next piece available using RandomPiece, show next and current pieces.
- Inputs: NextPiece
- Output: NextPiece, CurrentPiece, Screen
- Owner: Nathan Gosse
DrawPiece
- Purpose: Draw a piece onto screen
- Inputs: AL = offset of pixel buffer in lookup table
  DX = position of upper lefthand corner on screen
- Output: Screen
- Owner: Peter Jones
DrawBoard
- Purpose: Draw all pieces residing in GameBoard onto video screen
- Inputs: GameBoard
- Output: Screen
- Owner: Peter Jones
StepPiece
- Purpose: Takes the next step in a piece's motion. Checs for collision with pieces, walls, back wall, and takes correct action
- Inputs: GameBoard, SI = Current location, Angle, AVar, BVar, Time
- Output: GameBoard, SI = old location, DI = new location, Angle, AVar, BVar, AL =1 if piece comes to rest
- Owner: Jon Agnich
DisplayPicture
- Purpose: Draw small .PCX files in a defined location on the 320x200 screen.
- Inputs: BL = Type of picture (limited to file names included in the 'PicFileOffsets'lookup table, currently 0=commands.pcx, 1=quit.pcx, 2=pause.pcx, 3=new.pcx).
  [PicDisplayStart] = Pixel position of upper lefthand corner of image
  .PCX file with appropriate header information
- Output: Draw to screen
- Description: Display dialog boxes and other small .PCX files on screen without writing over other images.
- Owner: Nathan Gosse
LoadPixelArrays
- Purpose: Load graphical data for each piece into piece pixel buffers
- Inputs: BL = Type of piece (defined by constants).
  .PCX file with appropriate header information
- Output: Pixel arrays located at WALLarray, REDLarray, etc.
- Description: Fills pixel buffers so that drawing pieces to screen does not require reading from disk each time
- Owner: Nathan Gosse

Constants: WALL, BACK, BRICK, REDL, REDR, GREENL, GREENR, BLUEL, BLUER, WHITEL, WHITER

Complete Code: Snood.asm
Complete Directory: \snood\