CS2261 LAB 08: Solution

Tiled, Mode 0 Backgrounds &
Sprite Animation
Provided Files
● Tiles
○ chipSprite.bmp, chipSprite.pal
○ connectFour.bmp, connectFour.pal
○ connectFourTilemap.tmx, connectFourTiles.tsx
○ tiled-to-gba-export.js
● Example.gba
● game.h
● gba.h, gba.c
● Makefile
● mode0.h, mode0.c
● print.h, print.c
● README.md
● sprites.h, sprites.c
Files to Edit/Add
● .vscode
○ tasks.json
● chipSprite.h, chipSprite.c
● connectFour.h, connectFour.c
● connectFourTiled.h, connectFourTiled.c
● game.c ● main.c

Instructions
In this lab, you will be implementing a sprite that cycles through a simple looping animation. Then, you will create a tiled background in Mode 0 and modify individual tiles at runtime to complete a working version of Connect Four! An Example.gba file with the completed lab has been provided for reference, and the controls for it can be found in README.md.
TODO 0 – Tiled Installation/Setup
For this lab, you will be using a program called Tiled to create and export a background for Mode 0. If you have not done so already, open this Tiled Tutorial document and follow the steps up to and including “Installing GBA Libraries.” You do not need to follow the steps for setting up a Tiled project as we will already be providing the files you need to modify for this lab.
TODO 1 – Sprite Animation
In this TODO, you will use the provided spritesheet to create a sprite that loops through six frames of animation.
TODO 1.0
● In Usenti, open chipSprite.bmp.
● Import chipSprite.pal into the project (Image > Import, select .pal as file type). The palette import screen should look like this:

● Export the spritesheet as a C source file named chipSprite (Image > Export, select GBA source file as file type) using these settings:

● After you have completed these steps, chipSprite.h and chipSprite.c should have been created in your project.
○ Make sure that any .c/.h files that you create through Usenti or Tiled are not saved in the Tiles folder! The only files that will be compiled into your projects are the ones that are stored in the same folder as the Makefile.
TODO 1.1
● At the top of main.c, include chipSprite.h.
TODO 1.2
● In the initialize function of main.c, copy the palette and tiles from chipSprite.h into the correct memory locations using DMA.
○ Since we’re working in Mode 0, which character block should the sprite tiles be copied into?
○ Make sure to hide sprites here to prevent cornerface! There is non-transparent color data at tile 0, so it will show up as a tiny square in the top-left corner of the screen by default unless we do this.
TODO 1.3
● In the initGame function of game.c, initialize the struct members of chipSprite that will be used to display different animation frames over time. ○ timeUntilNextFrame should be set to 10.
○ currentFrame should be set to 0 (starts at the 0th image).
○ numFrames should be set to 6 (6 total images in the animation).
○ hide should be set to 0 (show sprite at the start of the program).
TODO 1.4
● In the animateChip function of game.c, set attribute 2 of the chip sprite.
○ The x value of the tile ID will change depending on the current animation frame. Each frame is 2 tiles wide.
○ The palette row should be set to currentColor->spritePaletteRow.
■ The chip sprite will switch between red and yellow based on which player is having their turn, and this variable will be set to the palette row needed to display this for you.
TODO 1.5
● If the hide member of chipSprite is true, hide the sprite in the OAM.
○ Hint: The |= operator will be useful in this step!
TODO 1.6
● In the dropChip function of game.c, set the hide member of the chipSprite struct to 1 at the start of the function.
● Later in the same function, set hide to 0 to make the chip reappear.
TODO 1.7
● In the animateChip function of game.c, handle the animation logic for switching to the next animation frame.
○ timeUntilNextFrame should be decremented every time animateChip is called.
○ If timeUntilNextFrame is equal to 0:
■ timeUntilNextFrame should be reset to 10.
■ currentFrame should be incremented to the next frame.
● What should happen when currentFrame reaches the end of the animation?
Build and run. You should see a spinning yellow chip on a black background that moves horizontally whenever LEFT and RIGHT are pressed. If not, fix this before moving on to the next step.
TODO 2 – Mode 0 Background with Usenti & Tiled
In this TODO, you will be using Usenti to import a tileset, and you will use Tiled to build a background tilemap. Make sure that you have completed TODO 0 before completing the following sections.
TODO 2.0
● In Usenti, open connectFour.bmp and import connectFour.pal.
○ Follow the same steps and settings from TODO 1.0 to import the palette and export the tiles as GBA source files in your project. ○ Name the export connectFour.
TODO 2.1
● At the top of main.c, include connectFour.h.
TODO 2.2
● In the initialize function of main.c, copy the palette and tiles from connectFour.h into the correct memory locations using DMA.
○ The palette should be copied into BG_PALETTE.
○ Find where REG_BG0CNT is being set. Which character block should the tiles be copied to to make them appear on background 0?
● If you build and run the program now, you should be able to see the palette and tiles being stored in your memory! (Tools > View palette / Tools > View tiles)

TODO 2.3
● In Tiled, open connectFourTilemap.tmx. You should see the following:

● The large square in the center of the screen is the tilemap, which determines how the tiles will be arranged on-screen. The tiles in the tileset shown on the right side can be drawn onto the tilemap using the stamp brush. Using these tools, create the background shown below:

○ For reference, the top-left cell of the grid should be located at (10, 5). The position of the tile your cursor is hovering over is shown in the bottom-left corner of the Tiled application window.
● Export the tilemap as a C source file named connectFourTiled (File > Export As, select GBA source files as file type).
TODO 2.4
● At the top of game.c, include connectFourTiled.h.
TODO 2.5
● In the initGame function of game.c, copy the tilemap from connectFour.h into the correct memory locations using DMA.
○ Find where REG_BG0CNT is being set. Which screen block should the tilemap be copied to to make it appear on background 0?
Build and run. You should see the tilemap you built displayed on screen. Additionally, pressing the DOWN button will now cause the chip to disappear, and yellow tiles will start to populate the grid in the column you choose (pressing START resets the grid). If you are seeing unexpected behavior with the chip, revisit TODO 1. If there’s something wrong with the tilemap, revisit TODO 2.
TODO 3 – Tilemap Modification
In this TODO, you will be writing code to modify your tilemap at runtime. At this point, the DOWN button causes an entire column to be filled with yellow tiles after one chip is dropped, which results in an instant win for yellow. In order to make a functional game of Connect Four, we need to change that!
TODO 3.0
● In dropChip.c, use the TILEMAP_ENTRY_TILEID macro to remove the yellow tile directly above the one being placed.
○ The tilemap modification code that causes yellow chips to descend down the grid is written just above this TODO. Your answer for this part will be very similar in structure.
○ The tile ID for an empty Connect Four cell is EMPTY_CELL (2).
TODO 3.1
● In dropChip.c, change the color of the ASCII text (CONNECT FOUR!) when a player wins the game.
● For each tile containing a letter, use the TILEMAP_ENTRY_PALROW macro to change the value of the palette row without altering its tile ID.
○ Hint 1: Tilemap modification in tiled modes is analogous to setting background pixels in bitmapped modes. This will be a sort of tiled version of the drawRectangle function!
■ The tile containing a “C” (top-left tile for the text) should be located at (10, 13), and the letters should take up a 2x7 area of tiles.
■ The palette row that turns all the letters yellow/red is currentColor->winTextPaletteRow (value depends on who placed the last chip).
○ Hint 2: See TODO 1.5!
Build and run. At this point, you should be able to play a fully functional game of Connect Four! Check your submission against the given Example.gba before turning in the assignment to ensure that you’ve completed every step correctly.

Submission Instructions:
Ensure that cleaning and building/running your project still gives the expected results. Please reference the last page of previous assignments for instructions on how to perform a "clean" command.
Zip up your entire project folder, including all source files, the Makefile, and everything produced during compilation (including the .gba file). Submit this zip on Canvas. Name your submission Lab08_LastnameFirstname, for example:
“Lab08_WexlerHoward.zip”
It is your responsibility to ensure that all the appropriate files have been submitted, and that your submitted zip can be opened and everything cleans, builds, and runs.