wasmboy/core/debug/debug-graphics.ts

Gameboy / Gameboy Color Emulator written for Web Assembly using AssemblyScript. Shell/Debugger in Preact

// Functions to debug graphical output
import { BACKGROUND_MAP_LOCATION, TILE_DATA_LOCATION, OAM_TILES_LOCATION } from '../constants';
import {
  Graphics,
  Lcd,
  getTileDataAddress,
  drawPixelsFromLineOfTile,
  getMonochromeColorFromPalette,
  getColorizedGbHexColorFromPalette,
  getRedFromHexColor,
  getGreenFromHexColor,
  getBlueFromHexColor,
  getRgbColorFromPalette,
  getColorComponentFromRgb,
  loadFromVramBank
} from '../graphics/index';
import { Cpu } from '../cpu/index';
import { eightBitLoadFromGBMemory, Memory } from '../memory/index';
import { checkBitOnByte } from '../helpers/index';

// Some Simple internal getters
export function getLY(): i32 {
  return Graphics.scanlineRegister;
}

export function getScrollX(): i32 {
  return Graphics.scrollX;
}

export function getScrollY(): i32 {
  return Graphics.scrollY;
}

export function getWindowX(): i32 {
  return Graphics.windowX;
}

export function getWindowY(): i32 {
  return Graphics.windowY;
}

// TODO: Render by tile, rather than by pixel
export function drawBackgroundMapToWasmMemory(showColor: i32): void {
  // http://www.codeslinger.co.uk/pages/projects/gameboy/graphics.html
  // Bit 7 - LCD Display Enable (0=Off, 1=On)
  // Bit 6 - Window Tile Map Display Select (0=9800-9BFF, 1=9C00-9FFF)
  // Bit 5 - Window Display Enable (0=Off, 1=On)
  // Bit 4 - BG & Window Tile Data Select (0=8800-97FF, 1=8000-8FFF)
  // Bit 3 - BG Tile Map Display Select (0=9800-9BFF, 1=9C00-9FFF)
  // Bit 2 - OBJ (Sprite) Size (0=8x8, 1=8x16)
  // Bit 1 - OBJ (Sprite) Display Enable (0=Off, 1=On)
  // Bit 0 - BG Display (for CGB see below) (0=Off, 1=On)

  // Get our seleted tile data memory location
  let tileDataMemoryLocation = Graphics.memoryLocationTileDataSelectZeroStart;
  if (Lcd.bgWindowTileDataSelect) {
    tileDataMemoryLocation = Graphics.memoryLocationTileDataSelectOneStart;
  }

  let tileMapMemoryLocation = Graphics.memoryLocationTileMapSelectZeroStart;
  if (Lcd.bgTileMapDisplaySelect) {
    tileMapMemoryLocation = Graphics.memoryLocationTileMapSelectOneStart;
  }

  for (let y: i32 = 0; y < 256; y++) {
    for (let x: i32 = 0; x < 256; x++) {
      // Get our current Y
      let pixelYPositionInMap: i32 = y;

      // Get our Current X position of our pixel on the on the 160x144 camera
      // this is done by getting the current scroll X position,
      // and adding it do what X Value the scanline is drawing on the camera.
      let pixelXPositionInMap: i32 = x;

      // Divide our pixel position by 8 to get our tile.
      // Since, there are 256x256 pixels, and 32x32 tiles.
      // 256 / 8 = 32.
      // Also, bitshifting by 3, do do a division by 8
      // Need to use u16s, as they will be used to compute an address, which will cause weird errors and overflows
      let tileXPositionInMap: i32 = pixelXPositionInMap >> 3;
      let tileYPositionInMap: i32 = pixelYPositionInMap >> 3;

      // Get our tile address on the tileMap
      // NOTE: (tileMap represents where each tile is displayed on the screen)
      // NOTE: (tile map represents the entire map, now just what is within the "camera")
      // For instance, if we have y pixel 144. 144 / 8 = 18. 18 * 32 = line address in map memory.
      // And we have x pixel 160. 160 / 8 = 20.
      // * 32, because remember, this is NOT only for the camera, the actual map is 32x32. Therefore, the next tile line of the map, is 32 byte offset.
      // Think like indexing a 2d array, as a 1d array and it make sense :)
      let tileMapAddress: i32 = tileMapMemoryLocation + tileYPositionInMap * 32 + tileXPositionInMap;

      // Get the tile Id on the Tile Map
      let tileIdFromTileMap: i32 = loadFromVramBank(tileMapAddress, 0);

      // Now get our tileDataAddress for the corresponding tileID we found in the map
      // Read the comments in _getTileDataAddress() to see what's going on.
      // tl;dr if we had the tile map of "a b c d", and wanted tileId 2.
      // This funcitons returns the start of memory locaiton for the tile 'c'.
      let tileDataAddress: i32 = getTileDataAddress(tileDataMemoryLocation, tileIdFromTileMap);

      // Now we can process the the individual bytes that represent the pixel on a tile

      // Get the y pixel of the 8 by 8 tile.
      // Simply modulo the scanline.
      // For instance, let's say we are printing the first line of pixels on our camera,
      // And the first line of pixels on our tile.
      // yPixel = 1. 1 % 8 = 1.
      // And for the last line
      // yPixel = 144. 144 % 8 = 0.
      // 0 Represents last line of pixels in a tile, 1 represents first. 1 2 3 4 5 6 7 0.
      // Because remember, we are counting lines on the display NOT including zero
      let pixelYInTile: i32 = pixelYPositionInMap % 8;

      // Same logic as pixelYInTile.
      // However, We need to reverse our byte,
      // As pixel 0 is on byte 7, and pixel 1 is on byte 6, etc...
      // Therefore, is pixelX was 2, then really is need to be 5
      // So 2 - 7 = -5, * 1 = 5
      // Or to simplify, 7 - 2 = 5 haha!
      let pixelXInTile: i32 = pixelXPositionInMap % 8;
      pixelXInTile = 7 - pixelXInTile;

      // Get the GB Map Attributes
      // Bit 0-2  Background Palette number  (BGP0-7)
      // Bit 3    Tile VRAM Bank number      (0=Bank 0, 1=Bank 1)
      // Bit 4    Not used
      // Bit 5    Horizontal Flip            (0=Normal, 1=Mirror horizontally)
      // Bit 6    Vertical Flip              (0=Normal, 1=Mirror vertically)
      // Bit 7    BG-to-OAM Priority         (0=Use OAM priority bit, 1=BG Priority)
      let bgMapAttributes: i32 = 0;
      if (Cpu.GBCEnabled && showColor > 0) {
        bgMapAttributes = loadFromVramBank(tileMapAddress, 1);
      }

      if (checkBitOnByte(6, bgMapAttributes)) {
        // We are mirroring the tile, therefore, we need to opposite byte
        // So if our pizel was 0 our of 8, it wild become 7 :)
        // TODO: This may be wrong :p
        pixelYInTile = 7 - pixelYInTile;
      }

      // Remember to represent a single line of 8 pixels on a tile, we need two bytes.
      // Therefore, we need to times our modulo by 2, to get the correct line of pixels on the tile.
      // But we need to load the time from a specific Vram bank
      let vramBankId: i32 = 0;
      if (checkBitOnByte(3, bgMapAttributes)) {
        vramBankId = 1;
      }

      // Remember to represent a single line of 8 pixels on a tile, we need two bytes.
      // Therefore, we need to times our modulo by 2, to get the correct line of pixels on the tile.
      // Again, think like you had to map a 2d array as a 1d.
      let byteOneForLineOfTilePixels: i32 = loadFromVramBank(tileDataAddress + pixelYInTile * 2, vramBankId);
      let byteTwoForLineOfTilePixels: i32 = loadFromVramBank(tileDataAddress + pixelYInTile * 2 + 1, vramBankId);

      // Now we can get the color for that pixel
      // Colors are represented by getting X position of ByteTwo, and X positon of Byte One
      // To Get the color Id.
      // For example, the result of the color id is 0000 00[xPixelByteTwo][xPixelByteOne]
      // See: How to draw a tile/sprite from memory: http://www.codeslinger.co.uk/pages/projects/gameboy/graphics.html
      let paletteColorId: i32 = 0;
      if (checkBitOnByte(pixelXInTile, byteTwoForLineOfTilePixels)) {
        // Byte one represents the second bit in our color id, so bit shift
        paletteColorId += 1;
        paletteColorId = paletteColorId << 1;
      }
      if (checkBitOnByte(pixelXInTile, byteOneForLineOfTilePixels)) {
        paletteColorId += 1;
      }

      // FINALLY, RENDER THAT PIXEL!
      let pixelStart: i32 = (y * 256 + x) * 3;

      if (Cpu.GBCEnabled && showColor > 0) {
        // Finally lets add some, C O L O R
        // Want the botom 3 bits
        let bgPalette: i32 = bgMapAttributes & 0x07;

        // Call the helper function to grab the correct color from the palette
        let rgbColorPalette: i32 = getRgbColorFromPalette(bgPalette, paletteColorId, false);

        // Split off into red green and blue
        let red: i32 = getColorComponentFromRgb(0, rgbColorPalette);
        let green: i32 = getColorComponentFromRgb(1, rgbColorPalette);
        let blue: i32 = getColorComponentFromRgb(2, rgbColorPalette);

        let offset: i32 = BACKGROUND_MAP_LOCATION + pixelStart;
        store<u8>(offset, <u8>red);
        store<u8>(offset + 1, <u8>green);
        store<u8>(offset + 2, <u8>blue);
      } else {
        // Only rendering camera for now, so coordinates are for the camera.
        // Get the rgb value for the color Id, will be repeated into R, G, B (if not colorized)
        let hexColor: i32 = getColorizedGbHexColorFromPalette(paletteColorId, Graphics.memoryLocationBackgroundPalette);

        let offset: i32 = BACKGROUND_MAP_LOCATION + pixelStart;

        // Red
        store<u8>(offset + 0, <u8>getRedFromHexColor(hexColor));
        // Green
        store<u8>(offset + 1, <u8>getGreenFromHexColor(hexColor));
        // Blue
        store<u8>(offset + 2, <u8>getBlueFromHexColor(hexColor));
      }
    }
  }
}

export function drawTileDataToWasmMemory(): void {
  for (let tileDataMapGridY: i32 = 0; tileDataMapGridY < 0x17; tileDataMapGridY++) {
    for (let tileDataMapGridX: i32 = 0; tileDataMapGridX < 0x1f; tileDataMapGridX++) {
      // Get Our VramBankID
      let vramBankId: i32 = 0;
      if (tileDataMapGridX > 0x0f) {
        vramBankId = 1;
      }

      // Get our tile ID
      let tileId: i32 = tileDataMapGridY;
      if (tileDataMapGridY > 0x0f) {
        tileId -= 0x0f;
      }
      tileId = tileId << 4;
      if (tileDataMapGridX > 0x0f) {
        tileId = tileId + (tileDataMapGridX - 0x0f);
      } else {
        tileId = tileId + tileDataMapGridX;
      }

      // Finally get our tile Data location
      let tileDataMemoryLocation: i32 = Graphics.memoryLocationTileDataSelectOneStart;
      if (tileDataMapGridY > 0x0f) {
        tileDataMemoryLocation = Graphics.memoryLocationTileDataSelectZeroStart;
      }

      // Let's see if we have C O L O R
      // Set the map and sprite attributes to -1
      // Meaning, we will draw monochrome
      let paletteLocation: i32 = Graphics.memoryLocationBackgroundPalette;
      let bgMapAttributes: i32 = -1;
      let spriteAttributes: i32 = -1;

      // Let's see if the tile is being used by a sprite
      for (let spriteRow: i32 = 0; spriteRow < 8; spriteRow++) {
        for (let spriteColumn: i32 = 0; spriteColumn < 5; spriteColumn++) {
          let spriteIndex = spriteColumn * 8 + spriteRow;

          // Sprites occupy 4 bytes in the sprite attribute table
          let spriteTableIndex: i32 = spriteIndex * 4;
          let spriteTileId: i32 = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 2);

          if (tileId === spriteTileId) {
            let currentSpriteAttributes: i32 = eightBitLoadFromGBMemory(
              Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 3
            );

            let spriteVramBankId: i32 = 0;
            if (Cpu.GBCEnabled && checkBitOnByte(3, currentSpriteAttributes)) {
              spriteVramBankId = 1;
            }

            if (spriteVramBankId === vramBankId) {
              spriteAttributes = currentSpriteAttributes;
              spriteRow = 8;
              spriteColumn = 5;

              // Set our paletteLocation
              paletteLocation = Graphics.memoryLocationSpritePaletteOne;
              if (checkBitOnByte(4, spriteAttributes)) {
                paletteLocation = Graphics.memoryLocationSpritePaletteTwo;
              }
            }
          }
        }
      }

      // If we didn't find a sprite,
      // Let's see if the tile is on the bg tile map
      // If so, use that bg map for attributes
      if (Cpu.GBCEnabled && spriteAttributes < 0) {
        let tileMapMemoryLocation = Graphics.memoryLocationTileMapSelectZeroStart;
        if (Lcd.bgTileMapDisplaySelect) {
          tileMapMemoryLocation = Graphics.memoryLocationTileMapSelectOneStart;
        }
        // Loop through the tileMap, and find if we have our current ID
        let foundTileMapAddress: i32 = -1;
        for (let x: i32 = 0; x < 32; x++) {
          for (let y: i32 = 0; y < 32; y++) {
            let tileMapAddress: i32 = tileMapMemoryLocation + y * 32 + x;
            let tileIdFromTileMap: i32 = loadFromVramBank(tileMapAddress, 0);

            // Check if we found our tileId
            if (tileId === tileIdFromTileMap) {
              foundTileMapAddress = tileMapAddress;
              x = 32;
              y = 32;
            }
          }
        }

        if (foundTileMapAddress >= 0) {
          bgMapAttributes = loadFromVramBank(foundTileMapAddress, 1);
        }
      }

      // Draw each Y line of the tile
      for (let tileLineY: i32 = 0; tileLineY < 8; tileLineY++) {
        drawPixelsFromLineOfTile(
          tileId, // tileId
          tileDataMemoryLocation, // Graphics.memoryLocationTileDataSelect
          vramBankId, // Vram Bank
          0, // Tile Line X Start
          7, // Tile Line X End
          tileLineY, // Tile Line Y
          tileDataMapGridX * 8, // Output line X
          tileDataMapGridY * 8 + tileLineY, // Output line Y
          0x1f * 8, // Output Width
          TILE_DATA_LOCATION, // Wasm Memory Start
          false, // shouldRepresentMonochromeColorByColorId
          paletteLocation, // paletteLocation
          bgMapAttributes, // bgMapAttributes
          spriteAttributes // spriteAttributes
        );
      }
    }
  }
}

export function drawOamToWasmMemory(): void {
  // Draw all 40 sprites
  // Going to be like BGB and do 8 x 5 sprites
  for (let spriteRow: i32 = 0; spriteRow < 8; spriteRow++) {
    for (let spriteColumn: i32 = 0; spriteColumn < 5; spriteColumn++) {
      let spriteIndex = spriteColumn * 8 + spriteRow;

      // Sprites occupy 4 bytes in the sprite attribute table
      let spriteTableIndex: i32 = spriteIndex * 4;

      // Y positon is offset by 16, X position is offset by 8

      let spriteYPosition: i32 = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex);
      let spriteXPosition: i32 = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 1);
      let spriteTileId: i32 = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 2);

      let tilesToDraw: i32 = 1;
      if (Lcd.tallSpriteSize) {
        // @binji says in 8x16 mode, even tileId always drawn first
        // This will fix shantae sprites which always uses odd numbered indexes

        // TODO: Do the actual Pandocs thing:
        // "In 8x16 mode, the lower bit of the tile number is ignored. Ie. the upper 8x8 tile is "NN AND FEh", and the lower 8x8 tile is "NN OR 01h"."
        // So just knock off the last bit? :)
        if (spriteTileId % 2 === 1) {
          spriteTileId -= 1;
        }

        tilesToDraw += 1;
      }

      // Get our sprite attributes since we know we shall be drawing the tile
      let spriteAttributes: i32 = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 3);

      // Check if we should flip the sprite on the x or y axis
      let flipSpriteY: boolean = checkBitOnByte(6, spriteAttributes);
      let flipSpriteX: boolean = checkBitOnByte(5, spriteAttributes);

      // Find which VRAM Bank to load from
      let vramBankId: i32 = 0;
      if (Cpu.GBCEnabled && checkBitOnByte(3, spriteAttributes)) {
        vramBankId = 1;
      }

      // Find which monochrome palette we should use
      let paletteLocation: i32 = Graphics.memoryLocationSpritePaletteOne;
      if (checkBitOnByte(4, spriteAttributes)) {
        paletteLocation = Graphics.memoryLocationSpritePaletteTwo;
      }

      // Start Drawing our tiles
      for (let i: i32 = 0; i < tilesToDraw; i++) {
        // Draw each Y line of the tile
        for (let tileLineY: i32 = 0; tileLineY < 8; tileLineY++) {
          drawPixelsFromLineOfTile(
            spriteTileId + i, // tileId
            Graphics.memoryLocationTileDataSelectOneStart, // Graphics.memoryLocationTileDataSelect
            vramBankId, // VRAM Bank
            0, // Tile Line X Start
            7, // Tile Line X End
            tileLineY, // Tile Line Y
            spriteRow * 8, // Output line X
            spriteColumn * 16 + tileLineY + i * 8, // Output line Y
            8 * 8, // Output Width
            OAM_TILES_LOCATION, // Wasm Memory Start
            false, // shouldRepresentMonochromeColorByColorId
            paletteLocation, // paletteLocation
            -1, // bgMapAttributes
            spriteAttributes // spriteAttributes
          );
        }
      }
    }
  }
}