// Functions for rendering the sprites import { Graphics, loadFromVramBank, setPixelOnFrame } from './graphics'; import { Lcd } from './lcd'; import { Cpu } from '../cpu/index'; import { getTileDataAddress } from './tiles'; import { getColorizedGbHexColorFromPalette, getRgbColorFromPalette, getColorComponentFromRgb } from './palette'; import { getRedFromHexColor, getGreenFromHexColor, getBlueFromHexColor } from './colors'; import { getPriorityforPixel } from './priority'; // Assembly script really not feeling the reexport // using Skip Traps, because LCD has unrestricted access // http://gbdev.gg8.se/wiki/articles/Video_Display#LCD_OAM_DMA_Transfers import { eightBitLoadFromGBMemory } from '../memory/load'; import { checkBitOnByte } from '../helpers/index'; // Inlined because closure compiler inlines export function renderSprites(scanlineRegister: i32, useLargerSprites: boolean): void { // Need to loop through all 40 sprites to check their status // Going backwards since lower sprites draw over higher ones // Will fix dragon warrior 3 intro for (let i = 39; i >= 0; --i) { // Sprites occupy 4 bytes in the sprite attribute table let spriteTableIndex = i * 4; // Y positon is offset by 16, X position is offset by 8 let index = Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex; let spriteYPosition = eightBitLoadFromGBMemory(index + 0); let spriteXPosition = eightBitLoadFromGBMemory(index + 1); let spriteTileId = eightBitLoadFromGBMemory(index + 2); // Pan docs of sprite attirbute table // Bit7 OBJ-to-BG Priority (0=OBJ Above BG, 1=OBJ Behind BG color 1-3) // (Used for both BG and Window. BG color 0 is always behind OBJ) // Bit6 Y flip (0=Normal, 1=Vertically mirrored) // Bit5 X flip (0=Normal, 1=Horizontally mirrored) // Bit4 Palette number **Non CGB Mode Only** (0=OBP0, 1=OBP1) // Bit3 Tile VRAM-Bank **CGB Mode Only** (0=Bank 0, 1=Bank 1) // Bit2-0 Palette number **CGB Mode Only** (OBP0-7) // Apply sprite X and Y offset // TODO: Sprites are overflowing on x if less than 8 spriteYPosition -= 16; spriteXPosition -= 8; // Find our sprite height let spriteHeight = 8; if (useLargerSprites) { spriteHeight = 16; // @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? :) spriteTileId -= spriteTileId & 1; } // Find if our sprite is on the current scanline if (scanlineRegister >= spriteYPosition && scanlineRegister < spriteYPosition + spriteHeight) { // Then we need to draw the current sprite // Get our sprite attributes since we know we shall be drawing the tile let spriteAttributes = eightBitLoadFromGBMemory(Graphics.memoryLocationSpriteAttributesTable + spriteTableIndex + 3); // Check sprite Priority let isSpritePriorityBehindWindowAndBackground = checkBitOnByte(7, spriteAttributes); // Check if we should flip the sprite on the x or y axis let flipSpriteY = checkBitOnByte(6, spriteAttributes); let flipSpriteX = checkBitOnByte(5, spriteAttributes); // TODO: Torch2424 continue here. // Find which line on the sprite we are on let currentSpriteLine = scanlineRegister - spriteYPosition; // If we fliiped the Y axis on our sprite, need to read from memory backwards to acheive the same effect if (flipSpriteY) { currentSpriteLine = spriteHeight - currentSpriteLine; // Bug fix for the flipped flies in link's awakening currentSpriteLine -= 1; } // Each line of a tile takes two bytes of memory currentSpriteLine <<= 1; // Get our sprite tile address, need to also add the current sprite line to get the correct bytes let spriteTileAddressStart = getTileDataAddress(Graphics.memoryLocationTileDataSelectOneStart, spriteTileId); spriteTileAddressStart += currentSpriteLine; let spriteTileAddress = spriteTileAddressStart; // Find which VRAM Bank to load from let vramBankId = (Cpu.GBCEnabled && checkBitOnByte(3, spriteAttributes)); let spriteDataByteOneForLineOfTilePixels = loadFromVramBank(spriteTileAddress + 0, vramBankId); let spriteDataByteTwoForLineOfTilePixels = loadFromVramBank(spriteTileAddress + 1, vramBankId); // Iterate over the width of our sprite to find our individual pixels for (let tilePixel = 7; tilePixel >= 0; --tilePixel) { // Get our spritePixel, and check for flipping let spritePixelXInTile = tilePixel; if (flipSpriteX) { spritePixelXInTile -= 7; spritePixelXInTile = -spritePixelXInTile; } // Get the color Id of our sprite, similar to renderBackground() // With the first byte, and second byte lined up method thing // Yes, the second byte comes before the first, see ./background.ts let spriteColorId = 0; if (checkBitOnByte(spritePixelXInTile, spriteDataByteTwoForLineOfTilePixels)) { // Byte one represents the second bit in our color id, so bit shift spriteColorId = (spriteColorId + 1) << 1; } if (checkBitOnByte(spritePixelXInTile, spriteDataByteOneForLineOfTilePixels)) { spriteColorId += 1; } // ColorId zero (last two bits of pallette) are transparent // http://gbdev.gg8.se/wiki/articles/Video_Display if (spriteColorId !== 0) { // Find our actual X pixel location on the gameboy "camera" view // This cannot be less than zero, i32 will overflow let spriteXPixelLocationInCameraView = spriteXPosition + (7 - tilePixel); if (spriteXPixelLocationInCameraView >= 0 && spriteXPixelLocationInCameraView <= 160) { // There are two cases where wouldnt draw the pixel on top of the Bg/window // 1. if isSpritePriorityBehindWindowAndBackground, sprite can only draw over color 0 // 2. if bit 2 of our priority is set, then BG-to-OAM Priority from pandoc // is active, meaning BG tile will have priority above all OBJs // (regardless of the priority bits in OAM memory) // But if GBC and Bit 0 of LCDC is set, we always draw the object let shouldShowFromLcdcPriority = Cpu.GBCEnabled && !Lcd.bgDisplayEnabled; // LCDC Priority let shouldHideFromOamPriority = false; let shouldHideFromBgPriority = false; if (!shouldShowFromLcdcPriority) { // Now that we have our coordinates, check for sprite priority // Lets get the priority byte we put in memory let bgPriorityByte = getPriorityforPixel(spriteXPixelLocationInCameraView, scanlineRegister); let bgColorFromPriorityByte = bgPriorityByte & 0x03; // Doing an else if, since either will automatically stop drawing the pixel if (isSpritePriorityBehindWindowAndBackground && bgColorFromPriorityByte > 0) { // OAM Priority shouldHideFromOamPriority = true; } else if (Cpu.GBCEnabled && checkBitOnByte(2, bgPriorityByte) && bgColorFromPriorityByte > 0) { // Bg priority shouldHideFromBgPriority = true; } } if (shouldShowFromLcdcPriority || (!shouldHideFromOamPriority && !shouldHideFromBgPriority)) { if (!Cpu.GBCEnabled) { // Get our monochrome color RGB from the current sprite pallete // Get our sprite pallete let spritePaletteLocation = Graphics.memoryLocationSpritePaletteOne; if (checkBitOnByte(4, spriteAttributes)) { spritePaletteLocation = Graphics.memoryLocationSpritePaletteTwo; } let hexColor = getColorizedGbHexColorFromPalette(spriteColorId, spritePaletteLocation); // Finally set the pixel! setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 0, getRedFromHexColor(hexColor)); setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 1, getGreenFromHexColor(hexColor)); setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 2, getBlueFromHexColor(hexColor)); } else { // Get our RGB Color // Finally lets add some, C O L O R // Want the botom 3 bits let bgPalette = spriteAttributes & 0x07; // Call the helper function to grab the correct color from the palette let rgbColorPalette = getRgbColorFromPalette(bgPalette, spriteColorId, true); // Split off into red green and blue let red = getColorComponentFromRgb(0, rgbColorPalette); let green = getColorComponentFromRgb(1, rgbColorPalette); let blue = getColorComponentFromRgb(2, rgbColorPalette); // Finally Place our colors on the things setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 0, red); setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 1, green); setPixelOnFrame(spriteXPixelLocationInCameraView, scanlineRegister, 2, blue); } } } } } } } }