Finally got sprites somewhat working :')

Author: torch2424

core/graphics/pixelPipeline/pixelFetcher.ts

@@ -43,6 +43,7 @@ export class PixelFetcher {
 
   static reset(): void {
     PixelFetcher.currentStatus = 0;
+    PixelFetcher.isSprite = false;
 
     // Clear the pixel fifo memory
     for (let pixelIndex = 0; pixelIndex < 160; pixelIndex++) {
@@ -96,7 +97,7 @@ export class PixelFetcher {
     // Pixel Fetcher won't add more pixels unless there are only 8 pixels left
     let pixelsRemainingInFifo = PixelFifo.numberOfPixelsInFifo - PixelFifo.currentIndex;
     if (PixelFetcher.currentStatus === 0 || PixelFetcher.currentStatus === 4) {
-      if (PixelFetcher.currentStatus === 4 && pixelsRemainingInFifo <= 8) {
+      if (PixelFetcher.currentStatus === 4 && (PixelFetcher.isSprite || pixelsRemainingInFifo <= 8)) {
         // Place into the fifo
         _storeFetchIntoFifo();
 
@@ -122,7 +123,7 @@ export class PixelFetcher {
       // Read the tile data
       _readTileData(1);
 
-      if (pixelsRemainingInFifo <= 8) {
+      if (PixelFetcher.isSprite || pixelsRemainingInFifo <= 8) {
         // Place into the fifo
         _storeFetchIntoFifo();
 
@@ -153,10 +154,8 @@ function _readTileIdFromTileMap(): void {
       // So just knock off the last bit? :)
       spriteTileId -= spriteTileId & 1;
 
-      // Check if we wanted to draw the second tile though
-      if (PixelFetcher.tileLine >= 8) {
-        spriteTileId += 1;
-      }
+      // NOTE: We don't need to do any tile line stuf here, as tall
+      // sprites will automatically go into the next tile :)
     }
 
     PixelFetcher.tileIdFromTileMap = spriteTileId;
@@ -258,6 +257,8 @@ function _readTileData(byteNumber: i32): void {
   }
 }
 
+// Note: We should only store when we are storing a sprite
+// Or if we have <= 8 pixels left in the fifo.
 function _storeFetchIntoFifo(): void {
   if (PixelFetcher.isSprite) {
     // Need to mix the pixel on top of the old data
@@ -322,17 +323,6 @@ function _storeFetchIntoFifo(): void {
         // Set that we are a sprite
         fifoTypePerPixel = setBitOnByte(i, fifoTypePerPixel);
 
-        // Debug / TODO : Firgure our why sprites aren't shoing up...
-        // fifoTypePerPixel is correct, maybe is is the data bytes?
-        // log(0x87, fifoTypePerPixel);
-        // log(0x89, spritePaletteColorId);
-        // log(0x90, fifoTileDataByteZero);
-        // log(0x91, fifoTileDataByteOne);
-
-        // Debug: Are we writing sprites?
-        // Yes we are, and what seems like correct scanlines
-        // log(0x99, Graphics.scanlineRegister);
-
         // Write back to the fifo
         storePixelFifoByteForPixelIndexIntoWasmBoyMemory(0, PixelFifo.currentIndex, fifoTileDataByteZero);
         storePixelFifoByteForPixelIndexIntoWasmBoyMemory(1, PixelFifo.currentIndex, fifoTileDataByteOne);

core/graphics/pixelPipeline/pixelFifo.ts

@@ -31,7 +31,9 @@ export class PixelFifo {
   }
 
   static stopSpriteIdle(): void {
-    PixelFifo.currentStatus = 0;
+    if (PixelFifo.currentStatus === 2) {
+      PixelFifo.currentStatus = 0;
+    }
   }
 
   static step(): void {

core/graphics/pixelPipeline/pixelPipeline.ts

@@ -20,6 +20,9 @@ export class PixelPipeline {
   // When Cycles == 1, we will step the fetcher.
   static cycles: i32 = 0;
 
+  // The X index of the previous sprite that was fetched
+  static previousSpriteIndex: i32 = -1;
+
   // The last recorded scrollX value
   // Useful for checking background pixels
   static previousScrollX: i32 = 0;
@@ -39,10 +42,6 @@ export class PixelPipeline {
     cpuCycles = cpuCycles >> (<i32>Cpu.GBCDoubleSpeed);
 
     for (let pixelPipelineCyclesStepped: i32 = 0; pixelPipelineCyclesStepped < cpuCycles; pixelPipelineCyclesStepped++) {
-      // Debug:
-      // The problem with sprites is that we are still pushing pixels, while we are trying to fetch sprites.
-      // We need to do checks, and then proceed down a certain path
-
       // Push our a pixel
       PixelFifo.step();
 
@@ -64,11 +63,12 @@ export class PixelPipeline {
       }
        */
 
-      // DEBUG: Just do sprites and BG
+      // Figure out what we should be fetching next
+      // First check if we should fetch a sprite
       if (_tryToFetchSprite()) {
         // We are fetching a sprite!
         PixelFifo.startSpriteIdle();
-      } else {
+      } else if (!isFetchingSprite()) {
         PixelFifo.stopSpriteIdle();
         _tryToFetchBackground();
       }
@@ -90,9 +90,15 @@ export class PixelPipeline {
     PixelFifo.reset();
 
     PixelPipeline.cycles = 0;
+    PixelPipeline.previousScrollX = 0;
+    PixelPipeline.previousSpriteIndex = -1;
   }
 }
 
+function isFetchingSprite(): boolean {
+  return PixelFetcher.isSprite && PixelFetcher.currentStatus !== 0;
+}
+
 // Returns if we started fetching / we are fetching sprites
 function _tryToFetchSprite(): boolean {
   // Check if sprites are enabled
@@ -107,6 +113,11 @@ function _tryToFetchSprite(): boolean {
     return false;
   }
 
+  // Can only show one sprite per x value
+  if (PixelFifo.currentIndex <= PixelPipeline.previousSpriteIndex) {
+    return false;
+  }
+
   for (let i = 0; i < Sprites.numberOfVisibleSprites; i++) {
     // Grab our sprite info from our visible sprites
     let spriteIndex: i32 = Sprites.getVisibleSpriteIndex(i);
@@ -138,25 +149,15 @@ function _tryToFetchSprite(): boolean {
     if (PixelFifo.currentIndex === spriteXPosition) {
       // We need to fetch this sprite!
 
-      // Debug: also need to fix tile line in the fetcher!!!
-      // getting off train
-
       // Get which line of the 8x8 or 8x16 tile.
-      // Need to sub tract 16 from the total because of the tile height, to get the line
-      // Debug, may need to put the sprite height here in stead of 16.
-      let spriteTileLine = Graphics.scanlineRegister - spriteYPosition - 16;
+      let spriteTileLine = Graphics.scanlineRegister - spriteYPosition;
 
       // Check if we are already fetching the sprite,
       // If not, start fetching it
       if (!PixelFetcher.isFetchingSpriteTileLine(spriteTileLine, spriteIndex)) {
-        // Debug: We are fetching this sprite
-        // But which line and things?
-        let spriteHeight: i32 = Lcd.tallSpriteSize ? 16 : 8;
-        log(Graphics.scanlineRegister, spriteYPosition);
-        log(0x01, spriteHeight);
-
-        // Just reset everything, and start fetching the sprite
+        // Start fetching the sprite
         PixelFetcher.startSpriteFetch(spriteTileLine, spriteIndex);
+        PixelPipeline.previousSpriteIndex = PixelFifo.currentIndex;
       }
 
       return true;