Move render functions to core

core/ppu_render.go

@@ -1,6 +1,16 @@
 package core
 
-import "fmt"
+import (
+	"fmt"
+
+	"github.com/snes-emu/gose/bit"
+)
+
+type pixel struct {
+	bgr      uint16
+	visible  bool
+	priority uint8
+}
 
 func (ppu *PPU) renderLine() {
 	fmt.Printf("Render line: %v\n", ppu.vCounter)
@@ -15,3 +25,145 @@ func (ppu *PPU) renderLine() {
 		ppu.cpu.leavVblank()
 	}
 }
+
+func (ppu PPU) decodeTilePixel(tileAddress, colorDepth, x, y uint16) uint8 {
+	var colorIndex uint8
+
+	lineBaseAddress := tileAddress + 2*y
+	colorIndex += (ppu.vram.bytes[lineBaseAddress+0x00] >> x & 1) << 0
+	colorIndex += (ppu.vram.bytes[lineBaseAddress+0x01] >> x & 1) << 1
+	if colorDepth >= 4 {
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x10] >> x & 1) << 2
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x11] >> x & 1) << 3
+	}
+	if colorDepth >= 8 {
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x20] >> x & 1) << 4
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x21] >> x & 1) << 5
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x30] >> x & 1) << 6
+		colorIndex += (ppu.vram.bytes[lineBaseAddress+0x31] >> x & 1) << 7
+	}
+	return colorIndex
+}
+
+func (ppu PPU) renderSpriteLine() [HMax]pixel {
+	// Initialize pixel line
+	var pixels [HMax]pixel
+	sprites := make([]uint16, 0, 32)
+	firstSprite := uint16(0)
+	if ppu.oam.priorityBit {
+		firstSprite = (ppu.oam.addr >> 2) & 0xFF
+	}
+	// Choose the first 32 sprites to appear on screen
+	for i := firstSprite; i < firstSprite+128; i++ {
+		// Check if line intersects sprite
+		spriteIndex := i % 128
+		if ppu.vCounter >= uint16(ppu.oam.bytes[4*spriteIndex+1]) && ppu.vCounter < uint16(ppu.oam.bytes[4*spriteIndex+1])+uint16(spriteSizeTable[ppu.oam.objectSize|((ppu.oam.bytes[0x200+i/4]&(1<<(2*(spriteIndex%4)+1)))>>(1<<(2*(spriteIndex%4)+1)))<<4][1]) {
+			if len(sprites) == 32 {
+				ppu.status.rangeOver = true
+				break
+			} else {
+				sprites = append(sprites, i)
+			}
+		}
+	}
+	// Go through all the selected sprites in reverse order (up to 34 tiles)
+	tiles := uint16(0)
+	for i := uint16(len(sprites) - 1); i >= 0; i-- {
+		sprite := ppu.decodeSprite(i)
+		// Go through all tiles containing the line
+		// Tiles are stored in the 2D-array 0xNyx
+
+		// Y coordinate of the tile containing the line
+		var yTile uint16
+		// Y coordinate of the line in the tile
+		var y uint16
+		if sprite.vFlip {
+			yTile = (sprite.vSize - 1 - (ppu.vCounter - sprite.y)) / 8
+			y = (sprite.vSize - 1 - (ppu.vCounter - sprite.y)) % 8
+		} else {
+			yTile = (ppu.vCounter - sprite.y) / 8
+			y = (ppu.vCounter - sprite.y) % 8
+		}
+		// Go through pixels in reverse order if hFlip is true
+		for baseTileCoor := yTile << 4; baseTileCoor < yTile<<4+sprite.hSize/8; baseTileCoor++ {
+			if tiles == 34 {
+				ppu.status.timeOver = true
+				break
+			}
+			// Tile coordinate in the form 0xYX
+			var tileCoor uint16
+			if sprite.hFlip {
+				tileCoor = 2*(yTile<<4) + sprite.hSize/8 - 1 - baseTileCoor
+			} else {
+				tileCoor = baseTileCoor
+			}
+			// Go through all pixel in the line
+			for pix := uint16(0); pix < 8; pix++ {
+				var x uint16
+				if sprite.hFlip {
+					x = 7 - pix
+				} else {
+					x = pix
+				}
+				//Address of the current tile in VRAM
+				tileAddress := sprite.tileAddress + tileCoor<<5
+				// Get the color index of the pixel
+				colorIndex := ppu.decodeTilePixel(tileAddress, 16, x, y)
+				// If color is not tansparent, write color value in the pixel
+				if colorIndex != 0 {
+					colorAddress := 2 * (128 + 16*sprite.paletteIndex + uint16(colorIndex))
+					pixels[(sprite.x+8*(tileCoor&0xF)+x)%HMax] = pixel{
+						bgr:      bit.JoinUint16(ppu.cgram.bytes[colorAddress], ppu.cgram.bytes[colorAddress+1]),
+						visible:  true,
+						priority: sprite.priority,
+					}
+				}
+			}
+			tiles++
+		}
+	}
+	return pixels
+}
+
+func (ppu PPU) renderBgLine(BG uint8, colorDepth uint16) [HMax]pixel {
+	var pixels [HMax]pixel
+	bg := ppu.backgroundData.bg[BG]
+	y := ppu.vCounter
+	var size uint16
+	if bg.tileSize {
+		size = 16
+	} else {
+		size = 8
+	}
+	x := uint16(0)
+	for x < HMax {
+		tile := ppu.decodeTile(BG, (x+bg.horizontalScroll)/size, (y+bg.verticalScroll)/size)
+		tileAddress := bg.tileSetBaseAddress<<13 + tile.characterIndex*8*colorDepth
+		var yTile uint16
+		if tile.vFlip {
+			yTile = size - 1 - (y+bg.verticalScroll)%size
+		} else {
+			yTile = (y + bg.verticalScroll) % size
+		}
+		for xTile := (x + bg.horizontalScroll) % size; xTile < size; xTile++ {
+			colorIndex := ppu.decodeTilePixel(tileAddress, colorDepth, xTile, yTile)
+			var colorAddress uint16
+			if ppu.backgroundData.screenMode == 0 {
+				colorAddress = (uint16(BG)<<5 + tile.paletteIndex<<colorDepth + uint16(colorIndex)) << 1
+			} else {
+				colorAddress = (tile.paletteIndex<<colorDepth + uint16(colorIndex)) << 1
+			}
+			if colorIndex != 0 {
+				if tile.vFlip {
+					pixels[x+(size-1-xTile)] = pixel{
+						bgr:      bit.JoinUint16(ppu.cgram.bytes[colorAddress], ppu.cgram.bytes[colorAddress+1]),
+						visible:  true,
+						priority: bit.BoolToUint8(tile.priority),
+					}
+				}
+			}
+		}
+		x += size - (x+bg.horizontalScroll)%size
+	}
+	return pixels
+}