sprites!!!!!!

1 files changed, 11 insertions, 4 deletions

diff --git a/ppu/ppu.go b/ppu/ppu.go
index 322cf3d..42b3b4c 100644
--- a/ppu/ppu.go
+++ b/ppu/ppu.go
@@ -3,13 +3,16 @@ package ppu
 import "crecher.net/gones/v2/cart"
 
 const (
-	ctrlNametableMask = 0x03
-	ctrlIncrement32   = 0x04
-	ctrlBGPatternHigh = 0x10
-	ctrlNMIEnable     = 0x80
+	ctrlNametableMask     = 0x03
+	ctrlIncrement32       = 0x04
+	ctrlSpritePatternHigh = 0x08
+	ctrlBGPatternHigh     = 0x10
+	ctrlSpriteSize16      = 0x20
+	ctrlNMIEnable         = 0x80
 
 	maskGreyscale          = 0x01
 	maskShowBackgroundLeft = 0x02
+	maskShowSpritesLeft    = 0x04
 	maskShowBackground     = 0x08
 	maskShowSprites        = 0x10
 
@@ -59,6 +62,10 @@ type PPU struct {
 	patternLo, patternHi uint16
 	attrLo, attrHi       uint16
 
+	// sprites for the line being drawn, picked at the end of the previous line
+	spriteLine  [8]sprite
+	spriteCount int
+
 	nmiOutput  bool // PPUCTRL bit 7
 	nmiLine    bool // vblank && nmiOutput, latched each tick for edge detection
 	nmiPending bool // set on nmiLine's rising edge, consumed by PollNMI