From 96af4b94a158a88237c15f858d937cbf37fe895e Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Thu, 9 Feb 2023 16:57:01 +1100
Subject: [PATCH] minor gpu improvements

---
 src/processor/gpu.rs       | 15 ++++++++-------
 src/processor/gpu/types.rs |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/processor/gpu.rs b/src/processor/gpu.rs
index af711fe..75cef70 100644
--- a/src/processor/gpu.rs
+++ b/src/processor/gpu.rs
@@ -169,7 +169,7 @@ impl CPU {
         let mode_1_vblank_enabled = get_bit(stat, 4);
         let mode_0_hblank_enabled = get_bit(stat, 3);
 
-        let lyc_eq_ly = self.memory.get(0xFF44) == self.memory.get(0xFF45);
+        let lyc_eq_ly = self.gpu.scanline == self.memory.get(0xFF45);
         let mode_2 = self.gpu.mode == DrawMode::Mode2;
         let mode_1_vblank = self.gpu.mode == DrawMode::VBlank;
         let mode_0_hblank = self.gpu.mode == DrawMode::HBlank;
@@ -232,18 +232,16 @@ impl CPU {
     fn render_scanline_window(&mut self, scanline: u8, lcdc: &LCDC, palette: Palette) {
         let pos_y = self.memory.get(0xFF4A);
         // subtracting 7 to get the Real Number...
-        let pos_x = self.memory.get(0xFF4B).wrapping_sub(7);
-        if pos_y < 143 && pos_x < 166 {
+        let pos_x = self.memory.get(0xFF4B);
             self.render_tiles(
                 scanline,
                 &lcdc.window_tilemap,
                 &lcdc.tile_area,
                 palette,
-                pos_x,
+            pos_x.wrapping_sub(7),
                 pos_y,
                 false,
-            )
-        }
+        );
     }
 
     fn render_scanline_obj(&mut self, scanline: u8, lcdc: &LCDC, bg_palette: Palette) {
@@ -304,6 +302,9 @@ impl CPU {
             let lsb = get_bit(lsbs, x_addr);
             let msb = get_bit(msbs, x_addr);
             let colour = bits_to_mapped_colour(lsb, msb, object.flags.palette);
+            if colour == object.flags.palette.zero {
+                continue;
+            }
             let x_coord_uncorrected = (object.x as usize) + (px_x as usize);
             if x_coord_uncorrected < 8 {
                 continue;
@@ -331,7 +332,7 @@ impl CPU {
         wrap: bool,
     ) {
         let tile_line_y = scanline.wrapping_add(offset_y);
-        if (scanline as usize + offset_y as usize) % 0xFF > 0 && !wrap {
+        if ((scanline as usize + offset_y as usize) / 0xFF) > 0 && !wrap {
             return;
         }
         let tilemap_row = tile_line_y / 8;
diff --git a/src/processor/gpu/types.rs b/src/processor/gpu/types.rs
index 3b37887..575f9bc 100644
--- a/src/processor/gpu/types.rs
+++ b/src/processor/gpu/types.rs
@@ -65,7 +65,7 @@ pub(super) struct LCDC {
     pub(super) bg_window_enable: bool,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub(super) enum Colour {
     White,
     LightGray,