Fix Mode 4 sprite collision flag

1 files changed, 7 insertions, 2 deletions

diff --git a/vdp.c b/vdp.c
index af04a05..0f772d0 100644
--- a/vdp.c
+++ b/vdp.c
@@ -251,8 +251,13 @@ static void render_sprite_cells_mode4(vdp_context * context)
 		int x = d->x_pos & 0xFF;
 		for (int i = 28; i >= 0; i -= 4, x++)
 		{
-			if (context->linebuf[x]) {
-				context->flags2 |= FLAG2_SPRITE_COLLIDE;
+			if (context->linebuf[x] && (pixels >> i & 0xF)) {
+				if (
+					((context->regs[REG_MODE_1] & BIT_SPRITE_8PX) && x > 8)
+					|| ((!(context->regs[REG_MODE_1] & BIT_SPRITE_8PX)) && x < 256)
+				) {
+					context->flags2 |= FLAG2_SPRITE_COLLIDE;
+				}
 			} else {
 				context->linebuf[x] = pixels >> i & 0xF;
 			}