update px

2 files changed, 28 insertions, 11 deletions

diff --git a/src/px.c b/src/px.c
index 8b6e531..20bd218 100644
--- a/src/px.c
+++ b/src/px.c
@@ -4,6 +4,7 @@
 #include <assert.h>
 
 PxCol pxbuf[PX_WIDTH * PX_HEIGHT] = {0};
+unsigned int pxzbuf[PX_WIDTH * PX_HEIGHT] = {0};
 PxPal pxpal[256] = {
 	/* PICO-8 palette */
 	{0x00, 0x00, 0x00, false, 0, 0},
@@ -30,6 +31,7 @@ static struct {
 	int h;
 } pxclip = {0, 0, PX_WIDTH, PX_HEIGHT};
 static SDL_Texture *pxtexture = NULL;
+static unsigned int pxz = 0;
 
 int
 pxInit(void)
@@ -57,7 +59,6 @@ pxDeinit(void)
 int
 pxFlip(void)
 {
-	extern int flip_offset_x;
 	extern int flip_offset_y;
 
 	uint8_t *pixels = NULL;
@@ -68,11 +69,11 @@ pxFlip(void)
 	}
 
 	for (int y = 0; y < PX_HEIGHT; y++) {
-		const int iy = (y + flip_offset_y) % PX_HEIGHT;
+		const int iy = (y + flip_offset_y % PX_HEIGHT + PX_HEIGHT)
+		               % PX_HEIGHT;
 		for (int x = 0; x < PX_WIDTH; x++) {
-			const int ax = (x + flip_offset_x) % PX_WIDTH;
 			const int ix = x << 2;
-			PxCol col = pxbuf[ax + iy * PX_WIDTH];
+			PxCol col = pxbuf[x + iy * PX_WIDTH];
 			if (pxpal[col].spal)
 				col = pxpal[col].spal - 1;
 			pixels[ix + y * pitch + 0] = pxpal[col].b;
@@ -84,15 +85,18 @@ pxFlip(void)
 
 	SDL_UnlockTexture(pxtexture);
 	SDL_RenderCopy(___tzr_renderer, pxtexture, NULL, NULL);
+
 	return 0;
 }
 
 void
 pxCls(PxCol c)
 {
-	for (int y = 0; y < PX_HEIGHT; y++)
-		for (int x = 0; x < PX_WIDTH; x++)
-			pxPset(x, y, c);
+	for (int y = pxclip.y; y < pxclip.y + pxclip.h; y++)
+		for (int x = pxclip.x; x < pxclip.x + pxclip.w; x++) {
+			pxbuf[x + y * PX_WIDTH] = c;
+			pxzbuf[x + y * PX_WIDTH] = 0;
+		}
 }
 
 void
@@ -111,14 +115,24 @@ pxClipReset(void)
 }
 
 void
+pxZ(unsigned int z)
+{
+	pxz = z;
+}
+
+void
 pxPset(int x, int y, PxCol c)
 {
 	if (x < pxclip.x || x >= pxclip.x + pxclip.w ||
 	    y < pxclip.y || y >= pxclip.y + pxclip.h)
 		return;
-	if (pxpal[c].pal)
-		c = pxpal[c].pal - 1;
-	pxbuf[x + y * PX_WIDTH] = c;
+
+	/* z sorting */
+	if (pxz < pxzbuf[x + y * PX_WIDTH])
+		return;
+	pxzbuf[x + y * PX_WIDTH] = pxz;
+
+	pxbuf[x + y * PX_WIDTH] = pxpal[c].pal ? pxpal[c].pal : c;
 }
 
 uint8_t
diff --git a/src/px.h b/src/px.h
index cc59c7f..713f245 100644
--- a/src/px.h
+++ b/src/px.h
@@ -64,7 +64,7 @@ void pxDeinit(void);
 int pxFlip(void);
 
 /*** DRAW ***/
-/* Fill the clipping region with color 'c'. */
+/* Fill and reset Z on the clipping region with color 'c'. */
 void pxCls(PxCol c);
 
 /* Set the clipping region. */
@@ -73,6 +73,9 @@ void pxClip(int x, int y, int w, int h);
 /* Reset the clipping region. */
 void pxClipReset(void);
 
+/* Set Z layer. */
+void pxZ(unsigned int z);
+
 /* Put a pixel. */
 void pxPset(int x, int y, PxCol c);