From a65e725d0df94f41fb3030b9d61aa625e6cd5df8 Mon Sep 17 00:00:00 2001
From: kdx <kikoodx@paranoici.org>
Date: Fri, 1 Sep 2023 23:40:43 +0200
Subject: fragment shader

---
 src/main.c |  2 +-
 src/px.c   | 22 ++++++++++++++++++----
 src/px.h   |  8 +++++++-
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/main.c b/src/main.c
index 514db1a..e7a1fc9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -69,7 +69,7 @@ main(void)
 		pxPset(0, 1, pxPget(0, 0));
 
 		TZR_DrawBegin();
-		pxFlip();
+		pxFlip(NULL);
 		TZR_DrawEnd();
 	}
 
diff --git a/src/px.c b/src/px.c
index d7c8650..56c5706 100644
--- a/src/px.c
+++ b/src/px.c
@@ -57,7 +57,7 @@ pxDeinit(void)
 }
 
 int
-pxFlip(void)
+pxFlip(PxRawCol (*fs)(PxRawCol c, int x, int y))
 {
 	uint8_t *pixels = NULL;
 	int pitch = 0;
@@ -72,9 +72,12 @@ pxFlip(void)
 			PxCol col = pxbuf[x + y * PX_WIDTH];
 			if (pxpal[col].spal)
 				col = pxpal[col].spal - 1;
-			pixels[ix + y * pitch + 0] = pxpal[col].b;
-			pixels[ix + y * pitch + 1] = pxpal[col].g;
-			pixels[ix + y * pitch + 2] = pxpal[col].r;
+			PxRawCol raw = pxRawCol(col);
+			if (fs != NULL)
+				raw = fs(raw, x, y);
+			pixels[ix + y * pitch + 0] = raw.a[2];
+			pixels[ix + y * pitch + 1] = raw.a[1];
+			pixels[ix + y * pitch + 2] = raw.a[0];
 			pixels[ix + y * pitch + 3] = 255;
 		}
 	}
@@ -284,9 +287,20 @@ pxCol(uint8_t r, uint8_t g, uint8_t b)
 		if (pal->r == r && pal->g == g && pal->b == b)
 			return i;
 	}
+	assert(0);
 	return -1;
 }
 
+PxRawCol
+pxRawCol(PxCol c)
+{
+	return (PxRawCol){{
+		pxpal[c].r,
+		pxpal[c].g,
+		pxpal[c].b
+	}};
+}
+
 int
 pxMin(int a, int b)
 {
diff --git a/src/px.h b/src/px.h
index 3d0db03..2d8f39b 100644
--- a/src/px.h
+++ b/src/px.h
@@ -12,6 +12,10 @@
 
 typedef uint8_t PxCol;
 
+typedef struct {
+	uint8_t a[3];
+} PxRawCol;
+
 typedef struct {
 	uint8_t r, g, b;
 	bool t; /* tranparency */
@@ -62,7 +66,7 @@ void pxDeinit(void);
 
 /* Return -1 on error.
  * Should be called between TZR_DrawBegin and TZR_DrawEnd. */
-int pxFlip(void);
+int pxFlip(PxRawCol (*fs)(PxRawCol c, int x, int y));
 
 /*** DRAW ***/
 /* Fill and reset Z on the clipping region with color 'c'. */
@@ -116,6 +120,8 @@ void _pxPalt(const PxPaltArgs *args);
 /* Try to find a color in palette, return 255 on error. */
 PxCol pxCol(uint8_t r, uint8_t g, uint8_t b);
 
+PxRawCol pxRawCol(PxCol c);
+
 /*** MATH ***/
 int pxMin(int a, int b);
 int pxMax(int a, int b);
-- 
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