From 52557c8a1c78ee02bd0eda1c740a37f8d6759b0c Mon Sep 17 00:00:00 2001
From: ubq323 <ubq323@ubq323.website>
Date: Sun, 24 Mar 2024 22:28:12 +0000
Subject: multiple chunks, and drawing works completely correctly with moving
 around

---
 drawing.ha | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

(limited to 'drawing.ha')

diff --git a/drawing.ha b/drawing.ha
index 804aee4..5812109 100644
--- a/drawing.ha
+++ b/drawing.ha
@@ -1,4 +1,5 @@
 use sdl2;
+use fmt;
 
 // 2d position, x and y
 type pos = (i32, i32);
@@ -7,13 +8,20 @@ type drawing_state = struct {
 	// is the mouse button held down?
 	drawing: bool,
 	pos: pos,
-	picture: *picture,
+	pictures: []picture,
 };
 
 type picture = struct {
+	// the surface data as u32s
 	d: *[*]u32,
 	w: size,
 	h: size,
+
+	// backreference to the surface whose data we're using
+	surf: *sdl2::SDL_Surface,
+
+	pos: pos,
+
 };
 
 // Returns array index of the pixel at position pos.
@@ -33,10 +41,12 @@ fn pidx(pic: *picture, pos: pos) size = {
 fn pic_set(pic: *picture, pos: pos, val: u32) void =
 	pic.d[pidx(pic,pos)] = val;
 
-fn picture_from_surface(surf: *sdl2::SDL_Surface) picture = picture {
+fn picture_from_surface(surf: *sdl2::SDL_Surface, pos: pos) picture = picture {
 	w = surf.w: size,
 	h = surf.h: size,
 	d = (surf.pixels as *opaque: *[*]u32),
+	surf = surf,
+	pos = pos,
 };
 
 fn clear_picture(pic: *picture, color: u32) void = {
@@ -57,14 +67,15 @@ fn outline_picture(pic: *picture) void = {
 fn min(a: i32, b: i32) i32 = if (a<b) a else b;
 fn max(a: i32, b: i32) i32 = if (a<b) b else a;
 
-// Draws a circle onto the dstate's picture, at given position radius color
+// Draws a circle onto the picture, at given position radius color
 // Clips at the boundaries of the picture to avoid overflow.
-fn circle(dstate: *drawing_state, c: pos, r: i32, color: u32) void = {
+fn circle(picture: *picture, c: pos, r: i32, color: u32) void = {
+	// fmt::printfln("C {} {} {} {:x}",c.0,c.1,r,color)!;
 	const (cx,cy) = c;
 	const ymin = max(0, cy-r);
-	const ymax = min(dstate.picture.h:i32-1, cy+r);
+	const ymax = min(picture.h:i32-1, cy+r);
 	const xmin = max(0, cx-r);
-	const xmax = min(dstate.picture.w:i32-1, cx+r);
+	const xmax = min(picture.w:i32-1, cx+r);
 
 	const r2 = r*r + r;
 
@@ -73,12 +84,17 @@ fn circle(dstate: *drawing_state, c: pos, r: i32, color: u32) void = {
 		for (let x = xmin; x<=xmax; x+=1) {
 			const xd = x-cx;
 			if (yd*yd + xd*xd <= r2) {
-				pic_set(dstate.picture, (x,y), color);
+				pic_set(picture, (x,y), color);
 			};
 		};
 	};
 };
 
 fn do_drawing(dstate: *drawing_state) void = {
-	if (dstate.drawing) circle(dstate, dstate.pos, 20, 0xff0088);
+	if (dstate.drawing) for (let i = 0z; i < 4; i+=1) {
+		const pic = &dstate.pictures[i];
+		const p = (dstate.pos.0 - pic.pos.0, dstate.pos.1 - pic.pos.1);
+		circle(pic, p, 20, 0xff0088);
+	};
 };
+
-- 
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