2 files changed, 93 insertions, 0 deletions
diff --git a/drawing/drawing.ha b/drawing/drawing.ha
new file mode 100644
index 0000000..70bd7af
--- /dev/null
+++ b/drawing/drawing.ha
@@ -0,0 +1,89 @@
+use sdl2;
+use fmt;
+use io;
+use endian;
+use math::random;
+
+export type pos = (i32, i32);
+
+export type picture = struct {
+	// the surface data as u32s
+	d: *[*]u32,
+	w: size,
+	h: size,
+
+	// position of topleft corner in the world
+	world_pos: pos,
+
+};
+
+// Returns array index of the pixel at position pos.
+// Bounds check happens in here instead of using a slice type, so
+// that it's easier to remove later.
+fn pidx(pic: *picture, pos: pos) size = {
+	const (x,y) = pos;
+	const (xs,ys) = (x:size, y:size);
+	assert(0 <= x, "x position must not be less than 0");
+	assert(0 <= y, "y position must not be less than 0");
+	assert(xs < pic.w, "x position must be less than picture width");
+	assert(ys < pic.h, "y position must be less than picture height");
+
+	return xs + pic.w*ys;
+};
+
+export fn pic_set(pic: *picture, pos: pos, val: u32) void =
+	pic.d[pidx(pic,pos)] = val;
+
+export fn clear_picture(pic: *picture, color: u32) void = {
+	for (let i = 0z; i < pic.w*pic.h; i+=1) pic.d[i] = color;
+};
+
+export fn outline_picture(pic: *picture) void = {
+	for (let x = 0; x:size < pic.w; x+=1) {
+		pic_set(pic, (x, 0), 0);
+		pic_set(pic, (x, pic.h:int-1), 0);
+	};
+	for (let y = 0; y:size < pic.h; y+=1) {
+		pic_set(pic, (0, y), 0);
+		pic_set(pic, (pic.w:int-1, y), 0);
+	};
+};
+
+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 picture, at given position radius color
+// Clips at the boundaries of the picture to avoid overflow.
+export 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(picture.h:i32-1, cy+r);
+	const xmin = max(0, cx-r);
+	const xmax = min(picture.w:i32-1, cx+r);
+
+	const r2 = r*r + r;
+
+	for (let y = ymin; y<=ymax; y+=1) {
+		const yd = y-cy;
+		for (let x = xmin; x<=xmax; x+=1) {
+			const xd = x-cx;
+			if (yd*yd + xd*xd <= r2) {
+				pic_set(picture, (x,y), color);
+			};
+		};
+	};
+};
+
+export fn perform(pictures: []picture, op: op) void = {
+	match (op) {
+	case op_other => abort("oopsy");
+	case let o: op_circle =>
+		const x = o.0, y=o.1;
+		for (const pic &.. pictures) {
+			let pos_within_pic =
+				(x - pic.world_pos.0, y - pic.world_pos.1): pos;
+			circle(pic, pos_within_pic, 20, 0xff0088);
+		};
+	};
+};
diff --git a/drawing/op.ha b/drawing/op.ha
new file mode 100644
index 0000000..ef39161
--- /dev/null
+++ b/drawing/op.ha
@@ -0,0 +1,4 @@
+export type op_circle = pos;
+export type op_other = void;
+
+export type op = (op_circle| op_other);