faster sort of command queue

lib/ugui.c3l/src/cmd.c3

@@ -59,6 +59,35 @@ fn int Cmd.compare_to(Cmd a, Cmd b)
 	return a.z_index > b.z_index ? 1 : -1;
 }
 
+
+// FIXME: This sorting method does not fully respect layer ordering for popups.
+//        Popups that start on the same layer but are enqueued at different times
+//        may still be rendered on top of each other, even if the first popup
+//        has elements in higher layers than the second. The current approach
+//        does not truly sort by layer; it only moves elements from higher layers
+//        to the end of the queue as they are encountered.
+fn void? CmdQueue.sort(&queue)
+{
+	CmdQueue stack;
+	stack.init(allocator::tmem);
+
+	for (isz i = queue.len()-1; i > 0; i--) {
+		Cmd cur = (*queue)[i];
+		Cmd next = (*queue)[i - 1];
+		// cur < next
+		if (cur.compare_to(next) < 0) {
+			stack.push(next);
+			queue.remove_at(i-1);
+		}
+	}
+
+	usz l = stack.len();
+	for (usz i; i < l; i++) {
+		queue.push(stack.pop())!;
+	}
+
+}
+
 // implement the Printable interface
 fn usz? Cmd.to_format(Cmd* cmd, Formatter *f) @dynamic
 {

lib/ugui.c3l/src/core.c3

@@ -294,6 +294,12 @@ fn void? Ctx.frame_end(&ctx)
 		ctx.sprite_atlas.should_update = false;
 	}
 
+	// sort the command buffer by the z-index
+	// FIXME: sorting the buffer fucks with scissor commands that have to be kept in place
+	// TODO: instead of sorting at the end perform ordered inserts into the command buffer
+	//sort::countingsort(ctx.cmd_queue, fn uint(Cmd c) => c.z_index+1);
+	ctx.cmd_queue.sort()!;
+
 	// debug
 $if $feature(DEBUG_POINTER):
 	// draw mouse position
@@ -311,11 +317,6 @@ $if $feature(DEBUG_POINTER):
 	ctx.cmd_queue.push(cmd);
 $endif
 
-	// sort the command buffer by the z-index
-	// FIXME: sorting the buffer fucks with scissor commands that have to be kept in place
-	// TODO: instead of sorting at the end perform ordered inserts into the command buffer
-	sort::countingsort(ctx.cmd_queue, fn uint(Cmd c) => c.z_index+1);
-
 //	foreach (i, c: ctx.cmd_queue) {
 //		io::printf("[%d]: ", i);
 //		io::printn(c);