--- a/content/blog/2012/07/caves-of-clojure-03-2.html Sun Jul 08 21:32:01 2012 -0400
+++ b/content/blog/2012/07/caves-of-clojure-03-2.html Sun Jul 08 22:48:44 2012 -0400
@@ -34,7 +34,9 @@
a roguelike.
This post is going to show how I added Trystan's world smoothing to make
-nicer-looking caves. Read his post and the link to learn the ideas behind it.
+nicer-looking caves. He uses a [cellular automata-based world-smoothing
+algorithm][ca-wiki] that I think is really cool, so I'm going to do pretty much
+the same thing.
Debugging
---------
@@ -241,8 +243,8 @@
game))
Yes, it only took one line to add that. I simply replace the world with the
-smooth world and return the resulting game. I don't need to touch the UI stack
-because I want to remain at the play UI for subsequent commands.
+smooth(er) world and return the resulting game. I don't need to touch the UI
+stack because I want to remain at the play UI for subsequent commands.
I'm really liking this immutable game structure so far!
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/content/blog/2012/07/caves-of-clojure-03-3.html Sun Jul 08 22:48:44 2012 -0400
@@ -0,0 +1,157 @@
+ {% extends "_post.html" %}
+
+ {% hyde
+ title: "The Caves of Clojure: Part 3.3"
+ snip: "Scrolling."
+ created: 2012-07-11 9:45:00
+ flattr: true
+ %}
+
+{% block article %}
+
+This post is part of an ongoing series. If you haven't already done so, you
+should probably start at [the beginning][].
+
+This entry corresponds to [post three in Trystan's tutorial][trystan-tut].
+
+If you want to follow along, the code for the series is [on Bitbucket][bb] and
+[on GitHub][gh]. Update to the `entry-03-3` tag to see the code as it stands
+after this post.
+
+[the beginning]: /blog/2012/07/caves-of-clojure-01/
+[trystan-tut]: http://trystans.blogspot.com/2011/08/roguelike-tutorial-03-scrolling-through.html
+[bb]: http://bitbucket.org/sjl/caves/
+[gh]: http://github.com/sjl/caves/
+
+[TOC]
+
+Summary
+-------
+
+When the last post left off I had a random world generated and smoothed to
+create some nice looking caves. The world was displayed on the screen, but it
+would only display the upper left corner of the map.
+
+This post is going to be about scrolling the viewport so we can view the entire
+map. It's the last remaining piece of Trystan's third post that I still need to
+implement.
+
+Refactoring
+-----------
+
+This is going to involve changing the worst function in the code so far
+(`draw-ui` for `:player` UIs), so before I start hacking away I want to factor
+out a bit of functionality so things are a bit cleaner.
+
+Right now that `draw-ui` function in `core.clj` looks like this:
+
+ :::clojure
+ (defmethod draw-ui :play [ui {{:keys [tiles]} :world :as game} screen]
+ (let [[cols rows] screen-size
+ vcols cols
+ vrows (dec rows)
+ start-x 0
+ start-y 0
+ end-x (+ start-x vcols)
+ end-y (+ start-y vrows)]
+ (doseq [[vrow-idx mrow-idx] (map vector
+ (range 0 vrows)
+ (range start-y end-y))
+ :let [row-tiles (subvec (tiles mrow-idx) start-x end-x)]]
+ (doseq [vcol-idx (range vcols)
+ :let [{:keys [glyph color]} (row-tiles vcol-idx)]]
+ (s/put-string screen vcol-idx vrow-idx glyph {:fg color})))))
+
+I decided to pull out the guts of that function into a helper function:
+
+ :::clojure
+ (defn draw-world [screen vrows vcols start-x start-y end-x end-y tiles]
+ (doseq [[vrow-idx mrow-idx] (map vector
+ (range 0 vrows)
+ (range start-y end-y))
+ :let [row-tiles (subvec (tiles mrow-idx) start-x end-x)]]
+ (doseq [vcol-idx (range vcols)
+ :let [{:keys [glyph color]} (row-tiles vcol-idx)]]
+ (s/put-string screen vcol-idx vrow-idx glyph {:fg color}))))
+
+ (defmethod draw-ui :play [ui {{:keys [tiles]} :world :as game} screen]
+ (let [[cols rows] screen-size
+ vcols cols
+ vrows (dec rows)
+ start-x 0
+ start-y 0
+ end-x (+ start-x vcols)
+ end-y (+ start-y vrows)]
+ (draw-world screen vrows vcols start-x start-y end-x end-y tiles)))
+
+No functionality has changed, I just pulled the body out into its own function.
+This will make things cleaner as we add more functionality.
+
+I also don't like the distructuring in the argument list here. Let's remove
+that:
+
+ :::clojure
+ (defmethod draw-ui :play [ui game screen]
+ (let [world (:world game)
+ tiles (:tiles world)
+ [cols rows] screen-size
+ vcols cols
+ vrows (dec rows)
+ start-x 0
+ start-y 0
+ end-x (+ start-x vcols)
+ end-y (+ start-y vrows)]
+ (draw-world screen vrows vcols start-x start-y end-x end-y tiles)))
+
+It's a few more lines of code but I find it more readable. If you prefer the
+more consice syntax feel free to use the destructuring -- it's not really that
+important either way.
+
+Crosshairs
+----------
+
+Trystan draws an `X` as a kind of crosshair to take the place of the traditional
+roguelike `@` (since there's no player yet), so let's do that. I made
+a separate function to draw the crosshair as a red `X` in the center of the
+screen:
+
+ :::clojure
+ (defn draw-crosshairs [screen vcols vrows]
+ (let [crosshair-x (int (/ vcols 2))
+ crosshair-y (int (/ vrows 2))]
+ (s/put-string screen crosshair-x crosshair-y "X" {:fg :red})
+ (s/move-cursor screen crosshair-x crosshair-y)))
+
+And I need to call that in the `:play` UI:
+
+ :::clojure
+ (defmethod draw-ui :play [ui game screen]
+ (let [world (:world game)
+ tiles (:tiles world)
+ [cols rows] screen-size
+ vcols cols
+ vrows (dec rows)
+ start-x 0
+ start-y 0
+ end-x (+ start-x vcols)
+ end-y (+ start-y vrows)]
+ (draw-world screen vrows vcols start-x start-y end-x end-y tiles)
+ (draw-crosshairs screen vcols vrows)))
+
+The only change here is the `(draw-crosshairs screen vcols vrows)` after I draw
+the world. This draws the crosshair `X` on top of the world, which isn't an
+issue because Lanterna's double buffering will ensure that the user never sees
+an intermediate render that's missing the `X`.
+
+Now there's a red `X` in the center of the screen. Great, but we still need to
+add the main point of this post: scrolling.
+
+Scrolling
+---------
+
+Results
+-------
+
+
+
+{% endblock article %}