# HG changeset patch
# User Steve Losh <steve@stevelosh.com>
# Date 1521088081 14400
# Node ID 630bc79afdfdbf3875adf66409d3b6c63c405a9d
# Parent  cb69666ad32fec3a8273f6f885c7466f57dee27f
Add tracing lines

diff -r cb69666ad32f -r 630bc79afdfd flax.asd
--- a/flax.asd	Wed Mar 14 22:52:58 2018 -0400
+++ b/flax.asd	Thu Mar 15 00:28:01 2018 -0400
@@ -39,5 +39,6 @@
        (:file "002-wobbly-lines")
        (:file "003-basic-l-systems")
        (:file "004-turtle-curves")
-       (:file "005-simple-triangulations")))))))
+       (:file "005-simple-triangulations")
+       (:file "006-tracing-lines")))))))
 
diff -r cb69666ad32f -r 630bc79afdfd package.lisp
--- a/package.lisp	Wed Mar 14 22:52:58 2018 -0400
+++ b/package.lisp	Thu Mar 15 00:28:01 2018 -0400
@@ -1,6 +1,6 @@
 (defpackage :flax.base
   (:use :cl :iterate :losh :flax.quickutils)
-  (:export :rand :with-seed))
+  (:export :rand :with-seed :round-to))
 
 (defpackage :flax.coordinates
   (:use :cl :iterate :losh :flax.base :flax.quickutils)
@@ -62,4 +62,10 @@
     :flax.coordinates)
   (:export :loom))
 
+(defpackage :flax.looms.006-tracing-lines
+  (:use :cl :iterate :losh :flax.base :flax.quickutils
+    :flax.colors
+    :flax.coordinates)
+  (:export :loom))
 
+
diff -r cb69666ad32f -r 630bc79afdfd src/base.lisp
--- a/src/base.lisp	Wed Mar 14 22:52:58 2018 -0400
+++ b/src/base.lisp	Thu Mar 15 00:28:01 2018 -0400
@@ -4,5 +4,20 @@
   (pcg:pcg-random t bound))
 
 (defmacro with-seed (seed &body body)
-  `(let ((pcg::*global-generator* (pcg:make-pcg :seed ,seed))) ,@body))
+  `(let ((pcg::*global-generator* (pcg:make-pcg :seed ,seed)))
+     (losh::clear-gaussian-spare)
+     ,@body))
+
+
+(defun round-to (number precision)
+  "Round `number` to the given `precision`.
 
+  Examples:
+
+    (round-to 13 10)      ; => 10
+    (round-to 15 10)      ; => 20
+    (round-to 44 25)      ; => 50
+    (round-to 457/87 1/2) ; => 11/2
+
+  "
+  (* precision (round number precision)))
diff -r cb69666ad32f -r 630bc79afdfd src/looms/006-tracing-lines.lisp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/looms/006-tracing-lines.lisp	Thu Mar 15 00:28:01 2018 -0400
@@ -0,0 +1,67 @@
+(in-package :flax.looms.006-tracing-lines)
+
+;;;; Config -------------------------------------------------------------------
+(defparameter *spread* 0.0020)
+
+
+;;;; Convert ------------------------------------------------------------------
+(defun convert-point (point x y)
+  (coord x (+ y point)))
+
+(defun convert-line (line y)
+  (flax.drawing:path
+    (iterate (for point :in-vector line)
+             (for x :from 0.0 :by (/ (1- (length line))))
+             (collect (convert-point point x y)))
+    :color (hsv 0 0 1)))
+
+(defun convert-lines (lines)
+  (iterate (for line :in lines)
+           (for y :from 0.0 :by (/ (length lines)))
+           (collect (convert-line line y))))
+
+
+;;;; Generate -----------------------------------------------------------------
+(defun make-initial-line (points)
+  (make-array points :initial-element 0.0))
+
+(defun perturb (point)
+  (random-around point *spread* #'rand))
+
+(defun wrapping-aref (array i)
+  (aref array (mod i (length array))))
+
+(defun average (sequence)
+  (iterate (for x :in-whatever sequence)
+           (averaging x)))
+
+(defun next-line (line)
+  (iterate (for i :index-of-vector line)
+           (collect (random-gaussian
+                      (average (subseq line
+                                       (max 0 (- i 2))
+                                       (min (1- (length line)) (+ i 1))))
+                      *spread* #'rand)
+                    :result-type 'vector)))
+
+(defun generate-lines (points lines)
+  (iterate
+    (repeat lines)
+    (for line :first (make-initial-line points) :then (next-line line))
+    (collect line)))
+
+
+;;;; Main ---------------------------------------------------------------------
+(defun loom (seed filename filetype width height)
+  (nest
+    (with-seed seed)
+    (flax.drawing:with-rendering (canvas filetype filename width height
+                                         :background (hsv 0 0 0.05)))
+    (let* ((points (round-to (random-range 100 150 #'rand) 10))
+           (lines (round-to (random-range 80 140 #'rand) 10))
+           (*spread* (/ 0.15 lines))))
+    (progn
+      (flax.drawing:render canvas (convert-lines (generate-lines points lines)))
+      (list points lines))))
+
+;; (time (loom nil "out" :svg 800 800))