From: ian <ian>
Date: Sat, 12 Mar 2005 18:25:32 +0000 (+0000)
Subject: extractgraph wip - currently written node comparer and librarian, but no edge librari... 
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=f87e89b86c37b4d65013ca9f162abffddf351b7e;p=trains.git

extractgraph wip - currently written node comparer and librarian, but no edge librarian code and no output code
---

diff --git a/layout/extractgraph b/layout/extractgraph
new file mode 100755
index 0000000..7a5c30d
--- /dev/null
+++ b/layout/extractgraph
@@ -0,0 +1,121 @@
+#!/usr/bin/perl
+#
+# Reads the special comments in the subsegment encoding output from
+# layout, determines the segment graph, and outputs a description of
+# that graph.
+
+# Approach/algorithm:
+#
+#  We read the segenco.ps and each time we find a `%L segmentpart'
+#  comment we add it to an annotated graph we construct.  Each node in
+#  the annotated graph is a tuple consisting of a loc and range of
+#  layer levels.  Each edge is a segment part from a %L comment.  Each
+#  node has a `front' and a `back', and each edget attach either to
+#  one or the other.
+#
+#  Only segment parts with certain layer kinds are processed: by
+#  default, only the empty layer kind.
+#
+#  When a loc is found in the input, as one end of a segmentpart, it
+#  is considered identical to a existing node (if its details are
+#  sufficiently similar) or creates a new node (if its details are
+#  sufficiently different).  If the segmentpart's end is considered
+#  identical to an existing node then the existing node's layer level
+#  range is extended, but the existing node's X Y and A are not
+#  modified.
+#
+#  A loc and layer level are compared with a node as follows:
+#
+#    The difference between each of the loc's details and the node's
+#    details is computed.  If any of the differences is at least the
+#    min clearance, then the loc/layerb is a new node.  Otherwise, all
+#    of the differences must be within the max tolerance and the
+#    loc/layer is the same as the node (coming out of the back if the
+#    180deg was added to make the angle difference).  Otherwise it is
+#    an error.
+#
+#    The detail differences are:
+#       Position difference: horizontal distance between loc and node
+#       Angle difference: difference betwen loc's and node's A, or
+#        difference minus 180deg between loc's and node's A, whichever
+#        is the smaller (both reduced mod 360deg to value with 
+#        smallest magnitude).
+#       Level difference: 0 if layer level is within node's range
+#        or distance by which it is outside that range.
+
+$conf{MinClearLayer}= 6;
+$conf{MaxTolerLayer}= 4;
+$conf{MinClearDist}= 2.0;
+$conf{MaxTolerDist}= 0.2;
+$conf{MinClearAngle}= 5.0;
+$conf{MaxTolerAngle}= 0.5;
+$conf{LayerKinds}= ''; # comma-separated list
+
+our @nodes;
+# $nodes[$nodenum]{X}
+# $nodes[$nodenum]{Y}
+# $nodes[$nodenum]{A}
+# $nodes[$nodenum]{LayerMin}
+# $nodes[$nodenum]{LayerMax}
+
+sub find_node (@) {
+    my ($l,$x,$y,$a) = @_;
+    my ($any_outside_tol);
+    for ($ni=0; $ni<@nodes; $ni++) {
+	$node= $nodes[$ni];
+	$diff{Layer}= (($d = $l - $node->{LayerMin}) < 0 ? $d :
+		       ($d = $l - $node->{LayerMax}) > 0 ? $d :
+		       0);
+	$diff{Dist}= sqrt(sqr($x - $node->{X}) +
+			  sqr($y - $node->{Y}));
+	$diff{Angle}= $a - $node->{A};                    # <-360,360>
+	if ($diff{Angle} < 0) { $diff{Angle} += 360; }    # [0,360>
+	$back= $diff{Angle} >= 90 && $diff{Angle} < 270;  # $back <=> [90,270>
+	if ($back) { $diff{Angle} -= 180; }               # [0,90> or [270,360>
+	if ($diff{Angle} > 180) { $diff{Angle} -= 360; }  # [-90,90>
+	$any_outside_clear= 0;
+	$any_outside_toler= 0;
+	foreach $k (keys %diff) {
+	    if (abs($diff{$k}) >= $conf{"MinClear$k"}) {
+		$any_outside_clear=1; last;
+	    } elsif (abs($diff{$k}) <= $conf{"MaxToler$k"}) {
+	    } else {
+		$any_outside_toler=1;
+	    }
+	}
+	if ($any_outside_clear) {
+	} else if ($any_outside_toler) {
+	    die "$l,$x,$y,$a vs. $node->{LayerMin}..$node->{LayerMax}".
+		",$node->{X},$node->{Y},$node->{A}";
+	} else {
+	    if ($diff{Layer} < 0) { $node->{LayerMin}= $l }
+	    if ($diff{Layer} > 0) { $node->{LayerMax}= $l }
+	    return ($node,$back);
+	}
+    }
+    $node= { X => $x, Y => $y, A => $a,
+	     LayerMin => $l, LayerMax => $l };
+    push @nodes, $node;
+    return ($node,0);
+}
+    
+while (<>) {
+    next unless m/^\%L /;
+    die unless m/^\%L (\w+)\b/;
+    next unless $1 eq 'segmentpart';
+    die unless m/^\%L segmentpart ([A-Za-z_]*)(\d+) (\S+) ([-.eE0-9 ]+)$/;
+    ($layerkind, $level, $subsegspec, $numbers) = ($1,$2,$3,$4);
+    next unless grep { $layerkind eq $_ } split /\,/, $conf{LayerKinds};
+    @numbers = map { $_ + 0 } split / /, $numbers;
+    for ($pti=0; $pti<2; $pti++) {
+	($node[$pti], $back[$pti])=
+	    find_node($level, $numbers[($i*3)..($i*3+2)]);
+    }
+}
+
+    ($pts[0]{X}, $pts[0]{Y}, $pts[0]{A},
+     $pts[1]{X}, $pts[1]{Y}, $pts[1]{A}) = 
+    $node[0]
+     
+
+(\w+(?:(?:\/([A-Za-z]+)(\d+))?)?)