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mathlib/datagen.pl

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+#! perl
+use Text::Wrap;
+
+# generate output data for noise generators
+
+srand(31456);
+
+print <<END
+//========= Copyright <20> 1996-2006, Valve Corporation, All rights reserved. ============//
+//
+// Purpose: static data for noise() primitives.
+//
+// \$Workfile:     \$
+// \$NoKeywords: \$
+//=============================================================================//
+//
+//    **** DO NOT EDIT THIS FILE. GENERATED BY DATAGEN.PL ****
+//
+
+END
+;
+
+@perm_a=0..255;
+
+&fisher_yates_shuffle(\@perm_a);
+
+$Text::Wrap::Columns=78;
+$Text::Wrap::break=",";
+$Text::Wrap::separator=",\n";
+
+print "static int perm_a[]={\n",wrap('    ','   ',join(",",@perm_a)),"\n};\n\n";
+&fisher_yates_shuffle(\@perm_a);
+print "static int perm_b[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+&fisher_yates_shuffle(\@perm_a);
+print "static int perm_c[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+&fisher_yates_shuffle(\@perm_a);
+print "static int perm_d[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+
+for ($i=0;$i<256;$i++)
+  {
+	$float_perm=(1.0/255.0)*$perm_a[$i];
+	$perm_a[$i] = sprintf("%f",$float_perm);
+  }
+&fisher_yates_shuffle(\@perm_a);
+print "static float impulse_xcoords[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+&fisher_yates_shuffle(\@perm_a);
+print "static float impulse_ycoords[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+&fisher_yates_shuffle(\@perm_a);
+print "static float impulse_zcoords[]={\n",wrap('    ','    ',join(",",@perm_a)),"\n};\n\n";
+
+
+
+# fisher_yates_shuffle( \@array ) : generate a random permutation
+# of @array in place
+sub fisher_yates_shuffle {
+    my $array = shift;
+    my $i;
+    for ($i = @$array; --$i; ) {
+        my $j = int rand ($i+1);
+        next if $i == $j;
+        @$array[$i,$j] = @$array[$j,$i];
+    }
+}