Apply the rotation in Penrose grid descriptions by rotating in the

4-vector representation, rather than mucking about with sines and
cosines after grid generation. _Should_ make no difference in the
generated grids (there's a theoretical risk of an unlucky rounding
error just about managing to push some point in or out of bounds, but
I think it's vanishingly small), but simplifies the coordinate-
flattening procedure, and in particular increases its chance of
getting vertical lines actually vertical.

(Prior to this change, the game ID
10x10t12:G2554,-31,108_a3b12h0a212a3d102b2a23a2e3b01b0a2c2a0c0 was
generating a not-quite-vertical edge at top left, in the Java port but
not on Linux; I suspect differences in sin and cos as the cause of the
discrepancy. With the rotation done like this, the points'
x-coordinates are now computed without reference to their
y-coordinates.)

[originally from svn r9168]

1 files changed, 1 insertions, 1 deletions

diff --git a/penrose.h b/penrose.h
index f7b23e2..ba5ae16 100644
--- a/penrose.h
+++ b/penrose.h
@@ -42,7 +42,7 @@ struct penrose_state {
 
 enum { PENROSE_P2, PENROSE_P3 };
 
-extern int penrose(penrose_state *state, int which);
+extern int penrose(penrose_state *state, int which, int angle);
 
 /* Returns the side-length of a penrose tile at recursion level
  * gen, given a starting side length. */