From 250c28ccdef5f238677b34f21ec7fab06588a127 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Thu, 28 Jul 2011 21:34:45 -0600
Subject: Make the checker pattern a singleton.

---
 libdimension-python/dimension.pxd |  2 +-
 libdimension-python/dimension.pyx |  8 --------
 libdimension/checker.c            | 11 ++++++++---
 libdimension/dimension/pattern.h  | 12 ------------
 libdimension/dimension/refcount.h |  9 ++++++++-
 libdimension/pattern.c            |  9 ---------
 libdimension/pigment_map.c        |  1 -
 7 files changed, 17 insertions(+), 35 deletions(-)

diff --git a/libdimension-python/dimension.pxd b/libdimension-python/dimension.pxd
index da4ac12..cda2c59 100644
--- a/libdimension-python/dimension.pxd
+++ b/libdimension-python/dimension.pxd
@@ -198,7 +198,7 @@ cdef extern from "../libdimension/dimension.h":
   ############
 
   ctypedef struct dmnsn_pattern:
-    dmnsn_matrix trans
+    pass
 
   void dmnsn_delete_pattern(dmnsn_pattern *pattern)
 
diff --git a/libdimension-python/dimension.pyx b/libdimension-python/dimension.pyx
index 2cde396..3fd64d1 100644
--- a/libdimension-python/dimension.pyx
+++ b/libdimension-python/dimension.pyx
@@ -543,14 +543,6 @@ cdef class Pattern:
   def __dealloc__(self):
     dmnsn_delete_pattern(self._pattern)
 
-  def transform(self, Matrix trans not None):
-    """Transform a pattern."""
-    if self._pattern == NULL:
-      raise TypeError("attempt to transform base Pattern")
-
-    self._pattern.trans = dmnsn_matrix_mul(trans._m, self._pattern.trans)
-    return self
-
 cdef class Checker(Pattern):
   """A checkerboard pattern."""
   def __init__(self):
diff --git a/libdimension/checker.c b/libdimension/checker.c
index 84b13bd..aa663ed 100644
--- a/libdimension/checker.c
+++ b/libdimension/checker.c
@@ -51,10 +51,15 @@ dmnsn_checker_pattern_fn(const dmnsn_pattern *checker, dmnsn_vector v)
   return (n%2 == 0) ? 0.0 : 1.0;
 }
 
+/** The singleton instance. */
+static dmnsn_pattern dmnsn_checker_instance = {
+  .pattern_fn = dmnsn_checker_pattern_fn,
+  .refcount = 1,
+};
+
 dmnsn_pattern *
 dmnsn_new_checker_pattern(void)
 {
-  dmnsn_pattern *checker = dmnsn_new_pattern();
-  checker->pattern_fn = dmnsn_checker_pattern_fn;
-  return checker;
+  DMNSN_INCREF(&dmnsn_checker_instance);
+  return &dmnsn_checker_instance;
 }
diff --git a/libdimension/dimension/pattern.h b/libdimension/dimension/pattern.h
index de37286..596ed35 100644
--- a/libdimension/dimension/pattern.h
+++ b/libdimension/dimension/pattern.h
@@ -40,9 +40,6 @@ struct dmnsn_pattern {
   dmnsn_pattern_fn *pattern_fn; /**< The pattern callback. */
   dmnsn_free_fn    *free_fn;    /**< The destructor callback. */
 
-  dmnsn_matrix trans;     /**< The transformation matrix of the pattern. */
-  dmnsn_matrix trans_inv; /**< The inverse of the transformation matrix. */
-
   void *ptr; /**< Generic pointer. */
 
   dmnsn_refcount refcount; /**< @internal Reference count. */
@@ -60,15 +57,6 @@ dmnsn_pattern *dmnsn_new_pattern(void);
  */
 void dmnsn_delete_pattern(dmnsn_pattern *pattern);
 
-/**
- * Initialize a pattern.  This precomputes some values that are used during
- * ray-tracing; the pattern will not work until it has been initialized, but
- * should not be modified after it has been initialized.  Patterns are generally
- * initialized for you.
- * @param[in,out] pattern  The pattern to initialize.
- */
-void dmnsn_initialize_pattern(dmnsn_pattern *pattern);
-
 /**
  * Invoke the pattern callback with the right transformation.
  * @param[in] pattern  The pattern to evaluate.
diff --git a/libdimension/dimension/refcount.h b/libdimension/dimension/refcount.h
index 5ffde4c..a0f5b6e 100644
--- a/libdimension/dimension/refcount.h
+++ b/libdimension/dimension/refcount.h
@@ -32,7 +32,14 @@ typedef unsigned int dmnsn_refcount;
  * Increment a reference count.
  * @param[in,out] object  The reference-counted object to acquire.
  */
-#define DMNSN_INCREF(object) ((void)((object) && ++(object)->refcount))
+#define DMNSN_INCREF(object)                                            \
+  do {                                                                  \
+    /* Suppress "address will always evaluate to true" warning */       \
+    void *testptr = (object);                                           \
+    if (testptr) {                                                      \
+      ++(object)->refcount;                                             \
+    }                                                                   \
+  } while (0)
 
 /**
  * @internal
diff --git a/libdimension/pattern.c b/libdimension/pattern.c
index 368755a..1db2244 100644
--- a/libdimension/pattern.c
+++ b/libdimension/pattern.c
@@ -30,7 +30,6 @@ dmnsn_pattern *
 dmnsn_new_pattern(void)
 {
   dmnsn_pattern *pattern = dmnsn_malloc(sizeof(dmnsn_pattern));
-  pattern->trans    = dmnsn_identity_matrix();
   pattern->free_fn  = NULL;
   pattern->refcount = 1;
   return pattern;
@@ -48,17 +47,9 @@ dmnsn_delete_pattern(dmnsn_pattern *pattern)
   }
 }
 
-/* Precompute the transformation matrix inverse */
-void
-dmnsn_initialize_pattern(dmnsn_pattern *pattern)
-{
-  pattern->trans_inv = dmnsn_matrix_inverse(pattern->trans);
-}
-
 /* Invoke the pattern callback with the right transformation */
 double
 dmnsn_pattern_value(const dmnsn_pattern *pattern, dmnsn_vector v)
 {
-  v = dmnsn_transform_vector(pattern->trans_inv, v);
   return pattern->pattern_fn(pattern, v);
 }
diff --git a/libdimension/pigment_map.c b/libdimension/pigment_map.c
index 4ffb129..e87584e 100644
--- a/libdimension/pigment_map.c
+++ b/libdimension/pigment_map.c
@@ -102,7 +102,6 @@ static void
 dmnsn_pigment_map_initialize_fn(dmnsn_pigment *pigment)
 {
   dmnsn_pigment_map_payload *payload = pigment->ptr;
-  dmnsn_initialize_pattern(payload->pattern);
   dmnsn_map_apply(payload->map, dmnsn_initialize_mapped_pigment);
 }
 
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