[Gnash-commit] /srv/bzr/gnash/trunk r9761: libcore/matrix.cpp: document determinant() implementation.

[Bastiaan Jacques]

------------------------------------------------------------
revno: 9761
committer: Bastiaan Jacques <address@hidden>
branch nick: trunk
timestamp: Wed 2008-09-17 11:30:25 +0200
message:
  libcore/matrix.cpp: document determinant() implementation.
  libcore/vm/CallStack.h: allow vector as_value class visibility; fixes compile.
modified:
  libcore/matrix.cpp
  libcore/vm/CallStack.h

=== modified file 'libcore/matrix.cpp'
--- a/libcore/matrix.cpp        2008-08-26 12:26:38 +0000
+++ b/libcore/matrix.cpp        2008-09-17 09:30:25 +0000
@@ -327,6 +327,14 @@
 matrix::determinant() const
 // Return the 32.32 fixed point determinant of this matrix.
 {
+    // | sx    shy     tx |
+    // | shx   sy      ty |   = T. Using the Leibniz formula:
+    // | 0     0       1  |
+    //
+    // Det(T) = ( (sx * sy * 1 ) + (shy * ty * 0) + (tx * shx *  0) ) -
+    //          ( (0  * sy * tx) + (0  * ty * sx) + (1 * shy * shx) )
+    //        = sx * sy - shx * shy
+
     return (boost::int64_t)sx * sy - (boost::int64_t)shx * shy;
 }
 

=== modified file 'libcore/vm/CallStack.h'
--- a/libcore/vm/CallStack.h    2008-09-16 12:03:31 +0000
+++ b/libcore/vm/CallStack.h    2008-09-17 09:30:25 +0000
@@ -19,12 +19,12 @@
 #define GNASH_VM_CALL_STACK_H
 
 #include <vector>
+#include "as_value.h"
 
 // Forward declarations
 namespace gnash {
     class as_object;
     class as_function;
-    class as_value;
 }
 
 namespace gnash {