BLI: Refactor vector types & functions to use templates

This patch implements the vector types (i.e:float2) by making heavy
usage of templating. All vector functions are now outside of the vector
classes (inside the blender::math namespace) and are not vector size
dependent for the most part.

In the ongoing effort to make shaders less GL centric, we are aiming
to share more code between GLSL and C++ to avoid code duplication.

Motivations:
- We are aiming to share UBO and SSBO structures between GLSL and C++.
  This means we will use many of the existing vector types and others we
  currently don't have (uintX, intX). All these variations were asking
  for many more code duplication.
- Deduplicate existing code which is duplicated for each vector size.
- We also want to share small functions. Which means that vector functions
  should be static and not in the class namespace.
- Reduce friction to use these types in new projects due to their
  incompleteness.
- The current state of the BLI_(float|double|mpq)(2|3|4).hh is a bit of a
  let down. Most clases are incomplete, out of sync with each others with
  different codestyles, and some functions that should be static are not
  (i.e: float3::reflect()).

Upsides:
- Still support .x, .y, .z, .w for readability.
- Compact, readable and easilly extendable.
- All of the vector functions are available for all the vectors types and
  can be restricted to certain types. Also template specialization let us
  define exception for special class (like mpq).
- With optimization ON, the compiler unroll the loops and performance is
  the same.

Downsides:
- Might impact debugability. Though I would arge that the bugs are rarelly
  caused by the vector class itself (since the operations are quite trivial)
  but by the type conversions.
- Might impact compile time. I did not saw a significant impact since the
  usage is not really widespread.
- Functions needs to be rewritten to support arbitrary vector length. For
  instance, one can't call len_squared_v3v3 in math::length_squared() and
  call it a day.
- Type cast does not work with the template version of the math:: vector
  functions. Meaning you need to manually cast float * and (float *)[3] to
  float3 for the function calls.
  i.e: math::distance_squared(float3(nearest.co), positions[i]);
- Some parts might loose in readability:
  float3::dot(v1.normalized(), v2.normalized())
  becoming
  math::dot(math::normalize(v1), math::normalize(v2))
  But I propose, when appropriate, to use
  using namespace blender::math; on function local or file scope to
  increase readability. dot(normalize(v1), normalize(v2))

Consideration:
- Include back .length() method. It is quite handy and is more C++
  oriented.
- I considered the GLM library as a candidate for replacement.
  It felt like too much for what we need and would be difficult to
  extend / modify to our needs.
- I used Macros to reduce code in operators declaration and potential
  copy paste bugs. This could reduce debugability and could be reverted.
- This touches delaunay_2d.cc and the intersection code. I would like to
  know @Howard Trickey (howardt) opinion on the matter.
- The noexcept on the copy constructor of mpq(2|3) is being removed.
  But according to @Jacques Lucke (JacquesLucke) it is not a real problem
  for now.

I would like to give a huge thanks to @Jacques Lucke (JacquesLucke) who
helped during this and pushed me to reduce the duplication further.

Reviewed By: brecht, sergey, JacquesLucke

Differential Revision: http://developer.blender.org/D13791

1 files changed, 10 insertions, 9 deletions

diff --git a/source/blender/blenlib/BLI_path_util.h b/source/blender/blenlib/BLI_path_util.h
index 658cc0c3825..16f479cb3b8 100644
--- a/source/blender/blenlib/BLI_path_util.h
+++ b/source/blender/blenlib/BLI_path_util.h
@@ -75,15 +75,16 @@ bool BLI_make_existing_file(const char *name);
  * - Doesn't use CWD, or deal with relative paths.
  * - Only fill's in \a dir and \a file when they are non NULL.
  */
-void BLI_split_dirfile(const char *string, char *dir, char *file, size_t dirlen, size_t filelen);
+void BLI_split_dirfile(
+    const char *string, char *dir, char *file, const size_t dirlen, const size_t filelen);
 /**
  * Copies the parent directory part of string into `dir`, max length `dirlen`.
  */
-void BLI_split_dir_part(const char *string, char *dir, size_t dirlen);
+void BLI_split_dir_part(const char *string, char *dir, const size_t dirlen);
 /**
  * Copies the leaf filename part of string into `file`, max length `filelen`.
  */
-void BLI_split_file_part(const char *string, char *file, size_t filelen);
+void BLI_split_file_part(const char *string, char *file, const size_t filelen);
 /**
  * Returns a pointer to the last extension (e.g. the position of the last period).
  * Returns NULL if there is no extension.
@@ -93,7 +94,7 @@ const char *BLI_path_extension(const char *filepath) ATTR_NONNULL();
 /**
  * Append a filename to a dir, ensuring slash separates.
  */
-void BLI_path_append(char *__restrict dst, size_t maxlen, const char *__restrict file)
+void BLI_path_append(char *__restrict dst, const size_t maxlen, const char *__restrict file)
     ATTR_NONNULL();
 /**
  * Simple appending of filename to dir, does not check for valid path!
@@ -103,7 +104,7 @@ void BLI_path_append(char *__restrict dst, size_t maxlen, const char *__restrict
  * that de-duplicates separators and can handle an arbitrary number of paths.
  */
 void BLI_join_dirfile(char *__restrict dst,
-                      size_t maxlen,
+                      const size_t maxlen,
                       const char *__restrict dir,
                       const char *__restrict file) ATTR_NONNULL();
 /**
@@ -113,7 +114,7 @@ void BLI_join_dirfile(char *__restrict dst,
  * \note If you want a trailing slash, add `SEP_STR` as the last path argument,
  * duplicate slashes will be cleaned up.
  */
-size_t BLI_path_join(char *__restrict dst, size_t dst_len, const char *path_first, ...)
+size_t BLI_path_join(char *__restrict dst, const size_t dst_len, const char *path_first, ...)
     ATTR_NONNULL(1, 3) ATTR_SENTINEL(0);
 /**
  * Like Python's `os.path.basename()`
@@ -163,12 +164,12 @@ void BLI_path_slash_rstrip(char *string) ATTR_NONNULL();
 void BLI_path_slash_native(char *path) ATTR_NONNULL();
 
 #ifdef _WIN32
-bool BLI_path_program_extensions_add_win32(char *name, size_t maxlen);
+bool BLI_path_program_extensions_add_win32(char *name, const size_t maxlen);
 #endif
 /**
  * Search for a binary (executable)
  */
-bool BLI_path_program_search(char *fullname, size_t maxlen, const char *name);
+bool BLI_path_program_search(char *fullname, const size_t maxlen, const char *name);
 
 /**
  * \return true when `str` end with `ext` (case insensitive).
@@ -352,7 +353,7 @@ bool BLI_path_is_abs_from_cwd(const char *path) ATTR_NONNULL();
  * This is _not_ something Blender's internal paths support, instead they use the "//" prefix.
  * In most cases #BLI_path_abs should be used instead.
  */
-bool BLI_path_abs_from_cwd(char *path, size_t maxlen) ATTR_NONNULL();
+bool BLI_path_abs_from_cwd(char *path, const size_t maxlen) ATTR_NONNULL();
 /**
  * Replaces `file` with a relative version (prefixed by "//") such that #BLI_path_abs, given
  * the same `relfile`, will convert it back to its original value.