When a solver error arises after a change to the sketch, it should
be easy to understand exactly why it happened. Before this change,
two functionally distinct modes of failure were lumped into one:
the same "redundant constraints" message was displayed when all
degrees of freedom were exhausted and the had a solution, but also
when it had not.
To understand why this is problematic, let's examine several ways
in which we can end up with linearly dependent equations in our
system:
0) create a triangle, then constrain two different pairs of edges
to be perpendicular
1) add two distinct distance constraints on the same segment
2) add two identical distance constraints on the same segment
3) create a triangle, then constrain edges to lengths a, b, and c
so that a+b=c
The case (0) is our baseline case: the constraints in it make
the system unsolvable yet they do not remove more degrees of freedom
than the amount we started with. So the displayed error is
"unsolvable constraints".
The constraints in case (1) remove one too many degrees of freedom,
but otherwise are quite like the case (0): the cause of failure that
is useful to the user is that the constraints are mutually
incompatible.
The constraints in cases (2) and (3) however are not like the others:
there is a set of parameters that satisfies all of the constraints,
but the constraints still remove one degree of freedom too many.
It makes sense to display a different error message for cases (2)
and (3) because in practice, cases like this are likely to arise from
adjustment of constraint values on sketches corresponding to systems
that have a small amount of degenerate solutions, and this is very
different from systems arising in cases like (0) where no adjustment
of constraint values will ever result in a successful solution.
So the error message displayed is "redundant constraints".
At last, this commit makes cases (0) and (1) display a message
with only a minor difference in wording. This is deliberate.
The reason is that the facts "the system is unsolvable" and
"the system is unsolvable and also has linearly dependent equations"
present no meaningful, actionable difference to the user, and placing
emphasis on it would only cause confusion.
However, they are still distinguished, because in case (0) we
list all relevant constraints (and thus we say they are "mutually
incompatible") but in case (1) we only list the ones that constrain
the sketch further than some valid solution (and we say they are
"unsatisfied").
Before this change, it was possible to adjust constraints in a way
that removes a degree of freedom and makes the sketch unsolvable,
but rank test was performed before solving the system, and an error
was not displayed immediately. Instead, a solution would seemingly
be found, but it would be very unstable--unrelated changes to
the sketch would cause rank test to fail.
To reproduce the bug, do this:
* Draw a triangle.
* Create a length constraint for all sides.
* Set side lengths to a, b, and c such that a + b = c.
* Add a line segment.
The current messages accurately reflect what happens to the system
of equations that represents the sketch, but can be quite confusing
to users that only think in terms of the constraints.
We use "unsolvable" and not "impossible" because while most of
the cases that result in this error message will indeed stem from
mutually exclusive sets of constraints, it is still possible that
there is some solution that our solver is unable to find using
numeric methods.
After commit 11f29b12, we no longer have a convenient way to indicate
that the edit control should be moved without changing its contents;
the old code trying to do this caused a crash, since constructing
an std::string from a NULL char* is invalid.
This went undetected during testing, since on Linux, recent
GTK versions will munge scroll events while the edit box has
a modal grab.
I could've fixed the feature, but opted to remove it, since being able
to scroll the edit box out of visible region is more likely to result
in confusion than ever be useful.
Most people just want a single self-contained .html file, but more
advanced usage will involve embedding in a webpage, where the default
viewer would be copied and customized, and fed with bare mesh export.
Make the union anonymous so that its elements can be addressed
directly. Then, move the Expr *b field into the union, as it
already is never used at the same time as any of the union members.
It works. Mostly. Sort of. Only on Windows fonts. Sometimes it
randomly refuses to render glyphs (try `х`, that's not a latin ex).
I'm not really sure why, the logic seems right.
Why do we have a homegrown TTF parser anyway? It's kind of awful.
It breaks on any slightly unusual input. It plows through UTF-16BE
font names like a nuclear-powered steamroller. It outright ignores
composite glyphs (is that why it's broken this time?). The kerning
is seizure-inducing. It ignores any characters outside BMP by design.
Maybe we should just replace it with freetype.
This removes the arbitrary 64 byte restriction (which effectively
limits us to as little as 16 Unicode characters with CJK encodings),
makes classes smaller, and is easier to use.
As a consequence of making the length of all ex-NameStr fields
unbounded, all functions that returned a buffer derived from those
were changed to return std::string. Then, functions that are
contextually similar to the ones described above were changed
to return std::string. Then, functions that now happened to mostly
take an std::string argument converted to a C string were changed
to accept std::string.
This has produced a bit of churn, but is probably for the better.
Now it is possible to give non-ASCII names to groups
as well as see non-ASCII filenames of imported files.
In the future this makes localization possible.
This works for LTR languages, such as European and CJK,
but not RTL such as Arabic. Does Arabic even exist in
monospaced form? I have no idea.
After this commit, SolveSpace can robustly handle non-ASCII filenames
on every OS. Additionally, on Windows, filenames longer than 260
characeters can be used, and files on network shares can be opened
directly, without mounting them as a network drive.
After this commit, SolveSpace always uses UTF-8 strings internally
(represented as char* and std::string) on every OS, for everything:
UI labels, paths and user input. OS X always uses UTF-8; on Windows,
strings are converted at boundary; and on Linux/BSD/etc SolveSpace
refuses to start unless the current locale is UTF-8. This will
negatively affect literally no one.
This commit does not bring forth any user-visible improvement yet;
in order to correctly handle Unicode in filenames, it is still
necessary to change the fopen calls to _wfopen on Windows.
After this commit, SolveSpace deals with paths as follows:
* Paths are generally treated as opaque platform-specific strings.
This helps on Linux, because paths on Linux don't have any
specific encoding and it helps to avoid any operations on them.
* The UI in some places wants to get a basename. In this case,
the newly introduced PATH_SEP is used. This allows to treat
backslash as a regular character, which it is on Linux and OS X.
* The only place where any nontrivial operations on paths are
performed is the g->impFile/impFileRel logic.
Specifically, when saved, g->impFile always contains an absolute
path with separators of the current platform, and g->impFileRel
always contains a relative path with UNIX separators. This allows
to treat backslash as a regular character.
Old files will contain g->impFileRel with Windows separators;
these are detected by looking for a drive letter in g->impFile
and in that case mapping Windows separators to UNIX ones.
There is no need to treat UNIX separators (forward slashes) in
any special way on Windows because there is no way on Windows,
not even via UNC paths, to create or address a directory entry
with a forward slash in its name.
What do we gain from this? Several things.
* First, usage of PATH_MAX (the POSIX constant) is eliminated.
PATH_MAX is actually a lie; Linux and OS X (and probably other BSDs
too) do not have an actual path length limit. Linux claims 4096,
OS X claims 1024, but it is trivial to construct paths that are
longer.
* Second, while Windows does enforce a limit of MAX_PATH (the Win32
constant) for its ASCII functions, the Unicode variants, when
used with UNC paths, do not have this restriction.
The capability to use UNC paths is useful by itself, as it allows
to access files on network shares directly.
* Third, representing paths as std::string will make it easier to
interoperate with *W WinAPI functions later.
On Windows, freeze.{cpp,h} was factored into w32main.cpp.
The old implementation was too redundant and leaked registry
key handles.
On all platforms, Cnf* functions now use std::string.
This simplifies code everywhere, but will be particularly useful
when the Windows port switches to the *W WinAPI functions.
This is necessary to store non-POD classes in these containers.
Note that List and IdList do not use MemRealloc anymore;
this is necessarily (slightly) less efficient, but is the right
semantics, as you cannot just move non-POD types, e.g. std::string,
around in memory. All STL containers provide the same guarantees
and share the performance hit.
The slowdown is mostly mitigated by moving the contained objects,
so that no additional heap allocations or copies occur beyond
that of the object itself.
This will allow us to use non-POD classes inside these objects
in future and is otherwise functionally equivalent, as well
as more concise.
Note that there are some subtleties with handling of
brace-initialization. Specifically:
On aggregates (e.g. simple C-style structures) using an empty
brace-initializer zero-initializes the aggregate, i.e. it makes
all members zero.
On non-aggregates an empty brace-initializer calls the default
constructor. And if the constructor doesn't explicitly initialize
the members (which the auto-generated constructor doesn't) then
the members will be constructed but otherwise uninitialized.
So, what is an aggregate class? To quote the C++ standard
(C++03 8.5.1 §1):
An aggregate is an array or a class (clause 9) with no
user-declared constructors (12.1), no private or protected
non-static data members (clause 11), no base classes (clause 10),
and no virtual functions (10.3).
In SolveSpace, we only have to handle the case of base classes;
Constraint and Entity have those. Thus, they had to gain a default
constructor that does nothing but initializes the members to zero.
After this change, SolveSpace does not contain nonfree assets.
Additionally, Perl is not required for the build.
Note that in the US, case law suggests that copyright does
not apply to bitmap fonts:
http://www.renpy.org/wiki/renpy/misc/Bitmap_Fonts_and_Copyright
Nevertheless, it was prudent to replace the asset with something
that is unambiguously free.
Almost all construction requests are lines, and allowing to
draw them as construction obviates the need to select them one
by one afterwards to convert them. Also, it removes the "not closed
contour" error message, which is a nice usability improvement.
This is equivalent to adding a constraint, then making it a reference.
The benefits are that:
* it's quicker;
* it avoids having an over-constrained system, with an associated
angry red flash and a regeneration delay.
The latter in particular is a very substantial usability improvement.
The reference distance command is useful most of the time,
but the reference angle one is also added for consistency.
The main benefit is that std::swap will ensure that the type
of arguments is copy-constructible and move-constructible.
It is more concise as well.
When min and max are defined as macros, they will conflict
with STL header files included by other C++ libraries;
in this case STL will #undef any other definition.
EvilSpirit
whitequark
ruevs
William D. Jones