Add support for pygame.math. #74

hodgestar · 2016-10-09T21:29:35Z

Work in progress.

hodgestar · 2016-10-09T21:30:15Z

@ajoubertza I created a pull request for this so we can see how builds are going and have a unified place to make comments. Thanks for working on this!

hodgestar

I left a bunch of small comments. Generally looking like a good start though!

hodgestar · 2016-10-09T21:32:04Z

pygame/mask.py

@@ -1,6 +1,6 @@
 # Implement the pygame API for the bitmask functions

-from math import atan2, pi
+import math


If this is intended to import from pygame.math it should use an explicit relative import, otherwise we should probably for from __future__ import absolute_import to avoid confusion.

mask.py is intending to import the standard math module - this code was there before the local math module was added. Should I still add the absolute_import? That's default behaviour isn't it, or are we aiming to support Python < 2.7?

hodgestar · 2016-10-09T21:33:04Z

pygame/math.py

+
+    def __getitem__(self, key):
+        """Provide indexed read access (vec[0] is x vec[1] is y)."""
+        if isinstance(key, slice):


I wonder if we could implement this whole function as return [self.x, self.y][key]?

Wow, that's a simple way to do it! I tried it, and it works.

hodgestar · 2016-10-09T21:38:32Z

pygame/math.py

+            except TypeError:
+                # Doesn't seem to be vector2-like, so NotImplemented
+                return False
+        return False


I think this should return NotImplemented instead of return False in both cases (see https://docs.python.org/2/library/stdtypes.html#the-notimplemented-object).

If pygame already returns False here it's probably slightly better to follow its implementation though.

Tried with NotImplemented, but the existing unit tests prefer returning False, so leaving it that way.

hodgestar · 2016-10-09T21:53:22Z

pygame/math.py

+        return False
+
+    def __ne__(self, other):
+        return not self.__eq__(other)


I think we need to do something like return not (self == other) here so that the comparison dispatch can do its thing.

If pygame already implements it this way, then maybe it's better to keep it this way.

hodgestar · 2016-10-09T21:58:17Z

pygame/math.py

+            self.y = args[1]
+
+    def __repr__(self):
+        return "<Vector2({}, {})>".format(self.x, self.y)


We should probably use self._x and self._y whenever we read x or y internally to avoid going through the property lookup.

Good point. Will do.

ajoubertza · 2016-10-10T07:00:37Z

Thanks for the review and suggestions @hodgestar. I'll have a look at in the course of the week.

…em__

hodgestar · 2017-02-10T20:47:12Z

@ajoubertza How is this going? :)

ajoubertza · 2017-02-11T14:23:27Z

Hi @hodgestar. Hasn't been going for a while, but am looking at it again now!
The Vector3 class is still required. Easiest will be a copy and paste job from the Vector2 code. Generalising for N-dimensions doesn't seem worth the effort. Is that OK?

hodgestar · 2017-02-11T16:43:22Z

@ajoubertza Definitely happy with that for a first pass. We can decide later if it's worth refactoring.

- Comparisons with NaNs and small deltas were not handled the same as the original pygame implementation. - Some of the "elementwise op vector" tests were passing even though the comparison functions returned NotImplemented. Added reverse checks that break in that case. Fixed the elementwise operations in those cases.

- Fixed imports for math_test, so it can also be run as part of the whole test module, as Travis does. - Draw tests run after test_circle_limits were failing because subsequent Surface constructor calls got back an 8 bpp surface, from sdl.SDL_GetVideoSurface() instead of making a new one. With the 8 bpp surface an exception is raised in _get_default_masks(..., alpha=True). Fix is to use the surface already created in setUp() instead of accessing the screen. - Fix some Python 2/3 compatibility issues.

# Conflicts: # pygame/draw.py

drnlm · 2017-03-19T15:23:32Z

pygame/math.py

@@ -0,0 +1,1529 @@
+""" Math module """
+


Could you add a suitable LGPL header to this file, please?

Sure. Whose names do I include?
For math_test.py, most of it came from the original pygame repo, so leave it as is?

You've done the vast majority of the work on math.py, so add whichever names you think are relevant.

For the test cases, we've been leaving largely unchanged, so leaving math_test.py as is seems fine.

drnlm · 2017-03-19T15:34:20Z

pygame/math.py

+            return Vector2(self.vector.x ** other.x, self.vector.y ** other.y)
+        elif isinstance(other, ElementwiseVector2Proxy):
+            return Vector2(self.vector.x ** other.vector.x,
+                           self.vector.y ** other.vector.y)


pygame explicity checks for a complex result and returns a ValueError to handle python3's behaviour. We should probably do the same here (pygame/src/math.c:3395, for example)

Thanks @drnlm. I have done something like that in f849efd. Please have a look.

The behaviour of the power operator, '**' and built-in pow() function, changed in Python 3.x. In Python 3.x raising a negative number to a fractional power results in a complex number, while in earlier versions it raised a ValueError. Matching the behaviour of pygame, as per the math unit tests, requires a ValueError instead of a complex result.

drnlm

There are a few discrepencies between pygame and our behaviour that need to be either fixed or documented, but overall this looks really good.

drnlm · 2017-03-20T10:09:13Z

pygame/math.py

+                                        format(args[0]))
+                else:
+                    raise TypeError("Invalid string argument - not like __repr__ ({}).".
+                                    format(args[0]))


pygame supports initiliasing Vector2 with a single number:

>>> Vector2(2) <Vector2(2, 0)>

This should either be supported, or the discrepency should be noted.

Sure, I'll add that, and a test. Same for Vector3.

drnlm · 2017-03-20T10:10:43Z

pygame/math.py

+            self.x = args[0]
+            self.y = args[1]
+            self.z = args[2]
+


Likewise pygame supports initiliasing Vector3 with either 1 or 2 numbers. Again this should be supported or the discrepency should be documented.

drnlm · 2017-03-20T10:20:30Z

test/draw_test.py

-        r = draw.circle(screen, (0xff, 0xff, 0xff), (((2**16)//2 + 1),
-                                                     ((2**16)//2 + 1)), 0)
+        r = draw.circle(self.surf, (0xff, 0xff, 0xff), (((2**16)//2 + 1),
+                                                        ((2**16)//2 + 1)), 0)
        self.assertEqual(r.x, 32769)
        self.assertEqual(r.y, 32769)
        self.assertEqual(r.w, 0)


I would prefer to handle this bug fix as a separate pull request, rather than including it with the math work.

OK, will do that. I was just trying to get the tests to pass.

See PR #81.

@drnlm Would you like me to revert the draw_test.py changes on this branch as well?

I think just merging in master is good enough.

drnlm · 2017-03-20T10:33:40Z

pygame/math.py

+from pygame.compat import string_types, pow_compat
+
+VECTOR_EPSILON = 1e-6  # For equality tests
+


in pygame, VECTOR_EPSILON is not directly exposed to the module since it's part of the C implementaton.

We may want to use __all__ to define the public API we expose explicitly.

The same concern applies to the pow_compat helper.

I understand that you want to hide some of these details, but not sure how to use __all__ for this. If I add something like __all__ = ['enable_swizzling', 'disable_swizzling', 'Vector2', 'Vector3'] to math.py, then the dir() and ipython autocomplete output is still the same. It only makes a difference if I do from pygame.math import *. Adding __all__ to the top level __init__.py file would be hard, since I'd have to list every single function in the package.

How closely do we need to match pygame?
E.g. It provides:

In [15]: dir(pygame.math) Out[15]: ['Vector2', 'Vector3', 'VectorElementwiseProxy', 'VectorIterator', '_PYGAME_C_API', '__doc__', '__file__', '__name__', '__package__', 'disable_swizzling', 'enable_swizzling']

So far, this module provides:

In [2]: dir(pygame.math) Out[2]: ['ElementwiseVector2Proxy', 'ElementwiseVector3Proxy', 'ElementwiseVectorProxyBase', 'Number', 'VECTOR_EPSILON', 'Vector2', 'Vector3', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_rotate_2d', 'absolute_import', 'disable_swizzling', 'division', 'enable_swizzling', 'math', 'pow_compat', 'string_types']

I prefer @hodgestar's suggestion to use the _ prefix to imply private use. Is the same required for imports, e.g. from numbers import Number -> from numbers import Number as _Number, so that they don't show up so easily?

We don't need to match pygaqme exactly, but we do want to make the public API we expose explicit, so it's clear when people are poking at something internal.

Using _VECTOR_EPSILON is fine, since it's then clear that it's internal. I would personally also mark classes like ElementwiseVector2Proxy, which are not intended to be used outside of math.py as such, even though that difffers from what pygame itself exposes.

drnlm · 2017-03-20T10:41:12Z

pygame/math.py

+                abs(dx) < VECTOR_EPSILON and
+                abs(dy) < VECTOR_EPSILON and
+                abs(dz) < VECTOR_EPSILON)
+


pygame exposes epsilon as a attribute on Vector2 and Vector3 to control the comparison accuracy

>>> from pygame.math import Vector2 >>> s=Vector2(2,2) >>> s2=s+Vector2(1e-8,1e-8) >>> s2 == s True >>> s2.epsilon = 1e-10 >>> s2 == s False >>> s == s2 True

We should either match this behaviour, or document the discrepency.

Ok, I'll add that too, and a test.

hodgestar · 2017-03-20T10:46:42Z

Another option would be to rename `VECTOR_EPSILON` to `_VECTOR_EPSILON` to indicate that it's an internal implementation detail?

drnlm · 2017-03-20T11:01:59Z

That would also work, yes.

ajoubertza · 2017-03-20T17:39:54Z

Thanks for the review @drnlm

- Rename internals with underscores to indicate usage - Add epsilon attribute to vectors - Allow initialisation for partial values (zero the rest) - Include math module in __init__.py

drnlm

Looks good

Thanks

ajoubertza · 2017-03-22T18:59:52Z

Great. Thanks @drnlm. And it only took me a mere 5 months! 🐌

hodgestar

I've left a couple of additional comments, but in general looks awesome.

There are quite a few places where we might we able to speed things up considerably by avoiding the property look up for vec.x, vec.y, vec.z but I think that is best tackled in a separate branch later if we want to (we can either carefully use _x a lot, or we can remove _x and try use just a setter for x without a getter -- which is a bit fiddly to arrange, but doable).

hodgestar · 2017-03-22T20:38:47Z

benchmarks/run_benchmark.py

@@ -1,3 +1,4 @@
+from __future__ import absolute_import


I think we're missing a blank line after the future import (at least we seem to do that elsewhere).

Sure. I like consistency too.

hodgestar · 2017-03-22T20:41:29Z

pygame/compat.py

+# fractional power results in a complex number, while in earlier versions
+# it raised a ValueError.  Matching the behaviour of pygame requires
+# the ValueError instead of a complex result.  The compatibility function
+# defined below is provided for this purpose.


It looks like math.pow(-2.2, 1.1) raises the ValueError on both Python 2.7.12 and 3.5.2, so maybe we can just use math.pow instead of our own function?

While math.pow will return a ValueError, it is also using the underlying C math library and will have a different precision from pow.

pygame is explicitly using pow underneath it's implementation, so if we use math.pow(), there will be differences between the implementations. Whether these will matter is another question, since they'll arguably only show up in odd corner cases.

I tried math.pow(), but there's an issue with 0 ** -1, which raises a ZeroDivisionError, while the math module raises a ValueError. The unit tests have a check or the former.
Interesting point about the implementation differences.

Tx for the discussion. Happy for it to stay this way then.

hodgestar · 2017-03-22T20:42:28Z

pygame/mask.py

@@ -18,7 +18,8 @@

 # Implement the pygame API for the bitmask functions

-from math import atan2, pi
+from __future__ import absolute_import
+import math


Another place where I think we should have a blank line for consistency.

There are a few more of these cases, but I'm not going to comment on them all individually. :)

hodgestar · 2017-03-22T20:43:35Z

test/draw_test.py

-        r = draw.circle(screen, (0xff, 0xff, 0xff), (((2**16)//2 + 1),
-                                                     ((2**16)//2 + 1)), 0)
+        r = draw.circle(self.surf, (0xff, 0xff, 0xff), (((2**16)//2 + 1),
+                                                        ((2**16)//2 + 1)), 0)
        self.assertEqual(r.x, 32769)
        self.assertEqual(r.y, 32769)
        self.assertEqual(r.w, 0)


I think just merging in master is good enough.

hodgestar · 2017-03-22T20:50:37Z

pygame/math.py

+    Vector2.__getattr__ = Vector2.__getattr_swizzle__
+    Vector3.__getattr__ = Vector3.__getattr_swizzle__
+
+    if '__oldsetattr__' not in dir(Vector2):


I'm not following why we need to have __oldsetattr__ if __getattr__ is not set when swizzle is disabled? We could just set and delete __getattr__ to enable / disable swizzling. If this is just following the Python API pygame exposes, then I think that's a good enough reason to keep them, if not, I'd remove the extra complexity. Also, maybe I'm just missing something entirely. :)

To enable swizzling we need to replace both __getattr__ and __setattr__. When we disable we are deleting the replacement __getattr__, and restoring the old __setattr__. Does that help?

Where is the original __setattr__ defined? Possibly I'm still being silly but my Ctrl-F def __setattr__ is not finding anything. :/

We don't define one, it is just the built in one we inherit from our parent, object.

/me learns something new about Python objects. :)

hodgestar · 2017-03-23T07:50:57Z

Looks good to me. Landing!

ajoubertza · 2017-03-23T08:19:29Z

Yay! Thanks for the reviews.

hodgestar · 2017-03-23T08:52:56Z

Thank you for doing the work and putting up with silly review comments. :)

ajoubertza added 2 commits October 9, 2016 20:26

Started adding math module - all tests do not pass yet.

af1fc89

Add additional __repr__ tests

9510a28

hodgestar commented Oct 9, 2016

View reviewed changes

ajoubertza added 3 commits October 10, 2016 22:04

Vector2 reads local vars instead of properties, and simplify __get_it…

859a6e5

…em__

Implement most of Vector2

b69d0d3

Implement last of Vector2 (all tests passing)

efb7ca4

Add absolute_import so pygame.math isn't imported

f2cbb91

ajoubertza added 6 commits February 13, 2017 22:45

Implement Vector3 - elementwise and swizzle still todo

296174b

Implement Vector3 elementwise operations

458e1e6

Implement swizzling for Vector3

361c8c6

Merge branch 'master' into issue-53-add-pygame-math

f846f6f

# Conflicts: # pygame/draw.py

drnlm reviewed Mar 19, 2017

View reviewed changes

ajoubertza added 2 commits March 19, 2017 21:21

Add LGPL header to math.py

c085311

drnlm requested changes Mar 20, 2017

View reviewed changes

Improve pygame.math public API and conformance

a57f07e

- Rename internals with underscores to indicate usage - Add epsilon attribute to vectors - Allow initialisation for partial values (zero the rest) - Include math module in __init__.py

drnlm approved these changes Mar 22, 2017

View reviewed changes

hodgestar commented Mar 22, 2017

View reviewed changes

Improve formatting consistency for __future__ imports

e06b19a

hodgestar merged commit dbcb41e into CTPUG:master Mar 23, 2017

drnlm mentioned this pull request Mar 23, 2017

Add support for pygame.math. #53

Closed

ajoubertza deleted the issue-53-add-pygame-math branch March 23, 2017 08:19

		from pygame.compat import string_types, pow_compat

		VECTOR_EPSILON = 1e-6 # For equality tests

Add support for pygame.math. #74

Add support for pygame.math. #74

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hodgestar commented Oct 9, 2016

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ajoubertza commented Oct 10, 2016

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hodgestar commented Mar 23, 2017

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