[Bf-committers] [Bf-blender-cvs] SVN commit: /data/svn/bf-blender [43733] trunk/blender/source/blender/ blenlib/intern/math_matrix.c: Fix orthogonality check for mat3 and mat4

[Lockal S]

Sorry for double posting, I'm not sure if the previous mail got to the list.

Old behavior:
  Matrix(((0, 0, 10), (0, 20, 0), (0, 0, 0))).is_orthogonal returned
true, but this matrix is not orthogonal

  Matrix(((0, 0, 1, 42), (0, 1, 0, 0x42), (0, 0, 0, 100500), (-42, 42,
0xDEAD, 0))).is_orthogonal also returned true (but this matrix is not
orthogonal)

So as you can see m3 version completely ignored the main diagonal and
m4 version also ignored 4-th column and 4-th row. Now it works as it
described in Wikipedia and Wolfram MathWorld.

At this moment orthogonality check is being used only one time in
blender (in draw_manipulator_rotate), and this one case seems to be a
real orthogonality check.

Also it should not be a big problem with this "1", because floatval -
intval => floatval - (float)intval in C.

- Sv. Lockal

2012/1/26 Campbell Barton <ideasman42 at gmail.com>:
> Can you give an example as to what case this fixes?
>
> On Fri, Jan 27, 2012 at 4:11 AM, Sv. Lockal <lockalsash at gmail.com> wrote:
>> Revision: 43733
>>          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=43733
>> Author:   lockal
>> Date:     2012-01-26 17:11:43 +0000 (Thu, 26 Jan 2012)
>> Log Message:
>> -----------
>> Fix orthogonality check for mat3 and mat4
>>
>> Modified Paths:
>> --------------
>>    trunk/blender/source/blender/blenlib/intern/math_matrix.c
>>
>> Modified: trunk/blender/source/blender/blenlib/intern/math_matrix.c
>> ===================================================================
>> --- trunk/blender/source/blender/blenlib/intern/math_matrix.c   2012-01-26 17:03:30 UTC (rev 43732)
>> +++ trunk/blender/source/blender/blenlib/intern/math_matrix.c   2012-01-26 17:11:43 UTC (rev 43733)
>> @@ -778,32 +778,38 @@
>>        mul_v3_fl(mat[2], size[2]);
>>  }
>>
>> -int is_orthogonal_m3(float mat[][3])
>> +int is_orthogonal_m3(float m[][3])
>>  {
>> -       if (fabsf(dot_v3v3(mat[0], mat[1])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> +    int i, j;
>>
>> -       if (fabsf(dot_v3v3(mat[1], mat[2])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> +    for (i = 0; i < 3; i++) {
>> +        for (j = 0; j < i; j++) {
>> +            if (fabsf(dot_v3v3(m[i], m[j])) > 1.5f * FLT_EPSILON)
>> +                return 0;
>> +        }
>>
>> -       if (fabsf(dot_v3v3(mat[0], mat[2])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> -
>> -       return 1;
>> +        if (fabsf(dot_v3v3(m[i], m[i]) - 1) > 1.5f * FLT_EPSILON)
>> +            return 0;
>> +    }
>> +
>> +    return 1;
>>  }
>>
>> -int is_orthogonal_m4(float mat[][4])
>> +int is_orthogonal_m4(float m[][4])
>>  {
>> -       if (fabsf(dot_v3v3(mat[0], mat[1])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> +    int i, j;
>>
>> -       if (fabsf(dot_v3v3(mat[1], mat[2])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> +    for (i = 0; i < 4; i++) {
>> +        for (j = 0; j < i; j++) {
>> +            if (fabsf(dot_vn_vn(m[i], m[j], 4)) > 1.5f * FLT_EPSILON)
>> +                return 0;
>> +        }
>>
>> -       if (fabsf(dot_v3v3(mat[0], mat[2])) > 1.5f * FLT_EPSILON)
>> -               return 0;
>> -
>> -       return 1;
>> +        if (fabsf(dot_vn_vn(m[i], m[i], 4) - 1) > 1.5f * FLT_EPSILON)
>> +            return 0;
>> +    }
>> +
>> +    return 1;
>>  }
>>
>>  void normalize_m3(float mat[][3])
>>
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>
>
>
> --
> - Campbell