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matrix: add cogl_matrix_equal API

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This adds a way to compare two CoglMatrix structures to see if they
represent the same transformations. memcmp can't be used because a
CoglMatrix contains private flags and padding.
This commit is contained in:
Robert Bragg 2010-04-26 09:55:50 +01:00
parent 8ee099d204
commit 1047c1c082
2 changed files with 60 additions and 0 deletions
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45
cogl/cogl-matrix.c
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@ -303,6 +303,51 @@ cogl_matrix_init_from_array (CoglMatrix *matrix, const float *array)
_COGL_MATRIX_DEBUG_PRINT (matrix);
}
gboolean
cogl_matrix_equal (gconstpointer v1, gconstpointer v2)
{
const CoglMatrix *a = v1;
const CoglMatrix *b = v2;
g_return_val_if_fail (v1 != NULL, FALSE);
g_return_val_if_fail (v2 != NULL, FALSE);
/* We want to avoid having a fuzzy _equal() function (e.g. that uses
* an arbitrary epsilon value) since this function noteably conforms
* to the prototype suitable for use with g_hash_table_new() and a
* fuzzy hash function isn't really appropriate for comparing hash
* table keys since it's possible that you could end up fetching
* different values if you end up with multiple similar keys in use
* at the same time. If you consider that fuzzyness allows cases
* such as A == B == C but A != C then you could also end up loosing
* values in a hash table.
*
* We do at least use the == operator to compare values though so
* that -0 is considered equal to 0.
*/
/* XXX: We don't compare the flags, inverse matrix or padding */
if (a->xx == b->xx &&
a->xy == b->xy &&
a->xz == b->xz &&
a->xw == b->xw &&
a->yx == b->yx &&
a->yy == b->yy &&
a->yz == b->yz &&
a->yw == b->yw &&
a->zx == b->zx &&
a->zy == b->zy &&
a->zz == b->zz &&
a->zw == b->zw &&
a->wx == b->wx &&
a->wy == b->wy &&
a->wz == b->wz &&
a->ww == b->ww)
return TRUE;
else
return FALSE;
}
const float *
cogl_matrix_get_array (const CoglMatrix *matrix)
{

15
cogl/cogl-matrix.h
View file

@ -277,6 +277,21 @@ cogl_matrix_init_from_array (CoglMatrix *matrix,
G_CONST_RETURN float *
cogl_matrix_get_array (const CoglMatrix *matrix);
/**
* cogl_matrix_equal:
* @v1: A 4x4 transformation matrix
* @v2: A 4x4 transformation matrix
*
* Compares two matrices to see if they represent the same
* transformation. Although internally the matrices may have different
* annotations associated with them and may potentially have a cached
* inverse matrix these are not considered in the comparison.
*
* Since: 1.4
*/
gboolean
cogl_matrix_equal (gconstpointer v1, gconstpointer v2);
/**
* cogl_matrix_get_inverse:
* @matrix: A 4x4 transformation matrix