[Bf-committers] [Bf-blender-cvs] SVN commit: /data/svn/bf-blender [59821] trunk/blender/source/blender: add positive_mod() utility function.

[IRIE Shinsuke]

Hi Campbell,

Did you assume the 2nd argument in positive_mod() is a positive number?
This function returns a strange value if the devisor is negative.

Anyway, I think the function name "positive_mod" is inappropriate,
because the mathematically proper modulo operation always yields a
positive number if the deviser is a positive number.  The binary %
operator in C language is not an actual modulo operator.

IRIE Shinsuke

13/09/05, Campbell Barton wrote:
> Revision: 59821
>            http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=59821
> Author:   campbellbarton
> Date:     2013-09-05 10:12:00 +0000 (Thu, 05 Sep 2013)
> Log Message:
> -----------
> add positive_mod() utility function.
>
> Modified Paths:
> --------------
>      trunk/blender/source/blender/blenlib/BLI_math_base.h
>      trunk/blender/source/blender/blenlib/intern/math_base_inline.c
>      trunk/blender/source/blender/bmesh/operators/bmo_bridge.c
>
> Modified: trunk/blender/source/blender/blenlib/BLI_math_base.h
> ===================================================================
> --- trunk/blender/source/blender/blenlib/BLI_math_base.h	2013-09-05 09:39:38 UTC (rev 59820)
> +++ trunk/blender/source/blender/blenlib/BLI_math_base.h	2013-09-05 10:12:00 UTC (rev 59821)
> @@ -222,6 +222,7 @@
>   MINLINE int power_of_2_min_i(int n);
>
>   MINLINE int divide_round_i(int a, int b);
> +MINLINE int positive_mod(int i, int n);
>
>   MINLINE float shell_angle_to_dist(const float angle);
>
>
> Modified: trunk/blender/source/blender/blenlib/intern/math_base_inline.c
> ===================================================================
> --- trunk/blender/source/blender/blenlib/intern/math_base_inline.c	2013-09-05 09:39:38 UTC (rev 59820)
> +++ trunk/blender/source/blender/blenlib/intern/math_base_inline.c	2013-09-05 10:12:00 UTC (rev 59821)
> @@ -153,6 +153,11 @@
>   	return (2 * a + b) / (2 * b);
>   }
>
> +MINLINE int positive_mod(int i, int n)
> +{
> +	return ((i = i % n) < 0) ? i + n : i;
> +}
> +
>   MINLINE unsigned int highest_order_bit_i(unsigned int n)
>   {
>   	n |= (n >>  1);
>
> Modified: trunk/blender/source/blender/bmesh/operators/bmo_bridge.c
> ===================================================================
> --- trunk/blender/source/blender/bmesh/operators/bmo_bridge.c	2013-09-05 09:39:38 UTC (rev 59820)
> +++ trunk/blender/source/blender/bmesh/operators/bmo_bridge.c	2013-09-05 10:12:00 UTC (rev 59821)
> @@ -273,8 +273,7 @@
>   		if (twist_offset != 0) {
>   			const int len_b = BM_edgeloop_length_get(el_store_b);
>   			ListBase *lb_b = BM_edgeloop_verts_get(el_store_b);
> -			const int offset = twist_offset % len_b;
> -			LinkData *el_b = BLI_rfindlink(lb_b, (offset < 0) ? (offset + len_b) : offset);
> +			LinkData *el_b = BLI_rfindlink(lb_b, positive_mod(twist_offset, len_b));
>   			BLI_rotatelist(lb_b, el_b);
>   		}
>   	}
>
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