clutter/utils: Remove magic numbers from fixed point calculations
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2587>
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@ -25,6 +25,9 @@
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#include <math.h>
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#define FIXED_SHIFT 8
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#define FIXED_ONE (1 << FIXED_SHIFT)
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/* This file uses pixel-aligned region computation to determine what
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* can be clipped out. This only really works if everything is aligned
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* to the pixel grid - not scaled or rotated and at integer offsets.
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@ -46,12 +49,12 @@
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*/
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/* The definition of "close enough" to integral pixel values is
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* equality when we convert to 24.8 fixed-point.
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* equality when we convert to fixed-point.
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*/
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static inline int
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round_to_fixed (float x)
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{
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return roundf (x * 256);
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return roundf (x * FIXED_ONE);
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}
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/* Help macros to scale from OpenGL <-1,1> coordinates system to
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@ -84,10 +87,10 @@ meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
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v3x = round_to_fixed (verts[3].x); v3y = round_to_fixed (verts[3].y);
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/* Using shifting for converting fixed => int, gets things right for
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* negative values. / 256. wouldn't do the same
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* negative values. / FIXED_ONE wouldn't do the same
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*/
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x = v0x >> 8;
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y = v0y >> 8;
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x = v0x >> FIXED_SHIFT;
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y = v0y >> FIXED_SHIFT;
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if (out_transforms)
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{
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@ -98,7 +101,7 @@ meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
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}
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/* At integral coordinates? */
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if (x * 256 != v0x || y * 256 != v0y)
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if (x * FIXED_ONE != v0x || y * FIXED_ONE != v0y)
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return FALSE;
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/* Not scaled? */
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