diff options
| author | Brian Paul <[email protected]> | 2010-09-25 13:10:26 -0600 |
|---|---|---|
| committer | Brian Paul <[email protected]> | 2010-09-25 13:37:05 -0600 |
| commit | 5ba62cd4139e95c752453a1591eb3e47b6b18238 (patch) | |
| tree | 08bebad949bb055c8254614230693298a3d09037 /src/mesa | |
| parent | 4e2f53bacb670b824593dce70668a8f92796ed93 (diff) | |
swrast: update comments for REMAINDER() macro
Diffstat (limited to 'src/mesa')
| -rw-r--r-- | src/mesa/swrast/s_texfilter.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/src/mesa/swrast/s_texfilter.c b/src/mesa/swrast/s_texfilter.c index 3fc554c5a20..1aa2bcaf74d 100644 --- a/src/mesa/swrast/s_texfilter.c +++ b/src/mesa/swrast/s_texfilter.c @@ -135,8 +135,11 @@ lerp_rgba_3d(GLfloat result[4], GLfloat a, GLfloat b, GLfloat c, /** - * If A is a signed integer, A % B doesn't give the right value for A < 0 - * (in terms of texture repeat). Just casting to unsigned fixes that. + * Used for GL_REPEAT wrap mode. Using A % B doesn't produce the + * right results for A<0. Casting to A to be unsigned only works if B + * is a power of two. Adding a bias to A (which is a multiple of B) + * avoids the problems with A < 0 (for reasonable A) without using a + * conditional. */ #define REMAINDER(A, B) (((A) + (B) * 1024) % (B)) |