diff options
| author | Giorgio Vazzana <mywing81@gmail.com> | 2011-11-13 16:09:58 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2011-11-13 17:33:09 +0100 |
| commit | e555119c739fb35e3bdd8905050104ae0a4692e2 (patch) | |
| tree | 17c04d9f4058b8a4f7bee2859d38346e9ecdf7b7 /libavfilter | |
| parent | ad0bdd2fd26a151404c505a1d610bf95773ae18f (diff) | |
mandelbrot: correct and simplify the formula used in NORMALIZED_ITERATION_COUNT
Use log(sqrt(mb->bailout)) instead of log(mb->bailout) because mb->bailout represent
the bailout radius squared, and then simplify the two sqrt().
This is also slightly faster.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libavfilter')
| -rw-r--r-- | libavfilter/vsrc_mandelbrot.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/libavfilter/vsrc_mandelbrot.c b/libavfilter/vsrc_mandelbrot.c index 719e169928..7a1a864fef 100644 --- a/libavfilter/vsrc_mandelbrot.c +++ b/libavfilter/vsrc_mandelbrot.c @@ -185,7 +185,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize, if(zr*zr + zi*zi > mb->bailout){ switch(mb->outer){ case ITERATION_COUNT: zr= i; break; - case NORMALIZED_ITERATION_COUNT: zr= i + (log(log(mb->bailout)) - log(log(sqrt(zr*zr + zi*zi))))/log(2); break; + case NORMALIZED_ITERATION_COUNT: zr= i + log2(log(mb->bailout) / log(zr*zr + zi*zi)); break; } c= lrintf((sin(zr)+1)*127) + lrintf((sin(zr/1.234)+1)*127)*256*256 + lrintf((sin(zr/100)+1)*127)*256; break; @@ -200,7 +200,7 @@ static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize, if(t*t + zi*zi > mb->bailout){ switch(mb->outer){ case ITERATION_COUNT: zr= i; break; - case NORMALIZED_ITERATION_COUNT: zr= i + (log(log(mb->bailout)) - log(log(sqrt(t*t + zi*zi))))/log(2); break; + case NORMALIZED_ITERATION_COUNT: zr= i + log2(log(mb->bailout) / log(t*t + zi*zi)); break; } c= lrintf((sin(zr)+1)*127) + lrintf((sin(zr/1.234)+1)*127)*256*256 + lrintf((sin(zr/100)+1)*127)*256; break; |