nerdcruft/libcruft-util
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noise-tool: give a random offset per-image

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prevents gridpoint artefacts being so obvious
This commit is contained in:
Danny Robson 2015-09-25 15:16:15 +10:00
parent 4310366987
commit 91a01c2742
1 changed files with 8 additions and 4 deletions
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12
tools/noise.cpp
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@ -20,7 +20,7 @@
#include "netpbm.hpp"
#include "types.hpp"
#include "cmdopt.hpp"
#include "hash.hpp"
#include "region.hpp"
@ -171,6 +171,7 @@ main (int argc, char **argv)
util::extent2u res {1920, 1080};
#endif
srand (time (nullptr));
uint64_t seed = time (nullptr);
basis_t basis = PERLIN;
@ -310,12 +311,15 @@ main (int argc, char **argv)
util::image::buffer<float> img (res);
// XXX: offset slightly to avoid origin artefacts in some basis functions
static const auto OFFSET = util::vector2f { -100 };
const auto OFFSET = util::vector2f {
(util::hash::mix ( seed) & 0xFFFF) / float (0xFFFF),
(util::hash::mix (util::hash::mix (seed)) & 0xFFFF) / float (0xFFFF)
} / f.frequency ();
{
for (size_t y = 0; y < res.h; ++y)
for (size_t x = 0; x < res.w; ++x)
img.data ()[y * img.s + x] = t (util::point2f {float (x), float (y)} + OFFSET);
img[{x, y}] = t (util::point2f {float (x), float (y)} + OFFSET);
}
// working on the assumption that all octave images are based on summation,
@ -329,7 +333,7 @@ main (int argc, char **argv)
for (size_t y = 0; y < res.h; ++y)
for (size_t x = 0; x < res.w; ++x)
prev.data ()[y * img.s + x] = t (util::point2f {float (x), float (y)} + OFFSET);
prev[{x,y}] = t (util::point2f {float (x), float (y)} + OFFSET);
CHECK_EQ (img.stride (), prev.stride ());
for (size_t i = 0; i < img.size (); ++i)