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BLI: add probabilistic rounding utility

This commit is contained in:
Jacques Lucke 2022-03-17 12:48:41 +01:00
parent 8f68cff01b
commit d0968a9c52
4 changed files with 19 additions and 13 deletions
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6
source/blender/blenlib/BLI_rand.hh
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@ -103,6 +103,12 @@ class RandomNumberGenerator {
return float3(rand1, rand2, 1.0f - rand1 - rand2);
}
/**
* Round value to the next integer randomly.
* 4.9f is more likely to round to 5 than 4.6f.
*/
int round_probabilistic(float x);
float2 get_unit_float2();
float3 get_unit_float3();
/**

9
source/blender/blenlib/intern/rand.cc
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@ -374,6 +374,15 @@ void RandomNumberGenerator::seed_random(uint32_t seed)
this->seed(seed + hash[seed & 255]);
}
int RandomNumberGenerator::round_probabilistic(float x)
{
/* Support for negative values can be added when necessary. */
BLI_assert(x >= 0.0f);
const float round_up_probability = fractf(x);
const bool round_up = round_up_probability > this->get_float();
return (int)x + (int)round_up;
}
float2 RandomNumberGenerator::get_unit_float2()
{
float a = (float)(M_PI * 2.0) * this->get_float();

11
source/blender/editors/sculpt_paint/curves_sculpt_ops.cc
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@ -378,13 +378,6 @@ class AddOperation : public CurvesSculptStrokeOperation {
return kdtree;
}
int float_to_int_amount(float amount_f, RandomNumberGenerator &rng)
{
const float add_probability = fractf(amount_f);
const bool add_point = add_probability > rng.get_float();
return (int)amount_f + (int)add_point;
}
bool is_too_close_to_existing_point(const float3 position, const float minimum_distance) const
{
if (old_kdtree_ == nullptr) {
@ -439,7 +432,7 @@ class AddOperation : public CurvesSculptStrokeOperation {
* the triangle directly. If the triangle is larger than the brush, distribute new points
* in a circle on the triangle plane. */
if (looptri_area < area_threshold) {
const int amount = this->float_to_int_amount(looptri_area * density, looptri_rng);
const int amount = looptri_rng.round_probabilistic(looptri_area * density);
threading::parallel_for(IndexRange(amount), 512, [&](const IndexRange amount_range) {
RandomNumberGenerator point_rng{rng_base_seed + looptri_index * 1000 +
@ -476,7 +469,7 @@ class AddOperation : public CurvesSculptStrokeOperation {
const float radius_proj = std::sqrt(radius_proj_sq);
const float circle_area = M_PI * radius_proj_sq;
const int amount = this->float_to_int_amount(circle_area * density, rng);
const int amount = rng.round_probabilistic(circle_area * density);
const float3 axis_1 = math::normalize(v1 - v0) * radius_proj;
const float3 axis_2 = math::normalize(

6
source/blender/nodes/geometry/nodes/node_geo_distribute_points_on_faces.cc
View File

@ -114,10 +114,8 @@ static void sample_mesh_surface(const Mesh &mesh,
const int looptri_seed = noise::hash(looptri_index, seed);
RandomNumberGenerator looptri_rng(looptri_seed);
const float points_amount_fl = area * base_density * looptri_density_factor;
const float add_point_probability = fractf(points_amount_fl);
const bool add_point = add_point_probability > looptri_rng.get_float();
const int point_amount = (int)points_amount_fl + (int)add_point;
const int point_amount = looptri_rng.round_probabilistic(area * base_density *
looptri_density_factor);
for (int i = 0; i < point_amount; i++) {
const float3 bary_coord = looptri_rng.get_barycentric_coordinates();