e955c94ed3
Listing the "Blender Foundation" as copyright holder implied the Blender Foundation holds copyright to files which may include work from many developers. While keeping copyright on headers makes sense for isolated libraries, Blender's own code may be refactored or moved between files in a way that makes the per file copyright holders less meaningful. Copyright references to the "Blender Foundation" have been replaced with "Blender Authors", with the exception of `./extern/` since these this contains libraries which are more isolated, any changed to license headers there can be handled on a case-by-case basis. Some directories in `./intern/` have also been excluded: - `./intern/cycles/` it's own `AUTHORS` file is planned. - `./intern/opensubdiv/`. An "AUTHORS" file has been added, using the chromium projects authors file as a template. Design task: #110784 Ref !110783.
129 lines
3.6 KiB
C
129 lines
3.6 KiB
C
/* SPDX-FileCopyrightText: 2015 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup bli
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*/
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#include "BLI_math_base.h"
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#include "BLI_math_statistics.h"
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#include "BLI_math_vector.h"
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#include "MEM_guardedalloc.h"
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#include "BLI_task.h"
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#include "BLI_utildefines.h"
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#include "BLI_strict_flags.h"
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/********************************** Covariance Matrices *********************************/
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typedef struct CovarianceData {
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const float *cos_vn;
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const float *center;
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float *r_covmat;
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float covfac;
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int n;
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int cos_vn_num;
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} CovarianceData;
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static void covariance_m_vn_ex_task_cb(void *__restrict userdata,
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const int a,
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const TaskParallelTLS *__restrict UNUSED(tls))
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{
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CovarianceData *data = userdata;
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const float *cos_vn = data->cos_vn;
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const float *center = data->center;
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float *r_covmat = data->r_covmat;
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const int n = data->n;
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const int cos_vn_num = data->cos_vn_num;
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int k;
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/* Covariance matrices are always symmetrical, so we can compute only one half of it,
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* and mirror it to the other half (at the end of the func).
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*
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* This allows using a flat loop of n*n with same results as imbricated one over half the matrix:
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*
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* for (i = 0; i < n; i++) {
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* for (j = i; j < n; j++) {
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* ...
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* }
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* }
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*/
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const int i = a / n;
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const int j = a % n;
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if (j < i) {
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return;
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}
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if (center) {
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for (k = 0; k < cos_vn_num; k++) {
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r_covmat[a] += (cos_vn[k * n + i] - center[i]) * (cos_vn[k * n + j] - center[j]);
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}
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}
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else {
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for (k = 0; k < cos_vn_num; k++) {
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r_covmat[a] += cos_vn[k * n + i] * cos_vn[k * n + j];
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}
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}
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r_covmat[a] *= data->covfac;
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if (j != i) {
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/* Mirror result to other half... */
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r_covmat[j * n + i] = r_covmat[a];
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}
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}
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void BLI_covariance_m_vn_ex(const int n,
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const float *cos_vn,
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const int cos_vn_num,
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const float *center,
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const bool use_sample_correction,
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float *r_covmat)
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{
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/* Note about that division: see https://en.wikipedia.org/wiki/Bessel%27s_correction.
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* In a nutshell, it must be 1 / (n - 1) for 'sample data', and 1 / n for 'population data'...
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*/
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const float covfac = 1.0f / (float)(use_sample_correction ? cos_vn_num - 1 : cos_vn_num);
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memset(r_covmat, 0, sizeof(*r_covmat) * (size_t)(n * n));
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CovarianceData data = {
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.cos_vn = cos_vn,
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.center = center,
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.r_covmat = r_covmat,
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.covfac = covfac,
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.n = n,
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.cos_vn_num = cos_vn_num,
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};
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TaskParallelSettings settings;
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BLI_parallel_range_settings_defaults(&settings);
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settings.use_threading = ((cos_vn_num * n * n) >= 10000);
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BLI_task_parallel_range(0, n * n, &data, covariance_m_vn_ex_task_cb, &settings);
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}
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void BLI_covariance_m3_v3n(const float (*cos_v3)[3],
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const int cos_v3_num,
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const bool use_sample_correction,
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float r_covmat[3][3],
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float r_center[3])
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{
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float center[3];
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const float mean_fac = 1.0f / (float)cos_v3_num;
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int i;
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zero_v3(center);
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for (i = 0; i < cos_v3_num; i++) {
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/* Applying mean_fac here rather than once at the end reduce compute errors... */
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madd_v3_v3fl(center, cos_v3[i], mean_fac);
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}
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if (r_center) {
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copy_v3_v3(r_center, center);
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}
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BLI_covariance_m_vn_ex(
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3, (const float *)cos_v3, cos_v3_num, center, use_sample_correction, (float *)r_covmat);
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}
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