Files
Jungfraujoch/image_analysis/structure_refinement/ModelGrid.cpp
T
leonarski_fandClaude Opus 5.5 9ad92b6bfe Move the atomic-model code to image_analysis/structure_refinement/ and WriteModel to writer/
A pure move. ModelValidation, RigidBodyRefine, RigidBodyGPU, ModelFFT, ModelGrid,
ModelScaling, ModelMaskGPU, ModelScaleGPU and SigmaA - everything that works on an
atomic model - become the JFJochStructureRefinement library, linked by
JFJochImageAnalysis. WriteModel (the placed-model mmCIF/PDB writer) goes to writer/
as its own small JFJochModelWriter target, so JFJochWriter, which a writer-only build
compiles, does not gain a gemmi dependency. Only include paths and CMake lists change.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SVmAWnzCmRKAXVUCdc4iNi
2026-10-07 14:05:37 +02:00

253 lines
12 KiB
C++

// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only
#include "ModelGrid.h"
#include <algorithm>
#include <array>
#include <cmath>
#include <utility>
#include "gemmi/solmask.hpp" // SolventMasker
#include "../../common/ParallelFor.h"
namespace {
using Table = gemmi::IT92<float>;
// The box of grid points gemmi's Grid::use_points_in_box<true>() walks around one atom.
struct AtomBox {
gemmi::Fractional fpos;
int du = 0, dv = 0, dw = 0;
double radius = 0;
};
// The box of use_points_around<true>(fpos, radius, ..., false), sized and clamped as gemmi does it.
AtomBox MakeAtomBox(const gemmi::Grid<float> &grid, const gemmi::Fractional &fpos, double radius) {
AtomBox box;
box.fpos = fpos;
box.radius = radius;
box.du = std::min(static_cast<int>(std::ceil(radius / grid.spacing[0])), grid.nu - 1);
box.dv = std::min(static_cast<int>(std::ceil(radius / grid.spacing[1])), grid.nv - 1);
box.dw = std::min(static_cast<int>(std::ceil(radius / grid.spacing[2])), grid.nw - 1);
return box;
}
// gemmi's use_points_in_box<true>() run over a list of atoms (grid.hpp, do_use_points_in_box), in
// parallel over the grid's w planes: a plane is one task, and it walks every atom whose box reaches
// it, in list order, visiting only that plane's points. Every point is so handed exactly the calls
// gemmi's serial loop over the atoms hands it, in the same order, and the grid comes out bit for bit
// the same whatever the thread count. func_for(i) gives atom i's func(point, d2, delta), taken as a
// local copy so that the compiler can hold it in registers while the atom's points are written.
template <typename FuncFor>
void UseAtomBoxesByPlane(gemmi::Grid<float> &grid, const std::vector<AtomBox> &boxes, size_t nthreads,
FuncFor func_for) {
const int nu = grid.nu, nv = grid.nv, nw = grid.nw;
std::vector<std::vector<int>> plane_atoms(nw);
for (int i = 0; i < static_cast<int>(boxes.size()); i++) {
const int w0 = gemmi::iround(boxes[i].fpos.z * nw);
for (int w = w0 - boxes[i].dw; w <= w0 + boxes[i].dw; w++) {
std::vector<int> &atoms = plane_atoms[gemmi::modulo(w, nw)];
if (atoms.empty() || atoms.back() != i)
atoms.push_back(i);
}
}
ParallelFor(nw, nthreads, [&](int plane) {
for (int i : plane_atoms[plane]) {
const AtomBox &b = boxes[i];
const auto func = func_for(i);
const double max_dist_sq = b.radius * b.radius;
const gemmi::Fractional nctr(b.fpos.x * nu, b.fpos.y * nv, b.fpos.z * nw);
const int u_lo = gemmi::iround(nctr.x) - b.du, u_hi = gemmi::iround(nctr.x) + b.du;
const int v_lo = gemmi::iround(nctr.y) - b.dv, v_hi = gemmi::iround(nctr.y) + b.dv;
const int w_lo = gemmi::iround(nctr.z) - b.dw, w_hi = gemmi::iround(nctr.z) + b.dw;
const int u_0 = gemmi::modulo(u_lo, nu), v_0 = gemmi::modulo(v_lo, nv);
gemmi::Fractional fdelta(nctr.x - u_lo, 0, 0);
// The box's w that fall on this plane, ascending as gemmi walks them: one, unless the box is
// wider than the cell.
for (int w = w_lo + gemmi::modulo(plane - w_lo, nw); w <= w_hi; w += nw) {
fdelta.z = nctr.z - w;
for (int v = v_lo, v_ = v_0; v <= v_hi; ++v, v_ = (v_ + 1 == nv ? 0 : v_ + 1)) {
fdelta.y = nctr.y - v;
gemmi::Position delta(grid.orth_n.multiply(fdelta));
const double dist_sq0 = gemmi::sq(delta.y) + gemmi::sq(delta.z);
if (dist_sq0 > max_dist_sq)
continue;
float *t = &grid.data[grid.index_q(u_0, v_, plane)];
for (int u = u_lo, u_ = u_0;;) {
const double dist_sq = dist_sq0 + gemmi::sq(delta.x);
if (!(dist_sq > max_dist_sq))
func(*t, dist_sq, delta);
if (u >= u_hi)
break;
++u;
++u_;
++t;
if (u_ == nu) {
u_ = 0;
t -= nu;
}
delta.x -= grid.orth_n.a11;
}
}
}
}
});
}
// gemmi's Grid::symmetrize() in parallel over the orbits found by OrbitLeaders(): each orbit is reduced
// by one thread, into its leader, with gemmi's operands in gemmi's order, and the value written to its
// leader and mates as gemmi writes it. Orbits share no points, so the grid is gemmi's, bit for bit.
template <typename Func>
void SymmetrizeOrbits(gemmi::Grid<float> &grid, const std::vector<size_t> &leaders, size_t nthreads,
Func func) {
const std::vector<gemmi::GridOp> ops = grid.get_scaled_ops_except_id();
const size_t nu = grid.nu, nv = grid.nv;
ParallelChunks(static_cast<int>(leaders.size()), nthreads, [&](int lo, int hi) {
std::vector<size_t> mates(ops.size());
for (int i = lo; i < hi; i++) {
const size_t idx = leaders[i];
const int u = static_cast<int>(idx % nu), v = static_cast<int>(idx / nu % nv),
w = static_cast<int>(idx / (nu * nv));
for (size_t k = 0; k < ops.size(); ++k) {
const std::array<int, 3> t = ops[k].apply(u, v, w);
mates[k] = grid.index_n(t[0], t[1], t[2]);
}
float value = grid.data[idx];
for (size_t k : mates)
value = func(value, grid.data[k]);
grid.data[idx] = value;
for (size_t k : mates)
grid.data[k] = value;
}
});
}
std::vector<const gemmi::Atom *> ModelAtoms(const gemmi::Model &model) {
std::vector<const gemmi::Atom *> atoms;
for (const gemmi::Chain &ch : model.chains)
for (const gemmi::Residue &r : ch.residues)
for (const gemmi::Atom &a : r.atoms)
atoms.push_back(&a);
return atoms;
}
// One atom's density, added to a grid point as gemmi's do_add_atom_density_to_grid() adds it.
struct AtomDensity {
using CReal = Table::Coef::coef_type;
using IsoSum = decltype(std::declval<const Table::Coef &>().precalculate_density_iso(CReal(), CReal()));
using AnisoSum = decltype(std::declval<const Table::Coef &>().precalculate_density_aniso_b(
gemmi::SMat33<CReal>(), CReal()));
bool is_aniso = false;
float occ = 0;
IsoSum iso{};
AnisoSum aniso{};
void operator()(float &point, double r2, const gemmi::Position &delta) const {
if (!is_aniso)
point += float(occ * iso.calculate((CReal)r2));
else
point += float(occ * aniso.calculate(delta));
}
};
} // namespace
// The points gemmi's Grid::symmetrize() (grid.hpp) reduces the grid's orbits into, ascending. gemmi
// walks the points by index and takes the orbit of every point it has not visited yet, so it reduces
// each orbit into the orbit's lowest index - the point none of whose mates has a lower one. They depend
// on the grid's size and space group only, so a zone finds them once for all its evaluations.
std::vector<size_t> OrbitLeaders(const gemmi::Grid<float> &grid, size_t nthreads) {
const std::vector<gemmi::GridOp> ops = grid.get_scaled_ops_except_id();
if (ops.empty())
return {}; // P1: nothing to symmetrize
std::vector<std::vector<size_t>> plane_leaders(grid.nw);
ParallelFor(grid.nw, nthreads, [&](int w) {
for (int v = 0; v < grid.nv; ++v)
for (int u = 0; u < grid.nu; ++u) {
const size_t idx = grid.index_q(u, v, w);
bool lowest = true;
for (size_t k = 0; k < ops.size() && lowest; ++k) {
const std::array<int, 3> t = ops[k].apply(u, v, w);
lowest = grid.index_n(t[0], t[1], t[2]) >= idx;
}
if (lowest)
plane_leaders[w].push_back(idx);
}
});
std::vector<size_t> leaders;
for (const std::vector<size_t> &l : plane_leaders)
leaders.insert(leaders.end(), l.begin(), l.end());
return leaders;
}
// DensityCalculator::put_model_density_on_grid() (gemmi dencalc.hpp, do_add_atom_density_to_grid)
// with the atoms and the symmetry spread over the threads as above - the same grid, bit for bit. Each
// atom's density coefficients and radius are worked out once, up front, rather than once per plane.
void PutModelDensityOnGrid(gemmi::DensityCalculator<Table, float> &dc, const gemmi::Model &model,
const std::vector<size_t> &orbit_leaders, size_t nthreads) {
using CReal = AtomDensity::CReal;
dc.initialize_grid();
const std::vector<const gemmi::Atom *> atoms = ModelAtoms(model);
const int n = static_cast<int>(atoms.size());
std::vector<AtomBox> boxes(n);
std::vector<AtomDensity> density(n);
ParallelChunks(n, nthreads, [&](int lo, int hi) {
for (int i = lo; i < hi; i++) {
const gemmi::Atom &atom = *atoms[i];
const auto &coef = Table::get(atom.element, atom.charge, atom.serial);
const float addend = dc.addends.get(atom.element);
const gemmi::Fractional fpos = dc.grid.unit_cell.fractionalize(atom.pos);
AtomDensity &d = density[i];
d.occ = atom.occ;
d.is_aniso = atom.aniso.nonzero();
if (!d.is_aniso) {
const CReal b = static_cast<CReal>(atom.b_iso + dc.blur);
d.iso = coef.precalculate_density_iso(b, addend);
boxes[i] = MakeAtomBox(dc.grid, fpos, dc.estimate_radius(d.iso, b));
} else {
const auto aniso_b = atom.aniso.scaled(CReal(gemmi::u_to_b())).added_kI(CReal(dc.blur));
const CReal b_max = std::max(std::max(aniso_b.u11, aniso_b.u22), aniso_b.u33);
const double radius = dc.estimate_radius(coef.precalculate_density_iso(b_max, addend), b_max);
d.aniso = coef.precalculate_density_aniso_b(aniso_b, addend);
boxes[i] = MakeAtomBox(dc.grid, fpos, radius);
}
}
});
UseAtomBoxesByPlane(dc.grid, boxes, nthreads, [&](int i) { return density[i]; });
SymmetrizeOrbits(dc.grid, orbit_leaders, nthreads, [](float a, float b) { return a + b; });
}
// SolventMasker(AtomicRadiiSet::Refmac).put_mask_on_grid() (gemmi solmask.hpp) with the atoms and the
// symmetry spread over the threads as above - the same mask, bit for bit. The island removal and the
// shrink that follow are gemmi's own, except that the shrink is skipped where it cannot change a point:
// it looks at the grid offsets within rshrink of each point (set_margin_around), and on a grid whose
// spacing is coarser than rshrink along all three axes there are none - which is every rigid-body zone -
// yet it still walks the whole grid.
void PutMaskOnGrid(gemmi::Grid<float> &grid, const gemmi::Model &model, const std::vector<size_t> &orbit_leaders,
size_t nthreads) {
const gemmi::SolventMasker masker(gemmi::AtomicRadiiSet::Refmac);
masker.clear(grid);
std::vector<AtomBox> boxes;
for (const gemmi::Atom *atom : ModelAtoms(model)) {
if ((masker.ignore_hydrogen && atom->is_hydrogen()) ||
(masker.ignore_zero_occupancy_atoms && atom->occ <= 0))
continue;
double r = masker.constant_r + masker.rprobe;
r += gemmi::refmac_radius_for_bulk_solvent(atom->element.elem);
boxes.push_back(MakeAtomBox(grid, grid.unit_cell.fractionalize(atom->pos), r));
}
UseAtomBoxesByPlane(grid, boxes, nthreads, [](int) {
return [](float &point, double, const gemmi::Position &) { point = 0.f; };
});
SymmetrizeOrbits(grid, orbit_leaders, nthreads, [](float a, float b) { return a < b ? a : b; });
masker.remove_islands(grid);
bool shrink_has_offsets = false;
for (int i = 0; i < 3; i++)
shrink_has_offsets = shrink_has_offsets || static_cast<int>(std::floor(masker.rshrink / grid.spacing[i])) > 0;
if (shrink_has_offsets)
masker.shrink(grid);
}