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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "simulation_solver.hh"
#include "BKE_customdata.h"
#include "BLI_rand.hh"
namespace blender::sim {
ParticleForce::~ParticleForce()
{
}
class CustomDataAttributesRef {
private:
Vector<void *> buffers_;
uint size_;
std::unique_ptr<fn::AttributesInfo> info_;
public:
CustomDataAttributesRef(CustomData &custom_data, uint size)
{
fn::AttributesInfoBuilder builder;
for (const CustomDataLayer &layer : Span(custom_data.layers, custom_data.totlayer)) {
buffers_.append(layer.data);
switch (layer.type) {
case CD_PROP_INT32: {
builder.add<int32_t>(layer.name, 0);
break;
}
case CD_PROP_FLOAT3: {
builder.add<float3>(layer.name, {0, 0, 0});
break;
}
}
}
info_ = std::make_unique<fn::AttributesInfo>(builder);
size_ = size;
}
operator fn::MutableAttributesRef()
{
return fn::MutableAttributesRef(*info_, buffers_, size_);
}
operator fn::AttributesRef() const
{
return fn::AttributesRef(*info_, buffers_, size_);
}
};
static void ensure_attributes_exist(ParticleSimulationState *state)
{
if (CustomData_get_layer_named(&state->attributes, CD_PROP_FLOAT3, "Position") == nullptr) {
CustomData_add_layer_named(
&state->attributes, CD_PROP_FLOAT3, CD_CALLOC, nullptr, state->tot_particles, "Position");
}
if (CustomData_get_layer_named(&state->attributes, CD_PROP_FLOAT3, "Velocity") == nullptr) {
CustomData_add_layer_named(
&state->attributes, CD_PROP_FLOAT3, CD_CALLOC, nullptr, state->tot_particles, "Velocity");
}
if (CustomData_get_layer_named(&state->attributes, CD_PROP_INT32, "ID") == nullptr) {
CustomData_add_layer_named(
&state->attributes, CD_PROP_INT32, CD_CALLOC, nullptr, state->tot_particles, "ID");
}
}
void initialize_simulation_states(Simulation &simulation,
Depsgraph &UNUSED(depsgraph),
const SimulationInfluences &UNUSED(influences))
{
RandomNumberGenerator rng;
LISTBASE_FOREACH (ParticleSimulationState *, state, &simulation.states) {
state->tot_particles = 1000;
CustomData_realloc(&state->attributes, state->tot_particles);
ensure_attributes_exist(state);
CustomDataAttributesRef custom_data_attributes{state->attributes, (uint)state->tot_particles};
fn::MutableAttributesRef attributes = custom_data_attributes;
MutableSpan<float3> positions = attributes.get<float3>("Position");
MutableSpan<float3> velocities = attributes.get<float3>("Velocity");
MutableSpan<int32_t> ids = attributes.get<int32_t>("ID");
for (uint i : positions.index_range()) {
positions[i] = {i / 100.0f, 0, 0};
velocities[i] = {0, rng.get_float() - 0.5f, rng.get_float() - 0.5f};
ids[i] = i;
}
}
}
void solve_simulation_time_step(Simulation &simulation,
Depsgraph &UNUSED(depsgraph),
const SimulationInfluences &influences,
float time_step)
{
LISTBASE_FOREACH (ParticleSimulationState *, state, &simulation.states) {
ensure_attributes_exist(state);
CustomDataAttributesRef custom_data_attributes{state->attributes, (uint)state->tot_particles};
fn::MutableAttributesRef attributes = custom_data_attributes;
MutableSpan<float3> positions = attributes.get<float3>("Position");
MutableSpan<float3> velocities = attributes.get<float3>("Velocity");
Array<float3> force_vectors{(uint)state->tot_particles, {0, 0, 0}};
const Vector<const ParticleForce *> *forces = influences.particle_forces.lookup_ptr(
state->head.name);
if (forces != nullptr) {
for (const ParticleForce *force : *forces) {
force->add_force(attributes, force_vectors);
}
}
for (uint i : positions.index_range()) {
velocities[i] += force_vectors[i] * time_step;
positions[i] += velocities[i] * time_step;
}
}
}
} // namespace blender::sim
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