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#include "BLI_noise.h"
#include "forces.hpp"
namespace BParticles {
Force::~Force()
{
}
void GravityForce::add_force(ForceInterface &interface)
{
MutableArrayRef<float3> destination = interface.combined_destination();
auto inputs = m_inputs_fn->compute(interface);
for (uint pindex : interface.pindices()) {
float3 acceleration = inputs->get<float3>("Acceleration", 0, pindex);
float weight = inputs->get<float>("Weight", 1, pindex);
destination[pindex] += acceleration * weight;
}
};
void TurbulenceForce::add_force(ForceInterface &interface)
{
MutableArrayRef<float3> destination = interface.combined_destination();
auto positions = interface.attributes().get<float3>("Position");
auto inputs = m_inputs_fn->compute(interface);
for (uint pindex : interface.pindices()) {
float3 pos = positions[pindex];
float3 strength = inputs->get<float3>("Strength", 0, pindex);
float size = inputs->get<float>("Size", 1, pindex);
float weight = inputs->get<float>("Weight", 2, pindex);
float x = (BLI_gNoise(size, pos.x, pos.y, pos.z + 1000.0f, false, 1) - 0.5f) * strength.x;
float y = (BLI_gNoise(size, pos.x, pos.y + 1000.0f, pos.z, false, 1) - 0.5f) * strength.y;
float z = (BLI_gNoise(size, pos.x + 1000.0f, pos.y, pos.z, false, 1) - 0.5f) * strength.z;
destination[pindex] += float3(x, y, z) * weight;
}
}
void DragForce::add_force(ForceInterface &interface)
{
MutableArrayRef<float3> destination = interface.combined_destination();
auto velocities = interface.attributes().get<float3>("Velocity");
auto inputs = m_inputs_fn->compute(interface);
for (uint pindex : interface.pindices()) {
float3 velocity = velocities[pindex];
float strength = inputs->get<float>("Strength", 0, pindex);
float weight = inputs->get<float>("Weight", 1, pindex);
destination[pindex] -= velocity * strength * weight;
}
}
void MeshForce::add_force(ForceInterface &interface)
{
MutableArrayRef<float3> destination = interface.combined_destination();
auto positions = interface.attributes().get<float3>("Position");
auto inputs = m_inputs_fn->compute(interface);
for (uint pindex : interface.pindices()) {
float3 position = positions[pindex];
float3 local_position = m_world_to_local.transform_position(position);
BVHTreeNearest nearest = {0};
nearest.dist_sq = 10000.0f;
nearest.index = -1;
BLI_bvhtree_find_nearest(m_bvhtree_data.tree,
local_position,
&nearest,
m_bvhtree_data.nearest_callback,
(void *)&m_bvhtree_data);
if (nearest.index == -1) {
continue;
}
float3 difference_local = float3(nearest.co) - local_position;
float3 difference = m_local_to_world.transform_direction(difference_local);
float distance_squared = difference.length_squared();
float factor = 1 / std::max(0.1f, distance_squared);
float strength = inputs->get<float>("Strength", 1, pindex);
destination[pindex] += difference * strength * factor;
}
}
} // namespace BParticles
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