diff options
author | Jacques Lucke <jacques@blender.org> | 2020-07-23 23:30:05 +0300 |
---|---|---|
committer | Jacques Lucke <jacques@blender.org> | 2020-07-23 23:30:22 +0300 |
commit | f359672c3589c5c474abe1de78fcf39dd59e3532 (patch) | |
tree | bafb3806a8eab57f2def3b28c64e71450d9bec9b /source/blender/simulation/intern/particle_mesh_emitter.cc | |
parent | c049fe7979de5a3a904a6528878df95ade8e358a (diff) |
Particles: spawn particles on mesh surface
Diffstat (limited to 'source/blender/simulation/intern/particle_mesh_emitter.cc')
-rw-r--r-- | source/blender/simulation/intern/particle_mesh_emitter.cc | 255 |
1 files changed, 225 insertions, 30 deletions
diff --git a/source/blender/simulation/intern/particle_mesh_emitter.cc b/source/blender/simulation/intern/particle_mesh_emitter.cc index ab2ee0c81ed..486cd1142c3 100644 --- a/source/blender/simulation/intern/particle_mesh_emitter.cc +++ b/source/blender/simulation/intern/particle_mesh_emitter.cc @@ -18,6 +18,9 @@ #include "BLI_float4x4.hh" #include "BLI_rand.hh" +#include "BLI_vector_adaptor.hh" + +#include "BKE_mesh_runtime.h" #include "DNA_mesh_types.h" #include "DNA_meshdata_types.h" @@ -26,14 +29,14 @@ namespace blender::sim { struct EmitterSettings { - const Object *object; + Object *object; float rate; }; -static void compute_birth_times(float rate, - TimeInterval emit_interval, - ParticleMeshEmitterSimulationState &state, - Vector<float> &r_birth_times) +static BLI_NOINLINE void compute_birth_times(float rate, + TimeInterval emit_interval, + ParticleMeshEmitterSimulationState &state, + Vector<float> &r_birth_times) { const float time_between_particles = 1.0f / rate; int counter = 0; @@ -51,51 +54,237 @@ static void compute_birth_times(float rate, } } -static void compute_new_particle_attributes(EmitterSettings &settings, - TimeInterval emit_interval, - ParticleMeshEmitterSimulationState &state, - Vector<float3> &r_positions, - Vector<float3> &r_velocities, - Vector<float> &r_birth_times) +static BLI_NOINLINE Span<MLoopTri> get_mesh_triangles(Mesh &mesh) { - if (settings.object == nullptr) { + const MLoopTri *triangles = BKE_mesh_runtime_looptri_ensure(&mesh); + int amount = BKE_mesh_runtime_looptri_len(&mesh); + return Span(triangles, amount); +} + +static BLI_NOINLINE void compute_triangle_areas(Mesh &mesh, + Span<MLoopTri> triangles, + MutableSpan<float> r_areas) +{ + assert_same_size(triangles, r_areas); + + for (int i : triangles.index_range()) { + const MLoopTri &tri = triangles[i]; + + const float3 v1 = mesh.mvert[mesh.mloop[tri.tri[0]].v].co; + const float3 v2 = mesh.mvert[mesh.mloop[tri.tri[1]].v].co; + const float3 v3 = mesh.mvert[mesh.mloop[tri.tri[2]].v].co; + + const float area = area_tri_v3(v1, v2, v3); + r_areas[i] = area; + } +} + +static BLI_NOINLINE void compute_triangle_weights(Mesh &mesh, + Span<MLoopTri> triangles, + MutableSpan<float> r_weights) +{ + assert_same_size(triangles, r_weights); + compute_triangle_areas(mesh, triangles, r_weights); +} + +static BLI_NOINLINE void compute_cumulative_distribution(Span<float> weights, + MutableSpan<float> r_cumulative_weights) +{ + BLI_assert(weights.size() + 1 == r_cumulative_weights.size()); + + r_cumulative_weights[0] = 0; + for (int i : weights.index_range()) { + r_cumulative_weights[i + 1] = r_cumulative_weights[i] + weights[i]; + } +} + +static void sample_cumulative_distribution_recursive(RandomNumberGenerator &rng, + int amount, + int start, + int one_after_end, + Span<float> cumulative_weights, + VectorAdaptor<int> &r_sampled_indices) +{ + BLI_assert(start <= one_after_end); + const int size = one_after_end - start; + if (size == 0) { + BLI_assert(amount == 0); + } + else if (amount == 0) { return; } + else if (size == 1) { + r_sampled_indices.append_n_times(start, amount); + } + else { + const int middle = start + size / 2; + const float left_weight = cumulative_weights[middle] - cumulative_weights[start]; + const float right_weight = cumulative_weights[one_after_end] - cumulative_weights[middle]; + BLI_assert(left_weight >= 0.0f && right_weight >= 0.0f); + const float weight_sum = left_weight + right_weight; + BLI_assert(weight_sum > 0.0f); + + const float left_factor = left_weight / weight_sum; + const float right_factor = right_weight / weight_sum; + + int left_amount = amount * left_factor; + int right_amount = amount * right_factor; + + if (left_amount + right_amount < amount) { + BLI_assert(left_amount + right_amount + 1 == amount); + const float weight_per_item = weight_sum / amount; + const float total_remaining_weight = weight_sum - + (left_amount + right_amount) * weight_per_item; + const float left_remaining_weight = left_weight - left_amount * weight_per_item; + const float left_remaining_factor = left_remaining_weight / total_remaining_weight; + if (rng.get_float() < left_remaining_factor) { + left_amount++; + } + else { + right_amount++; + } + } + + sample_cumulative_distribution_recursive( + rng, left_amount, start, middle, cumulative_weights, r_sampled_indices); + sample_cumulative_distribution_recursive( + rng, right_amount, middle, one_after_end, cumulative_weights, r_sampled_indices); + } +} + +static BLI_NOINLINE void sample_cumulative_distribution(RandomNumberGenerator &rng, + Span<float> cumulative_weights, + MutableSpan<int> r_samples) +{ + VectorAdaptor<int> sampled_indices(r_samples); + sample_cumulative_distribution_recursive(rng, + r_samples.size(), + 0, + cumulative_weights.size() - 1, + cumulative_weights, + sampled_indices); + BLI_assert(sampled_indices.is_full()); +} + +static BLI_NOINLINE bool sample_weighted_buckets(RandomNumberGenerator &rng, + Span<float> weights, + MutableSpan<int> r_samples) +{ + Array<float> cumulative_weights(weights.size() + 1); + compute_cumulative_distribution(weights, cumulative_weights); + + if (r_samples.size() > 0 && cumulative_weights.as_span().last() == 0.0f) { + /* All weights are zero. */ + return false; + } + + sample_cumulative_distribution(rng, cumulative_weights, r_samples); + return true; +} + +static BLI_NOINLINE void sample_looptris(RandomNumberGenerator &rng, + Mesh &mesh, + Span<MLoopTri> triangles, + Span<int> triangles_to_sample, + MutableSpan<float3> r_sampled_positions, + MutableSpan<float3> r_sampled_normals) +{ + assert_same_size(triangles_to_sample, r_sampled_positions, r_sampled_normals); + + MLoop *loops = mesh.mloop; + MVert *verts = mesh.mvert; + + for (uint i : triangles_to_sample.index_range()) { + const uint triangle_index = triangles_to_sample[i]; + const MLoopTri &triangle = triangles[triangle_index]; + + const float3 v1 = verts[loops[triangle.tri[0]].v].co; + const float3 v2 = verts[loops[triangle.tri[1]].v].co; + const float3 v3 = verts[loops[triangle.tri[2]].v].co; + + const float3 bary_coords = rng.get_barycentric_coordinates(); + + float3 position; + interp_v3_v3v3v3(position, v1, v2, v3, bary_coords); + + float3 normal; + normal_tri_v3(normal, v1, v2, v3); + + r_sampled_positions[i] = position; + r_sampled_normals[i] = normal; + } +} + +static BLI_NOINLINE bool compute_new_particle_attributes(EmitterSettings &settings, + TimeInterval emit_interval, + ParticleMeshEmitterSimulationState &state, + Vector<float3> &r_positions, + Vector<float3> &r_velocities, + Vector<float> &r_birth_times) +{ + if (settings.object == nullptr) { + return false; + } if (settings.rate <= 0.000001f) { - return; + return false; } if (settings.object->type != OB_MESH) { - return; + return false; } - const Mesh &mesh = *(Mesh *)settings.object->data; + Mesh &mesh = *(Mesh *)settings.object->data; if (mesh.totvert == 0) { - return; + return false; } - float4x4 local_to_world = settings.object->obmat; + const float4x4 local_to_world = settings.object->obmat; + float4x4 local_to_world_normal = local_to_world.inverted_affine().transposed(); const float start_time = emit_interval.start(); const uint32_t seed = DefaultHash<StringRef>{}(state.head.name); RandomNumberGenerator rng{(*(uint32_t *)&start_time) ^ seed}; compute_birth_times(settings.rate, emit_interval, state, r_birth_times); - if (r_birth_times.is_empty()) { - return; + const int particle_amount = r_birth_times.size(); + if (particle_amount == 0) { + return false; } - state.last_birth_time = r_birth_times.last(); + rng.shuffle(r_birth_times.as_mutable_span()); + + Span<MLoopTri> triangles = get_mesh_triangles(mesh); + if (triangles.is_empty()) { + return false; + } + + Array<float> triangle_weights(triangles.size()); + compute_triangle_weights(mesh, triangles, triangle_weights); - for (int i : r_birth_times.index_range()) { - UNUSED_VARS(i); - const int vertex_index = rng.get_int32() % mesh.totvert; - float3 vertex_position = mesh.mvert[vertex_index].co; - r_positions.append(local_to_world * vertex_position); - r_velocities.append(rng.get_unit_float3()); + Array<int> triangles_to_sample(particle_amount); + if (!sample_weighted_buckets(rng, triangle_weights, triangles_to_sample)) { + return false; } + + Array<float3> local_positions(particle_amount); + Array<float3> local_normals(particle_amount); + sample_looptris(rng, mesh, triangles, triangles_to_sample, local_positions, local_normals); + + r_positions.reserve(particle_amount); + r_velocities.reserve(particle_amount); + for (int i : IndexRange(particle_amount)) { + float3 position = local_to_world * local_positions[i]; + float3 normal = local_to_world_normal.ref_3x3() * local_normals[i]; + normal.normalize(); + + r_positions.append(position); + r_velocities.append(normal); + } + + state.last_birth_time = r_birth_times.last(); + return true; } -static EmitterSettings compute_settings(const fn::MultiFunction &inputs_fn, - ParticleEmitterContext &context) +static BLI_NOINLINE EmitterSettings compute_settings(const fn::MultiFunction &inputs_fn, + ParticleEmitterContext &context) { EmitterSettings parameters; @@ -126,8 +315,14 @@ void ParticleMeshEmitter::emit(ParticleEmitterContext &context) const Vector<float3> new_velocities; Vector<float> new_birth_times; - compute_new_particle_attributes( - settings, context.emit_interval(), *state, new_positions, new_velocities, new_birth_times); + if (!compute_new_particle_attributes(settings, + context.emit_interval(), + *state, + new_positions, + new_velocities, + new_birth_times)) { + return; + } for (StringRef name : particle_names_) { ParticleAllocator *allocator = context.try_get_particle_allocator(name); |