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Optimize lightmapper using triangle clusters on the acceleration structure. #83284

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Oct 20, 2023
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Optimize lightmapper using triangle clusters on the acceleration structure. #83284

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174 changes: 148 additions & 26 deletions modules/lightmapper_rd/lightmapper_rd.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ void LightmapperRD::add_probe(const Vector3 &p_position) {
probe_positions.push_back(probe);
}

void LightmapperRD::_plot_triangle_into_triangle_index_list(int p_size, const Vector3i &p_ofs, const AABB &p_bounds, const Vector3 p_points[3], uint32_t p_triangle_index, LocalVector<TriangleSort> &triangles, uint32_t p_grid_size) {
void LightmapperRD::_plot_triangle_into_triangle_index_list(int p_size, const Vector3i &p_ofs, const AABB &p_bounds, const Vector3 p_points[3], uint32_t p_triangle_index, LocalVector<TriangleSort> &p_triangles_sort, uint32_t p_grid_size) {
int half_size = p_size / 2;

for (int i = 0; i < 8; i++) {
Expand Down Expand Up @@ -159,13 +159,69 @@ void LightmapperRD::_plot_triangle_into_triangle_index_list(int p_size, const Ve
TriangleSort ts;
ts.cell_index = n.x + (n.y * p_grid_size) + (n.z * p_grid_size * p_grid_size);
ts.triangle_index = p_triangle_index;
triangles.push_back(ts);
ts.triangle_aabb.position = p_points[0];
ts.triangle_aabb.size = Vector3();
ts.triangle_aabb.expand_to(p_points[1]);
ts.triangle_aabb.expand_to(p_points[2]);
p_triangles_sort.push_back(ts);
} else {
_plot_triangle_into_triangle_index_list(half_size, n, aabb, p_points, p_triangle_index, triangles, p_grid_size);
_plot_triangle_into_triangle_index_list(half_size, n, aabb, p_points, p_triangle_index, p_triangles_sort, p_grid_size);
}
}
}

void LightmapperRD::_sort_triangle_clusters(uint32_t p_cluster_size, uint32_t p_cluster_index, uint32_t p_index_start, uint32_t p_count, LocalVector<TriangleSort> &p_triangle_sort, LocalVector<ClusterAABB> &p_cluster_aabb) {
if (p_count == 0) {
return;
}

// Compute AABB for all triangles in the range.
SortArray<TriangleSort, TriangleSortAxis<0>> triangle_sorter_x;
SortArray<TriangleSort, TriangleSortAxis<1>> triangle_sorter_y;
SortArray<TriangleSort, TriangleSortAxis<2>> triangle_sorter_z;
AABB cluster_aabb = p_triangle_sort[p_index_start].triangle_aabb;
for (uint32_t i = 1; i < p_count; i++) {
cluster_aabb.merge_with(p_triangle_sort[p_index_start + i].triangle_aabb);
}

if (p_count > p_cluster_size) {
int longest_axis_index = cluster_aabb.get_longest_axis_index();
switch (longest_axis_index) {
case 0:
triangle_sorter_x.sort(&p_triangle_sort[p_index_start], p_count);
break;
case 1:
triangle_sorter_y.sort(&p_triangle_sort[p_index_start], p_count);
break;
case 2:
triangle_sorter_z.sort(&p_triangle_sort[p_index_start], p_count);
break;
default:
DEV_ASSERT(false && "Invalid axis returned by AABB.");
break;
}

uint32_t left_cluster_count = next_power_of_2(p_count / 2);
left_cluster_count = MAX(left_cluster_count, p_cluster_size);
left_cluster_count = MIN(left_cluster_count, p_count);
_sort_triangle_clusters(p_cluster_size, p_cluster_index, p_index_start, left_cluster_count, p_triangle_sort, p_cluster_aabb);

if (left_cluster_count < p_count) {
uint32_t cluster_index_right = p_cluster_index + (left_cluster_count / p_cluster_size);
_sort_triangle_clusters(p_cluster_size, cluster_index_right, p_index_start + left_cluster_count, p_count - left_cluster_count, p_triangle_sort, p_cluster_aabb);
}
} else {
ClusterAABB &aabb = p_cluster_aabb[p_cluster_index];
Vector3 aabb_end = cluster_aabb.get_end();
aabb.min_bounds[0] = cluster_aabb.position.x;
aabb.min_bounds[1] = cluster_aabb.position.y;
aabb.min_bounds[2] = cluster_aabb.position.z;
aabb.max_bounds[0] = aabb_end.x;
aabb.max_bounds[1] = aabb_end.y;
aabb.max_bounds[2] = aabb_end.z;
}
}

Lightmapper::BakeError LightmapperRD::_blit_meshes_into_atlas(int p_max_texture_size, Vector<Ref<Image>> &albedo_images, Vector<Ref<Image>> &emission_images, AABB &bounds, Size2i &atlas_size, int &atlas_slices, BakeStepFunc p_step_function, void *p_bake_userdata) {
Vector<Size2i> sizes;

Expand Down Expand Up @@ -281,7 +337,7 @@ Lightmapper::BakeError LightmapperRD::_blit_meshes_into_atlas(int p_max_texture_
return BAKE_OK;
}

void LightmapperRD::_create_acceleration_structures(RenderingDevice *rd, Size2i atlas_size, int atlas_slices, AABB &bounds, int grid_size, Vector<Probe> &p_probe_positions, GenerateProbes p_generate_probes, Vector<int> &slice_triangle_count, Vector<int> &slice_seam_count, RID &vertex_buffer, RID &triangle_buffer, RID &lights_buffer, RID &triangle_cell_indices_buffer, RID &probe_positions_buffer, RID &grid_texture, RID &seams_buffer, BakeStepFunc p_step_function, void *p_bake_userdata) {
void LightmapperRD::_create_acceleration_structures(RenderingDevice *rd, Size2i atlas_size, int atlas_slices, AABB &bounds, int grid_size, uint32_t p_cluster_size, Vector<Probe> &p_probe_positions, GenerateProbes p_generate_probes, Vector<int> &slice_triangle_count, Vector<int> &slice_seam_count, RID &vertex_buffer, RID &triangle_buffer, RID &lights_buffer, RID &r_triangle_indices_buffer, RID &r_cluster_indices_buffer, RID &r_cluster_aabbs_buffer, RID &probe_positions_buffer, RID &grid_texture, RID &seams_buffer, BakeStepFunc p_step_function, void *p_bake_userdata) {
HashMap<Vertex, uint32_t, VertexHash> vertex_map;

//fill triangles array and vertex array
Expand Down Expand Up @@ -433,31 +489,70 @@ void LightmapperRD::_create_acceleration_structures(RenderingDevice *rd, Size2i
//sort it
triangle_sort.sort();

LocalVector<uint32_t> cluster_indices;
LocalVector<ClusterAABB> cluster_aabbs;
Vector<uint32_t> triangle_indices;
triangle_indices.resize(triangle_sort.size());
Vector<uint32_t> grid_indices;
grid_indices.resize(grid_size * grid_size * grid_size * 2);
memset(grid_indices.ptrw(), 0, grid_indices.size() * sizeof(uint32_t));
Vector<bool> solid;
solid.resize(grid_size * grid_size * grid_size);
memset(solid.ptrw(), 0, solid.size() * sizeof(bool));

{
uint32_t *tiw = triangle_indices.ptrw();
// Fill grid with cell indices.
uint32_t last_cell = 0xFFFFFFFF;
uint32_t *giw = grid_indices.ptrw();
bool *solidw = solid.ptrw();
uint32_t cluster_count = 0;
uint32_t solid_cell_count = 0;
for (uint32_t i = 0; i < triangle_sort.size(); i++) {
uint32_t cell = triangle_sort[i].cell_index;
if (cell != last_cell) {
//cell changed, update pointer to indices
giw[cell * 2 + 1] = i;
solidw[cell] = true;
giw[cell * 2 + 1] = solid_cell_count;
solid_cell_count++;
}
tiw[i] = triangle_sort[i].triangle_index;
giw[cell * 2]++; //update counter

if ((giw[cell * 2] % p_cluster_size) == 0) {
// Add an extra cluster every time the triangle counter reaches a multiple of the cluster size.
cluster_count++;
}

giw[cell * 2]++;
last_cell = cell;
}

// Build fixed-size triangle clusters for all the cells to speed up the traversal. A cell can hold multiple clusters that each contain a fixed
// amount of triangles and an AABB. The tracer will check against the AABBs first to know whether it needs to visit the cell's triangles.
//
// The building algorithm will divide the triangles recursively contained inside each cell, sorting by the longest axis of the AABB on each step.
//
// - If the amount of triangles is less or equal to the cluster size, the AABB will be stored and the algorithm stops.
//
// - The division by two is increased to the next power of two of half the amount of triangles (with cluster size as the minimum value) to
// ensure the first half always fills the cluster.

cluster_indices.resize(solid_cell_count * 2);
cluster_aabbs.resize(cluster_count);

uint32_t i = 0;
uint32_t cluster_index = 0;
uint32_t solid_cell_index = 0;
uint32_t *tiw = triangle_indices.ptrw();
while (i < triangle_sort.size()) {
cluster_indices[solid_cell_index * 2] = cluster_index;
cluster_indices[solid_cell_index * 2 + 1] = i;

uint32_t cell = triangle_sort[i].cell_index;
uint32_t triangle_count = giw[cell * 2];
uint32_t cell_cluster_count = (triangle_count + p_cluster_size - 1) / p_cluster_size;
_sort_triangle_clusters(p_cluster_size, cluster_index, i, triangle_count, triangle_sort, cluster_aabbs);

for (uint32_t j = 0; j < triangle_count; j++) {
tiw[i + j] = triangle_sort[i + j].triangle_index;
}

i += triangle_count;
cluster_index += cell_cluster_count;
solid_cell_index++;
}
}
#if 0
for (int i = 0; i < grid_size; i++) {
Expand Down Expand Up @@ -507,7 +602,13 @@ void LightmapperRD::_create_acceleration_structures(RenderingDevice *rd, Size2i
triangle_buffer = rd->storage_buffer_create(tb.size(), tb);

Vector<uint8_t> tib = triangle_indices.to_byte_array();
triangle_cell_indices_buffer = rd->storage_buffer_create(tib.size(), tib);
r_triangle_indices_buffer = rd->storage_buffer_create(tib.size(), tib);

Vector<uint8_t> cib = cluster_indices.to_byte_array();
r_cluster_indices_buffer = rd->storage_buffer_create(cib.size(), cib);

Vector<uint8_t> cab = cluster_aabbs.to_byte_array();
r_cluster_aabbs_buffer = rd->storage_buffer_create(cab.size(), cab);

Vector<uint8_t> lb = lights.to_byte_array();
if (lb.size() == 0) {
Expand Down Expand Up @@ -1020,24 +1121,29 @@ LightmapperRD::BakeError LightmapperRD::bake(BakeQuality p_quality, bool p_use_d
RID vertex_buffer;
RID triangle_buffer;
RID lights_buffer;
RID triangle_cell_indices_buffer;
RID triangle_indices_buffer;
RID cluster_indices_buffer;
RID cluster_aabbs_buffer;
RID grid_texture;
RID seams_buffer;
RID probe_positions_buffer;

Vector<int> slice_seam_count;

#define FREE_BUFFERS \
rd->free(bake_parameters_buffer); \
rd->free(vertex_buffer); \
rd->free(triangle_buffer); \
rd->free(lights_buffer); \
rd->free(triangle_cell_indices_buffer); \
rd->free(grid_texture); \
rd->free(seams_buffer); \
#define FREE_BUFFERS \
rd->free(bake_parameters_buffer); \
rd->free(vertex_buffer); \
rd->free(triangle_buffer); \
rd->free(lights_buffer); \
rd->free(triangle_indices_buffer); \
rd->free(cluster_indices_buffer); \
rd->free(cluster_aabbs_buffer); \
rd->free(grid_texture); \
rd->free(seams_buffer); \
rd->free(probe_positions_buffer);

_create_acceleration_structures(rd, atlas_size, atlas_slices, bounds, grid_size, probe_positions, p_generate_probes, slice_triangle_count, slice_seam_count, vertex_buffer, triangle_buffer, lights_buffer, triangle_cell_indices_buffer, probe_positions_buffer, grid_texture, seams_buffer, p_step_function, p_bake_userdata);
const uint32_t cluster_size = 16;
_create_acceleration_structures(rd, atlas_size, atlas_slices, bounds, grid_size, cluster_size, probe_positions, p_generate_probes, slice_triangle_count, slice_seam_count, vertex_buffer, triangle_buffer, lights_buffer, triangle_indices_buffer, cluster_indices_buffer, cluster_aabbs_buffer, probe_positions_buffer, grid_texture, seams_buffer, p_step_function, p_bake_userdata);

// Create global bake parameters buffer.
BakeParameters bake_parameters;
Expand Down Expand Up @@ -1133,7 +1239,7 @@ LightmapperRD::BakeError LightmapperRD::bake(BakeQuality p_quality, bool p_use_d
RD::Uniform u;
u.uniform_type = RD::UNIFORM_TYPE_STORAGE_BUFFER;
u.binding = 3;
u.append_id(triangle_cell_indices_buffer);
u.append_id(triangle_indices_buffer);
base_uniforms.push_back(u);
}
{
Expand Down Expand Up @@ -1185,6 +1291,20 @@ LightmapperRD::BakeError LightmapperRD::bake(BakeQuality p_quality, bool p_use_d
u.append_id(sampler);
base_uniforms.push_back(u);
}
{
RD::Uniform u;
u.uniform_type = RD::UNIFORM_TYPE_STORAGE_BUFFER;
u.binding = 11;
u.append_id(cluster_indices_buffer);
base_uniforms.push_back(u);
}
{
RD::Uniform u;
u.uniform_type = RD::UNIFORM_TYPE_STORAGE_BUFFER;
u.binding = 12;
u.append_id(cluster_aabbs_buffer);
base_uniforms.push_back(u);
}
}

RID raster_base_uniform = rd->uniform_set_create(base_uniforms, rasterize_shader, 0);
Expand Down Expand Up @@ -1230,6 +1350,8 @@ LightmapperRD::BakeError LightmapperRD::bake(BakeQuality p_quality, bool p_use_d

Ref<RDShaderFile> compute_shader;
String defines = "";
defines += "\n#define CLUSTER_SIZE " + uitos(cluster_size) + "\n";

if (p_bake_sh) {
defines += "\n#define USE_SH_LIGHTMAPS\n";
}
Expand Down
19 changes: 18 additions & 1 deletion modules/lightmapper_rd/lightmapper_rd.h
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Original file line number Diff line number Diff line change
Expand Up @@ -192,19 +192,36 @@ class LightmapperRD : public Lightmapper {
}
};

struct ClusterAABB {
float min_bounds[3];
float pad0 = 0.0f;
float max_bounds[3];
float pad1 = 0.0f;
};

Vector<MeshInstance> mesh_instances;

Vector<Light> lights;

struct TriangleSort {
uint32_t cell_index = 0;
uint32_t triangle_index = 0;
AABB triangle_aabb;

bool operator<(const TriangleSort &p_triangle_sort) const {
return cell_index < p_triangle_sort.cell_index; //sorting by triangle index in this case makes no sense
}
};

template <int T>
struct TriangleSortAxis {
bool operator()(const TriangleSort &p_a, const TriangleSort &p_b) const {
return p_a.triangle_aabb.get_center()[T] < p_b.triangle_aabb.get_center()[T];
}
};

void _plot_triangle_into_triangle_index_list(int p_size, const Vector3i &p_ofs, const AABB &p_bounds, const Vector3 p_points[3], uint32_t p_triangle_index, LocalVector<TriangleSort> &triangles, uint32_t p_grid_size);
void _sort_triangle_clusters(uint32_t p_cluster_size, uint32_t p_cluster_index, uint32_t p_index_start, uint32_t p_count, LocalVector<TriangleSort> &p_triangle_sort, LocalVector<ClusterAABB> &p_cluster_aabb);

struct RasterPushConstant {
float atlas_size[2] = {};
Expand Down Expand Up @@ -250,7 +267,7 @@ class LightmapperRD : public Lightmapper {
};

BakeError _blit_meshes_into_atlas(int p_max_texture_size, Vector<Ref<Image>> &albedo_images, Vector<Ref<Image>> &emission_images, AABB &bounds, Size2i &atlas_size, int &atlas_slices, BakeStepFunc p_step_function, void *p_bake_userdata);
void _create_acceleration_structures(RenderingDevice *rd, Size2i atlas_size, int atlas_slices, AABB &bounds, int grid_size, Vector<Probe> &probe_positions, GenerateProbes p_generate_probes, Vector<int> &slice_triangle_count, Vector<int> &slice_seam_count, RID &vertex_buffer, RID &triangle_buffer, RID &lights_buffer, RID &triangle_cell_indices_buffer, RID &probe_positions_buffer, RID &grid_texture, RID &seams_buffer, BakeStepFunc p_step_function, void *p_bake_userdata);
void _create_acceleration_structures(RenderingDevice *rd, Size2i atlas_size, int atlas_slices, AABB &bounds, int grid_size, uint32_t p_cluster_size, Vector<Probe> &probe_positions, GenerateProbes p_generate_probes, Vector<int> &slice_triangle_count, Vector<int> &slice_seam_count, RID &vertex_buffer, RID &triangle_buffer, RID &lights_buffer, RID &r_triangle_indices_buffer, RID &r_cluster_indices_buffer, RID &r_cluster_aabbs_buffer, RID &probe_positions_buffer, RID &grid_texture, RID &seams_buffer, BakeStepFunc p_step_function, void *p_bake_userdata);
void _raster_geometry(RenderingDevice *rd, Size2i atlas_size, int atlas_slices, int grid_size, AABB bounds, float p_bias, Vector<int> slice_triangle_count, RID position_tex, RID unocclude_tex, RID normal_tex, RID raster_depth_buffer, RID rasterize_shader, RID raster_base_uniform);

BakeError _dilate(RenderingDevice *rd, Ref<RDShaderFile> &compute_shader, RID &compute_base_uniform_set, PushConstant &push_constant, RID &source_light_tex, RID &dest_light_tex, const Size2i &atlas_size, int atlas_slices);
Expand Down
21 changes: 19 additions & 2 deletions modules/lightmapper_rd/lm_common_inc.glsl
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Original file line number Diff line number Diff line change
Expand Up @@ -42,15 +42,22 @@ struct Triangle {
uint pad1;
};

struct ClusterAABB {
vec3 min_bounds;
uint pad0;
vec3 max_bounds;
uint pad1;
};

layout(set = 0, binding = 2, std430) restrict readonly buffer Triangles {
Triangle data[];
}
triangles;

layout(set = 0, binding = 3, std430) restrict readonly buffer GridIndices {
layout(set = 0, binding = 3, std430) restrict readonly buffer TriangleIndices {
uint data[];
}
grid_indices;
triangle_indices;

#define LIGHT_TYPE_DIRECTIONAL 0
#define LIGHT_TYPE_OMNI 1
Expand Down Expand Up @@ -104,6 +111,16 @@ layout(set = 0, binding = 9) uniform texture2DArray emission_tex;

layout(set = 0, binding = 10) uniform sampler linear_sampler;

layout(set = 0, binding = 11, std430) restrict readonly buffer ClusterIndices {
uint data[];
}
cluster_indices;

layout(set = 0, binding = 12, std430) restrict readonly buffer ClusterAABBs {
ClusterAABB data[];
}
cluster_aabbs;

// Fragment action constants
const uint FA_NONE = 0;
const uint FA_SMOOTHEN_POSITION = 1;
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