start work on meshlet dag algorithm

src/experimental/meshlets/flat_cull.glsl

@@ -7,8 +7,6 @@ struct mesh_data {
 
 struct meshlet_data {
     vec4 bounds; // xyz, radius
-    vec4 cone_apex; // xyz, unused
-    vec4 cone_axis_cutoff; // xyz, cutoff = w
     uint mesh_index;
     uint first_index;
     uint base_vertex;
@@ -44,17 +42,10 @@ void main() {
     meshlet_data meshlet = meshlets[meshlet_idx];
     mesh_data mesh       = meshes[meshlet.mesh_index];
 
-    vec3 cone_axis    = (mesh.model * vec4(meshlet.cone_axis_cutoff.xyz, 0)).xyz;
-    vec3 cone_apex    = (mesh.model * vec4(meshlet.cone_apex.xyz, 1)).xyz;
-    float cone_cutoff = meshlet.cone_axis_cutoff.w;
-
-    
-    if (dot(normalize(cone_apex - camera_pos), cone_axis) < cone_cutoff) {
-        uint draw_idx                          = atomicAdd(draw_count, 1);
-        draw_commands[draw_idx].count          = meshlet.index_count;
-        draw_commands[draw_idx].instance_count = 1;
-        draw_commands[draw_idx].first_index    = meshlet.first_index;
-        draw_commands[draw_idx].base_vertex    = int(meshlet.base_vertex);
-        draw_commands[draw_idx].base_instance  = 0;
-    }
+    uint draw_idx                          = atomicAdd(draw_count, 1);
+    draw_commands[draw_idx].count          = meshlet.index_count;
+    draw_commands[draw_idx].instance_count = 1;
+    draw_commands[draw_idx].first_index    = meshlet.first_index;
+    draw_commands[draw_idx].base_vertex    = int(meshlet.base_vertex);
+    draw_commands[draw_idx].base_instance  = 0;
 }

src/experimental/meshlets/hierarchical_cull.glsl

@@ -0,0 +1 @@
+    

src/experimental/meshlets/main.cpp

@@ -112,7 +112,7 @@ struct file_picker {
     }
 
     /* Returns true if a new file was selected */
-    bool RunFlat() {
+    bool Run() {
         bool opened=false;
         if (ImGui::Begin("File Selection", &m_open)) {
             ImGui::InputTextWithHint("Path",
@@ -125,6 +125,7 @@ struct file_picker {
                 strcpy(m_input_buf[m_active_input], m_picked);
                 opened         = true;
             }
+            ImGui::Checkbox("Flat", &m_flat);
             ImGui::End();
         }
         return opened;
@@ -138,6 +139,7 @@ struct file_picker {
         return m_picked != nullptr;
     }
     
+    bool m_flat          = true;
     const char *m_picked=nullptr;
     bool m_open = true;
     char m_input_buf[2][260];
@@ -191,15 +193,22 @@ int main() {
     meshlet_renderer ren;
     ren.Initialize();
 
+    bool flat = true;
+    uint32_t root_idx;
+
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
         ImGui_ImplOpenGL3_NewFrame();
         ImGui_ImplGlfw_NewFrame();
         ImGui::NewFrame();
 
-        if (picker.RunFlat()) {
+        if (picker.Run()) {
             gen.LoadObj(picker.GetPicked());
-            gen.RunFlat();
+            flat = picker.m_flat;
+            if (flat)
+                gen.RunFlat();
+            else
+                gen.RunHierarchical(0,&root_idx);
         }
         ren.SettingMenu();
 
@@ -212,7 +221,8 @@ int main() {
 
         if (picker.HasPickedFile()) {
             ren.m_aspect = (float)display_w / (float)display_h;
-            ren.RenderFlat(gen.m_meshlets, gen.m_num_meshlets);
+            if (flat)
+                ren.RenderFlat(gen.m_meshlets, gen.m_num_meshlets);
         }
 
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

src/experimental/meshlets/meshlet_generator.cpp

@@ -5,6 +5,9 @@
 #include <tiny_obj_loader.h>
 #pragma warning(pop)
 
+#include <unordered_map>
+#include <vector>
+
 #include "meshlet_generator.hpp"
 #include <runtime/mem_arena.h>
 
@@ -118,13 +121,13 @@ rt_result meshlet_generator::RunFlat(uint32_t mesh_idx) {
     rt_temp_arena temp = rtGetTemporaryArena(NULL, 0);
 
     size_t max_meshlets       = meshopt_buildMeshletsBound(m_meshes[mesh_idx].num_indices,
-                                                     MESHLET_VERTICES,
-                                                     MESHLET_TRIANGLES);
+                                                     L0_MESHLET_VERTICES,
+                                                     L0_MESHLET_TRIANGLES);
     meshopt_Meshlet *meshlets = RT_ARENA_PUSH_ARRAY(temp.arena, meshopt_Meshlet, max_meshlets);
     unsigned int *meshlet_vertices =
-        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned int, max_meshlets *MESHLET_VERTICES);
+        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned int, max_meshlets *L0_MESHLET_VERTICES);
     unsigned char *meshlet_triangles =
-        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned char, max_meshlets *MESHLET_INDICES);
+        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned char, max_meshlets *L0_MESHLET_INDICES);
 
     size_t meshlet_count = meshopt_buildMeshlets(meshlets,
                                                  meshlet_vertices,
@@ -134,8 +137,8 @@ rt_result meshlet_generator::RunFlat(uint32_t mesh_idx) {
                                                  &m_meshes[mesh_idx].vertices[0].vx,
                                                  m_meshes[mesh_idx].num_vertices,
                                                  sizeof(vertex),
-                                                 MESHLET_VERTICES,
-                                                 MESHLET_TRIANGLES,
+                                                 L0_MESHLET_VERTICES,
+                                                 L0_MESHLET_TRIANGLES,
                                                  cone_weight);
 
     m_meshlets     = new meshlet[meshlet_count];
@@ -155,24 +158,26 @@ rt_result meshlet_generator::RunFlat(uint32_t mesh_idx) {
                                          m_meshes[mesh_idx].num_vertices,
                                          sizeof(vertex));
 
-        m_meshlets[i].vertices     = new vertex[MESHLET_VERTICES];
-        m_meshlets[i].indices      = new uint8_t[MESHLET_INDICES];
+        m_meshlets[i].vertices     = new vertex[L0_MESHLET_VERTICES];
+        m_meshlets[i].indices      = new uint16_t[L0_MESHLET_INDICES];
         m_meshlets[i].num_vertices = meshlets[i].vertex_count;
         m_meshlets[i].num_indices  = meshlets[i].triangle_count * 3;
         memcpy(m_meshlets[i].center, bounds.center, sizeof(bounds.center));
         m_meshlets[i].radius = bounds.radius;
-        memcpy(m_meshlets[i].cone_axis, bounds.cone_axis, sizeof(bounds.cone_axis));
-        m_meshlets[i].cone_cutoff = bounds.cone_cutoff;
-        memcpy(m_meshlets[i].cone_apex, bounds.cone_apex, sizeof(bounds.cone_apex));
 
         for (unsigned int vert_idx = 0; vert_idx < meshlets[i].vertex_count; ++vert_idx) {
             unsigned int vert = meshlet_vertices[meshlets[i].vertex_offset + vert_idx];
             m_meshlets[i].vertices[vert_idx] = m_meshes[mesh_idx].vertices[vert];
         }
 
-        memcpy(m_meshlets[i].indices,
-               meshlet_triangles + meshlets[i].triangle_offset,
-               meshlets[i].triangle_count * 3);
+        for (unsigned int tri_idx = 0; tri_idx < meshlets[i].triangle_count; ++tri_idx) {
+            m_meshlets[i].indices[tri_idx * 3 + 0] =
+                (uint16_t)meshlet_triangles[meshlets[i].triangle_offset + 3 * tri_idx + 0];
+            m_meshlets[i].indices[tri_idx * 3 + 1] =
+                (uint16_t)meshlet_triangles[meshlets[i].triangle_offset + 3 * tri_idx + 1];
+            m_meshlets[i].indices[tri_idx * 3 + 2] =
+                (uint16_t)meshlet_triangles[meshlets[i].triangle_offset + 3 * tri_idx + 2];
+        }
         m_meshlets[i].num_children = 0u;
     }
 
@@ -184,49 +189,81 @@ rt_result meshlet_generator::RunHierarchical(uint32_t mesh_idx, uint32_t *out_ro
 
     rt_temp_arena temp = rtGetTemporaryArena(NULL, 0);
 
-    size_t max_meshlets       = meshopt_buildMeshletsBound(m_meshes[mesh_idx].num_indices,
-                                                     MESHLET_VERTICES,
-                                                     MESHLET_TRIANGLES);
-    meshopt_Meshlet *meshlets = RT_ARENA_PUSH_ARRAY(temp.arena, meshopt_Meshlet, max_meshlets);
-    unsigned int *meshlet_vertices =
-        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned int, max_meshlets *MESHLET_VERTICES);
-    unsigned char *meshlet_triangles =
-        RT_ARENA_PUSH_ARRAY(temp.arena, unsigned char, max_meshlets *MESHLET_INDICES);
-    meshopt_Bounds *meshlet_bounds = RT_ARENA_PUSH_ARRAY(temp.arena, meshopt_Bounds, max_meshlets);
+    // Convert meshopt meshlets into our meshlets, each with its own vertex and index buffer
+    std::vector<meshlet> meshlets;
+    {
+        size_t max_meshlets = meshopt_buildMeshletsBound(m_meshes[mesh_idx].num_indices,
+                                                         L0_MESHLET_VERTICES,
+                                                         L0_MESHLET_TRIANGLES);
+        meshopt_Meshlet *meshopt_meshlets =
+            RT_ARENA_PUSH_ARRAY(temp.arena, meshopt_Meshlet, max_meshlets);
+        unsigned int *meshlet_vertices =
+            RT_ARENA_PUSH_ARRAY(temp.arena, unsigned int, max_meshlets *L0_MESHLET_VERTICES);
+        unsigned char *meshlet_triangles =
+            RT_ARENA_PUSH_ARRAY(temp.arena, unsigned char, max_meshlets *L0_MESHLET_INDICES);
 
-    uint32_t meshlet_count = (uint32_t)meshopt_buildMeshlets(meshlets,
-                                                             meshlet_vertices,
-                                                             meshlet_triangles,
-                                                             m_meshes[mesh_idx].indices,
-                                                             m_meshes[mesh_idx].num_indices,
-                                                             &m_meshes[mesh_idx].vertices[0].vx,
-                                                             m_meshes[mesh_idx].num_vertices,
-                                                             sizeof(vertex),
-                                                             MESHLET_VERTICES,
-                                                             MESHLET_TRIANGLES,
-                                                             cone_weight);
+        uint32_t meshlet_count = (uint32_t)meshopt_buildMeshlets(meshopt_meshlets,
+                                                                 meshlet_vertices,
+                                                                 meshlet_triangles,
+                                                                 m_meshes[mesh_idx].indices,
+                                                                 m_meshes[mesh_idx].num_indices,
+                                                                 &m_meshes[mesh_idx].vertices[0].vx,
+                                                                 m_meshes[mesh_idx].num_vertices,
+                                                                 sizeof(vertex),
+                                                                 L0_MESHLET_VERTICES,
+                                                                 L0_MESHLET_TRIANGLES,
+                                                                 cone_weight);
 
-    for (size_t i = 0; i < meshlet_count; ++i) {
-        meshopt_optimizeMeshlet(&meshlet_vertices[meshlets[i].vertex_offset],
-                                &meshlet_triangles[meshlets[i].triangle_offset],
-                                meshlets[i].triangle_count,
-                                meshlets[i].vertex_count);
+        for (size_t i = 0; i < meshlet_count; ++i) {
+            meshopt_optimizeMeshlet(&meshlet_vertices[meshopt_meshlets[i].vertex_offset],
+                                    &meshlet_triangles[meshopt_meshlets[i].triangle_offset],
+                                    meshopt_meshlets[i].triangle_count,
+                                    meshopt_meshlets[i].vertex_count);
 
-        meshlet_bounds[i] =
-            meshopt_computeMeshletBounds(&meshlet_vertices[meshlets[i].vertex_offset],
-                                         &meshlet_triangles[meshlets[i].triangle_offset],
-                                         meshlets[i].triangle_count,
-                                         &m_meshes[mesh_idx].vertices[0].vx,
-                                         m_meshes[mesh_idx].num_vertices,
-                                         sizeof(vertex));
+            meshopt_Bounds bounds = meshopt_computeMeshletBounds(
+                &meshlet_vertices[meshopt_meshlets[i].vertex_offset],
+                &meshlet_triangles[meshopt_meshlets[i].triangle_offset],
+                meshopt_meshlets[i].triangle_count,
+                &m_meshes[mesh_idx].vertices[0].vx,
+                m_meshes[mesh_idx].num_vertices,
+                sizeof(vertex));
+
+            meshlet meshlet;
+            meshlet.vertices     = new vertex[L0_MESHLET_VERTICES];
+            meshlet.indices      = new uint16_t[L0_MESHLET_INDICES];
+            meshlet.num_vertices = meshopt_meshlets[i].vertex_count;
+            meshlet.num_indices  = meshopt_meshlets[i].triangle_count * 3;
+            memcpy(meshlet.center, bounds.center, sizeof(bounds.center));
+            meshlet.radius = bounds.radius;
+
+            for (unsigned int vert_idx = 0; vert_idx < meshopt_meshlets[i].vertex_count;
+                 ++vert_idx) {
+                unsigned int vert = meshlet_vertices[meshopt_meshlets[i].vertex_offset + vert_idx];
+                meshlet.vertices[vert_idx] = m_meshes[mesh_idx].vertices[vert];
+            }
+
+            for (unsigned int tri_idx = 0; tri_idx < meshopt_meshlets[i].triangle_count;
+                 ++tri_idx) {
+                meshlet.indices[tri_idx * 3 + 0] = (uint16_t)
+                    meshlet_triangles[meshopt_meshlets[i].triangle_offset + 3 * tri_idx + 0];
+                meshlet.indices[tri_idx * 3 + 1] = (uint16_t)
+                    meshlet_triangles[meshopt_meshlets[i].triangle_offset + 3 * tri_idx + 1];
+                meshlet.indices[tri_idx * 3 + 2] = (uint16_t)
+                    meshlet_triangles[meshopt_meshlets[i].triangle_offset + 3 * tri_idx + 2];
+            }
+
+            meshlet.num_children = 0u;
+
+            meshlets.push_back(meshlet);
+        }
     }
 
     // We now have a flat list of meshlets -> the highest lod ones
     // We now combine (up to 8) meshlets into one to generate the next hierarchy level
     // Repeat until we only have 1 meshlet left
     std::vector<uint32_t> unprocessed;
-    unprocessed.reserve(meshlet_count);
-    for (uint32_t i = 0; i < meshlet_count; ++i) {
+    unprocessed.reserve(meshlets.size());
+    for (uint32_t i = 0; i < meshlets.size(); ++i) {
         unprocessed.push_back(i);
     }
     std::vector<uint32_t> next_level;
@@ -241,11 +278,11 @@ rt_result meshlet_generator::RunHierarchical(uint32_t mesh_idx, uint32_t *out_ro
         unsigned int closest_count = 0u;
 
         float first_center[3];
-        memcpy(first_center, meshlet_bounds[first].center, sizeof(float) * 3);
+        memcpy(first_center, meshlets[first].center, sizeof(float) * 3);
 
         for (uint32_t i = 0; i < unprocessed.size(); ++i) {
             float center[3];
-            memcpy(center, meshlet_bounds[unprocessed[i]].center, sizeof(float) * 3);
+            memcpy(center, meshlets[unprocessed[i]].center, sizeof(float) * 3);
 
             float dist = sqrtf((center[0] - first_center[0]) * (center[0] - first_center[0]) +
                                (center[1] - first_center[1]) * (center[1] - first_center[1]) +
@@ -255,7 +292,7 @@ rt_result meshlet_generator::RunHierarchical(uint32_t mesh_idx, uint32_t *out_ro
                 // Check if we are closer than one of the other candidates
                 for (unsigned int j = 0; j < closest_count; ++j) {
                     uint32_t highest_idx = UINT_MAX;
-                    float highest_dist = dist;
+                    float highest_dist   = dist;
                     if (dist < distances[j]) {
                         if (distances[j] > highest_dist) {
                             highest_dist = distances[j];
@@ -263,14 +300,14 @@ rt_result meshlet_generator::RunHierarchical(uint32_t mesh_idx, uint32_t *out_ro
                         }
                     }
                     if (highest_idx < RT_ARRAY_COUNT(closest)) {
-                        const uint32_t replaced = highest_idx;
+                        const uint32_t replaced = closest[highest_idx];
                         distances[j]            = dist;
-                        closest[j]              = i;
+                        closest[j]              = unprocessed[i];
                         unprocessed.push_back(replaced);
                     }
                 }
             } else {
-                closest[closest_count]   = i;
+                closest[closest_count]   = unprocessed[i];
                 distances[closest_count] = dist;
                 closest_count++;
                 unprocessed.erase(unprocessed.begin() + i);
@@ -279,6 +316,81 @@ rt_result meshlet_generator::RunHierarchical(uint32_t mesh_idx, uint32_t *out_ro
 
         // Combine into a new meshlet
         // vertex *vertices = new vertex[MESHLET_VERTICES * 8];
+
+        vertex *in_vertices  = new vertex[L0_MESHLET_VERTICES * 8];
+        uint32_t *in_indices = new uint32_t[L0_MESHLET_INDICES * 8];
+        memcpy(in_vertices,
+               meshlets[first].vertices,
+               sizeof(vertex) * meshlets[first].num_vertices);
+        size_t at_vert = meshlets[first].num_vertices;
+        for (unsigned int i = 0; i < meshlets[first].num_indices; ++i)
+            in_indices[i] = static_cast<uint32_t>(meshlets[first].indices[i]);
+        size_t at_idx = meshlets[first].num_indices;
+        for (unsigned int i = 0; i < closest_count; ++i) {
+            memcpy(&in_vertices[at_vert],
+                   meshlets[closest[i]].vertices,
+                   sizeof(vertex) * meshlets[closest[i]].num_vertices);
+            at_vert += meshlets[closest[i]].num_vertices;
+
+            for (unsigned int j = 0; j < meshlets[closest[i]].num_indices; ++j)
+                in_indices[at_idx + j] = static_cast<uint32_t>(meshlets[closest[i]].indices[j]);
+            at_idx += meshlets[closest[i]].num_indices;
+        }
+
+        const float target_error =
+            0.10f; // Acept 10% error. We are simplifying meshlets, the extents are not very large
+        const size_t target_index_count     = L0_MESHLET_INDICES;
+        const unsigned int simplify_options = meshopt_SimplifyLockBorder;
+        const float threshold               = 1.f / 8.f;
+        std::vector<unsigned int> lod(UINT16_MAX);
+        float lod_error        = 0.f;
+        size_t out_index_count = meshopt_simplify(&lod[0],
+                                                  in_indices,
+                                                  at_idx,
+                                                  &in_vertices[0].vx,
+                                                  at_vert,
+                                                  sizeof(vertex),
+                                                  target_index_count,
+                                                  target_error,
+                                                  simplify_options,
+                                                  &lod_error);
+        lod.resize(out_index_count);
+        if (out_index_count < UINT16_MAX) {
+            rtLog("EXP", "Yay");
+        } else {
+            rtReportError("EXP", "Nay");
+        }
+
+        std::unordered_map<unsigned int, uint16_t> index_remap;
+        uint16_t *index_buffer = new uint16_t[out_index_count];
+        std::vector<vertex> merged_vertices;
+        merged_vertices.reserve(out_index_count);
+        for (size_t i = 0; i < out_index_count; ++i) {
+            if (index_remap.find(lod[i]) != index_remap.end()) {
+                index_buffer[i] = index_remap[lod[i]];
+            } else {
+                uint16_t index = (uint16_t)merged_vertices.size();
+                merged_vertices.push_back(in_vertices[lod[i]]);
+                index_buffer[i]     = index;
+                index_remap[lod[i]] = index;
+            }
+        }
+
+        meshlet merged      = {};
+        merged.num_children = closest_count + 1;
+        merged.children[0]  = first;
+        memcpy(merged.children, closest, sizeof(uint32_t) * closest_count);
+        merged.indices     = index_buffer;
+        merged.num_indices = (uint32_t)out_index_count;
+        merged.vertices    = new vertex[merged_vertices.size()];
+        merged.num_vertices = (uint32_t)merged_vertices.size();
+        memcpy(merged.vertices, merged_vertices.data(), sizeof(vertex) * merged_vertices.size());
+
+        // Determine center and bounds
+
+
+        meshlets.push_back(merged);
+        next_level.push_back((unsigned int)meshlets.size() - 1);
     }
     return RT_SUCCESS;
 }

src/experimental/meshlets/meshlet_generator.hpp

@@ -3,9 +3,9 @@
 
 #include "runtime/runtime.h"
 
-constexpr size_t MESHLET_VERTICES = 64;
-constexpr size_t MESHLET_TRIANGLES = 124;
-constexpr size_t MESHLET_INDICES   = MESHLET_TRIANGLES * 3;
+constexpr size_t L0_MESHLET_VERTICES = 64;
+constexpr size_t L0_MESHLET_TRIANGLES = 124;
+constexpr size_t L0_MESHLET_INDICES   = L0_MESHLET_TRIANGLES * 3;
 
 struct vertex {
     float vx, vy, vz;
@@ -13,18 +13,13 @@ struct vertex {
 
 struct meshlet {
     vertex *vertices;
-    uint8_t *indices;
+    uint16_t *indices;
     uint32_t num_vertices;
     uint32_t num_indices;
 
     float center[3];
     float radius;
 
-    // Normal cone for backface culling
-    float cone_apex[3];
-    float cone_axis[3];
-    float cone_cutoff;
-
     // child indices
     uint32_t children[8];
     uint32_t num_children;

src/experimental/meshlets/meshlet_renderer.cpp

@@ -108,8 +108,6 @@ struct gpu_mesh_data {
 
 struct gpu_meshlet_data {
     float bounds[4];    // xyz, radius
-    float cone_apex[4]; // xyz, unused
-    float cone_axis_cutoff[4];
     uint32_t mesh_index;
     uint32_t first_index;
     uint32_t base_vertex;
@@ -176,9 +174,58 @@ rt_result meshlet_renderer::Initialize() {
     m_single_meshlet_shader = shader::CompileSource(_single_vert, _single_frag);
     m_flat_cull_shader      = shader::CompileFile(_flat_cull);
     m_meshlet_shader        = shader::CompileSource(_meshlet_vert, _meshlet_frag);
+
+    InitFlat();
+
     return RT_SUCCESS;
 }
 
+void OnModelLoaded(meshlet_generator *gen);
+
+void meshlet_renderer::InitFlat(void) {
+    const size_t MAX_MESHLETS = 65556;
+
+    GLuint buffers[6];
+    glCreateBuffers(RT_ARRAY_COUNT(buffers), buffers);
+    m_flat.vbo          = buffers[0];
+    m_flat.ebo   = buffers[1];
+    m_flat.meshlet_ssbo = buffers[2];
+    m_flat.draw_ssbo    = buffers[3];
+    m_flat.cull_ssbo    = buffers[4];
+    m_flat.mesh_ssbo    = buffers[5];
+
+    // Create the vao
+    glGenVertexArrays(1, &m_flat.vao);
+    glBindVertexArray(m_flat.vao);
+    glBindBuffer(GL_ARRAY_BUFFER, m_flat.vbo);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_flat.ebo);
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), nullptr);
+    glEnableVertexAttribArray(0);
+    glBindVertexArray(0);
+
+    // Reserve space
+    glNamedBufferStorage(m_flat.vbo,
+                         MAX_MESHLETS * sizeof(vertex) * L0_MESHLET_VERTICES,
+                         nullptr,
+                         GL_DYNAMIC_STORAGE_BIT);
+    glNamedBufferStorage(m_flat.ebo,
+                         MAX_MESHLETS * sizeof(uint16_t) * L0_MESHLET_INDICES,
+                         nullptr,
+                         GL_DYNAMIC_STORAGE_BIT);
+    glNamedBufferStorage(m_flat.meshlet_ssbo,
+                         MAX_MESHLETS * sizeof(gpu_meshlet_data),
+                         nullptr,
+                         GL_DYNAMIC_STORAGE_BIT);
+    glNamedBufferStorage(m_flat.draw_ssbo,
+                         MAX_MESHLETS * sizeof(draw_elements_indirect_command),
+                         nullptr,
+                         0);
+    glNamedBufferStorage(m_flat.cull_ssbo, sizeof(cull_output), nullptr, GL_MAP_READ_BIT | GL_DYNAMIC_STORAGE_BIT);
+
+    glNamedBufferStorage(m_flat.mesh_ssbo, sizeof(gpu_mesh_data), nullptr, GL_DYNAMIC_STORAGE_BIT);
+}
+
+
 void meshlet_renderer::RenderFlat(const meshlet *meshlets, unsigned int count) {
     if (m_settings.separate_rendering) {
         SeparateRendering(meshlets, count);
@@ -193,88 +240,56 @@ void meshlet_renderer::DrawIndirectFlat(const meshlet *meshlets, unsigned int co
     // Do compute "culling" (generate drawindirect) into 1 ssbo
     // DrawIndirect
 
-    GLuint vbo, ebo, meshlet_ssbo, draw_ssbo, cull_ssbo, mesh_ssbo;
-    GLuint buffers[6];
-    glCreateBuffers(RT_ARRAY_COUNT(buffers), buffers);
-    vbo          = buffers[0];
-    ebo          = buffers[1];
-    meshlet_ssbo = buffers[2];
-    draw_ssbo    = buffers[3];
-    cull_ssbo    = buffers[4];
-    mesh_ssbo    = buffers[5];
-
     // Store vertices and indices at idx * MESHLET_VERTICES/MESHLET_INDICES
-    glNamedBufferStorage(vbo,
-                         count * sizeof(vertex) * MESHLET_VERTICES,
-                         nullptr,
-                         GL_DYNAMIC_STORAGE_BIT);
-    glNamedBufferStorage(ebo, count * MESHLET_INDICES, nullptr, GL_DYNAMIC_STORAGE_BIT);
+   
     for (unsigned int i = 0; i < count; ++i) {
-        glNamedBufferSubData(vbo,
-                             i * sizeof(vertex) * MESHLET_VERTICES,
+        glNamedBufferSubData(m_flat.vbo,
+                             i * sizeof(vertex) * L0_MESHLET_VERTICES,
                              meshlets[i].num_vertices * sizeof(vertex),
                              meshlets[i].vertices);
-        glNamedBufferSubData(ebo,
-                             i * MESHLET_INDICES,
-                             meshlets[i].num_indices,
+        glNamedBufferSubData(m_flat.ebo,
+                             i * L0_MESHLET_INDICES * sizeof(uint16_t),
+                             meshlets[i].num_indices * sizeof(uint16_t),
                              meshlets[i].indices);
     }
 
     // Store meshlet information
-    glNamedBufferStorage(meshlet_ssbo,
-                         count * sizeof(gpu_meshlet_data),
-                         nullptr,
-                         GL_DYNAMIC_STORAGE_BIT);
     for (unsigned int i = 0; i < count; ++i) {
         gpu_meshlet_data meshlet;
         // Only have one right now
         meshlet.mesh_index  = 0;
-        meshlet.first_index = i * MESHLET_INDICES;
-        meshlet.base_vertex = i * MESHLET_VERTICES;
+        meshlet.first_index = i * L0_MESHLET_INDICES;
+        meshlet.base_vertex = i * L0_MESHLET_VERTICES;
         meshlet.index_count = meshlets[i].num_indices;
         memcpy(meshlet.bounds, meshlets[i].center, 3 * sizeof(float));
         meshlet.bounds[3] = meshlets[i].radius;
-        memcpy(meshlet.cone_apex, meshlets[i].cone_apex, 3 * sizeof(float));
-        meshlet.cone_apex[3] = 0.f;
-        memcpy(meshlet.cone_axis_cutoff, meshlets[i].cone_axis, sizeof(meshlets[i].cone_axis));
-        glNamedBufferSubData(meshlet_ssbo,
+        glNamedBufferSubData(m_flat.meshlet_ssbo,
                              i * sizeof(gpu_meshlet_data),
                              sizeof(gpu_meshlet_data),
                              &meshlet);
     }
 
-    // Reserve space for the draw commands
-    glNamedBufferStorage(draw_ssbo, count * sizeof(draw_elements_indirect_command), nullptr, 0);
-
     // Prepare culling output
     cull_output cull_output = {0};
-    glNamedBufferStorage(cull_ssbo, sizeof(cull_output), &cull_output, GL_MAP_READ_BIT);
-
+    glNamedBufferSubData(m_flat.cull_ssbo, 0, sizeof(cull_output), &cull_output);
+    
     // Prepare mesh data
     gpu_mesh_data mesh_data;
     mesh_data.model = glm ::rotate(m_settings.rotation, glm::vec3(0, 1, 0)) *
                       glm::scale(glm::vec3(m_settings.scale));
-    glNamedBufferStorage(mesh_ssbo, sizeof(mesh_data), &mesh_data, GL_DYNAMIC_STORAGE_BIT);
+    glNamedBufferSubData(m_flat.mesh_ssbo, 0, sizeof(mesh_data), &mesh_data);
 
     glMemoryBarrier(GL_BUFFER_UPDATE_BARRIER_BIT);
 
     // Do culling. TODO: Get number of draws back
     m_flat_cull_shader.Use();
-    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, meshlet_ssbo);
-    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, draw_ssbo);
-    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, cull_ssbo);
-    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, mesh_ssbo);
+    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, m_flat.meshlet_ssbo);
+    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, m_flat.draw_ssbo);
+    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, m_flat.cull_ssbo);
+    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, m_flat.mesh_ssbo);
     glUniform3fv(0, 1, m_settings.eye);
     glDispatchCompute(count, 1, 1);
 
-    // Create the vao
-    GLuint vao;
-    glGenVertexArrays(1, &vao);
-    glBindVertexArray(vao);
-    glBindBuffer(GL_ARRAY_BUFFER, vbo);
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), nullptr);
-    glEnableVertexAttribArray(0);
 
     // DrawIndirect
     GLuint mvploc = glGetUniformLocation(m_meshlet_shader.m_prog, "mvp");
@@ -295,21 +310,20 @@ void meshlet_renderer::DrawIndirectFlat(const meshlet *meshlets, unsigned int co
     m_meshlet_shader.Use();
     glUniformMatrix4fv(mvploc, 1, GL_FALSE, &mvp[0][0]);
 
-    glBindBuffer(GL_DRAW_INDIRECT_BUFFER, draw_ssbo);
+    glBindBuffer(GL_DRAW_INDIRECT_BUFFER, m_flat.draw_ssbo);
     glMemoryBarrier(GL_COMMAND_BARRIER_BIT | GL_SHADER_STORAGE_BARRIER_BIT);
     {
-        void *out = glMapNamedBuffer(cull_ssbo, GL_READ_ONLY);
+        void *out = glMapNamedBuffer(m_flat.cull_ssbo, GL_READ_ONLY);
         memcpy(&cull_output, out, sizeof(cull_output));
-        glUnmapNamedBuffer(cull_ssbo);
+        glUnmapNamedBuffer(m_flat.cull_ssbo);
     }
 
+    glBindVertexArray(m_flat.vao);
     glMultiDrawElementsIndirect(GL_TRIANGLES,
-                                GL_UNSIGNED_BYTE,
+                                GL_UNSIGNED_SHORT,
                                 nullptr,
                                 cull_output.draw_count,
                                 sizeof(draw_elements_indirect_command));
-
-    glDeleteBuffers(RT_ARRAY_COUNT(buffers), buffers);
 }
 
 void meshlet_renderer::SeparateRendering(const meshlet *meshlets, unsigned int count) {
@@ -320,9 +334,9 @@ void meshlet_renderer::SeparateRendering(const meshlet *meshlets, unsigned int c
 
     glBindVertexArray(vao);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex) * MESHLET_VERTICES, nullptr, GL_STREAM_DRAW);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex) * L0_MESHLET_VERTICES, nullptr, GL_STREAM_DRAW);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
-    glBufferData(GL_ELEMENT_ARRAY_BUFFER, MESHLET_INDICES, nullptr, GL_STREAM_DRAW);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(uint16_t) * L0_MESHLET_INDICES, nullptr, GL_STREAM_DRAW);
 
     glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), nullptr);
     glEnableVertexAttribArray(0);
@@ -361,11 +375,11 @@ void meshlet_renderer::SeparateRendering(const meshlet *meshlets, unsigned int c
                         meshlets[i].vertices);
         glBufferSubData(GL_ELEMENT_ARRAY_BUFFER,
                         0,
-                        sizeof(uint8_t) * meshlets[i].num_indices,
+                        sizeof(uint16_t) * meshlets[i].num_indices,
                         meshlets[i].indices);
         glUniform3fv(colorloc, 1, colors[i % 5]);
 
-        glDrawElements(GL_TRIANGLES, meshlets[i].num_indices, GL_UNSIGNED_BYTE, nullptr);
+        glDrawElements(GL_TRIANGLES, meshlets[i].num_indices, GL_UNSIGNED_SHORT, nullptr);
     }
 
     glDeleteVertexArrays(1, &vao);

src/experimental/meshlets/meshlet_renderer.hpp

@@ -24,6 +24,7 @@ struct shader {
 };
 
 struct meshlet_renderer {
+  public:
     struct settings {
         bool separate_rendering = true;
         float scale             = 1.f;
@@ -33,6 +34,18 @@ struct meshlet_renderer {
         float fov;
     };
 
+  private:
+    struct flat_state {
+    GLuint vao;
+        GLuint vbo;
+        GLuint ebo;
+        GLuint meshlet_ssbo;
+        GLuint draw_ssbo;
+        GLuint cull_ssbo;
+        GLuint mesh_ssbo;
+    };
+
+  public:
     rt_result Initialize();
 
     void RenderFlat(const meshlet *meshlets, unsigned int count);
@@ -40,16 +53,21 @@ struct meshlet_renderer {
     void SettingMenu();
 
   private:
+    void InitFlat(void);
+
     void SeparateRendering(const meshlet *meshlets, unsigned int count);
     void DrawIndirectFlat(const meshlet *meshlets, unsigned int count);
 
   public:
     settings m_settings;
+    float m_aspect;
+
+  private:
+    flat_state m_flat;
 
     shader m_single_meshlet_shader;
     shader m_flat_cull_shader;
     shader m_meshlet_shader;
-    float m_aspect;
 };
 
 #endif