source/blender/draw/engines/overlay/overlay_empty.hh

@@ -58,7 +58,6 @@ template<typename SelectEngineT> class Empties {
     ExtraInstanceData data(
         float4x4(ob_ref.object->object_to_world), color, ob_ref.object->empty_drawsize);
 
-    /* TODO(fclem): Get selection ID from the selection engine. */
     const SelectID select_id = res.select_id(ob_ref);
 
     switch (ob_ref.object->empty_drawtype) {

source/blender/draw/engines/overlay/overlay_instance.cc

@@ -122,7 +122,7 @@ template<typename T> void Instance<T>::object_sync(ObjectRef &ob_ref)
 
 template<typename T> void Instance<T>::end_sync()
 {
-  metaballs.end_sync(resources, state);
+  metaballs.end_sync(resources, shapes, state);
   empties.end_sync(resources, shapes, state);
 }
 
@@ -190,3 +190,18 @@ template void Instance<>::end_sync();
 template void Instance<>::draw(Manager &manager);
 
 }  // namespace blender::draw::overlay
+
+/* TODO(fclem): Move elsewhere. */
+BoneInstanceData::BoneInstanceData(Object *ob,
+                                   const float *pos,
+                                   const float radius,
+                                   const float color[4])
+{
+  /* TODO(fclem): Use C++ math API. */
+  mul_v3_v3fl(this->mat[0], ob->object_to_world[0], radius);
+  mul_v3_v3fl(this->mat[1], ob->object_to_world[1], radius);
+  mul_v3_v3fl(this->mat[2], ob->object_to_world[2], radius);
+  mul_v3_m4v3(this->mat[3], ob->object_to_world, pos);
+  /* WATCH: Reminder, alpha is wire-size. */
+  OVERLAY_bone_instance_data_set_color(this, color);
+}

source/blender/draw/engines/overlay/overlay_metaball.hh

@@ -7,8 +7,8 @@
 #pragma once
 
 #include "DEG_depsgraph_query.h"
-#include "DNA_camera_types.h"
 #include "DNA_space_types.h"
+#include "ED_mball.h"
 #include "ED_view3d.h"
 #include "UI_resources.h"
 
@@ -20,14 +20,16 @@
 namespace blender::draw::overlay {
 
 template<typename SelectEngineT> class Metaballs {
+  using SelectID = typename SelectEngineT::ID;
   using ResourcesT = Resources<SelectEngineT>;
+  using SphereOutlineInstanceBuf = ShapeInstanceBuf<SelectEngineT, BoneInstanceData>;
 
  private:
   PassSimple metaball_ps_ = {"MetaBalls"};
   PassSimple metaball_in_front_ps_ = {"MetaBalls_In_front"};
 
-  ArmatureSphereBuf data_buf_ = {"metaball_data_buf"};
+  SphereOutlineInstanceBuf data_buf_ = {"metaball_data_buf"};
-  ArmatureSphereBuf data_in_front_buf_ = {"metaball_data_buf"};
+  SphereOutlineInstanceBuf data_in_front_buf_ = {"metaball_data_buf"};
 
  public:
   void begin_sync()
@@ -36,26 +38,11 @@ template<typename SelectEngineT> class Metaballs {
     data_in_front_buf_.clear();
   }
 
-  void metaball_instance_data_set(BoneInstanceData *data,
+  void edit_object_sync(const ObjectRef &ob_ref, ResourcesT &res)
-                                  Object *ob,
-                                  const float *pos,
-                                  const float radius,
-                                  const float color[4])
   {
-    /* Bone point radius is 0.05. Compensate for that. */
+    SphereOutlineInstanceBuf &data_buf = (ob_ref.object->dtx & OB_DRAW_IN_FRONT) != 0 ?
-    mul_v3_v3fl(data->mat[0], ob->object_to_world[0], radius / 0.05f);
+                                             data_in_front_buf_ :
-    mul_v3_v3fl(data->mat[1], ob->object_to_world[1], radius / 0.05f);
+                                             data_buf_;
-    mul_v3_v3fl(data->mat[2], ob->object_to_world[2], radius / 0.05f);
-    mul_v3_m4v3(data->mat[3], ob->object_to_world, pos);
-    /* WATCH: Reminder, alpha is wire-size. */
-    OVERLAY_bone_instance_data_set_color(data, color);
-  }
-
-  void edit_object_sync(const ObjectRef &ob_ref, const ResourcesT &res)
-  {
-    ArmatureSphereBuf &data_buf = (ob_ref.object->dtx & OB_DRAW_IN_FRONT) != 0 ?
-                                      data_in_front_buf_ :
-                                      data_buf_;
     MetaBall *mb = static_cast<MetaBall *>(ob_ref.object->data);
 
     const float *color;
@@ -68,47 +55,43 @@ template<typename SelectEngineT> class Metaballs {
       const bool is_selected = (ml->flag & SELECT) != 0;
       const bool is_scale_radius = (ml->flag & MB_SCALE_RAD) != 0;
       float stiffness_radius = ml->rad * atanf(ml->s) / float(M_PI_2);
-      BoneInstanceData instdata;
 
+      const SelectID radius_id = res.select_id(ob_ref, MBALLSEL_RADIUS);
       color = (is_selected && is_scale_radius) ? col_radius_select : col_radius;
-      metaball_instance_data_set(&instdata, ob_ref.object, &ml->x, ml->rad, color);
+      data_buf.append({ob_ref.object, &ml->x, ml->rad, color}, radius_id);
-      data_buf.append(*reinterpret_cast<float4x4 *>(&instdata));
 
+      const SelectID stiff_id = res.select_id(ob_ref, MBALLSEL_STIFF);
       color = (is_selected && !is_scale_radius) ? col_stiffness_select : col_stiffness;
-      metaball_instance_data_set(&instdata, ob_ref.object, &ml->x, stiffness_radius, color);
+      data_buf.append({ob_ref.object, &ml->x, stiffness_radius, color}, stiff_id);
-      data_buf.append(*reinterpret_cast<float4x4 *>(&instdata));
     }
   }
 
-  void object_sync(const ObjectRef &ob_ref, const ResourcesT &res, const State &state)
+  void object_sync(const ObjectRef &ob_ref, ResourcesT &res, const State &state)
   {
-    ArmatureSphereBuf &data_buf = (ob_ref.object->dtx & OB_DRAW_IN_FRONT) != 0 ?
+    SphereOutlineInstanceBuf &data_buf = (ob_ref.object->dtx & OB_DRAW_IN_FRONT) != 0 ?
-                                      data_in_front_buf_ :
+                                             data_in_front_buf_ :
-                                      data_buf_;
+                                             data_buf_;
     MetaBall *mb = static_cast<MetaBall *>(ob_ref.object->data);
 
     const float4 &color = res.object_wire_color(ob_ref, state);
+    const SelectID select_id = res.select_id(ob_ref);
 
     LISTBASE_FOREACH (MetaElem *, ml, &mb->elems) {
       /* Draw radius only. */
-      BoneInstanceData instdata;
+      data_buf.append({ob_ref.object, &ml->x, ml->rad, color}, select_id);
-      metaball_instance_data_set(&instdata, ob_ref.object, &ml->x, ml->rad, color);
-      data_buf.append(*reinterpret_cast<float4x4 *>(&instdata));
     }
   }
 
-  void end_sync(ResourcesT &res, const State &state)
+  void end_sync(ResourcesT &res, ShapeCache &shapes, const State &state)
   {
-    auto init_pass = [&](PassSimple &pass, ArmatureSphereBuf &data_buf) {
+    auto init_pass = [&](PassSimple &pass, SphereOutlineInstanceBuf &call_buf) {
-      data_buf.push_update();
-
       pass.init();
       pass.state_set(DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL |
                      state.clipping_state);
       pass.shader_set(OVERLAY_shader_armature_sphere(true));
       pass.bind_ubo("globalsBlock", &res.globals_buf);
-      pass.bind_ssbo("data_buf", &data_buf);
+
-      pass.draw(DRW_cache_bone_point_wire_outline_get(), data_buf.size());
+      call_buf.end_sync(pass, shapes.metaball_wire_circle);
     };
     init_pass(metaball_ps_, data_buf_);
     init_pass(metaball_in_front_ps_, data_in_front_buf_);

source/blender/draw/engines/overlay/overlay_private.hh

@@ -62,7 +62,6 @@ using blender::draw::StorageVectorBuffer;
 using blender::draw::Texture;
 using blender::draw::TextureFromPool;
 using blender::draw::TextureRef;
-using ArmatureSphereBuf = StorageVectorBuffer<float4x4>;
 
 template<typename SelectEngineT> struct Resources : public SelectEngineT::SelectMap {
   Framebuffer overlay_fb = {"overlay_fb"};
@@ -587,7 +586,7 @@ typedef struct OVERLAY_DupliData {
   short base_flag;
 } OVERLAY_DupliData;
 
-typedef struct BoneInstanceData {
+struct BoneInstanceData {
   /* Keep sync with bone instance vertex format (OVERLAY_InstanceFormats) */
   union {
     float mat[4][4];
@@ -604,7 +603,12 @@ typedef struct BoneInstanceData {
       float _pad03[3], amax_b;
     };
   };
-} BoneInstanceData;
+
+  BoneInstanceData() = default;
+  /* Constructor used by metaball overlays and expected to be used for drawing
+   * metaball_wire_sphere with armature wire shader that produces wide-lines. */
+  BoneInstanceData(Object *ob, const float *pos, const float radius, const float color[4]);
+};
 
 typedef struct OVERLAY_InstanceFormats {
   struct GPUVertFormat *instance_pos;

source/blender/draw/engines/overlay/overlay_shape.hh

@@ -360,6 +360,21 @@ class ShapeCache {
     return GPU_batch_create_ex(
         GPU_PRIM_LINES, vbo_from_vector(verts), nullptr, GPU_BATCH_OWNS_VBO);
   }();
+
+  AutoFreeGPUBatch metaball_wire_circle = [this]() {
+    /* A single ring of vertices. */
+    constexpr int resolution = 64;
+    constexpr float radius = 1.0f;
+    Vector<float2> ring = ring_vertices(radius, resolution);
+
+    Vector<Vertex> verts;
+    for (int i : IndexRange(resolution + 1)) {
+      float2 cv = ring[i % resolution];
+      verts.append({{cv[0], cv[1], 0.0f}, VCLASS_SCREENALIGNED});
+    }
+    return GPU_batch_create_ex(
+        GPU_PRIM_LINE_STRIP, vbo_from_vector(verts), nullptr, GPU_BATCH_OWNS_VBO);
+  }();
 };
 
 }  // namespace blender::draw::overlay

source/blender/draw/engines/select/select_empty.hh

@@ -24,7 +24,7 @@ struct EngineEmpty {
   };
 
   struct SelectMap {
-    [[nodiscard]] constexpr ID select_id(const ObjectRef &)
+    [[nodiscard]] const ID select_id(const ObjectRef &, uint = 0)
     {
       return {};
     }

source/blender/draw/engines/select/select_object.hh

@@ -52,10 +52,12 @@ struct EngineObject {
     uint next_id = 0;
     Map<uint, ObjectRef> map;
 
-    [[nodiscard]] const ID select_id(const ObjectRef &)
+    /* TODO(fclem): The sub_object_id id should eventually become some enum or take a sub-object
+     * reference directly. */
+    [[nodiscard]] const ID select_id(const ObjectRef &, uint sub_object_id = 0)
     {
       /* TODO Insert Ref into the map. */
-      return {next_id++};
+      return {sub_object_id | next_id++};
     }
   };
 };