Refactor: Move stroke_cache to gpencil runtime

This moves the `stroke_cache` that was previously stored on every
drawing to the `GreasePencilRuntime` struct.

Since this cache is only used for when a user is drawing a stroke, there
can only ever be one. It makes more sense to have this cache on the
data-block runtime data, rather than every drawings runtime data.

source/blender/blenkernel/BKE_grease_pencil.hh

@@ -61,8 +61,6 @@ class DrawingRuntime {
    * Triangle cache for all the strokes in the drawing.
    */
   mutable SharedCache<Vector<uint3>> triangles_cache;
-
-  StrokeCache stroke_cache;
 };
 
 class Drawing : public ::GreasePencilDrawing {
@@ -78,11 +76,6 @@ class Drawing : public ::GreasePencilDrawing {
    */
   Span<uint3> triangles() const;
   void tag_positions_changed();
-  /**
-   * A buffer for a single stroke while drawing.
-   */
-  Span<StrokePoint> stroke_buffer() const;
-  bool has_stroke_buffer() const;
 };
 
 class LayerGroup;
@@ -382,10 +375,17 @@ class GreasePencilRuntime {
    * Allocated and freed by the drawing code. See `DRW_grease_pencil_batch_cache_*` functions.
    */
   void *batch_cache = nullptr;
+  bke::greasepencil::StrokeCache stroke_cache;
 
  public:
   GreasePencilRuntime() {}
   ~GreasePencilRuntime() {}
+
+  /**
+   * A buffer for a single stroke while drawing.
+   */
+  Span<bke::greasepencil::StrokePoint> stroke_buffer() const;
+  bool has_stroke_buffer() const;
 };
 
 }  // namespace blender::bke

source/blender/blenkernel/intern/grease_pencil.cc

@@ -346,16 +346,6 @@ void Drawing::tag_positions_changed()
   this->runtime->triangles_cache.tag_dirty();
 }
 
-bool Drawing::has_stroke_buffer() const
-{
-  return this->runtime->stroke_cache.points.size() > 0;
-}
-
-Span<StrokePoint> Drawing::stroke_buffer() const
-{
-  return this->runtime->stroke_cache.points.as_span();
-}
-
 TreeNode::TreeNode()
 {
   this->next = this->prev = nullptr;
@@ -986,6 +976,23 @@ void BKE_grease_pencil_batch_cache_free(GreasePencil *grease_pencil)
 
 /** \} */
 
+/* ------------------------------------------------------------------- */
+/** \name Grease Pencil runtime API
+ * \{ */
+
+bool blender::bke::GreasePencilRuntime::has_stroke_buffer() const
+{
+  return this->stroke_cache.points.size() > 0;
+}
+
+blender::Span<blender::bke::greasepencil::StrokePoint> blender::bke::GreasePencilRuntime::
+    stroke_buffer() const
+{
+  return this->stroke_cache.points.as_span();
+}
+
+/** \} */
+
 /* ------------------------------------------------------------------- */
 /** \name Grease Pencil data-block API
  * \{ */

source/blender/draw/intern/draw_cache_impl_grease_pencil.cc

@@ -222,11 +222,6 @@ static void grease_pencil_geom_batch_ensure(GreasePencil &grease_pencil, int cfr
 
     int verts_start_offsets_size = curves.curves_num();
     int tris_start_offsets_size = curves.curves_num();
-    if (drawing->has_stroke_buffer()) {
-      verts_start_offsets_size++;
-      /* TODO: triangles for stroke buffer. */
-      // tris_start_offsets_size++;
-    }
     Array<int> verts_start_offsets(verts_start_offsets_size);
     Array<int> tris_start_offsets(tris_start_offsets_size);
 
@@ -258,19 +253,17 @@ static void grease_pencil_geom_batch_ensure(GreasePencil &grease_pencil, int cfr
     total_triangles_num += (curves.points_num() + num_cyclic) * 2;
     total_triangles_num += drawing->triangles().size();
 
-    if (drawing->has_stroke_buffer()) {
-      const int num_buffer_points = drawing->stroke_buffer().size();
-      total_verts_num += 1 + num_buffer_points + 1;
-      total_triangles_num += num_buffer_points * 2;
-      verts_start_offsets[curves.curves_range().size()] = v_offset;
-      /* TODO: triangles for stroke buffer. */
-      v_offset += 1 + num_buffer_points + 1;
-    }
-
     verts_start_offsets_per_visible_drawing.append(std::move(verts_start_offsets));
     tris_start_offsets_per_visible_drawing.append(std::move(tris_start_offsets));
   }
 
+  if (grease_pencil.runtime->has_stroke_buffer()) {
+    const int num_buffer_points = grease_pencil.runtime->stroke_buffer().size();
+    total_verts_num += 1 + num_buffer_points + 1;
+    total_triangles_num += num_buffer_points * 2;
+    /* TODO: triangles for stroke buffer. */
+  }
+
   static GPUVertFormat format_edit_points_pos = {0};
   if (format_edit_points_pos.attr_len == 0) {
     GPU_vertformat_attr_add(&format_edit_points_pos, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
@@ -432,51 +425,51 @@ static void grease_pencil_geom_batch_ensure(GreasePencil &grease_pencil, int cfr
         verts_slice.last().mat = -1;
       }
     });
+  }
 
-    if (drawing.has_stroke_buffer()) {
-      Span<bke::greasepencil::StrokePoint> points = drawing.stroke_buffer();
-      const int verts_start_offset = verts_start_offsets.last();
-      const int num_verts = 1 + points.size() + 1;
-      IndexRange verts_range = IndexRange(verts_start_offset, num_verts);
-      MutableSpan<GreasePencilStrokeVert> verts_slice = verts.slice(verts_range);
-      MutableSpan<GreasePencilColorVert> cols_slice = cols.slice(verts_range);
-      const int material_nr = drawing.runtime->stroke_cache.mat;
+  if (grease_pencil.runtime->has_stroke_buffer()) {
+    Span<bke::greasepencil::StrokePoint> points = grease_pencil.runtime->stroke_buffer();
+    const int verts_start_offset = v_offset;
+    const int num_verts = 1 + points.size() + 1;
+    IndexRange verts_range = IndexRange(verts_start_offset, num_verts);
+    MutableSpan<GreasePencilStrokeVert> verts_slice = verts.slice(verts_range);
+    MutableSpan<GreasePencilColorVert> cols_slice = cols.slice(verts_range);
+    const int material_nr = grease_pencil.runtime->stroke_cache.mat;
 
-      verts_slice.first().mat = -1;
-      for (const int i : IndexRange(points.size())) {
-        const int idx = i + 1;
-        GreasePencilStrokeVert &s_vert = verts_slice[idx];
-        GreasePencilColorVert &c_vert = cols_slice[idx];
-        const bke::greasepencil::StrokePoint &point = points[i];
+    verts_slice.first().mat = -1;
+    for (const int i : IndexRange(points.size())) {
+      const int idx = i + 1;
+      GreasePencilStrokeVert &s_vert = verts_slice[idx];
+      GreasePencilColorVert &c_vert = cols_slice[idx];
+      const bke::greasepencil::StrokePoint &point = points[i];
 
-        copy_v3_v3(s_vert.pos, point.position);
-        s_vert.radius = point.radius;
-        s_vert.opacity = point.opacity;
-        s_vert.point_id = verts_range[idx];
-        s_vert.stroke_id = verts_range.first();
-        s_vert.mat = material_nr;
+      copy_v3_v3(s_vert.pos, point.position);
+      s_vert.radius = point.radius;
+      s_vert.opacity = point.opacity;
+      s_vert.point_id = verts_range[idx];
+      s_vert.stroke_id = verts_range.first();
+      s_vert.mat = material_nr;
 
-        /* TODO */
-        s_vert.packed_asp_hard_rot = pack_rotation_aspect_hardness(0.0f, 1.0f, 1.0f);
-        /* TODO */
-        s_vert.u_stroke = 0;
-        /* TODO */
-        s_vert.uv_fill[0] = s_vert.uv_fill[1] = 0;
+      /* TODO */
+      s_vert.packed_asp_hard_rot = pack_rotation_aspect_hardness(0.0f, 1.0f, 1.0f);
+      /* TODO */
+      s_vert.u_stroke = 0;
+      /* TODO */
+      s_vert.uv_fill[0] = s_vert.uv_fill[1] = 0;
 
-        /* TODO */
-        copy_v4_v4(c_vert.vcol, float4(0.0f, 0.0f, 0.0f, 0.0f));
-        copy_v4_v4(c_vert.fcol, float4(0.0f, 0.0f, 0.0f, 0.0f));
+      /* TODO */
+      copy_v4_v4(c_vert.vcol, float4(0.0f, 0.0f, 0.0f, 0.0f));
+      copy_v4_v4(c_vert.fcol, float4(0.0f, 0.0f, 0.0f, 0.0f));
 
-        /* TODO */
-        c_vert.fcol[3] = (int(c_vert.fcol[3] * 10000.0f) * 10.0f) + 1.0f;
+      /* TODO */
+      c_vert.fcol[3] = (int(c_vert.fcol[3] * 10000.0f) * 10.0f) + 1.0f;
 
-        int v_mat = (verts_range[idx] << GP_VERTEX_ID_SHIFT) | GP_IS_STROKE_VERTEX_BIT;
-        GPU_indexbuf_add_tri_verts(&ibo, v_mat + 0, v_mat + 1, v_mat + 2);
-        GPU_indexbuf_add_tri_verts(&ibo, v_mat + 2, v_mat + 1, v_mat + 3);
-      }
-
-      verts_slice.last().mat = -1;
+      int v_mat = (verts_range[idx] << GP_VERTEX_ID_SHIFT) | GP_IS_STROKE_VERTEX_BIT;
+      GPU_indexbuf_add_tri_verts(&ibo, v_mat + 0, v_mat + 1, v_mat + 2);
+      GPU_indexbuf_add_tri_verts(&ibo, v_mat + 2, v_mat + 1, v_mat + 3);
     }
+
+    verts_slice.last().mat = -1;
   }
 
   /* Mark last 2 verts as invalid. */

source/blender/editors/sculpt_paint/grease_pencil_paint.cc

@@ -72,7 +72,7 @@ struct PaintOperationExecutor {
     bke::greasepencil::StrokePoint new_point{
         proj_pos, stroke_extension.pressure * 100.0f, 1.0f, float4(1.0f)};
 
-    drawing.runtime->stroke_cache.points.append(std::move(new_point));
+    grease_pencil.runtime->stroke_cache.points.append(std::move(new_point));
 
     BKE_grease_pencil_batch_cache_dirty_tag(&grease_pencil, BKE_GREASEPENCIL_BATCH_DIRTY_ALL);
   }
@@ -106,7 +106,8 @@ void PaintOperation::on_stroke_done(const bContext &C)
   bke::greasepencil::Drawing &drawing_eval =
       reinterpret_cast<GreasePencilDrawing *>(grease_pencil_eval.drawings()[index_eval])->wrap();
 
-  const Span<bke::greasepencil::StrokePoint> stroke_points = drawing_eval.stroke_buffer();
+  const Span<bke::greasepencil::StrokePoint> stroke_points =
+      grease_pencil_eval.runtime->stroke_buffer();
   CurvesGeometry &curves = drawing_orig.geometry.wrap();
 
   int num_old_curves = curves.curves_num();
@@ -162,7 +163,7 @@ void PaintOperation::on_stroke_done(const bContext &C)
         return true;
       });
 
-  drawing_eval.runtime->stroke_cache.clear();
+  grease_pencil_eval.runtime->stroke_cache.clear();
   drawing_orig.tag_positions_changed();
 
   radii.finish();