3D View: Move selection API to a Selection engine.

This commit moves the API of selecting faces, vertices and edges to a DRW manager engine.

Reviewers: campbellbarton, fclem

Subscribers: jbakker, brecht

Differential Revision: https://developer.blender.org/D5090

7 files changed, 818 insertions, 331 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 8631a9f556b..664484d9a57 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -126,6 +126,7 @@ set(SRC
   engines/gpencil/gpencil_engine.h
   engines/gpencil/gpencil_render.c
   engines/gpencil/gpencil_shader_fx.c
+  engines/select/select_engine.c
 
   DRW_engine.h
   intern/DRW_render.h
@@ -150,6 +151,7 @@ set(SRC
   engines/external/external_engine.h
   engines/workbench/workbench_engine.h
   engines/workbench/workbench_private.h
+  engines/select/select_engine.h
 )
 
 set(LIB
@@ -363,6 +365,9 @@ data_to_c_simple(engines/gpencil/shaders/fx/gpencil_fx_shadow_resolve_frag.glsl
 data_to_c_simple(engines/gpencil/shaders/fx/gpencil_fx_swirl_frag.glsl SRC)
 data_to_c_simple(engines/gpencil/shaders/fx/gpencil_fx_wave_frag.glsl SRC)
 
+data_to_c_simple(engines/select/shaders/selection_id_3D_vert.glsl SRC)
+data_to_c_simple(engines/select/shaders/selection_id_frag.glsl SRC)
+
 
 list(APPEND INC
 )
diff --git a/source/blender/draw/DRW_engine.h b/source/blender/draw/DRW_engine.h
index 5919e100ddd..64a02f3931b 100644
--- a/source/blender/draw/DRW_engine.h
+++ b/source/blender/draw/DRW_engine.h
@@ -26,6 +26,7 @@
 #include "BLI_sys_types.h" /* for bool */
 
 struct ARegion;
+struct Base;
 struct DRWInstanceDataList;
 struct DRWPass;
 struct Depsgraph;
@@ -136,19 +137,12 @@ void DRW_draw_depth_loop_gpencil(struct Depsgraph *depsgraph,
 void DRW_draw_depth_object(struct ARegion *ar,
                            struct GPUViewport *viewport,
                            struct Object *object);
-void DRW_draw_select_id_object(struct Scene *scene,
-                               struct RegionView3D *rv3d,
-                               struct Object *ob,
-                               short select_mode,
-                               bool draw_facedot,
-                               uint initial_offset,
-                               uint *r_vert_offset,
-                               uint *r_edge_offset,
-                               uint *r_face_offset);
-
-void DRW_framebuffer_select_id_setup(struct ARegion *ar, const bool clear);
-void DRW_framebuffer_select_id_release(struct ARegion *ar);
-void DRW_framebuffer_select_id_read(const struct rcti *rect, uint *r_buf);
+void DRW_draw_select_id(struct Depsgraph *depsgraph,
+                        struct ARegion *ar,
+                        struct View3D *v3d,
+                        struct Base **bases,
+                        const uint bases_len,
+                        short select_mode);
 
 /* grease pencil render */
 bool DRW_render_check_grease_pencil(struct Depsgraph *depsgraph);
@@ -181,4 +175,20 @@ void DRW_deferred_shader_remove(struct GPUMaterial *mat);
 struct DrawDataList *DRW_drawdatalist_from_id(struct ID *id);
 void DRW_drawdata_free(struct ID *id);
 
+/* select_engine.c */
+void DRW_select_context_create(struct Depsgraph *depsgraph,
+                               struct Base **bases,
+                               const uint bases_len,
+                               short select_mode);
+bool DRW_select_elem_get(const uint sel_id, uint *r_elem, uint *r_base_index, char *r_elem_type);
+uint DRW_select_context_offset_for_object_elem(const uint base_index, char elem_type);
+uint DRW_select_context_elem_len(void);
+void DRW_framebuffer_select_id_read(const struct rcti *rect, uint *r_buf);
+void DRW_draw_select_id_object(struct Depsgraph *depsgraph,
+                               struct ViewLayer *view_layer,
+                               struct ARegion *ar,
+                               struct View3D *v3d,
+                               struct Object *ob,
+                               short select_mode);
+
 #endif /* __DRW_ENGINE_H__ */
diff --git a/source/blender/draw/engines/select/select_engine.c b/source/blender/draw/engines/select/select_engine.c
new file mode 100644
index 00000000000..f1fc9cbc0d6
--- /dev/null
+++ b/source/blender/draw/engines/select/select_engine.c
@@ -0,0 +1,647 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright 2019, Blender Foundation.
+ */
+
+/** \file
+ * \ingroup draw_engine
+ *
+ * Engine for drawing a selection map where the pixels indicate the selection indices.
+ */
+
+#include "BLI_rect.h"
+
+#include "BKE_editmesh.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_screen_types.h"
+
+#include "ED_view3d.h"
+
+#include "GPU_shader.h"
+#include "GPU_select.h"
+
+#include "DEG_depsgraph.h"
+#include "DEG_depsgraph_query.h"
+
+#include "UI_resources.h"
+
+#include "DRW_engine.h"
+#include "DRW_render.h"
+
+#include "draw_cache_impl.h"
+
+#include "select_engine.h"
+/* Shaders */
+
+#define SELECT_ENGINE "SELECT_ENGINE"
+
+/* *********** LISTS *********** */
+
+/* GPUViewport.storage
+ * Is freed everytime the viewport engine changes */
+typedef struct SELECTID_StorageList {
+  struct SELECTID_PrivateData *g_data;
+} SELECTID_StorageList;
+
+typedef struct SELECTID_PassList {
+  struct DRWPass *select_id_face_pass;
+  struct DRWPass *select_id_edge_pass;
+  struct DRWPass *select_id_vert_pass;
+} SELECTID_PassList;
+
+typedef struct SELECTID_Data {
+  void *engine_type;
+  DRWViewportEmptyList *fbl;
+  DRWViewportEmptyList *txl;
+  SELECTID_PassList *psl;
+  SELECTID_StorageList *stl;
+} SELECTID_Data;
+
+typedef struct SELECTID_Shaders {
+  /* Depth Pre Pass */
+  struct GPUShader *select_id_flat;
+  struct GPUShader *select_id_uniform;
+} SELECTID_Shaders;
+
+/* *********** STATIC *********** */
+
+static struct {
+  SELECTID_Shaders sh_data[GPU_SHADER_CFG_LEN];
+
+  struct GPUFrameBuffer *framebuffer_select_id;
+  struct GPUTexture *texture_u32;
+
+  struct {
+    struct BaseOffset *base_array_index_offsets;
+    uint bases_len;
+    uint last_base_drawn;
+    /** Total number of items `base_array_index_offsets[bases_len - 1].vert`. */
+    uint last_index_drawn;
+
+    struct Depsgraph *depsgraph;
+    short select_mode;
+  } context;
+} e_data = {{{NULL}}}; /* Engine data */
+
+typedef struct SELECTID_PrivateData {
+  DRWShadingGroup *shgrp_face_unif;
+  DRWShadingGroup *shgrp_face_flat;
+  DRWShadingGroup *shgrp_edge;
+  DRWShadingGroup *shgrp_vert;
+
+  DRWView *view_faces;
+  DRWView *view_edges;
+  DRWView *view_verts;
+} SELECTID_PrivateData; /* Transient data */
+
+struct BaseOffset {
+  /* For convenience only. */
+  union {
+    uint offset;
+    uint face_start;
+  };
+  union {
+    uint face;
+    uint edge_start;
+  };
+  union {
+    uint edge;
+    uint vert_start;
+  };
+  uint vert;
+};
+
+/* Shaders */
+extern char datatoc_common_view_lib_glsl[];
+extern char datatoc_selection_id_3D_vert_glsl[];
+extern char datatoc_selection_id_frag_glsl[];
+
+/* -------------------------------------------------------------------- */
+/** \name Selection Utilities
+ * \{ */
+
+static void draw_select_framebuffer_select_id_setup(void)
+{
+  DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+  int size[2];
+  size[0] = GPU_texture_width(dtxl->depth);
+  size[1] = GPU_texture_height(dtxl->depth);
+
+  if (e_data.framebuffer_select_id == NULL) {
+    e_data.framebuffer_select_id = GPU_framebuffer_create();
+  }
+
+  if ((e_data.texture_u32 != NULL) && ((GPU_texture_width(e_data.texture_u32) != size[0]) ||
+                                       (GPU_texture_height(e_data.texture_u32) != size[1]))) {
+
+    GPU_texture_free(e_data.texture_u32);
+    e_data.texture_u32 = NULL;
+  }
+
+  if (e_data.texture_u32 == NULL) {
+    e_data.texture_u32 = GPU_texture_create_2d(size[0], size[1], GPU_R32UI, NULL, NULL);
+
+    GPU_framebuffer_texture_attach(e_data.framebuffer_select_id, dtxl->depth, 0, 0);
+    GPU_framebuffer_texture_attach(e_data.framebuffer_select_id, e_data.texture_u32, 0, 0);
+    GPU_framebuffer_check_valid(e_data.framebuffer_select_id, NULL);
+  }
+}
+
+static void draw_select_id_object(void *vedata,
+                                  Object *ob,
+                                  short select_mode,
+                                  bool draw_facedot,
+                                  uint initial_offset,
+                                  uint *r_vert_offset,
+                                  uint *r_edge_offset,
+                                  uint *r_face_offset)
+{
+  SELECTID_StorageList *stl = ((SELECTID_Data *)vedata)->stl;
+
+  BLI_assert(initial_offset > 0);
+
+  switch (ob->type) {
+    case OB_MESH:
+      if (ob->mode & OB_MODE_EDIT) {
+        Mesh *me = ob->data;
+        BMEditMesh *em = me->edit_mesh;
+        const bool use_faceselect = (select_mode & SCE_SELECT_FACE) != 0;
+
+        DRW_mesh_batch_cache_validate(me);
+
+        BM_mesh_elem_table_ensure(em->bm, BM_VERT | BM_EDGE | BM_FACE);
+
+        struct GPUBatch *geom_faces, *geom_edges, *geom_verts, *geom_facedots;
+        geom_faces = DRW_mesh_batch_cache_get_triangles_with_select_id(me);
+        if (select_mode & SCE_SELECT_EDGE) {
+          geom_edges = DRW_mesh_batch_cache_get_edges_with_select_id(me);
+        }
+        if (select_mode & SCE_SELECT_VERTEX) {
+          geom_verts = DRW_mesh_batch_cache_get_verts_with_select_id(me);
+        }
+        if (use_faceselect && draw_facedot) {
+          geom_facedots = DRW_mesh_batch_cache_get_facedots_with_select_id(me);
+        }
+        DRW_mesh_batch_cache_create_requested(ob, me, NULL, false, true);
+
+        DRWShadingGroup *face_shgrp;
+        if (use_faceselect) {
+          face_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_face_flat);
+          DRW_shgroup_uniform_int_copy(face_shgrp, "offset", *(int *)&initial_offset);
+
+          if (draw_facedot) {
+            DRW_shgroup_call(face_shgrp, geom_facedots, ob);
+          }
+          *r_face_offset = initial_offset + em->bm->totface;
+        }
+        else {
+          face_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_face_unif);
+          DRW_shgroup_uniform_int_copy(face_shgrp, "id", 0);
+
+          *r_face_offset = initial_offset;
+        }
+        DRW_shgroup_call(face_shgrp, geom_faces, ob);
+
+        /* Unlike faces, only draw edges if edge select mode. */
+        if (select_mode & SCE_SELECT_EDGE) {
+          DRWShadingGroup *edge_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_edge);
+          DRW_shgroup_uniform_int_copy(edge_shgrp, "offset", *(int *)r_face_offset);
+          DRW_shgroup_call(edge_shgrp, geom_edges, ob);
+          *r_edge_offset = *r_face_offset + em->bm->totedge;
+        }
+        else {
+          /* Note that `r_vert_offset` is calculated from `r_edge_offset`.
+           * Otherwise the first vertex is never selected, see: T53512. */
+          *r_edge_offset = *r_face_offset;
+        }
+
+        /* Unlike faces, only verts if vert select mode. */
+        if (select_mode & SCE_SELECT_VERTEX) {
+          DRWShadingGroup *vert_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_vert);
+          DRW_shgroup_uniform_int_copy(vert_shgrp, "offset", *(int *)r_edge_offset);
+          DRW_shgroup_call(vert_shgrp, geom_verts, ob);
+          *r_vert_offset = *r_edge_offset + em->bm->totvert;
+        }
+        else {
+          *r_vert_offset = *r_edge_offset;
+        }
+      }
+      else {
+        Mesh *me_orig = DEG_get_original_object(ob)->data;
+        Mesh *me_eval = ob->data;
+
+        DRW_mesh_batch_cache_validate(me_eval);
+        struct GPUBatch *geom_faces = DRW_mesh_batch_cache_get_triangles_with_select_id(me_eval);
+        if ((me_orig->editflag & ME_EDIT_PAINT_VERT_SEL) &&
+            /* Currently vertex select supports weight paint and vertex paint. */
+            ((ob->mode & OB_MODE_WEIGHT_PAINT) || (ob->mode & OB_MODE_VERTEX_PAINT))) {
+
+          struct GPUBatch *geom_verts = DRW_mesh_batch_cache_get_verts_with_select_id(me_eval);
+          DRW_mesh_batch_cache_create_requested(ob, me_eval, NULL, false, true);
+
+          /* Only draw faces to mask out verts, we don't want their selection ID's. */
+          DRWShadingGroup *face_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_face_unif);
+          DRW_shgroup_uniform_int_copy(face_shgrp, "id", 0);
+          DRW_shgroup_call(face_shgrp, geom_faces, ob);
+
+          DRWShadingGroup *vert_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_vert);
+          DRW_shgroup_uniform_int_copy(vert_shgrp, "offset", 1);
+          DRW_shgroup_call(vert_shgrp, geom_verts, ob);
+
+          *r_face_offset = *r_edge_offset = initial_offset;
+          *r_vert_offset = me_eval->totvert + 1;
+        }
+        else {
+          const bool use_hide = (me_orig->editflag & ME_EDIT_PAINT_FACE_SEL);
+          DRW_mesh_batch_cache_create_requested(ob, me_eval, NULL, false, use_hide);
+
+          DRWShadingGroup *face_shgrp = DRW_shgroup_create_sub(stl->g_data->shgrp_face_flat);
+          DRW_shgroup_uniform_int_copy(face_shgrp, "offset", *(int *)&initial_offset);
+          DRW_shgroup_call(face_shgrp, geom_faces, ob);
+
+          *r_face_offset = initial_offset + me_eval->totpoly;
+          *r_edge_offset = *r_vert_offset = *r_face_offset;
+        }
+      }
+      break;
+    case OB_CURVE:
+    case OB_SURF:
+      break;
+  }
+}
+
+static bool check_ob_drawface_dot(short select_mode, const View3D *v3d, char dt)
+{
+  if (select_mode & SCE_SELECT_FACE) {
+    if ((dt < OB_SOLID) || XRAY_FLAG_ENABLED(v3d)) {
+      return true;
+    }
+    if (v3d->overlay.edit_flag & V3D_OVERLAY_EDIT_FACE_DOT) {
+      return true;
+    }
+    if ((v3d->overlay.edit_flag & V3D_OVERLAY_EDIT_EDGES) == 0) {
+      /* Since we can't deduce face selection when edges aren't visible - show dots. */
+      return true;
+    }
+  }
+  return false;
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Engine Functions
+ * \{ */
+
+static void select_engine_init(void *vedata)
+{
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  eGPUShaderConfig sh_cfg = draw_ctx->sh_cfg;
+
+  SELECTID_StorageList *stl = ((SELECTID_Data *)vedata)->stl;
+  SELECTID_Shaders *sh_data = &e_data.sh_data[sh_cfg];
+
+  /* Prepass */
+  if (!sh_data->select_id_flat) {
+    const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
+    sh_data->select_id_flat = GPU_shader_create_from_arrays({
+        .vert = (const char *[]){sh_cfg_data->lib,
+                                 datatoc_common_view_lib_glsl,
+                                 datatoc_selection_id_3D_vert_glsl,
+                                 NULL},
+        .frag = (const char *[]){datatoc_selection_id_frag_glsl, NULL},
+        .defs = (const char *[]){sh_cfg_data->def, NULL},
+    });
+  }
+  if (!sh_data->select_id_uniform) {
+    const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
+    sh_data->select_id_uniform = GPU_shader_create_from_arrays({
+        .vert = (const char *[]){sh_cfg_data->lib,
+                                 datatoc_common_view_lib_glsl,
+                                 datatoc_selection_id_3D_vert_glsl,
+                                 NULL},
+        .frag = (const char *[]){datatoc_selection_id_frag_glsl, NULL},
+        .defs = (const char *[]){sh_cfg_data->def, "#define UNIFORM_ID\n", NULL},
+    });
+  }
+
+  if (!stl->g_data) {
+    /* Alloc transient pointers */
+    stl->g_data = MEM_mallocN(sizeof(*stl->g_data), __func__);
+  }
+
+  {
+    /* Create view with depth offset */
+    stl->g_data->view_faces = (DRWView *)DRW_view_default_get();
+    stl->g_data->view_edges = DRW_view_create_with_zoffset(draw_ctx->rv3d, 1.0f);
+    stl->g_data->view_verts = DRW_view_create_with_zoffset(draw_ctx->rv3d, 1.1f);
+  }
+}
+
+static void select_cache_init(void *vedata)
+{
+  SELECTID_PassList *psl = ((SELECTID_Data *)vedata)->psl;
+  SELECTID_StorageList *stl = ((SELECTID_Data *)vedata)->stl;
+
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  SELECTID_Shaders *sh_data = &e_data.sh_data[draw_ctx->sh_cfg];
+  {
+    psl->select_id_face_pass = DRW_pass_create("Face Pass", DRW_STATE_DEFAULT);
+    stl->g_data->shgrp_face_unif = DRW_shgroup_create(sh_data->select_id_uniform,
+                                                      psl->select_id_face_pass);
+
+    stl->g_data->shgrp_face_flat = DRW_shgroup_create(sh_data->select_id_flat,
+                                                      psl->select_id_face_pass);
+
+    psl->select_id_edge_pass = DRW_pass_create(
+        "Edge Pass", DRW_STATE_DEFAULT | DRW_STATE_FIRST_VERTEX_CONVENTION);
+
+    stl->g_data->shgrp_edge = DRW_shgroup_create(sh_data->select_id_flat,
+                                                 psl->select_id_edge_pass);
+
+    psl->select_id_vert_pass = DRW_pass_create("Vert Pass", DRW_STATE_DEFAULT);
+    stl->g_data->shgrp_vert = DRW_shgroup_create(sh_data->select_id_flat,
+                                                 psl->select_id_vert_pass);
+
+    DRW_shgroup_uniform_float_copy(stl->g_data->shgrp_vert, "sizeVertex", G_draw.block.sizeVertex);
+
+    if (draw_ctx->sh_cfg == GPU_SHADER_CFG_CLIPPED) {
+      DRW_shgroup_state_enable(stl->g_data->shgrp_face_unif, DRW_STATE_CLIP_PLANES);
+      DRW_shgroup_state_enable(stl->g_data->shgrp_face_flat, DRW_STATE_CLIP_PLANES);
+      DRW_shgroup_state_enable(stl->g_data->shgrp_edge, DRW_STATE_CLIP_PLANES);
+      DRW_shgroup_state_enable(stl->g_data->shgrp_vert, DRW_STATE_CLIP_PLANES);
+    }
+  }
+
+  e_data.context.last_base_drawn = 0;
+  e_data.context.last_index_drawn = 1;
+}
+
+static void select_cache_populate(void *vedata, Object *ob)
+{
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  short select_mode = e_data.context.select_mode;
+
+  if (select_mode == -1) {
+    ToolSettings *ts = draw_ctx->scene->toolsettings;
+    select_mode = ts->selectmode;
+  }
+
+  bool draw_facedot = check_ob_drawface_dot(select_mode, draw_ctx->v3d, ob->dt);
+
+  struct BaseOffset *base_ofs =
+      &e_data.context.base_array_index_offsets[e_data.context.last_base_drawn++];
+
+  uint offset = e_data.context.last_index_drawn;
+
+  draw_select_id_object(vedata,
+                        ob,
+                        select_mode,
+                        draw_facedot,
+                        offset,
+                        &base_ofs->vert,
+                        &base_ofs->edge,
+                        &base_ofs->face);
+
+  base_ofs->offset = offset;
+  e_data.context.last_index_drawn = base_ofs->vert;
+}
+
+static void select_draw_scene(void *vedata)
+{
+  SELECTID_StorageList *stl = ((SELECTID_Data *)vedata)->stl;
+  SELECTID_PassList *psl = ((SELECTID_Data *)vedata)->psl;
+
+  /* Setup framebuffer */
+  draw_select_framebuffer_select_id_setup();
+  GPU_framebuffer_bind(e_data.framebuffer_select_id);
+
+  /* dithering and AA break color coding, so disable */
+  glDisable(GL_DITHER);
+
+  GPU_framebuffer_clear_color_depth(e_data.framebuffer_select_id, (const float[4]){0.0f}, 1.0f);
+
+  DRW_view_set_active(stl->g_data->view_faces);
+  DRW_draw_pass(psl->select_id_face_pass);
+
+  DRW_view_set_active(stl->g_data->view_edges);
+  DRW_draw_pass(psl->select_id_edge_pass);
+
+  DRW_view_set_active(stl->g_data->view_verts);
+  DRW_draw_pass(psl->select_id_vert_pass);
+}
+
+static void select_engine_free(void)
+{
+  for (int sh_data_index = 0; sh_data_index < ARRAY_SIZE(e_data.sh_data); sh_data_index++) {
+    SELECTID_Shaders *sh_data = &e_data.sh_data[sh_data_index];
+    DRW_SHADER_FREE_SAFE(sh_data->select_id_flat);
+    DRW_SHADER_FREE_SAFE(sh_data->select_id_uniform);
+  }
+
+  DRW_TEXTURE_FREE_SAFE(e_data.texture_u32);
+  GPU_FRAMEBUFFER_FREE_SAFE(e_data.framebuffer_select_id);
+  MEM_SAFE_FREE(e_data.context.base_array_index_offsets);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Exposed `DRW_engine.h` functions
+ * \{ */
+
+bool DRW_select_elem_get(const uint sel_id, uint *r_elem, uint *r_base_index, char *r_elem_type)
+{
+  char elem_type = 0;
+  uint elem_id;
+  uint base_index = 0;
+
+  for (; base_index < e_data.context.bases_len; base_index++) {
+    struct BaseOffset *base_ofs = &e_data.context.base_array_index_offsets[base_index];
+
+    if (base_ofs->face > sel_id) {
+      elem_id = sel_id - base_ofs->face_start;
+      elem_type = SCE_SELECT_FACE;
+      break;
+    }
+    if (base_ofs->edge > sel_id) {
+      elem_id = sel_id - base_ofs->edge_start;
+      elem_type = SCE_SELECT_EDGE;
+      break;
+    }
+    if (base_ofs->vert > sel_id) {
+      elem_id = sel_id - base_ofs->vert_start;
+      elem_type = SCE_SELECT_VERTEX;
+      break;
+    }
+  }
+
+  if (base_index == e_data.context.bases_len) {
+    return false;
+  }
+
+  *r_elem = elem_id;
+
+  if (r_base_index) {
+    *r_base_index = base_index;
+  }
+
+  if (r_elem_type) {
+    *r_elem_type = elem_type;
+  }
+
+  return true;
+}
+
+uint DRW_select_context_offset_for_object_elem(const uint base_index, char elem_type)
+{
+  struct BaseOffset *base_ofs = &e_data.context.base_array_index_offsets[base_index];
+
+  if (elem_type == SCE_SELECT_VERTEX) {
+    return base_ofs->vert_start - 1;
+  }
+  if (elem_type == SCE_SELECT_EDGE) {
+    return base_ofs->edge_start - 1;
+  }
+  if (elem_type == SCE_SELECT_FACE) {
+    return base_ofs->face_start - 1;
+  }
+  BLI_assert(0);
+  return 0;
+}
+
+uint DRW_select_context_elem_len(void)
+{
+  return e_data.context.last_index_drawn;
+}
+
+/* Read a block of pixels from the select frame buffer. */
+void DRW_framebuffer_select_id_read(const rcti *rect, uint *r_buf)
+{
+  /* clamp rect by texture */
+  rcti r = {
+      .xmin = 0,
+      .xmax = GPU_texture_width(e_data.texture_u32),
+      .ymin = 0,
+      .ymax = GPU_texture_height(e_data.texture_u32),
+  };
+
+  rcti rect_clamp = *rect;
+  if (BLI_rcti_isect(&r, &rect_clamp, &rect_clamp)) {
+    DRW_opengl_context_enable();
+    GPU_framebuffer_bind(e_data.framebuffer_select_id);
+    glReadBuffer(GL_COLOR_ATTACHMENT0);
+    glReadPixels(rect_clamp.xmin,
+                 rect_clamp.ymin,
+                 BLI_rcti_size_x(&rect_clamp),
+                 BLI_rcti_size_y(&rect_clamp),
+                 GL_RED_INTEGER,
+                 GL_UNSIGNED_INT,
+                 r_buf);
+
+    GPU_framebuffer_restore();
+    DRW_opengl_context_disable();
+
+    if (!BLI_rcti_compare(rect, &rect_clamp)) {
+      GPU_select_buffer_stride_realign(rect, &rect_clamp, r_buf);
+    }
+  }
+  else {
+    size_t buf_size = BLI_rcti_size_x(rect) * BLI_rcti_size_y(rect) * sizeof(*r_buf);
+
+    memset(r_buf, 0, buf_size);
+  }
+}
+
+void DRW_select_context_create(Depsgraph *depsgraph,
+                               Base **UNUSED(bases),
+                               const uint bases_len,
+                               short select_mode)
+{
+  e_data.context.depsgraph = depsgraph;
+  e_data.context.select_mode = select_mode;
+  e_data.context.bases_len = bases_len;
+
+  MEM_SAFE_FREE(e_data.context.base_array_index_offsets);
+  e_data.context.base_array_index_offsets = MEM_mallocN(
+      sizeof(*e_data.context.base_array_index_offsets) * bases_len, __func__);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Legacy
+ * \{ */
+
+void DRW_draw_select_id_object(Depsgraph *depsgraph,
+                               ViewLayer *view_layer,
+                               ARegion *ar,
+                               View3D *v3d,
+                               Object *ob,
+                               short select_mode)
+{
+  Base *base = BKE_view_layer_base_find(view_layer, ob);
+  DRW_draw_select_id(depsgraph, ar, v3d, &base, 1, select_mode);
+}
+
+/** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Engine Type
+ * \{ */
+
+static const DrawEngineDataSize select_data_size = DRW_VIEWPORT_DATA_SIZE(SELECTID_Data);
+
+DrawEngineType draw_engine_select_type = {
+    NULL,
+    NULL,
+    N_("Select ID"),
+    &select_data_size,
+    &select_engine_init,
+    &select_engine_free,
+    &select_cache_init,
+    &select_cache_populate,
+    NULL,
+    NULL,
+    &select_draw_scene,
+    NULL,
+    NULL,
+    NULL,
+};
+
+/* Note: currently unused, we may want to register so we can see this when debugging the view. */
+
+RenderEngineType DRW_engine_viewport_select_type = {
+    NULL,
+    NULL,
+    SELECT_ENGINE,
+    N_("Select ID"),
+    RE_INTERNAL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    &draw_engine_select_type,
+    {NULL, NULL, NULL},
+};
+
+/** \} */
+
+#undef SELECT_ENGINE
diff --git a/source/blender/draw/engines/select/select_engine.h b/source/blender/draw/engines/select/select_engine.h
new file mode 100644
index 00000000000..5b900ccaf27
--- /dev/null
+++ b/source/blender/draw/engines/select/select_engine.h
@@ -0,0 +1,29 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright 2019, Blender Foundation.
+ */
+
+/** \file
+ * \ingroup draw_engine
+ */
+
+#ifndef __SELECT_ENGINE_H__
+#define __SELECT_ENGINE_H__
+
+extern DrawEngineType draw_engine_select_type;
+extern RenderEngineType DRW_engine_viewport_select_type;
+
+#endif /* __SELECT_ID_ENGINE_H__ */
diff --git a/source/blender/draw/engines/select/shaders/selection_id_3D_vert.glsl b/source/blender/draw/engines/select/shaders/selection_id_3D_vert.glsl
new file mode 100644
index 00000000000..9b0107cffdb
--- /dev/null
+++ b/source/blender/draw/engines/select/shaders/selection_id_3D_vert.glsl
@@ -0,0 +1,26 @@
+
+uniform float sizeVertex;
+
+in vec3 pos;
+
+#ifndef UNIFORM_ID
+uniform int offset;
+in uint color;
+
+flat out uint id;
+#endif
+
+void main()
+{
+#ifndef UNIFORM_ID
+  id = floatBitsToUint(intBitsToFloat(offset)) + color;
+#endif
+
+  vec3 world_pos = point_object_to_world(pos);
+  gl_Position = point_world_to_ndc(world_pos);
+  gl_PointSize = sizeVertex;
+
+#ifdef USE_WORLD_CLIP_PLANES
+  world_clip_planes_calc_clip_distance(world_pos);
+#endif
+}
diff --git a/source/blender/draw/engines/select/shaders/selection_id_frag.glsl b/source/blender/draw/engines/select/shaders/selection_id_frag.glsl
new file mode 100644
index 00000000000..ea86ddc7301
--- /dev/null
+++ b/source/blender/draw/engines/select/shaders/selection_id_frag.glsl
@@ -0,0 +1,14 @@
+
+#ifdef UNIFORM_ID
+uniform int id;
+#  define id floatBitsToUint(intBitsToFloat(id))
+#else
+flat in uint id;
+#endif
+
+out uint fragColor;
+
+void main()
+{
+  fragColor = id;
+}
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index 2841e017ef6..320a6f6aaaa 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -89,6 +89,7 @@
 #include "engines/workbench/workbench_engine.h"
 #include "engines/external/external_engine.h"
 #include "engines/gpencil/gpencil_engine.h"
+#include "engines/select/select_engine.h"
 
 #include "GPU_context.h"
 
@@ -2136,16 +2137,13 @@ void DRW_custom_pipeline(DrawEngineType *draw_engine_type,
 
 static struct DRWSelectBuffer {
   struct GPUFrameBuffer *framebuffer_depth_only;
-  struct GPUFrameBuffer *framebuffer_select_id;
   struct GPUTexture *texture_depth;
-  struct GPUTexture *texture_u32;
 } g_select_buffer = {NULL};
 
 static void draw_select_framebuffer_depth_only_setup(const int size[2])
 {
   if (g_select_buffer.framebuffer_depth_only == NULL) {
     g_select_buffer.framebuffer_depth_only = GPU_framebuffer_create();
-    g_select_buffer.framebuffer_select_id = GPU_framebuffer_create();
   }
 
   if ((g_select_buffer.texture_depth != NULL) &&
@@ -2162,32 +2160,7 @@ static void draw_select_framebuffer_depth_only_setup(const int size[2])
     GPU_framebuffer_texture_attach(
         g_select_buffer.framebuffer_depth_only, g_select_buffer.texture_depth, 0, 0);
 
-    GPU_framebuffer_texture_attach(
-        g_select_buffer.framebuffer_select_id, g_select_buffer.texture_depth, 0, 0);
-
     GPU_framebuffer_check_valid(g_select_buffer.framebuffer_depth_only, NULL);
-    GPU_framebuffer_check_valid(g_select_buffer.framebuffer_select_id, NULL);
-  }
-}
-
-static void draw_select_framebuffer_select_id_setup(const int size[2])
-{
-  draw_select_framebuffer_depth_only_setup(size);
-
-  if ((g_select_buffer.texture_u32 != NULL) &&
-      ((GPU_texture_width(g_select_buffer.texture_u32) != size[0]) ||
-       (GPU_texture_height(g_select_buffer.texture_u32) != size[1]))) {
-    GPU_texture_free(g_select_buffer.texture_u32);
-    g_select_buffer.texture_u32 = NULL;
-  }
-
-  if (g_select_buffer.texture_u32 == NULL) {
-    g_select_buffer.texture_u32 = GPU_texture_create_2d(size[0], size[1], GPU_R32UI, NULL, NULL);
-
-    GPU_framebuffer_texture_attach(
-        g_select_buffer.framebuffer_select_id, g_select_buffer.texture_u32, 0, 0);
-
-    GPU_framebuffer_check_valid(g_select_buffer.framebuffer_select_id, NULL);
   }
 }
 
@@ -2575,6 +2548,78 @@ void DRW_draw_depth_loop_gpencil(struct Depsgraph *depsgraph,
   DRW_opengl_context_disable();
 }
 
+void DRW_draw_select_id(Depsgraph *depsgraph,
+                        ARegion *ar,
+                        View3D *v3d,
+                        Base **bases,
+                        const uint bases_len,
+                        short select_mode)
+{
+  Scene *scene = DEG_get_evaluated_scene(depsgraph);
+  ViewLayer *view_layer = DEG_get_evaluated_view_layer(depsgraph);
+
+  DRW_select_context_create(depsgraph, bases, bases_len, select_mode);
+
+  DRW_opengl_context_enable();
+
+  /* Reset before using it. */
+  drw_state_prepare_clean_for_draw(&DST);
+  DST.buffer_finish_called = true;
+
+  /* Instead of 'DRW_context_state_init(C, &DST.draw_ctx)', assign from args */
+  DST.draw_ctx = (DRWContextState){
+      .ar = ar,
+      .rv3d = ar->regiondata,
+      .v3d = v3d,
+      .scene = scene,
+      .view_layer = view_layer,
+      .obact = OBACT(view_layer),
+      .depsgraph = depsgraph,
+  };
+
+  use_drw_engine(&draw_engine_select_type);
+  drw_context_state_init();
+
+  /* Setup viewport */
+  DST.viewport = WM_draw_region_get_viewport(ar, 0);
+  drw_viewport_var_init();
+
+  /* Update ubos */
+  DRW_globals_update();
+
+  /* Init engines */
+  drw_engines_init();
+
+  {
+    drw_engines_cache_init();
+
+    /* Keep `base_index` in sync with `e_data.context.last_base_drawn`.
+     * So don't skip objects. */
+    for (uint base_index = 0; base_index < bases_len; base_index++) {
+      Object *obj_eval = DEG_get_evaluated_object(depsgraph, bases[base_index]->object);
+      drw_engines_cache_populate(obj_eval);
+    }
+
+    drw_engines_cache_finish();
+  }
+
+  /* Start Drawing */
+  DRW_state_reset();
+  drw_engines_draw_scene();
+  DRW_state_reset();
+
+  drw_engines_disable();
+
+#ifdef DEBUG
+  /* Avoid accidental reuse. */
+  drw_state_ensure_not_reused(&DST);
+#endif
+
+  /* Changin context */
+  GPU_framebuffer_restore();
+  DRW_opengl_context_disable();
+}
+
 /** See #DRW_shgroup_world_clip_planes_from_rv3d. */
 static void draw_world_clip_planes_from_rv3d(GPUBatch *batch, const float world_clip_planes[6][4])
 {
@@ -2646,294 +2691,6 @@ void DRW_draw_depth_object(ARegion *ar, GPUViewport *viewport, Object *object)
   DRW_opengl_context_disable();
 }
 
-static void draw_mesh_verts(GPUBatch *batch, uint offset, const float world_clip_planes[6][4])
-{
-  GPU_point_size(UI_GetThemeValuef(TH_VERTEX_SIZE));
-
-  const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED :
-                                                      GPU_SHADER_CFG_DEFAULT;
-  GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_FLAT_SELECT_ID, sh_cfg);
-  GPU_batch_uniform_1ui(batch, "offset", offset);
-  if (world_clip_planes != NULL) {
-    draw_world_clip_planes_from_rv3d(batch, world_clip_planes);
-  }
-  GPU_batch_draw(batch);
-}
-
-static void draw_mesh_edges(GPUBatch *batch, uint offset, const float world_clip_planes[6][4])
-{
-  GPU_line_width(1.0f);
-  glProvokingVertex(GL_FIRST_VERTEX_CONVENTION);
-
-  const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED :
-                                                      GPU_SHADER_CFG_DEFAULT;
-  GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_FLAT_SELECT_ID, sh_cfg);
-  GPU_batch_uniform_1ui(batch, "offset", offset);
-  if (world_clip_planes != NULL) {
-    draw_world_clip_planes_from_rv3d(batch, world_clip_planes);
-  }
-  GPU_batch_draw(batch);
-
-  glProvokingVertex(GL_LAST_VERTEX_CONVENTION);
-}
-
-/* two options, facecolors or black */
-static void draw_mesh_face(GPUBatch *batch,
-                           uint offset,
-                           const bool use_select,
-                           const float world_clip_planes[6][4])
-{
-  if (use_select) {
-    const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED :
-                                                        GPU_SHADER_CFG_DEFAULT;
-    GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_FLAT_SELECT_ID, sh_cfg);
-    GPU_batch_uniform_1ui(batch, "offset", offset);
-    if (world_clip_planes != NULL) {
-      draw_world_clip_planes_from_rv3d(batch, world_clip_planes);
-    }
-    GPU_batch_draw(batch);
-  }
-  else {
-    const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED :
-                                                        GPU_SHADER_CFG_DEFAULT;
-    GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_UNIFORM_SELECT_ID, sh_cfg);
-    GPU_batch_uniform_1ui(batch, "id", 0);
-    if (world_clip_planes != NULL) {
-      draw_world_clip_planes_from_rv3d(batch, world_clip_planes);
-    }
-    GPU_batch_draw(batch);
-  }
-}
-
-static void draw_mesh_face_dot(GPUBatch *batch, uint offset, const float world_clip_planes[6][4])
-{
-  const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED :
-                                                      GPU_SHADER_CFG_DEFAULT;
-  GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_FLAT_SELECT_ID, sh_cfg);
-  GPU_batch_uniform_1ui(batch, "offset", offset);
-  if (world_clip_planes != NULL) {
-    draw_world_clip_planes_from_rv3d(batch, world_clip_planes);
-  }
-  GPU_batch_draw(batch);
-}
-
-void DRW_draw_select_id_object(Scene *scene,
-                               RegionView3D *rv3d,
-                               Object *ob,
-                               short select_mode,
-                               bool draw_facedot,
-                               uint initial_offset,
-                               uint *r_vert_offset,
-                               uint *r_edge_offset,
-                               uint *r_face_offset)
-{
-  ToolSettings *ts = scene->toolsettings;
-  if (select_mode == -1) {
-    select_mode = ts->selectmode;
-  }
-
-  /* Init the scene of the draw context. When using face dot selection on
-   * when the subsurf modifier is active on the cage, the scene needs to be
-   * valid. It is read from the context in the
-   * `DRW_mesh_batch_cache_create_requested` and used in the `isDisabled`
-   * method of the SubSurfModifier. */
-  DRWContextState *draw_ctx = &DST.draw_ctx;
-  draw_ctx->scene = scene;
-
-  GPU_matrix_mul(ob->obmat);
-
-  const float(*world_clip_planes)[4] = NULL;
-  if (rv3d->rflag & RV3D_CLIPPING) {
-    ED_view3d_clipping_local(rv3d, ob->obmat);
-    world_clip_planes = rv3d->clip_local;
-  }
-
-  BLI_assert(initial_offset > 0);
-
-  switch (ob->type) {
-    case OB_MESH:
-      if (ob->mode & OB_MODE_EDIT) {
-        Mesh *me = ob->data;
-        BMEditMesh *em = me->edit_mesh;
-        const bool use_faceselect = (select_mode & SCE_SELECT_FACE) != 0;
-
-        DRW_mesh_batch_cache_validate(me);
-
-        BM_mesh_elem_table_ensure(em->bm, BM_VERT | BM_EDGE | BM_FACE);
-
-        GPUBatch *geom_faces, *geom_edges, *geom_verts, *geom_facedots;
-        geom_faces = DRW_mesh_batch_cache_get_triangles_with_select_id(me);
-        if (select_mode & SCE_SELECT_EDGE) {
-          geom_edges = DRW_mesh_batch_cache_get_edges_with_select_id(me);
-        }
-        if (select_mode & SCE_SELECT_VERTEX) {
-          geom_verts = DRW_mesh_batch_cache_get_verts_with_select_id(me);
-        }
-        if (use_faceselect && draw_facedot) {
-          geom_facedots = DRW_mesh_batch_cache_get_facedots_with_select_id(me);
-        }
-        DRW_mesh_batch_cache_create_requested(ob, me, NULL, false, true);
-
-        draw_mesh_face(geom_faces, initial_offset, use_faceselect, world_clip_planes);
-
-        if (use_faceselect && draw_facedot) {
-          draw_mesh_face_dot(geom_facedots, initial_offset, world_clip_planes);
-        }
-
-        if (select_mode & SCE_SELECT_FACE) {
-          *r_face_offset = initial_offset + em->bm->totface;
-        }
-        else {
-          *r_face_offset = initial_offset;
-        }
-
-        ED_view3d_polygon_offset(rv3d, 1.0);
-
-        /* Unlike faces, only draw edges if edge select mode. */
-        if (select_mode & SCE_SELECT_EDGE) {
-          draw_mesh_edges(geom_edges, *r_face_offset, world_clip_planes);
-          *r_edge_offset = *r_face_offset + em->bm->totedge;
-        }
-        else {
-          /* Note that `r_vert_offset` is calculated from `r_edge_offset`.
-           * Otherwise the first vertex is never selected, see: T53512. */
-          *r_edge_offset = *r_face_offset;
-        }
-
-        ED_view3d_polygon_offset(rv3d, 1.1);
-
-        /* Unlike faces, only verts if vert select mode. */
-        if (select_mode & SCE_SELECT_VERTEX) {
-          draw_mesh_verts(geom_verts, *r_edge_offset, world_clip_planes);
-          *r_vert_offset = *r_edge_offset + em->bm->totvert;
-        }
-        else {
-          *r_vert_offset = *r_edge_offset;
-        }
-
-        ED_view3d_polygon_offset(rv3d, 0.0);
-      }
-      else {
-        Mesh *me_orig = DEG_get_original_object(ob)->data;
-        Mesh *me_eval = ob->data;
-
-        DRW_mesh_batch_cache_validate(me_eval);
-        GPUBatch *geom_faces = DRW_mesh_batch_cache_get_triangles_with_select_id(me_eval);
-        if ((me_orig->editflag & ME_EDIT_PAINT_VERT_SEL) &&
-            /* Currently vertex select supports weight paint and vertex paint. */
-            ((ob->mode & OB_MODE_WEIGHT_PAINT) || (ob->mode & OB_MODE_VERTEX_PAINT))) {
-
-          GPUBatch *geom_verts = DRW_mesh_batch_cache_get_verts_with_select_id(me_eval);
-          DRW_mesh_batch_cache_create_requested(ob, me_eval, NULL, false, true);
-
-          /* Only draw faces to mask out verts, we don't want their selection ID's. */
-          draw_mesh_face(geom_faces, 0, false, world_clip_planes);
-          draw_mesh_verts(geom_verts, 1, world_clip_planes);
-
-          *r_face_offset = *r_edge_offset = initial_offset;
-          *r_vert_offset = me_eval->totvert + 1;
-        }
-        else {
-          const bool use_hide = (me_orig->editflag & ME_EDIT_PAINT_FACE_SEL);
-          DRW_mesh_batch_cache_create_requested(ob, me_eval, NULL, false, use_hide);
-
-          draw_mesh_face(geom_faces, initial_offset, true, world_clip_planes);
-
-          *r_face_offset = initial_offset + me_eval->totpoly;
-          *r_edge_offset = *r_vert_offset = *r_face_offset;
-        }
-      }
-      break;
-    case OB_CURVE:
-    case OB_SURF:
-      break;
-  }
-
-  GPU_matrix_set(rv3d->viewmat);
-}
-
-/* Set an opengl context to be used with shaders that draw on U32 colors. */
-void DRW_framebuffer_select_id_setup(ARegion *ar, const bool clear)
-{
-  RegionView3D *rv3d = ar->regiondata;
-
-  DRW_opengl_context_enable();
-
-  /* Setup framebuffer */
-  int viewport_size[2] = {ar->winx, ar->winy};
-  draw_select_framebuffer_select_id_setup(viewport_size);
-  GPU_framebuffer_bind(g_select_buffer.framebuffer_select_id);
-
-  /* dithering and AA break color coding, so disable */
-  glDisable(GL_DITHER);
-
-  GPU_depth_test(true);
-  GPU_program_point_size(false);
-
-  if (clear) {
-    GPU_framebuffer_clear_color_depth(
-        g_select_buffer.framebuffer_select_id, (const float[4]){0.0f}, 1.0f);
-  }
-
-  if (rv3d->rflag & RV3D_CLIPPING) {
-    ED_view3d_clipping_set(rv3d);
-  }
-}
-
-/* Ends the context for selection and restoring the previous one. */
-void DRW_framebuffer_select_id_release(ARegion *ar)
-{
-  RegionView3D *rv3d = ar->regiondata;
-
-  if (rv3d->rflag & RV3D_CLIPPING) {
-    ED_view3d_clipping_disable();
-  }
-
-  GPU_depth_test(false);
-
-  GPU_framebuffer_restore();
-
-  DRW_opengl_context_disable();
-}
-
-/* Read a block of pixels from the select frame buffer. */
-void DRW_framebuffer_select_id_read(const rcti *rect, uint *r_buf)
-{
-  /* clamp rect by texture */
-  rcti r = {
-      .xmin = 0,
-      .xmax = GPU_texture_width(g_select_buffer.texture_u32),
-      .ymin = 0,
-      .ymax = GPU_texture_height(g_select_buffer.texture_u32),
-  };
-
-  rcti rect_clamp = *rect;
-  if (BLI_rcti_isect(&r, &rect_clamp, &rect_clamp)) {
-    DRW_opengl_context_enable();
-    GPU_framebuffer_bind(g_select_buffer.framebuffer_select_id);
-    glReadBuffer(GL_COLOR_ATTACHMENT0);
-    glReadPixels(rect_clamp.xmin,
-                 rect_clamp.ymin,
-                 BLI_rcti_size_x(&rect_clamp),
-                 BLI_rcti_size_y(&rect_clamp),
-                 GL_RED_INTEGER,
-                 GL_UNSIGNED_INT,
-                 r_buf);
-
-    GPU_framebuffer_restore();
-    DRW_opengl_context_disable();
-
-    if (!BLI_rcti_compare(rect, &rect_clamp)) {
-      GPU_select_buffer_stride_realign(rect, &rect_clamp, r_buf);
-    }
-  }
-  else {
-    size_t buf_size = BLI_rcti_size_x(rect) * BLI_rcti_size_y(rect) * sizeof(*r_buf);
-
-    memset(r_buf, 0, buf_size);
-  }
-}
-
 /** \} */
 
 /* -------------------------------------------------------------------- */
@@ -3089,6 +2846,7 @@ void DRW_engines_register(void)
   DRW_engine_register(&draw_engine_pose_type);
   DRW_engine_register(&draw_engine_sculpt_type);
   DRW_engine_register(&draw_engine_gpencil_type);
+  DRW_engine_register(&draw_engine_select_type);
 
   /* setup callbacks */
   {
@@ -3123,9 +2881,7 @@ void DRW_engines_free(void)
 
   DRW_opengl_context_enable();
 
-  DRW_TEXTURE_FREE_SAFE(g_select_buffer.texture_u32);
   DRW_TEXTURE_FREE_SAFE(g_select_buffer.texture_depth);
-  GPU_FRAMEBUFFER_FREE_SAFE(g_select_buffer.framebuffer_select_id);
   GPU_FRAMEBUFFER_FREE_SAFE(g_select_buffer.framebuffer_depth_only);
 
   DRW_hair_free();