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

4 files changed, 716 insertions, 0 deletions

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;
+}