GPencil: Merge GSoC curve edit mode

Differential Revision: https://developer.blender.org/D8660

This patch is the result of the GSoC 2020 "Editing Grease Pencil Strokes
Using Curves" project. It adds a submode to greasepencil edit mode that
allows for the transformation of greasepencil strokes using bezier
curves. More information about the project can be found
here: https://wiki.blender.org/wiki/User:Filedescriptor/GSoC_2020.

4 files changed, 72 insertions, 3 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_gpencil.c b/source/blender/draw/engines/overlay/overlay_gpencil.c
index ccc914e0422..7f9290a6c3a 100644
--- a/source/blender/draw/engines/overlay/overlay_gpencil.c
+++ b/source/blender/draw/engines/overlay/overlay_gpencil.c
@@ -49,6 +49,10 @@ void OVERLAY_edit_gpencil_cache_init(OVERLAY_Data *vedata)
   pd->edit_gpencil_wires_grp = NULL;
   psl->edit_gpencil_ps = NULL;
 
+  pd->edit_gpencil_curve_handle_grp = NULL;
+  pd->edit_gpencil_curve_points_grp = NULL;
+  psl->edit_gpencil_curve_ps = NULL;
+
   const DRWContextState *draw_ctx = DRW_context_state_get();
   View3D *v3d = draw_ctx->v3d;
   Object *ob = draw_ctx->obact;
@@ -105,7 +109,8 @@ void OVERLAY_edit_gpencil_cache_init(OVERLAY_Data *vedata)
                            (GPENCIL_EDIT_MODE(gpd) &&
                             (ts->gpencil_selectmode_edit != GP_SELECTMODE_STROKE));
 
-  if ((!GPENCIL_VERTEX_MODE(gpd) && !GPENCIL_PAINT_MODE(gpd)) || use_vertex_mask) {
+  if ((!GPENCIL_CURVE_EDIT_SESSIONS_ON(gpd)) &&
+      ((!GPENCIL_VERTEX_MODE(gpd) && !GPENCIL_PAINT_MODE(gpd)) || use_vertex_mask)) {
     DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS_EQUAL |
                      DRW_STATE_BLEND_ALPHA;
     DRW_PASS_CREATE(psl->edit_gpencil_ps, state | pd->clipping_state);
@@ -132,6 +137,37 @@ void OVERLAY_edit_gpencil_cache_init(OVERLAY_Data *vedata)
     }
   }
 
+  /* Handles and curve point for Curve Edit submode. */
+  if (GPENCIL_CURVE_EDIT_SESSIONS_ON(gpd)) {
+    DRWState state = DRW_STATE_WRITE_COLOR;
+    DRW_PASS_CREATE(psl->edit_gpencil_curve_ps, state | pd->clipping_state);
+
+    /* Edit lines. */
+    if (show_lines) {
+      sh = OVERLAY_shader_edit_gpencil_wire();
+      pd->edit_gpencil_wires_grp = grp = DRW_shgroup_create(sh, psl->edit_gpencil_curve_ps);
+      DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
+      DRW_shgroup_uniform_bool_copy(grp, "doMultiframe", show_multi_edit_lines);
+      DRW_shgroup_uniform_bool_copy(grp, "doWeightColor", is_weight_paint);
+      DRW_shgroup_uniform_bool_copy(grp, "hideSelect", hide_select);
+      DRW_shgroup_uniform_float_copy(grp, "gpEditOpacity", v3d->vertex_opacity);
+      DRW_shgroup_uniform_texture(grp, "weightTex", G_draw.weight_ramp);
+    }
+
+    sh = OVERLAY_shader_edit_curve_handle();
+    pd->edit_gpencil_curve_handle_grp = grp = DRW_shgroup_create(sh, psl->edit_gpencil_curve_ps);
+    DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
+    DRW_shgroup_uniform_bool_copy(grp, "showCurveHandles", pd->edit_curve.show_handles);
+    DRW_shgroup_uniform_int_copy(grp, "curveHandleDisplay", pd->edit_curve.handle_display);
+    DRW_shgroup_state_enable(grp, DRW_STATE_BLEND_ALPHA);
+
+    sh = OVERLAY_shader_edit_curve_point();
+    pd->edit_gpencil_curve_points_grp = grp = DRW_shgroup_create(sh, psl->edit_gpencil_curve_ps);
+    DRW_shgroup_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
+    DRW_shgroup_uniform_bool_copy(grp, "showCurveHandles", pd->edit_curve.show_handles);
+    DRW_shgroup_uniform_int_copy(grp, "curveHandleDisplay", pd->edit_curve.handle_display);
+  }
+
   /* control points for primitives and speed guide */
   const bool is_cppoint = (gpd->runtime.tot_cp_points > 0);
   const bool is_speed_guide = (ts->gp_sculpt.guide.use_guide &&
@@ -182,6 +218,7 @@ void OVERLAY_edit_gpencil_cache_init(OVERLAY_Data *vedata)
 void OVERLAY_gpencil_cache_init(OVERLAY_Data *vedata)
 {
   OVERLAY_PassList *psl = vedata->psl;
+  OVERLAY_PrivateData *pd = vedata->stl->pd;
   struct GPUShader *sh;
   DRWShadingGroup *grp;
 
@@ -196,6 +233,9 @@ void OVERLAY_gpencil_cache_init(OVERLAY_Data *vedata)
   ToolSettings *ts = scene->toolsettings;
   const View3DCursor *cursor = &scene->cursor;
 
+  pd->edit_curve.show_handles = v3d->overlay.handle_display != CURVE_HANDLE_NONE;
+  pd->edit_curve.handle_display = v3d->overlay.handle_display;
+
   if (gpd == NULL || ob->type != OB_GPENCIL) {
     return;
   }
@@ -303,6 +343,20 @@ static void OVERLAY_edit_gpencil_cache_populate(OVERLAY_Data *vedata, Object *ob
     struct GPUBatch *geom = DRW_cache_gpencil_edit_points_get(ob, pd->cfra);
     DRW_shgroup_call_no_cull(grp, geom, ob);
   }
+
+  if (pd->edit_gpencil_curve_handle_grp) {
+    struct GPUBatch *geom = DRW_cache_gpencil_edit_curve_handles_get(ob, pd->cfra);
+    if (geom) {
+      DRW_shgroup_call_no_cull(pd->edit_gpencil_curve_handle_grp, geom, ob);
+    }
+  }
+
+  if (pd->edit_gpencil_curve_points_grp) {
+    struct GPUBatch *geom = DRW_cache_gpencil_edit_curve_points_get(ob, pd->cfra);
+    if (geom) {
+      DRW_shgroup_call_no_cull(pd->edit_gpencil_curve_points_grp, geom, ob);
+    }
+  }
 }
 
 static void overlay_gpencil_draw_stroke_color_name(bGPDlayer *UNUSED(gpl),
@@ -407,4 +461,9 @@ void OVERLAY_edit_gpencil_draw(OVERLAY_Data *vedata)
   if (psl->edit_gpencil_ps) {
     DRW_draw_pass(psl->edit_gpencil_ps);
   }
+
+  /* Curve edit handles. */
+  if (psl->edit_gpencil_curve_ps) {
+    DRW_draw_pass(psl->edit_gpencil_curve_ps);
+  }
 }
diff --git a/source/blender/draw/engines/overlay/overlay_private.h b/source/blender/draw/engines/overlay/overlay_private.h
index c259d9351f3..b9d591a5642 100644
--- a/source/blender/draw/engines/overlay/overlay_private.h
+++ b/source/blender/draw/engines/overlay/overlay_private.h
@@ -77,6 +77,7 @@ typedef struct OVERLAY_PassList {
   DRWPass *edit_curve_handle_ps;
   DRWPass *edit_gpencil_ps;
   DRWPass *edit_gpencil_gizmos_ps;
+  DRWPass *edit_gpencil_curve_ps;
   DRWPass *edit_lattice_ps;
   DRWPass *edit_mesh_depth_ps[2];
   DRWPass *edit_mesh_verts_ps[2];
@@ -252,6 +253,8 @@ typedef struct OVERLAY_PrivateData {
   DRWShadingGroup *edit_lattice_wires_grp;
   DRWShadingGroup *edit_gpencil_points_grp;
   DRWShadingGroup *edit_gpencil_wires_grp;
+  DRWShadingGroup *edit_gpencil_curve_handle_grp;
+  DRWShadingGroup *edit_gpencil_curve_points_grp;
   DRWShadingGroup *edit_mesh_depth_grp[2];
   DRWShadingGroup *edit_mesh_faces_grp[2];
   DRWShadingGroup *edit_mesh_faces_cage_grp[2];
diff --git a/source/blender/draw/engines/overlay/shaders/edit_curve_handle_geom.glsl b/source/blender/draw/engines/overlay/shaders/edit_curve_handle_geom.glsl
index 9311542a79e..442f69aec7e 100644
--- a/source/blender/draw/engines/overlay/shaders/edit_curve_handle_geom.glsl
+++ b/source/blender/draw/engines/overlay/shaders/edit_curve_handle_geom.glsl
@@ -53,6 +53,9 @@ void main()
   bool edge_selected = (((vertFlag[1] | vertFlag[0]) & VERT_SELECTED) != 0);
   bool handle_selected = (showCurveHandles &&
                           (((vertFlag[1] | vertFlag[0]) & VERT_SELECTED_BEZT_HANDLE) != 0));
+  /* It reuses freestyle flag because the flag is 8 bits and all are already used and this
+   * flag is not used in this context. */
+  bool is_gpencil = ((vertFlag[1] & EDGE_FREESTYLE) != 0);
 
   /* If handle type is only selected and the edge is not selected, don't show. */
   if ((curveHandleDisplay != CURVE_HANDLE_ALL) && (!handle_selected)) {
@@ -61,6 +64,9 @@ void main()
     if ((!is_u_segment) && (color_id <= 4)) {
       return;
     }
+    if (is_gpencil) {
+      return;
+    }
   }
 
   vec4 inner_color;
diff --git a/source/blender/draw/engines/overlay/shaders/edit_curve_point_vert.glsl b/source/blender/draw/engines/overlay/shaders/edit_curve_point_vert.glsl
index a811fcca0d4..6b4edbfe578 100644
--- a/source/blender/draw/engines/overlay/shaders/edit_curve_point_vert.glsl
+++ b/source/blender/draw/engines/overlay/shaders/edit_curve_point_vert.glsl
@@ -17,16 +17,17 @@ void main()
 {
   GPU_INTEL_VERTEX_SHADER_WORKAROUND
 
+  /* Reuse the FREESTYLE flag to determine is GPencil. */
   if ((data & VERT_SELECTED) != 0) {
     if ((data & VERT_ACTIVE) != 0) {
       finalColor = colorEditMeshActive;
     }
     else {
-      finalColor = colorVertexSelect;
+      finalColor = ((data & EDGE_FREESTYLE) == 0) ? colorVertexSelect : colorGpencilVertexSelect;
     }
   }
   else {
-    finalColor = colorVertex;
+    finalColor = ((data & EDGE_FREESTYLE) == 0) ? colorVertex : colorGpencilVertex;
   }
 
   vec3 world_pos = point_object_to_world(pos);