Curves: Implement Handles for selected points only

When editing a complex curve is very annoying to have all handles at a time. Also, this is a requirement for the current GSoC Edit Grease Pencil using curves.
I have seen that this improvement can be used in any other area of blender, so I have decided to publish the option in the overlay panel..

Reviewed By: fclem, #user_interface, billreynish, Severin

Differential Revision: https://developer.blender.org/D7754

5 files changed, 33 insertions, 3 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_edit_curve.c b/source/blender/draw/engines/overlay/overlay_edit_curve.c
index 6456d6868a5..9a79c78c996 100644
--- a/source/blender/draw/engines/overlay/overlay_edit_curve.c
+++ b/source/blender/draw/engines/overlay/overlay_edit_curve.c
@@ -36,7 +36,8 @@ void OVERLAY_edit_curve_cache_init(OVERLAY_Data *vedata)
   GPUShader *sh;
   DRWState state;
 
-  pd->edit_curve.show_handles = (v3d->overlay.edit_flag & V3D_OVERLAY_EDIT_CU_HANDLES) != 0;
+  pd->edit_curve.show_handles = v3d->overlay.handle_display != CURVE_HANDLE_NONE;
+  pd->edit_curve.handle_display = v3d->overlay.handle_display;
   pd->shdata.edit_curve_normal_length = v3d->overlay.normals_length;
 
   /* Run Twice for in-front passes. */
@@ -62,11 +63,13 @@ void OVERLAY_edit_curve_cache_init(OVERLAY_Data *vedata)
     pd->edit_curve_handle_grp = grp = DRW_shgroup_create(sh, psl->edit_curve_handle_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_curve_points_grp = grp = DRW_shgroup_create(sh, psl->edit_curve_handle_ps);
     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_uniform_block(grp, "globalsBlock", G_draw.block_ubo);
   }
 }
diff --git a/source/blender/draw/engines/overlay/overlay_edit_text.c b/source/blender/draw/engines/overlay/overlay_edit_text.c
index 3de0155d6e0..c4d020adc11 100644
--- a/source/blender/draw/engines/overlay/overlay_edit_text.c
+++ b/source/blender/draw/engines/overlay/overlay_edit_text.c
@@ -38,7 +38,8 @@ void OVERLAY_edit_text_cache_init(OVERLAY_Data *vedata)
   GPUShader *sh;
   DRWState state;
 
-  pd->edit_curve.show_handles = (v3d->overlay.edit_flag & V3D_OVERLAY_EDIT_CU_HANDLES) != 0;
+  pd->edit_curve.show_handles = v3d->overlay.handle_display != CURVE_HANDLE_NONE;
+  pd->edit_curve.handle_display = v3d->overlay.handle_display;
   pd->shdata.edit_curve_normal_length = v3d->overlay.normals_length;
 
   /* Run Twice for in-front passes. */
diff --git a/source/blender/draw/engines/overlay/overlay_private.h b/source/blender/draw/engines/overlay/overlay_private.h
index fa7c7f6d090..8afa562c937 100644
--- a/source/blender/draw/engines/overlay/overlay_private.h
+++ b/source/blender/draw/engines/overlay/overlay_private.h
@@ -297,6 +297,7 @@ typedef struct OVERLAY_PrivateData {
   } antialiasing;
   struct {
     bool show_handles;
+    int handle_display;
   } edit_curve;
   struct {
     int ghost_ob;
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 b444b3b0fec..306fbb473ee 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
@@ -4,10 +4,15 @@
 #define EVEN_U_BIT 1 << 4
 #define COLOR_SHIFT 5
 
+/* Keep the same value in `handle_display` in `DNA_view3d_types.h` */
+#define CURVE_HANDLE_SELECTED 0
+#define CURVE_HANDLE_ALL 1
+
 layout(lines) in;
 layout(triangle_strip, max_vertices = 10) out;
 
 uniform bool showCurveHandles;
+uniform int curveHandleDisplay;
 
 flat in int vertFlag[];
 
@@ -46,6 +51,17 @@ void main()
   }
 
   bool edge_selected = (((vertFlag[1] | vertFlag[0]) & VERT_SELECTED) != 0);
+  bool handle_selected = (showCurveHandles &&
+                          (((vertFlag[1] | vertFlag[0]) & HANDLE_SELECTED) != 0));
+
+  /* If handle type is only selected and the edge is not selected, don't show. */
+  if ((curveHandleDisplay != CURVE_HANDLE_ALL) && (!handle_selected)) {
+    /* Nurbs must show the handles always. */
+    bool is_u_segment = (((vertFlag[1] ^ vertFlag[0]) & EVEN_U_BIT) != 0);
+    if (!is_u_segment) {
+      return;
+    }
+  }
 
   vec4 inner_color;
   if (color_id == 0) {
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 6fa4576ae71..b1e1c0879a5 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
@@ -2,7 +2,11 @@
 /* Keep the same value of `BEZIER_HANDLE` in `draw_cache_imp_curve.c` */
 #define BEZIER_HANDLE 1 << 3
 
+/* Keep the same value in `handle_display` in `DNA_view3d_types.h` */
+#define CURVE_HANDLE_SELECTED 0
+
 uniform bool showCurveHandles;
+uniform int curveHandleDisplay;
 
 in vec3 pos;
 in int data;
@@ -32,7 +36,12 @@ void main()
   world_clip_planes_calc_clip_distance(world_pos);
 #endif
 
-  if (!showCurveHandles && ((data & BEZIER_HANDLE) != 0)) {
+  bool show_handle = showCurveHandles;
+  if ((curveHandleDisplay == CURVE_HANDLE_SELECTED) && ((data & HANDLE_SELECTED) == 0)) {
+    show_handle = false;
+  }
+
+  if (!show_handle && ((data & BEZIER_HANDLE) != 0)) {
     /* We set the vertex at the camera origin to generate 0 fragments. */
     gl_Position = vec4(0.0, 0.0, -3e36, 0.0);
   }