Sculpt: Line Project Gesture tool

This tool projects all vertices to the right of the plane defined by the
line gesture towards the plane. By doing this, this tool can create cuts
and plane surfaces in the mesh without modifying the geometry or using
boolean operations, so it is much faster than bisecting the mesh for
cases where the geometry was going to be remeshed afterwards.

Added as experimental as it does not have icon.

Reviewed By: sergey, Severin

Differential Revision: https://developer.blender.org/D9021

release/scripts/startup/bl_ui/space_toolsystem_toolbar.py

@@ -1324,6 +1324,16 @@ class _defs_sculpt:
             keymap=(),
         )
 
+    @ToolDef.from_fn
+    def project_line():
+        return dict(
+            idname="builtin.line_project",
+            label="Line Project",
+            icon="ops.sculpt.line_project",
+            widget=None,
+            keymap=(),
+        )
+
     @ToolDef.from_fn
     def mesh_filter():
         def draw_settings(_context, layout, tool):
@@ -2702,6 +2712,13 @@ class VIEW3D_PT_tools_active(ToolSelectPanelHelper, Panel):
                         context.preferences.experimental.use_tools_missing_icons)
                 else ()
             ),
+            lambda context: (
+                (_defs_sculpt.project_line,)
+                if context is None or (
+                        context.preferences.view.show_developer_ui and
+                        context.preferences.experimental.use_tools_missing_icons)
+                else ()
+            ),
             None,
             _defs_sculpt.mesh_filter,
             _defs_sculpt.cloth_filter,