Curves: new Add brush

This adds a new Add brush for the new curves object type in sculpt mode.
The brush is used to insert new curves (typically hair) on the surface object.

Supported features:
* Add single curve exactly at the cursor position when `Add Amount` is 1.
* Front faces only.
* Independent interpolate shape and interpolate length settings.
* Smooth and flat shading affects curve shape interpolation.
* Spherical and projection brush.

This also adds the `surface_triangle_index` and `surface_triangle_coordinate`
attributes. Those store information about what position on the surface each
added curve is attached to:
* `surface_triangle_index` (`int`): Index of the internal triangle that a curve
  is attached to. `-1` when the curve is not attached to the surface.
* `surface_triangle_coordinate` (`float2`): First two numbers of a barycentric
  coordinate that reference a specific position within the triangle.

Ref T96444.

Differential Revision: https://developer.blender.org/D14340

1 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/blenloader/intern/versioning_300.c b/source/blender/blenloader/intern/versioning_300.c
index 5b1964aa35c..19b7e1e4f3c 100644
--- a/source/blender/blenloader/intern/versioning_300.c
+++ b/source/blender/blenloader/intern/versioning_300.c
@@ -2428,5 +2428,23 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
    */
   {
     /* Keep this block, even when empty. */
+
+    /* Initialize brush curves sculpt settings. */
+    LISTBASE_FOREACH (Brush *, brush, &bmain->brushes) {
+      if (brush->ob_mode != OB_MODE_SCULPT_CURVES) {
+        continue;
+      }
+      if (brush->curves_sculpt_settings != NULL) {
+        continue;
+      }
+      brush->curves_sculpt_settings = MEM_callocN(sizeof(BrushCurvesSculptSettings), __func__);
+      brush->curves_sculpt_settings->add_amount = 1;
+    }
+    LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+      if (scene->toolsettings && scene->toolsettings->curves_sculpt &&
+          scene->toolsettings->curves_sculpt->curve_length == 0.0f) {
+        scene->toolsettings->curves_sculpt->curve_length = 0.3f;
+      }
+    }
   }
 }