Volumes: support selection and outlines in viewport

Previously, one could only select a volume object in the outliner
or by clicking on the object origin. This patch allows you to click
on the actual volume.

Furthermore, the generated (invisible) mesh that is used for
selection is also used to draw an outline for the volume object now.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D9022

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_volume_render.h b/source/blender/blenkernel/BKE_volume_render.h
index a42f24a5312..593f296135c 100644
--- a/source/blender/blenkernel/BKE_volume_render.h
+++ b/source/blender/blenkernel/BKE_volume_render.h
@@ -58,6 +58,16 @@ void BKE_volume_grid_wireframe(const struct Volume *volume,
                                BKE_volume_wireframe_cb cb,
                                void *cb_userdata);
 
+/* Selection Surface */
+
+typedef void (*BKE_volume_selection_surface_cb)(
+    void *userdata, float (*verts)[3], int (*tris)[3], int totvert, int tottris);
+
+void BKE_volume_grid_selection_surface(const struct Volume *volume,
+                                       struct VolumeGrid *volume_grid,
+                                       BKE_volume_selection_surface_cb cb,
+                                       void *cb_userdata);
+
 /* Render */
 
 float BKE_volume_density_scale(const struct Volume *volume, const float matrix[4][4]);