1 files changed, 30 insertions, 1 deletions

diff --git a/source/blender/blenlib/BLI_boxpack_2d.h b/source/blender/blenlib/BLI_boxpack_2d.h
index 7e347d0b0d7..eee1a0d3d41 100644
--- a/source/blender/blenlib/BLI_boxpack_2d.h
+++ b/source/blender/blenlib/BLI_boxpack_2d.h
@@ -44,7 +44,21 @@ typedef struct BoxPack {
   int index;
 } BoxPack;
 
-void BLI_box_pack_2d(BoxPack *boxarray, const unsigned int len, float *r_tot_x, float *r_tot_y);
+/**
+ * Main box-packing function accessed from other functions
+ * This sets boxes x,y to positive values, sorting from 0,0 outwards.
+ * There is no limit to the space boxes may take, only that they will be packed
+ * tightly into the lower left hand corner (0,0)
+ *
+ * \param boxarray: a pre-allocated array of boxes.
+ *      only the 'box->x' and 'box->y' are set, 'box->w' and 'box->h' are used,
+ *      'box->index' is not used at all, the only reason its there
+ *          is that the box array is sorted by area and programs need to be able
+ *          to have some way of writing the boxes back to the original data.
+ * \param len: the number of boxes in the array.
+ * \param r_tot_x, r_tot_y: set so you can normalize the data.
+ */
+void BLI_box_pack_2d(BoxPack *boxarray, unsigned int len, float *r_tot_x, float *r_tot_y);
 
 typedef struct FixedSizeBoxPack {
   struct FixedSizeBoxPack *next, *prev;
@@ -52,6 +66,21 @@ typedef struct FixedSizeBoxPack {
   int w, h;
 } FixedSizeBoxPack;
 
+/**
+ * Packs boxes into a fixed area.
+ *
+ * Boxes and packed are linked lists containing structs that can be cast to
+ * #FixedSizeBoxPack (i.e. contains a #FixedSizeBoxPack as its first element).
+ * Boxes that were packed successfully are placed into *packed and removed from *boxes.
+ *
+ * The algorithm is a simplified version of https://github.com/TeamHypersomnia/rectpack2D.
+ * Better ones could be used, but for the current use case (packing Image tiles into GPU
+ * textures) this is fine.
+ *
+ * Note that packing efficiency depends on the order of the input boxes. Generally speaking,
+ * larger boxes should come first, though how exactly size is best defined (e.g. area, perimeter)
+ * depends on the particular application.
+ */
 void BLI_box_pack_2d_fixedarea(struct ListBase *boxes,
                                int width,
                                int height,