Transfer Data: add main core code and operators.

This add code needed to map a CD data layout from source mesh towards destination one,
and code needed to actually transfer data, using BKE's mesh remap generated data.

This allows to transfer most CD layers (vgroups, vcols, uvs...) as well as fake, boolean ones
(like smooth/sharp edges/faces, etc.). Some types are not yet transferable, mainly
shape keys, this is known TODO.

Data transfer can also use some advanced mixing in some cases (mostly, vgroups and vcols).

Notes:
* New transfer operators transfer data from active object towards selected ones.
* Modifier will be committed separately.
* Old weight transfer code (for vgroups) is kept for now, mostly because it is the only
  usable one in weightpaint mode (it transfers from selected object to active one,
  this is not sensible in Object mode, but needed in WeightPaint one). This will be addressed soon.

Again, heavily reviewed and enhanced by Campbell, thanks!

1 files changed, 86 insertions, 2 deletions

diff --git a/source/blender/blenkernel/BKE_customdata.h b/source/blender/blenkernel/BKE_customdata.h
index 30a58891bda..08edde1cec0 100644
--- a/source/blender/blenkernel/BKE_customdata.h
+++ b/source/blender/blenkernel/BKE_customdata.h
@@ -41,6 +41,8 @@ extern "C" {
 #include "BLI_sys_types.h"
 #include "BLI_utildefines.h"
 
+#include "DNA_customdata_types.h"
+
 struct BMesh;
 struct ID;
 struct CustomData;
@@ -77,6 +79,9 @@ extern const CustomDataMask CD_MASK_EVERYTHING;
 
 void customData_mask_layers__print(CustomDataMask mask);
 
+typedef void (*cd_interp)(void **sources, const float *weights, const float *sub_weights, int count, void *dest);
+typedef void (*cd_copy)(const void *source, void *dest, int count);
+
 /**
  * Checks if the layer at physical offset \a layer_n (in data->layers) support math
  * the below operations.
@@ -96,6 +101,9 @@ bool CustomData_bmesh_has_free(const struct CustomData *data);
  * implemented for mloopuv/mloopcol, for now.*/
 void CustomData_data_copy_value(int type, const void *source, void *dest);
 
+/* Same as above, but doing advanced mixing. Only available for a few types of data (like colors...). */
+void CustomData_data_mix_value(int type, const void *source, void *dest, const int mixmode, const float mixfactor);
+
 /* compares if data1 is equal to data2.  type is a valid CustomData type
  * enum (e.g. CD_MLOOPUV). the layer type's equal function is used to compare
  * the data, if it exists, otherwise memcmp is used.*/
@@ -246,14 +254,14 @@ void *CustomData_bmesh_get_n(const struct CustomData *data, void *block, int typ
 void *CustomData_bmesh_get_layer_n(const struct CustomData *data, void *block, int n);
 
 bool CustomData_set_layer_name(const struct CustomData *data, int type, int n, const char *name);
+const char *CustomData_get_layer_name(const struct CustomData *data, int type, int n);
 
 /* gets a pointer to the active or first layer of type
  * returns NULL if there is no layer of type
  */
 void *CustomData_get_layer(const struct CustomData *data, int type);
 void *CustomData_get_layer_n(const struct CustomData *data, int type, int n);
-void *CustomData_get_layer_named(const struct CustomData *data, int type,
-                                 const char *name);
+void *CustomData_get_layer_named(const struct CustomData *data, int type, const char *name);
 int CustomData_get_offset(const struct CustomData *data, int type);
 int CustomData_get_n_offset(const struct CustomData *data, int type, int n);
 
@@ -362,6 +370,82 @@ void CustomData_external_read(struct CustomData *data,
 void CustomData_external_reload(struct CustomData *data,
                                 struct ID *id, CustomDataMask mask, int totelem);
 
+/* Mesh-to-mesh transfer data. */
+
+struct MeshPairRemap;
+typedef struct CustomDataTransferLayerMap CustomDataTransferLayerMap;
+
+typedef void (*cd_datatransfer_interp)(
+        const CustomDataTransferLayerMap *laymap, void *dest,
+        void **sources, const float *weights, const int count, const float mix_factor);
+
+/**
+ * Fake CD_LAYERS (those are actually 'real' data stored directly into elements' structs, or otherwise not (directly)
+ * accessible to usual CDLayer system). */
+enum {
+	CD_FAKE             = 1 << 8,
+
+	/* Vertices. */
+	CD_FAKE_MDEFORMVERT = CD_FAKE | CD_MDEFORMVERT,  /* *sigh* due to how vgroups are stored :( . */
+	CD_FAKE_SHAPEKEY    = CD_FAKE | CD_SHAPEKEY,  /* Not available as real CD layer in non-bmesh context. */
+
+	/* Edges. */
+	CD_FAKE_SEAM        = CD_FAKE | 100,  /* UV seam flag for edges. */
+	CD_FAKE_CREASE      = CD_FAKE | CD_CREASE,  /* *sigh*. */
+
+	/* Multiple types of mesh elements... */
+	CD_FAKE_BWEIGHT     = CD_FAKE | CD_BWEIGHT,  /* *sigh*. */
+	CD_FAKE_UV          = CD_FAKE | CD_MLOOPUV,  /* UV flag, because we handle both loop's UVs and poly's textures. */
+
+	CD_FAKE_SHARP       = CD_FAKE | 200,  /* Sharp flag for edges, smooth flag for faces. */
+};
+
+enum {
+	ME_VERT = 1 << 0,
+	ME_EDGE = 1 << 1,
+	ME_POLY = 1 << 2,
+	ME_LOOP = 1 << 3,
+};
+
+/**
+ * How to filter out some elements (to leave untouched).
+ * Note those options are highly dependent on type of transferred data! */
+enum {
+	CDT_MIX_NOMIX                   = -1,  /* Special case, only used because we abuse 'copy' CD callback. */
+	CDT_MIX_TRANSFER                = 0,
+	CDT_MIX_REPLACE_ABOVE_THRESHOLD = 1,
+	CDT_MIX_REPLACE_BELOW_THRESHOLD = 2,
+	CDT_MIX_MIX                     = 16,
+	CDT_MIX_ADD                     = 17,
+	CDT_MIX_SUB                     = 18,
+	CDT_MIX_MUL                     = 19,
+	/* etc. etc. */
+};
+
+typedef struct CustomDataTransferLayerMap {
+	CustomDataTransferLayerMap *next, *prev;
+
+	int data_type;
+	int mix_mode;
+	float mix_factor;
+	const float *mix_weights;  /* If non-NULL, array of weights, one for each dest item, replaces mix_factor. */
+
+	void *data_src;      /* Data source array (can be regular CD data, vertices/edges/etc., keyblocks...). */
+	void *data_dst;      /* Data dest array (same type as dat_src). */
+	int   data_src_n;    /* Index to affect in data_src (used e.g. for vgroups). */
+	int   data_dst_n;    /* Index to affect in data_dst (used e.g. for vgroups). */
+	size_t elem_size;    /* Size of one element of data_src/data_dst. */
+
+	size_t data_size;    /* Size of actual data we transfer. */
+	size_t data_offset;  /* Offset of actual data we transfer (in element contained in data_src/dst). */
+	uint64_t data_flag;  /* For bitflag transfer, flag(s) to affect in transfered data. */
+
+	cd_datatransfer_interp interp;
+} CustomDataTransferLayerMap;
+
+/* Those functions assume src_n and dst_n layers of given type exist in resp. src and dst. */
+void CustomData_data_transfer(const struct MeshPairRemap *me_remap, const CustomDataTransferLayerMap *laymap);
+
 #ifdef __cplusplus
 }
 #endif