Add MDisps.hidden bitmap.

Updates SDNA, customdata functions, and file read/write. Also adds
accessor functions to BKE paint.

source/blender/blenkernel/BKE_paint.h

@@ -33,6 +33,7 @@
  */
 
 struct Brush;
+struct MDisps;
 struct MFace;
 struct MultireModifierData;
 struct MVert;
@@ -61,6 +62,11 @@ void paint_brush_set(struct Paint *paint, struct Brush *br);
 int paint_facesel_test(struct Object *ob);
 int paint_vertsel_test(struct Object *ob);
 
+/* partial visibility */
+int paint_is_face_hidden(const struct MFace *f, const struct MVert *mvert);
+int paint_is_grid_face_hidden(const unsigned int *grid_hidden,
+							  int gridsize, int x, int y);
+
 /* Session data (mode-specific) */
 
 typedef struct SculptSession {

source/blender/blenkernel/intern/customdata.c

@@ -484,6 +484,7 @@ static void layerCopy_mdisps(const void *source, void *dest, int count)
 	for(i = 0; i < count; ++i) {
 		if(s[i].disps) {
 			d[i].disps = MEM_dupallocN(s[i].disps);
+			d[i].hidden = MEM_dupallocN(s[i].hidden);
 			d[i].totdisp = s[i].totdisp;
 			d[i].level = s[i].level;
 		}
@@ -504,7 +505,10 @@ static void layerFree_mdisps(void *data, int count, int UNUSED(size))
 	for(i = 0; i < count; ++i) {
 		if(d[i].disps)
 			MEM_freeN(d[i].disps);
+		if(d[i].hidden)
+			MEM_freeN(d[i].hidden);
 		d[i].disps = NULL;
+		d[i].hidden = NULL;
 		d[i].totdisp = 0;
 		d[i].level = 0;
 	}

source/blender/blenkernel/intern/paint.c

@@ -33,15 +33,17 @@
 
 #include "DNA_object_types.h"
 #include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_brush_types.h"
 
+#include "BLI_bitmap.h"
 #include "BLI_utildefines.h"
 
-
 #include "BKE_brush.h"
 #include "BKE_library.h"
 #include "BKE_paint.h"
+#include "BKE_subsurf.h"
 
 #include <stdlib.h>
 #include <string.h>
@@ -147,3 +149,26 @@ void copy_paint(Paint *src, Paint *tar)
 	tar->brush= src->brush;
 	id_us_plus((ID *)tar->brush);
 }
+
+/* returns non-zero if any of the face's vertices
+   are hidden, zero otherwise */
+int paint_is_face_hidden(const MFace *f, const MVert *mvert)
+{
+	return ((mvert[f->v1].flag & ME_HIDE) ||
+			(mvert[f->v2].flag & ME_HIDE) ||
+			(mvert[f->v3].flag & ME_HIDE) ||
+			(f->v4 && (mvert[f->v4].flag & ME_HIDE)));
+}
+
+/* returns non-zero if any of the corners of the grid
+   face whose inner corner is at (x,y) are hidden,
+   zero otherwise */
+int paint_is_grid_face_hidden(const unsigned int *grid_hidden,
+							  int gridsize, int x, int y)
+{
+	/* skip face if any of its corners are hidden */
+	return (BLI_BITMAP_GET(grid_hidden, y * gridsize + x) ||
+			BLI_BITMAP_GET(grid_hidden, y * gridsize + x+1) ||
+			BLI_BITMAP_GET(grid_hidden, (y+1) * gridsize + x+1) ||
+			BLI_BITMAP_GET(grid_hidden, (y+1) * gridsize + x));
+}

source/blender/blenloader/intern/readfile.c

@@ -3750,6 +3750,7 @@ static void direct_link_mdisps(FileData *fd, int count, MDisps *mdisps, int exte
 
 		for(i = 0; i < count; ++i) {
 			mdisps[i].disps = newdataadr(fd, mdisps[i].disps);
+			mdisps[i].hidden = newdataadr(fd, mdisps[i].hidden);
 
 			if (mdisps[i].totdisp && !mdisps[i].level) {
 				/* this calculation is only correct for loop mdisps;

source/blender/blenloader/intern/writefile.c

@@ -135,6 +135,7 @@ Any case: direct data is ALWAYS after the lib block
 #include "DNA_movieclip_types.h"
 
 #include "MEM_guardedalloc.h" // MEM_freeN
+#include "BLI_bitmap.h"
 #include "BLI_blenlib.h"
 #include "BLI_linklist.h"
 #include "BLI_bpath.h"
@@ -1638,11 +1639,15 @@ static void write_mdisps(WriteData *wd, int count, MDisps *mdlist, int external)
 		int i;
 		
 		writestruct(wd, DATA, "MDisps", count, mdlist);
-		if(!external) {
+		for(i = 0; i < count; ++i) {
-			for(i = 0; i < count; ++i) {
+			MDisps *md = &mdlist[i];
-				if(mdlist[i].disps)
+			if(md->disps) {
-					writedata(wd, DATA, sizeof(float)*3*mdlist[i].totdisp, mdlist[i].disps);
+				if(!external)
+					writedata(wd, DATA, sizeof(float)*3*md->totdisp, md->disps);
 			}
+			
+			if(md->hidden)
+				writedata(wd, DATA, BLI_BITMAP_SIZE(md->totdisp), md->hidden);
 		}
 	}
 }

source/blender/makesdna/DNA_meshdata_types.h

@@ -166,6 +166,12 @@ typedef struct MDisps {
 	int totdisp;
 	int level;
 	float (*disps)[3];
+	
+	/* Used for hiding parts of a multires mesh. Essentially the multires
+	   equivalent of MVert.flag's ME_HIDE bit.
+	
+	   This is a bitmap, keep in sync with type used in BLI_bitmap.h */
+	unsigned int *hidden;
 } MDisps;
 
 /** Multires structs kept for compatibility with old files **/