Point Cache Refactoring

=======================

Caching and Baking:
- The point cache is now cleared on DAG_object_flush_update(), and not cleared for time dependency graph updates.
- There is now a Bake button instead of Protect. Also cache start and end frames were added to softbody and particles.
- The cloth autoprotect feature was removed.
- The Ctrl+B menu now also bakes cloth and particles next to softbody and fluids. Additionally there are now frree bake and free cache menu entries.
- The point cache api has been changed. There is now a PTCacheID struct for each point cache type that can be filled and then used to call the point cache functions.
- PointCache struct was added to DNA and is automatically allocated for each physics type.
- Soft body now supports Bake Editing just like cloth.
- Tried to make the systems deal consistently with time ipo's and offsets. Still not sure it all works correct, but too complicated to solve completely now.

Library Linking:
- Added some more warnings to prevent editing settings on library linked objects.
- Linked objects now read from the cache located next to the original library file, and never write to it. This restores old behavior for softbodies. For local simulation the mesh and not the object should be linked.
- Dupligroups and proxies can't create local point caches at the moment, how to implement that I'm not sure. We probably need a proxy point cache for that to work (ugh).

Physics UI:
- Renamed deflection panel to collision for consistency and reorganized the buttons. Also removed some softbody collision buttons from the softbody panel that were duplicated in this panel for cloth.
- Tweaked field panel buttons to not jump around when changing options.
- Tabbing e.g. Soft Body Collision into the Soft Body panel, it now only shows Collision to make the panel names readable.
- I tried to make enabled/disabling physics more consistent, since all three system did things different. Now the two modifier buttons to enable the modifier for the viewport and rendering are also duplicated in the physics panels. Toggling the Soft Body and Cloth buttons now both remove their modifiers.
- Fixed modifier error drawing glitch.

Particles:
- Particles are now recalculated more often than before. Previously it did partial updates based on the changes, but that doesn't work well with DAG_object_flush_update() ..
- Fixed memory leak loading keyed particle system. Now keys are not written to file anymore but always created after loading.
- Make particle threads work with autothreads.

Continue Physics:
- The timeline play now has a Continue Physics option in the playback menu, which keeps the simulations going without writing them to the cache.
- This doesn't always work that well, some changes are not immediately updated, but this can be improved later. Still it's fun to get a feel for the physics.

Todo:
- Point cache can get out of sync with and undo and changing a file without saving it.
- Change the point cache file format to store a version (so old point cache files can be either converted or at least ignored), and to do correct endian conversion.
- Menu item and/or buttons for Ctrl+B.
- A system("rm ..") was changed to remove() since the former is very slow for clearing point caches. These system() calls were already giving trouble in a bug in the tracker, but really most use of this system("") should be changed and tested.
- The Soft Body Collision and Clot Collision panel titles don't mention there's point cache settings there too, doing that makes them unreadable with the default panel setup.. but may need to make the names longer anyway.

1 files changed, 194 insertions, 345 deletions

diff --git a/source/blender/blenkernel/intern/cloth.c b/source/blender/blenkernel/intern/cloth.c
index 6123b1b5e35..15f4051c109 100644
--- a/source/blender/blenkernel/intern/cloth.c
+++ b/source/blender/blenkernel/intern/cloth.c
@@ -34,6 +34,7 @@
 
 #include "DNA_cloth_types.h"
 #include "DNA_mesh_types.h"
+#include "DNA_object_force.h"
 #include "DNA_scene_types.h"
 
 #include "BKE_deform.h"
@@ -92,7 +93,7 @@ static CM_SOLVER_DEF	solvers [] =
 */
 static void cloth_to_object (Object *ob,  ClothModifierData *clmd, DerivedMesh *dm);
 static void cloth_from_mesh ( Object *ob, ClothModifierData *clmd, DerivedMesh *dm );
-static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *dm, float framenr);
+static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *dm, float framenr, int first);
 int cloth_build_springs ( ClothModifierData *clmd, DerivedMesh *dm );
 static void cloth_apply_vgroup ( ClothModifierData *clmd, DerivedMesh *dm );
 
@@ -121,18 +122,11 @@ void cloth_init ( ClothModifierData *clmd )
 	clmd->sim_parms->Cvi = 1.0;
 	clmd->sim_parms->mass = 0.3f;
 	clmd->sim_parms->stepsPerFrame = 5;
-	clmd->sim_parms->sim_time = 1.0;
-	clmd->sim_parms->flags = CLOTH_SIMSETTINGS_FLAG_AUTOPROTECT;
+	clmd->sim_parms->flags = 0;
 	clmd->sim_parms->solver_type = 0;
 	clmd->sim_parms->preroll = 0;
 	clmd->sim_parms->maxspringlen = 10;
-	clmd->sim_parms->firstframe = 1;
-	clmd->sim_parms->lastframe = 250;
 	clmd->sim_parms->vgroup_mass = 0;
-	clmd->sim_parms->lastcachedframe = 0;
-	clmd->sim_parms->editedframe = 0;
-	clmd->sim_parms->autoprotect = 25;
-	clmd->sim_parms->firstcachedframe = -1.0;
 	clmd->sim_parms->avg_spring_len = 0.0;
 	clmd->sim_parms->presets = 2; /* cotton as start setting */
 	clmd->sim_parms->timescale = 1.0f; /* speed factor, describes how fast cloth moves */
@@ -246,395 +240,266 @@ int modifiers_indexInObject(Object *ob, ModifierData *md_seek);
 
 int cloth_read_cache(Object *ob, ClothModifierData *clmd, float framenr)
 {
-	FILE *fp = NULL;
-	int stack_index = -1;
-	unsigned int a, ret = 1;
+	PTCacheID pid;
+	PTCacheFile *pf;
 	Cloth *cloth = clmd->clothObject;
+	unsigned int a, ret = 1;
 	
 	if(!cloth)
 		return 0;
 	
-	stack_index = modifiers_indexInObject(ob, (ModifierData *)clmd);
-	
-	fp = BKE_ptcache_id_fopen((ID *)ob, 'r', framenr, stack_index);
-	if(!fp)
-		ret = 0;
-	else {
-		for(a = 0; a < cloth->numverts; a++)
-		{
-			if(fread(&cloth->verts[a].x, sizeof(float), 3, fp) != 3) 
-			{
+	BKE_ptcache_id_from_cloth(&pid, ob, clmd);
+	pf = BKE_ptcache_file_open(&pid, PTCACHE_FILE_READ, framenr);
+	if(pf) {
+		for(a = 0; a < cloth->numverts; a++) {
+			if(!BKE_ptcache_file_read_floats(pf, cloth->verts[a].x, 3)) {
 				ret = 0;
 				break;
 			}
-			if(fread(&cloth->verts[a].xconst, sizeof(float), 3, fp) != 3) 
-			{
+			if(!BKE_ptcache_file_read_floats(pf, cloth->verts[a].xconst, 3)) {
 				ret = 0;
 				break;
 			}
-			if(fread(&cloth->verts[a].v, sizeof(float), 3, fp) != 3) 
-			{
+			if(!BKE_ptcache_file_read_floats(pf, cloth->verts[a].v, 3)) {
 				ret = 0;
 				break;
 			}
 		}
 		
-		fclose(fp);
-		
-		if(clmd->sim_parms->lastcachedframe < framenr)
-		{
-			if(G.rt > 0)
-				printf("cloth_read_cache problem: lnex - f#: %f, lastCF: %d\n", framenr, clmd->sim_parms->lastcachedframe);
-		}
-		
-		if(G.rt > 0)
-			printf("cloth_read_cache: %f successfully \n", framenr);
+		BKE_ptcache_file_close(pf);
 	}
-	
-	if(G.rt > 0)
-		printf("cloth_read_cache: %f\n", framenr);
+	else
+		ret = 0;
 	
 	return ret;
 }
 
 void cloth_clear_cache(Object *ob, ClothModifierData *clmd, float framenr)
 {
-	int stack_index = -1;
+	PTCacheID pid;
 	
+	BKE_ptcache_id_from_cloth(&pid, ob, clmd);
+
 	// don't do anything as long as we're in editmode!
-	if(clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_EDITMODE)
-	{
-		/* delete cache free request */
-		clmd->sim_parms->flags &= ~CLOTH_SIMSETTINGS_FLAG_CCACHE_FFREE;
-		
+	if(pid.cache->flag & PTCACHE_BAKE_EDIT_ACTIVE)
 		return;
-	}
-	
-	/* clear cache if specific frame cleaning requested or cache is not protected */
-	if((!(clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_CCACHE_PROTECT)) || (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_CCACHE_FFREE))
-	{
-		stack_index = modifiers_indexInObject(ob, (ModifierData *)clmd);
-		
-		BKE_ptcache_id_clear((ID *)ob, PTCACHE_CLEAR_AFTER, framenr, stack_index);
-		
-		/* update last cached frame # */
-		clmd->sim_parms->lastcachedframe = framenr;
-		
-		/* update first cached frame # */
-		if((framenr < clmd->sim_parms->firstcachedframe) && (clmd->sim_parms->firstcachedframe >=0.0))
-			clmd->sim_parms->firstcachedframe = -1.0;
-		
-		if(G.rt > 0)
-			printf("cloth_clear_cache: %f\n", framenr);
-	}
-	
-	/* delete cache free request */
-	clmd->sim_parms->flags &= ~CLOTH_SIMSETTINGS_FLAG_CCACHE_FFREE;
-	
 	
+	BKE_ptcache_id_clear(&pid, PTCACHE_CLEAR_AFTER, framenr);
 }
+
 void cloth_write_cache(Object *ob, ClothModifierData *clmd, float framenr)
 {
-	FILE *fp = NULL;
-	int stack_index = -1;
-	unsigned int a;
 	Cloth *cloth = clmd->clothObject;
-	
-	if(G.rt > 0)
-		printf("cloth_write_cache: %f\n", framenr);
+	PTCacheID pid;
+	PTCacheFile *pf;
+	unsigned int a;
 	
 	if(!cloth)
-	{
-		if(G.rt > 0)
-			printf("cloth_write_cache: no cloth\n");
 		return;
-	}
-	
-	stack_index = modifiers_indexInObject(ob, (ModifierData *)clmd);
 	
-	fp = BKE_ptcache_id_fopen((ID *)ob, 'w', framenr, stack_index);
-	if(!fp)
-	{
-		if(G.rt > 0)
-			printf("cloth_write_cache: no fp\n");
+	BKE_ptcache_id_from_cloth(&pid, ob, clmd);
+	pf = BKE_ptcache_file_open(&pid, PTCACHE_FILE_WRITE, framenr);
+	if(!pf)
 		return;
-	}
 	
-	for(a = 0; a < cloth->numverts; a++)
-	{
-		fwrite(&cloth->verts[a].x, sizeof(float),3,fp);
-		fwrite(&cloth->verts[a].xconst, sizeof(float),3,fp);
-		fwrite(&cloth->verts[a].v, sizeof(float),3,fp);
+	for(a = 0; a < cloth->numverts; a++) {
+		BKE_ptcache_file_write_floats(pf, cloth->verts[a].x, 3);
+		BKE_ptcache_file_write_floats(pf, cloth->verts[a].xconst, 3);
+		BKE_ptcache_file_write_floats(pf, cloth->verts[a].v, 3);
 	}
 	
-	/* update last cached frame # */
-	clmd->sim_parms->lastcachedframe = MAX2(clmd->sim_parms->lastcachedframe, framenr);
+	BKE_ptcache_file_close(pf);
+}
+
+static int do_init_cloth(Object *ob, ClothModifierData *clmd, DerivedMesh *result, int framenr)
+{
+	PointCache *cache;
+
+	cache= clmd->point_cache;
+
+	/* initialize simulation data if it didn't exist already */
+	if(clmd->clothObject == NULL) {	
+		if(!cloth_from_object(ob, clmd, result, framenr, 1)) {
+			cache->flag &= ~PTCACHE_SIMULATION_VALID;
+			cache->simframe= 0;
+			return 0;
+		}
+	
+		if(clmd->clothObject == NULL) {
+			cache->flag &= ~PTCACHE_SIMULATION_VALID;
+			cache->simframe= 0;
+			return 0;
+		}
 	
-	/* update first cached frame # */
-	if((clmd->sim_parms->firstcachedframe < 0.0) || ((framenr < clmd->sim_parms->firstcachedframe) && (clmd->sim_parms->firstcachedframe > 0.0)))
-		clmd->sim_parms->firstcachedframe = framenr;
+		implicit_set_positions(clmd);
+	}
+
+	return 1;
+}
+
+static int do_step_cloth(Object *ob, ClothModifierData *clmd, DerivedMesh *result, int framenr)
+{
+	ClothVertex *verts = NULL;
+	Cloth *cloth;
+	ListBase *effectors = NULL;
+	MVert *mvert;
+	int i, ret = 0;
+
+	/* simulate 1 frame forward */
+	cloth = clmd->clothObject;
+	verts = cloth->verts;
+	mvert = result->getVertArray(result);
+
+	/* force any pinned verts to their constrained location. */
+	for(i = 0; i < clmd->clothObject->numverts; i++, verts++) {
+		/* save the previous position. */
+		VECCOPY(verts->xold, verts->xconst);
+		VECCOPY(verts->txold, verts->x);
+
+		/* Get the current position. */
+		VECCOPY(verts->xconst, mvert[i].co);
+		Mat4MulVecfl(ob->obmat, verts->xconst);
+	}
 	
-	if(G.rt > 0)
-		printf("lcf: %d, framenr: %f\n", clmd->sim_parms->lastcachedframe, framenr);
+	tstart();
+
+	/* call the solver. */
+	if(solvers [clmd->sim_parms->solver_type].solver)
+		ret = solvers[clmd->sim_parms->solver_type].solver(ob, framenr, clmd, effectors);
+
+	tend();
 
-	fclose(fp);
+	/* printf ( "Cloth simulation time: %f\n", ( float ) tval() ); */
+	
+	return ret;
 }
 
 /************************************************
  * clothModifier_do - main simulation function
 ************************************************/
-DerivedMesh *clothModifier_do(ClothModifierData *clmd,Object *ob, DerivedMesh *dm, int useRenderParams, int isFinalCalc)
-
+DerivedMesh *clothModifier_do(ClothModifierData *clmd, Object *ob, DerivedMesh *dm, int useRenderParams, int isFinalCalc)
 {
-	unsigned int i;
-	Cloth *cloth = clmd->clothObject;
-	float framenr = G.scene->r.cfra;
-	float current_time = bsystem_time ( ob, ( float ) G.scene->r.cfra, 0.0 );
-	ListBase *effectors = NULL;
-	ClothVertex *verts = NULL;
-	float deltaTime = current_time - clmd->sim_parms->sim_time;
-	unsigned int numverts = -1;
-	unsigned int numedges = -1;
-	unsigned int numfaces = -1;
-	MVert *mvert = NULL;
-	MEdge *medge = NULL;
-	MFace *mface = NULL;
-	DerivedMesh *result = NULL;
-	int ret = 0;
-	
-	if(G.rt > 0)
-		printf("clothModifier_do start\n");
-	
-	/* we're getting called two times during file load,
-	resulting in a not valid G.relbase on the first time (cache makes problems)
-	--> just return back */
-	if((clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_LOADED) && (!G.relbase_valid)) 
-	{
-		clmd->sim_parms->flags &= ~CLOTH_SIMSETTINGS_FLAG_LOADED;
-		return dm;
-	}
-	
+	DerivedMesh *result;
+	PointCache *cache;
+	PTCacheID pid;
+	float timescale;
+	int framedelta, framenr, startframe, endframe;
+
+	framenr= (int)G.scene->r.cfra;
+	cache= clmd->point_cache;
 	result = CDDM_copy(dm);
-	
-	if(!result)
-	{
+
+	BKE_ptcache_id_from_cloth(&pid, ob, clmd);
+	BKE_ptcache_id_time(&pid, framenr, &startframe, &endframe, &timescale);
+	clmd->sim_parms->timescale= timescale;
+
+	/* TODO: use timescale somewhere! */
+
+	if(!result) {
+		cache->flag &= ~PTCACHE_SIMULATION_VALID;
+		cache->simframe= 0;
 		return dm;
 	}
 	
-	numverts = result->getNumVerts(result);
-	numedges = result->getNumEdges(result);
-	numfaces = result->getNumFaces(result);
-	mvert = result->getVertArray(result);
-	medge = result->getEdgeArray(result);
-	mface = result->getFaceArray(result);
-	
-	/* check if cache is active / if file is already saved */
-	/*
-	if ((!G.relbase_valid) && ( deltaTime != 1.0f ))
-	{
-	clmd->sim_parms->flags |= CLOTH_SIMSETTINGS_FLAG_RESET;
-}
-	*/
-	
-	if(clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_RESET)
-	{	
-		cloth_free_modifier (ob, clmd);
-		if(G.rt > 0)
-			printf("clothModifier_do CLOTH_SIMSETTINGS_FLAG_RESET\n");
-		
-		// prevent rebuilding of cloth each time you move backward 
-		if(deltaTime < 0.0)
+	/* verify we still have the same number of vertices, if not do nothing.
+	 * note that this should only happen if the number of vertices changes
+	 * during an animation due to a preceding modifier, this should not
+	 * happen because of object changes! */
+	if(clmd->clothObject) {
+		if(result->getNumVerts(result) != clmd->clothObject->numverts) {
+			cache->flag &= ~PTCACHE_SIMULATION_VALID;
+			cache->simframe= 0;
 			return result;
+		}
 	}
 	
 	// unused in the moment, calculated seperately in implicit.c
 	clmd->sim_parms->dt = clmd->sim_parms->timescale / clmd->sim_parms->stepsPerFrame;
-	
-	if ( ( clmd->clothObject == NULL ) || (clmd->clothObject && (numverts != clmd->clothObject->numverts )) )
-	{	
-		/* only force free the cache if we have a different number of verts */
-		if(clmd->clothObject && (numverts != clmd->clothObject->numverts ))
-		{
-			if(G.rt > 0)
-				printf("Force Freeing: numverts != clmd->clothObject->numverts\n");
-			
-			clmd->sim_parms->flags |= CLOTH_SIMSETTINGS_FLAG_CCACHE_FFREE;
-			cloth_free_modifier ( ob, clmd );
-		}
-		
-		cloth_clear_cache(ob, clmd, 0);
-				
-		if ( !cloth_from_object ( ob, clmd, result, framenr ) )
-			return result;
-	
-		if ( clmd->clothObject == NULL )
+
+	/* handle continuous simulation with the play button */
+	if(BKE_ptcache_get_continue_physics()) {
+		cache->flag &= ~PTCACHE_SIMULATION_VALID;
+		cache->simframe= 0;
+
+		/* do simulation */
+		if(!do_init_cloth(ob, clmd, result, framenr))
 			return result;
-	
-		cloth = clmd->clothObject;
-		
-		if(!cloth_read_cache(ob, clmd, framenr))
-		{
-			/* save first frame in case we have a reseted object 
-			and we move one frame forward.
-			In that case we would only start with the SECOND frame
-			if we don't save the current state before 
-			TODO PROBLEM: IMHO we can't track external movement from the
-			first frame in this case! */
-			/*
-			if ( deltaTime == 1.0f )
-			cloth_write_cache(ob, clmd, framenr-1.0);
-			*/
-			if(G.rt > 0)
-				printf("cloth_from_object NO cloth_read_cache cloth_write_cache\n");
-		}
-		else
-		{
-			if(G.rt > 0)
-				printf("cloth_from_object cloth_read_cache\n");
-			
-			implicit_set_positions(clmd);
-		}
-		
-		clmd->sim_parms->sim_time = current_time;
-	}
-	
-	// only be active during a specific period:
-	// that's "first frame" and "last frame" on GUI
-	if ( current_time < clmd->sim_parms->firstframe )
-	{
-		if(G.rt > 0)
-			printf("current_time < clmd->sim_parms->firstframe\n");
+
+		do_step_cloth(ob, clmd, result, framenr);
+		cloth_to_object(ob, clmd, result);
+
 		return result;
 	}
-	else if ( current_time > clmd->sim_parms->lastframe )
-	{
-		int stack_index = modifiers_indexInObject(ob, (ModifierData *)clmd);
-			
-		if(G.rt > 0)
-			printf("current_time > clmd->sim_parms->lastframe\n");
-		
-		if(BKE_ptcache_id_exist((ID *)ob, clmd->sim_parms->lastcachedframe, stack_index))
-		{
-			if(cloth_read_cache(ob, clmd, clmd->sim_parms->lastcachedframe))
-			{
-				implicit_set_positions(clmd);
-				
-				// Copy the result back to the object.
-				cloth_to_object (ob, clmd, result);
-			}
-		}
+
+	/* simulation is only active during a specific period */
+	if(framenr < startframe) {
+		cache->flag &= ~PTCACHE_SIMULATION_VALID;
+		cache->simframe= 0;
 		return result;
 	}
-	
-	// check for autoprotection, but only if cache active
-	if (clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_AUTOPROTECT)
-	{
-		if((framenr >= clmd->sim_parms->autoprotect) && (G.relbase_valid))
-		{
-			if(G.rt > 0)
-				printf("fr#: %f, auto: %d\n", framenr, clmd->sim_parms->autoprotect);
-			
-			clmd->sim_parms->flags |= CLOTH_SIMSETTINGS_FLAG_CCACHE_PROTECT;
-		}
+	else if(framenr > endframe) {
+		framenr= endframe;
 	}
 	
-	/* nice moving one frame forward */
-	if ( deltaTime == 1.0f )
-	{
-		clmd->sim_parms->sim_time = current_time;
-			
-		if(G.rt > 0)
-			printf("clothModifier_do deltaTime=1\n");
-		
-		if(!cloth_read_cache(ob, clmd, framenr))
-		{
-			verts = cloth->verts;
+	/* dt is unused at the moment, calculated seperately in implicit.c */
+	clmd->sim_parms->dt= 1.0f/clmd->sim_parms->stepsPerFrame;
 
-			// Force any pinned verts to their constrained location.
-			for ( i = 0; i < clmd->clothObject->numverts; i++, verts++ )
-			{
-				// Save the previous position.
-				VECCOPY ( verts->xold, verts->xconst );
-				VECCOPY ( verts->txold, verts->x );
+	if(cache->flag & PTCACHE_SIMULATION_VALID)
+		framedelta= framenr - cache->simframe;
+	else
+		framedelta= -1;
 
-				// Get the current position.
-				VECCOPY ( verts->xconst, mvert[i].co );
-				Mat4MulVecfl ( ob->obmat, verts->xconst );
-			}
-			
-			tstart();
+	/* initialize simulation data if it didn't exist already */
+	if(!do_init_cloth(ob, clmd, result, framenr))
+		return result;
 
-			// Call the solver.
-			if ( solvers [clmd->sim_parms->solver_type].solver )
-			{
-				ret = solvers [clmd->sim_parms->solver_type].solver ( ob, framenr, clmd, effectors );
-			}
+	/* try to read from cache */
+	if(cloth_read_cache(ob, clmd, framenr)) {
+		cache->flag |= PTCACHE_SIMULATION_VALID;
+		cache->simframe= framenr;
 
-			tend();
-			// printf ( "Cloth simulation time: %f\n", ( float ) tval() );
-			
-			if(ret)
-				cloth_write_cache(ob, clmd, framenr);
-			else
-				clmd->sim_parms->sim_time--;
-		}
-		else
-		{
-			if(G.rt > 0)
-				printf("clothModifier_do deltaTime=1 cacheread\n");
-			implicit_set_positions(clmd);
-		}
-		
-		// Copy the result back to the object.
+		implicit_set_positions(clmd);
 		cloth_to_object (ob, clmd, result);
+
+		return result;
 	}
-	else if(deltaTime == 0.0f) 
-	{	
-		if(G.rt > 0)
-			printf("dt = 0, %f\n", framenr);
-		if(cloth_read_cache(ob, clmd, framenr))
-		{
-			cloth_to_object (ob, clmd, result);
-			implicit_set_positions(clmd);
-		}
-		else /* same cache parts are missing */
-		{
-			/* jump to a non-existing frame makes sim reset if cache is not protected */
-			if(!(clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_CCACHE_PROTECT))
-			{	
-				/* prevent freeing when used with vectorblur */
-				if(!useRenderParams)
-				{
-					clmd->sim_parms->flags |= CLOTH_SIMSETTINGS_FLAG_CCACHE_FFREE;
-					cloth_clear_cache(ob, clmd, 0);
-					
-					cloth_write_cache(ob, clmd, framenr);
-				}
-			}
-		}
+	else if(ob->id.lib || (cache->flag & PTCACHE_BAKED)) {
+		/* if baked and nothing in cache, do nothing */
+		cache->flag &= ~PTCACHE_SIMULATION_VALID;
+		cache->simframe= 0;
+		return result;
 	}
-	else
-	{	
-		if(G.rt > 0)
-			printf("dt > 1.0 || dt < 0.0, %f, st: %f, ct: %f\n", framenr, clmd->sim_parms->sim_time, current_time);
-		if(cloth_read_cache(ob, clmd, framenr))
-		{
-			cloth_to_object (ob, clmd, result);
-			implicit_set_positions(clmd);
+
+	if(framenr == startframe) {
+		cache->flag |= PTCACHE_SIMULATION_VALID;
+		cache->simframe= framenr;
+
+		/* don't write cache on first frame, but on second frame write
+		 * cache for frame 1 and 2 */
+	}
+	else if(framedelta == 1) {
+		/* if on second frame, write cache for first frame */
+		if(framenr == startframe+1)
+			cloth_write_cache(ob, clmd, startframe);
+
+		/* do simulation */
+		cache->flag |= PTCACHE_SIMULATION_VALID;
+		cache->simframe= framenr;
+
+		if(!do_step_cloth(ob, clmd, result, framenr)) {
+			cache->flag &= ~PTCACHE_SIMULATION_VALID;
+			cache->simframe= 0;
 		}
 		else
-		{
-			/* jump to a non-existing frame makes sim reset if cache is not protected */
-			if(!(clmd->sim_parms->flags & CLOTH_SIMSETTINGS_FLAG_CCACHE_PROTECT))
-			{
-				/* prevent freeing when used with vectorblur */
-				if(!useRenderParams)
-					clmd->sim_parms->flags |= CLOTH_SIMSETTINGS_FLAG_RESET;
-			}
-		}
-		clmd->sim_parms->sim_time = current_time;
+			cloth_write_cache(ob, clmd, framenr);
+
+		cloth_to_object (ob, clmd, result);
 	}
-	
+	else {
+		cache->flag &= ~PTCACHE_SIMULATION_VALID;
+		cache->simframe= 0;
+	}
+
 	return result;
 }
 
@@ -702,7 +567,6 @@ void cloth_free_modifier ( Object *ob, ClothModifierData *clmd )
 		MEM_freeN ( cloth );
 		clmd->clothObject = NULL;
 	}
-	clmd->sim_parms->flags &= ~CLOTH_SIMSETTINGS_FLAG_RESET;
 }
 
 /* frees all */
@@ -888,13 +752,12 @@ static void cloth_apply_vgroup ( ClothModifierData *clmd, DerivedMesh *dm )
 	}
 }
 
-static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *dm, float framenr)
+static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *dm, float framenr, int first)
 {
 	unsigned int i = 0;
 	MVert *mvert = NULL;
 	ClothVertex *verts = NULL;
 	float tnull[3] = {0,0,0};
-	int cache_there = 0;
 	Cloth *cloth = NULL;
 
 	// If we have a clothObject, free it. 
@@ -926,21 +789,6 @@ static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *d
 
 	cloth_from_mesh ( ob, clmd, dm );
 
-	if((clmd->sim_parms->firstcachedframe < 0.0) || ((clmd->sim_parms->firstcachedframe >= 0.0) && (!cloth_read_cache(ob, clmd, clmd->sim_parms->firstcachedframe))))
-	{
-		// no cache there
-		cache_there = 0;
-		if(G.rt > 0)
-			printf("cache_there = 0\n");
-	}
-	else
-	{
-		// we have a cache
-		cache_there = 1;
-		if(G.rt > 0)
-			printf("cache_there = 1, fcf: %d\n", clmd->sim_parms->firstcachedframe);
-	}
-	
 	// create springs 
 	clmd->clothObject->springs = NULL;
 	clmd->clothObject->numsprings = -1;
@@ -951,7 +799,7 @@ static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *d
 	// set initial values
 	for ( i = 0; i < dm->getNumVerts(dm); i++, verts++ )
 	{
-		if(!cache_there)
+		if(first)
 		{
 			VECCOPY ( verts->x, mvert[i].co );
 			Mat4MulVecfl ( ob->obmat, verts->x );
@@ -998,10 +846,11 @@ static int cloth_from_object(Object *ob, ClothModifierData *clmd, DerivedMesh *d
 	}
 	
 	// init our solver
-	if ( solvers [clmd->sim_parms->solver_type].init )
+	if ( solvers [clmd->sim_parms->solver_type].init ) {
 		solvers [clmd->sim_parms->solver_type].init ( ob, clmd );
+	}
 	
-	if(cache_there)
+	if(!first)
 		implicit_set_positions(clmd);
 
 	clmd->clothObject->tree = bvh_build_from_cloth ( clmd, clmd->coll_parms->epsilon );