/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2015 Blender Foundation.
 * All rights reserved.
 *
 * Original Author: Joshua Leung
 * Contributor(s): None Yet
 *
 * ***** END GPL LICENSE BLOCK *****
 *
 * Defines and code for core node types
 */

#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"
#include "BLI_listbase.h"
#include "BLI_math.h"

#include "DNA_armature_types.h"
#include "DNA_constraint_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"

#include "BKE_action.h"
#include "BKE_anim.h"
#include "BKE_armature.h"
#include "BKE_curve.h"
#include "BKE_depsgraph.h"
#include "BKE_displist.h"
#include "BKE_fcurve.h"
#include "BKE_scene.h"

#include "BIK_api.h"

#include "BKE_global.h"
#include "BKE_main.h"

#include "DEG_depsgraph.h"

#ifdef WITH_LEGACY_DEPSGRAPH
#  define DEBUG_PRINT if (!DEG_depsgraph_use_legacy() && G.debug & G_DEBUG_DEPSGRAPH) printf
#else
#  define DEBUG_PRINT if (G.debug & G_DEBUG_DEPSGRAPH) printf
#endif

/* ********************** SPLINE IK SOLVER ******************* */

/* Temporary evaluation tree data used for Spline IK */
typedef struct tSplineIK_Tree {
	struct tSplineIK_Tree *next, *prev;

	int type;                    /* type of IK that this serves (CONSTRAINT_TYPE_KINEMATIC or ..._SPLINEIK) */

	bool free_points;            /* free the point positions array */
	short chainlen;              /* number of bones in the chain */

	float *points;               /* parametric positions for the joints along the curve */
	bPoseChannel **chain;        /* chain of bones to affect using Spline IK (ordered from the tip) */

	bPoseChannel *root;          /* bone that is the root node of the chain */

	bConstraint *con;            /* constraint for this chain */
	bSplineIKConstraint *ikData; /* constraint settings for this chain */
} tSplineIK_Tree;

/* ----------- */

/* Tag the bones in the chain formed by the given bone for IK */
static void splineik_init_tree_from_pchan(Scene *scene, Object *UNUSED(ob), bPoseChannel *pchan_tip)
{
	bPoseChannel *pchan, *pchanRoot = NULL;
	bPoseChannel *pchanChain[255];
	bConstraint *con = NULL;
	bSplineIKConstraint *ikData = NULL;
	float boneLengths[255], *jointPoints;
	float totLength = 0.0f;
	bool free_joints = 0;
	int segcount = 0;

	/* find the SplineIK constraint */
	for (con = pchan_tip->constraints.first; con; con = con->next) {
		if (con->type == CONSTRAINT_TYPE_SPLINEIK) {
			ikData = con->data;

			/* target can only be curve */
			if ((ikData->tar == NULL) || (ikData->tar->type != OB_CURVE))
				continue;
			/* skip if disabled */
			if ((con->enforce == 0.0f) || (con->flag & (CONSTRAINT_DISABLE | CONSTRAINT_OFF)))
				continue;

			/* otherwise, constraint is ok... */
			break;
		}
	}
	if (con == NULL)
		return;

	/* make sure that the constraint targets are ok
	 *     - this is a workaround for a depsgraph bug...
	 */
	if (ikData->tar) {
		/* note: when creating constraints that follow path, the curve gets the CU_PATH set now,
		 *       currently for paths to work it needs to go through the bevlist/displist system (ton)
		 */

		/* only happens on reload file, but violates depsgraph still... fix! */
		if (ELEM(NULL,  ikData->tar->curve_cache, ikData->tar->curve_cache->path, ikData->tar->curve_cache->path->data)) {
			BKE_displist_make_curveTypes(scene, ikData->tar, 0);
			
			/* path building may fail in EditMode after removing verts [#33268]*/
			if (ELEM(NULL, ikData->tar->curve_cache->path, ikData->tar->curve_cache->path->data)) {
				/* BLI_assert(cu->path != NULL); */
				return;
			}
		}
	}

	/* find the root bone and the chain of bones from the root to the tip
	 * NOTE: this assumes that the bones are connected, but that may not be true... */
	for (pchan = pchan_tip; pchan && (segcount < ikData->chainlen); pchan = pchan->parent, segcount++) {
		/* store this segment in the chain */
		pchanChain[segcount] = pchan;

		/* if performing rebinding, calculate the length of the bone */
		boneLengths[segcount] = pchan->bone->length;
		totLength += boneLengths[segcount];
	}

	if (segcount == 0)
		return;
	else
		pchanRoot = pchanChain[segcount - 1];

	/* perform binding step if required */
	if ((ikData->flag & CONSTRAINT_SPLINEIK_BOUND) == 0) {
		float segmentLen = (1.0f / (float)segcount);
		int i;

		/* setup new empty array for the points list */
		if (ikData->points)
			MEM_freeN(ikData->points);
		ikData->numpoints = ikData->chainlen + 1;
		ikData->points = MEM_mallocN(sizeof(float) * ikData->numpoints, "Spline IK Binding");

		/* bind 'tip' of chain (i.e. first joint = tip of bone with the Spline IK Constraint) */
		ikData->points[0] = 1.0f;

		/* perform binding of the joints to parametric positions along the curve based
		 * proportion of the total length that each bone occupies
		 */
		for (i = 0; i < segcount; i++) {
			/* 'head' joints, traveling towards the root of the chain
			 *  - 2 methods; the one chosen depends on whether we've got usable lengths
			 */
			if ((ikData->flag & CONSTRAINT_SPLINEIK_EVENSPLITS) || (totLength == 0.0f)) {
				/* 1) equi-spaced joints */
				ikData->points[i + 1] = ikData->points[i] - segmentLen;
			}
			else {
				/* 2) to find this point on the curve, we take a step from the previous joint
				 *    a distance given by the proportion that this bone takes
				 */
				ikData->points[i + 1] = ikData->points[i] - (boneLengths[i] / totLength);
			}
		}

		/* spline has now been bound */
		ikData->flag |= CONSTRAINT_SPLINEIK_BOUND;
	}

	/* disallow negative values (happens with float precision) */
	CLAMP_MIN(ikData->points[segcount], 0.0f);

	/* apply corrections for sensitivity to scaling on a copy of the bind points,
	 * since it's easier to determine the positions of all the joints beforehand this way
	 */
	if ((ikData->flag & CONSTRAINT_SPLINEIK_SCALE_LIMITED) && (totLength != 0.0f)) {
		float splineLen, maxScale;
		int i;

		/* make a copy of the points array, that we'll store in the tree
		 *     - although we could just multiply the points on the fly, this approach means that
		 *       we can introduce per-segment stretchiness later if it is necessary
		 */
		jointPoints = MEM_dupallocN(ikData->points);
		free_joints = 1;

		/* get the current length of the curve */
		/* NOTE: this is assumed to be correct even after the curve was resized */
		splineLen = ikData->tar->curve_cache->path->totdist;

		/* calculate the scale factor to multiply all the path values by so that the
		 * bone chain retains its current length, such that
		 *     maxScale * splineLen = totLength
		 */
		maxScale = totLength / splineLen;

		/* apply scaling correction to all of the temporary points */
		/* TODO: this is really not adequate enough on really short chains */
		for (i = 0; i < segcount; i++)
			jointPoints[i] *= maxScale;
	}
	else {
		/* just use the existing points array */
		jointPoints = ikData->points;
		free_joints = 0;
	}

	/* make a new Spline-IK chain, and store it in the IK chains */
	/* TODO: we should check if there is already an IK chain on this, since that would take precedence... */
	{
		/* make new tree */
		tSplineIK_Tree *tree = MEM_callocN(sizeof(tSplineIK_Tree), "SplineIK Tree");
		tree->type = CONSTRAINT_TYPE_SPLINEIK;

		tree->chainlen = segcount;

		/* copy over the array of links to bones in the chain (from tip to root) */
		tree->chain = MEM_mallocN(sizeof(bPoseChannel *) * segcount, "SplineIK Chain");
		memcpy(tree->chain, pchanChain, sizeof(bPoseChannel *) * segcount);

		/* store reference to joint position array */
		tree->points = jointPoints;
		tree->free_points = free_joints;

		/* store references to different parts of the chain */
		tree->root = pchanRoot;
		tree->con = con;
		tree->ikData = ikData;

		/* AND! link the tree to the root */
		BLI_addtail(&pchanRoot->siktree, tree);
	}

	/* mark root channel having an IK tree */
	pchanRoot->flag |= POSE_IKSPLINE;
}

/* Tag which bones are members of Spline IK chains */
static void splineik_init_tree(Scene *scene, Object *ob, float UNUSED(ctime))
{
	bPoseChannel *pchan;

	/* find the tips of Spline IK chains, which are simply the bones which have been tagged as such */
	for (pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
		if (pchan->constflag & PCHAN_HAS_SPLINEIK)
			splineik_init_tree_from_pchan(scene, ob, pchan);
	}
}

/* ----------- */

/* Evaluate spline IK for a given bone */
static void splineik_evaluate_bone(tSplineIK_Tree *tree, Scene *scene, Object *ob, bPoseChannel *pchan,
                                   int index, float ctime)
{
	bSplineIKConstraint *ikData = tree->ikData;
	float poseHead[3], poseTail[3], poseMat[4][4];
	float splineVec[3], scaleFac, radius = 1.0f;

	/* firstly, calculate the bone matrix the standard way, since this is needed for roll control */
	BKE_pose_where_is_bone(scene, ob, pchan, ctime, 1);

	copy_v3_v3(poseHead, pchan->pose_head);
	copy_v3_v3(poseTail, pchan->pose_tail);

	/* step 1: determine the positions for the endpoints of the bone */
	{
		float vec[4], dir[3], rad;
		float tailBlendFac = 1.0f;

		/* determine if the bone should still be affected by SplineIK */
		if (tree->points[index + 1] >= 1.0f) {
			/* spline doesn't affect the bone anymore, so done... */
			pchan->flag |= POSE_DONE;
			return;
		}
		else if ((tree->points[index] >= 1.0f) && (tree->points[index + 1] < 1.0f)) {
			/* blending factor depends on the amount of the bone still left on the chain */
			tailBlendFac = (1.0f - tree->points[index + 1]) / (tree->points[index] - tree->points[index + 1]);
		}

		/* tail endpoint */
		if (where_on_path(ikData->tar, tree->points[index], vec, dir, NULL, &rad, NULL)) {
			/* apply curve's object-mode transforms to the position
			 * unless the option to allow curve to be positioned elsewhere is activated (i.e. no root)
			 */
			if ((ikData->flag & CONSTRAINT_SPLINEIK_NO_ROOT) == 0)
				mul_m4_v3(ikData->tar->obmat, vec);

			/* convert the position to pose-space, then store it */
			mul_m4_v3(ob->imat, vec);
			interp_v3_v3v3(poseTail, pchan->pose_tail, vec, tailBlendFac);

			/* set the new radius */
			radius = rad;
		}

		/* head endpoint */
		if (where_on_path(ikData->tar, tree->points[index + 1], vec, dir, NULL, &rad, NULL)) {
			/* apply curve's object-mode transforms to the position
			 * unless the option to allow curve to be positioned elsewhere is activated (i.e. no root)
			 */
			if ((ikData->flag & CONSTRAINT_SPLINEIK_NO_ROOT) == 0)
				mul_m4_v3(ikData->tar->obmat, vec);

			/* store the position, and convert it to pose space */
			mul_m4_v3(ob->imat, vec);
			copy_v3_v3(poseHead, vec);

			/* set the new radius (it should be the average value) */
			radius = (radius + rad) / 2;
		}
	}

	/* step 2: determine the implied transform from these endpoints
	 *     - splineVec: the vector direction that the spline applies on the bone
	 *     - scaleFac: the factor that the bone length is scaled by to get the desired amount
	 */
	sub_v3_v3v3(splineVec, poseTail, poseHead);
	scaleFac = len_v3(splineVec) / pchan->bone->length;

	/* step 3: compute the shortest rotation needed to map from the bone rotation to the current axis
	 *      - this uses the same method as is used for the Damped Track Constraint (see the code there for details)
	 */
	{
		float dmat[3][3], rmat[3][3], tmat[3][3];
		float raxis[3], rangle;

		/* compute the raw rotation matrix from the bone's current matrix by extracting only the
		 * orientation-relevant axes, and normalizing them
		 */
		copy_v3_v3(rmat[0], pchan->pose_mat[0]);
		copy_v3_v3(rmat[1], pchan->pose_mat[1]);
		copy_v3_v3(rmat[2], pchan->pose_mat[2]);
		normalize_m3(rmat);

		/* also, normalize the orientation imposed by the bone, now that we've extracted the scale factor */
		normalize_v3(splineVec);

		/* calculate smallest axis-angle rotation necessary for getting from the
		 * current orientation of the bone, to the spline-imposed direction
		 */
		cross_v3_v3v3(raxis, rmat[1], splineVec);

		rangle = dot_v3v3(rmat[1], splineVec);
		CLAMP(rangle, -1.0f, 1.0f);
		rangle = acosf(rangle);

		/* multiply the magnitude of the angle by the influence of the constraint to
		 * control the influence of the SplineIK effect
		 */
		rangle *= tree->con->enforce;

		/* construct rotation matrix from the axis-angle rotation found above
		 *	- this call takes care to make sure that the axis provided is a unit vector first
		 */
		axis_angle_to_mat3(dmat, raxis, rangle);

		/* combine these rotations so that the y-axis of the bone is now aligned as the spline dictates,
		 * while still maintaining roll control from the existing bone animation
		 */
		mul_m3_m3m3(tmat, dmat, rmat); /* m1, m3, m2 */
		normalize_m3(tmat); /* attempt to reduce shearing, though I doubt this'll really help too much now... */
		copy_m4_m3(poseMat, tmat);
	}

	/* step 4: set the scaling factors for the axes */
	{
		/* only multiply the y-axis by the scaling factor to get nice volume-preservation */
		mul_v3_fl(poseMat[1], scaleFac);

		/* set the scaling factors of the x and z axes from... */
		switch (ikData->xzScaleMode) {
			case CONSTRAINT_SPLINEIK_XZS_ORIGINAL:
			{
				/* original scales get used */
				float scale;

				/* x-axis scale */
				scale = len_v3(pchan->pose_mat[0]);
				mul_v3_fl(poseMat[0], scale);
				/* z-axis scale */
				scale = len_v3(pchan->pose_mat[2]);
				mul_v3_fl(poseMat[2], scale);
				break;
			}
			case CONSTRAINT_SPLINEIK_XZS_INVERSE:
			{
				/* old 'volume preservation' method using the inverse scale */
				float scale;

				/* calculate volume preservation factor which is
				 * basically the inverse of the y-scaling factor
				 */
				if (fabsf(scaleFac) != 0.0f) {
					scale = 1.0f / fabsf(scaleFac);

					/* we need to clamp this within sensible values */
					/* NOTE: these should be fine for now, but should get sanitised in future */
					CLAMP(scale, 0.0001f, 100000.0f);
				}
				else
					scale = 1.0f;

				/* apply the scaling */
				mul_v3_fl(poseMat[0], scale);
				mul_v3_fl(poseMat[2], scale);
				break;
			}
			case CONSTRAINT_SPLINEIK_XZS_VOLUMETRIC:
			{
				/* improved volume preservation based on the Stretch To constraint */
				float final_scale;
				
				/* as the basis for volume preservation, we use the inverse scale factor... */
				if (fabsf(scaleFac) != 0.0f) {
					/* NOTE: The method here is taken wholesale from the Stretch To constraint */
					float bulge = powf(1.0f / fabsf(scaleFac), ikData->bulge);
					
					if (bulge > 1.0f) {
						if (ikData->flag & CONSTRAINT_SPLINEIK_USE_BULGE_MAX) {
							float bulge_max = max_ff(ikData->bulge_max, 1.0f);
							float hard = min_ff(bulge, bulge_max);
							
							float range = bulge_max - 1.0f;
							float scale = (range > 0.0f) ? 1.0f / range : 0.0f;
							float soft = 1.0f + range * atanf((bulge - 1.0f) * scale) / (float)M_PI_2;
							
							bulge = interpf(soft, hard, ikData->bulge_smooth);
						}
					}
					if (bulge < 1.0f) {
						if (ikData->flag & CONSTRAINT_SPLINEIK_USE_BULGE_MIN) {
							float bulge_min = CLAMPIS(ikData->bulge_min, 0.0f, 1.0f);
							float hard = max_ff(bulge, bulge_min);
							
							float range = 1.0f - bulge_min;
							float scale = (range > 0.0f) ? 1.0f / range : 0.0f;
							float soft = 1.0f - range * atanf((1.0f - bulge) * scale) / (float)M_PI_2;
							
							bulge = interpf(soft, hard, ikData->bulge_smooth);
						}
					}
					
					/* compute scale factor for xz axes from this value */
					final_scale = sqrtf(bulge);
				}
				else {
					/* no scaling, so scale factor is simple */
					final_scale = 1.0f;
				}
				
				/* apply the scaling (assuming normalised scale) */
				mul_v3_fl(poseMat[0], final_scale);
				mul_v3_fl(poseMat[2], final_scale);
				break;
			}
		}

		/* finally, multiply the x and z scaling by the radius of the curve too,
		 * to allow automatic scales to get tweaked still
		 */
		if ((ikData->flag & CONSTRAINT_SPLINEIK_NO_CURVERAD) == 0) {
			mul_v3_fl(poseMat[0], radius);
			mul_v3_fl(poseMat[2], radius);
		}
	}

	/* step 5: set the location of the bone in the matrix */
	if (ikData->flag & CONSTRAINT_SPLINEIK_NO_ROOT) {
		/* when the 'no-root' option is affected, the chain can retain
		 * the shape but be moved elsewhere
		 */
		copy_v3_v3(poseHead, pchan->pose_head);
	}
	else if (tree->con->enforce < 1.0f) {
		/* when the influence is too low
		 *	- blend the positions for the 'root' bone
		 *	- stick to the parent for any other
		 */
		if (pchan->parent) {
			copy_v3_v3(poseHead, pchan->pose_head);
		}
		else {
			/* FIXME: this introduces popping artifacts when we reach 0.0 */
			interp_v3_v3v3(poseHead, pchan->pose_head, poseHead, tree->con->enforce);
		}
	}
	copy_v3_v3(poseMat[3], poseHead);

	/* finally, store the new transform */
	copy_m4_m4(pchan->pose_mat, poseMat);
	copy_v3_v3(pchan->pose_head, poseHead);

	/* recalculate tail, as it's now outdated after the head gets adjusted above! */
	BKE_pose_where_is_bone_tail(pchan);

	/* done! */
	pchan->flag |= POSE_DONE;
}

/* Evaluate the chain starting from the nominated bone */
static void splineik_execute_tree(Scene *scene, Object *ob, bPoseChannel *pchan_root, float ctime)
{
	tSplineIK_Tree *tree;

	/* for each pose-tree, execute it if it is spline, otherwise just free it */
	while ((tree = pchan_root->siktree.first) != NULL) {
		int i;

		/* walk over each bone in the chain, calculating the effects of spline IK
		 *     - the chain is traversed in the opposite order to storage order (i.e. parent to children)
		 *       so that dependencies are correct
		 */
		for (i = tree->chainlen - 1; i >= 0; i--) {
			bPoseChannel *pchan = tree->chain[i];
			splineik_evaluate_bone(tree, scene, ob, pchan, i, ctime);
		}

		/* free the tree info specific to SplineIK trees now */
		if (tree->chain)
			MEM_freeN(tree->chain);
		if (tree->free_points)
			MEM_freeN(tree->points);

		/* free this tree */
		BLI_freelinkN(&pchan_root->siktree, tree);
	}
}

void BKE_pose_splineik_init_tree(Scene *scene, Object *ob, float ctime)
{
	splineik_init_tree(scene, ob, ctime);
}

void BKE_splineik_execute_tree(Scene *scene, Object *ob, bPoseChannel *pchan_root, float ctime)
{
	splineik_execute_tree(scene, ob, pchan_root, ctime);
}

/* *************** Depsgraph evaluation callbacks ************ */

void BKE_pose_eval_init(EvaluationContext *UNUSED(eval_ctx),
                        Scene *UNUSED(scene),
                        Object *ob,
                        bPose *pose)
{
	bPoseChannel *pchan;

	DEBUG_PRINT("%s on %s\n", __func__, ob->id.name);

	BLI_assert(ob->type == OB_ARMATURE);

	/* We demand having proper pose. */
	BLI_assert(ob->pose != NULL);
	BLI_assert((ob->pose->flag & POSE_RECALC) == 0);

	/* imat is needed for solvers. */
	invert_m4_m4(ob->imat, ob->obmat);

	/* 1. clear flags */
	for (pchan = pose->chanbase.first; pchan != NULL; pchan = pchan->next) {
		pchan->flag &= ~(POSE_DONE | POSE_CHAIN | POSE_IKTREE | POSE_IKSPLINE);
	}
}

void BKE_pose_eval_init_ik(EvaluationContext *UNUSED(eval_ctx),
                           Scene *scene,
                           Object *ob,
                           bPose *UNUSED(pose))
{
	float ctime = BKE_scene_frame_get(scene); /* not accurate... */

	DEBUG_PRINT("%s on %s\n", __func__, ob->id.name);

	/* 2a. construct the IK tree (standard IK) */
	BIK_initialize_tree(scene, ob, ctime);

	/* 2b. construct the Spline IK trees
	 *  - this is not integrated as an IK plugin, since it should be able
	 *	  to function in conjunction with standard IK
	 */
	BKE_pose_splineik_init_tree(scene, ob, ctime);
}

void BKE_pose_eval_bone(EvaluationContext *UNUSED(eval_ctx),
                        Scene *scene,
                        Object *ob,
                        bPoseChannel *pchan)
{
	bArmature *arm = (bArmature *)ob->data;
	DEBUG_PRINT("%s on %s pchan %s\n", __func__, ob->id.name, pchan->name);
	BLI_assert(ob->type == OB_ARMATURE);
	if (arm->edbo || (arm->flag & ARM_RESTPOS)) {
		Bone *bone = pchan->bone;
		if (bone) {
			copy_m4_m4(pchan->pose_mat, bone->arm_mat);
			copy_v3_v3(pchan->pose_head, bone->arm_head);
			copy_v3_v3(pchan->pose_tail, bone->arm_tail);
		}
	}
	else {
		/* TODO(sergey): Currently if there are constraints full transform is being
		 * evaluated in BKE_pose_constraints_evaluate.
		 */
		if (pchan->constraints.first == NULL) {
			if (pchan->flag & POSE_IKTREE || pchan->flag & POSE_IKSPLINE) {
				/* pass */
			}
			else {
				if ((pchan->flag & POSE_DONE) == 0) {
					/* TODO(sergey): Use time source node for time. */
					float ctime = BKE_scene_frame_get(scene); /* not accurate... */
					BKE_pose_where_is_bone(scene, ob, pchan, ctime, 1);
				}
			}
		}
	}
}

void BKE_pose_constraints_evaluate(EvaluationContext *UNUSED(eval_ctx),
                                   Scene *scene,
                                   Object *ob,
                                   bPoseChannel *pchan)
{
	DEBUG_PRINT("%s on %s pchan %s\n", __func__, ob->id.name, pchan->name);
	bArmature *arm = (bArmature *)ob->data;
	if (arm->flag & ARM_RESTPOS) {
		return;
	}
	else if (pchan->flag & POSE_IKTREE || pchan->flag & POSE_IKSPLINE) {
		/* IK are being solved separately/ */
	}
	else {
		if ((pchan->flag & POSE_DONE) == 0) {
			float ctime = BKE_scene_frame_get(scene); /* not accurate... */
			BKE_pose_where_is_bone(scene, ob, pchan, ctime, 1);
		}
	}
}

void BKE_pose_bone_done(EvaluationContext *UNUSED(eval_ctx),
                        bPoseChannel *pchan)
{
	float imat[4][4];
	DEBUG_PRINT("%s on pchan %s\n", __func__, pchan->name);
	if (pchan->bone) {
		invert_m4_m4(imat, pchan->bone->arm_mat);
		mul_m4_m4m4(pchan->chan_mat, pchan->pose_mat, imat);
	}
}

void BKE_pose_iktree_evaluate(EvaluationContext *UNUSED(eval_ctx),
                              Scene *scene,
                              Object *ob,
                              bPoseChannel *rootchan)
{
	float ctime = BKE_scene_frame_get(scene); /* not accurate... */
	DEBUG_PRINT("%s on %s pchan %s\n", __func__, ob->id.name, rootchan->name);
	BIK_execute_tree(scene, ob, rootchan, ctime);
}

void BKE_pose_splineik_evaluate(EvaluationContext *UNUSED(eval_ctx),
                                Scene *scene,
                                Object *ob,
                                bPoseChannel *rootchan)
{
	float ctime = BKE_scene_frame_get(scene); /* not accurate... */
	DEBUG_PRINT("%s on %s pchan %s\n", __func__, ob->id.name, rootchan->name);
	BKE_splineik_execute_tree(scene, ob, rootchan, ctime);
}

void BKE_pose_eval_flush(EvaluationContext *UNUSED(eval_ctx),
                         Scene *scene,
                         Object *ob,
                         bPose *UNUSED(pose))
{
	float ctime = BKE_scene_frame_get(scene); /* not accurate... */
	DEBUG_PRINT("%s on %s\n", __func__, ob->id.name);
	BLI_assert(ob->type == OB_ARMATURE);

	/* 6. release the IK tree */
	BIK_release_tree(scene, ob, ctime);

	ob->recalc &= ~OB_RECALC_ALL;
}

void BKE_pose_eval_proxy_copy(EvaluationContext *UNUSED(eval_ctx), Object *ob)
{
	BLI_assert(ID_IS_LINKED_DATABLOCK(ob) && ob->proxy_from != NULL);
	DEBUG_PRINT("%s on %s\n", __func__, ob->id.name);
	if (BKE_pose_copy_result(ob->pose, ob->proxy_from->pose) == false) {
		printf("Proxy copy error, lib Object: %s proxy Object: %s\n",
		       ob->id.name + 2, ob->proxy_from->id.name + 2);
	}
	/* Rest of operations are NO-OP in depsgraph, so can clear
	 * flag now.
	 */
	ob->recalc &= ~OB_RECALC_ALL;
}
