Action Constraint: Add manual time factor input control

Adds an optional slider to the action constraint so that it can be
driven without a constraint target.

This is very helpful for more complex rigging and mechanical rigs, as it
means the action constraint can be controlled with a driver/custom
property directly, currently if we want to use a driver to control it we
must add a "dummy" bone/object inbetween to act as a control.

Reviewed By: Sebastian Parborg, Sybren A. Stüvel, Demeter Dzadik, Julian Eisel

Differential Revision: http://developer.blender.org/D8022

1 files changed, 41 insertions, 35 deletions

diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c
index fc1b4d82c20..9411f937f08 100644
--- a/source/blender/blenkernel/intern/constraint.c
+++ b/source/blender/blenkernel/intern/constraint.c
@@ -2634,7 +2634,7 @@ static void actcon_get_tarmat(struct Depsgraph *depsgraph,
 {
   bActionConstraint *data = con->data;
 
-  if (VALID_CONS_TARGET(ct)) {
+  if (VALID_CONS_TARGET(ct) || data->flag & ACTCON_USE_EVAL_TIME) {
     float tempmat[4][4], vec[3];
     float s, t;
     short axis;
@@ -2642,42 +2642,48 @@ static void actcon_get_tarmat(struct Depsgraph *depsgraph,
     /* initialize return matrix */
     unit_m4(ct->matrix);
 
-    /* get the transform matrix of the target */
-    constraint_target_to_mat4(ct->tar,
-                              ct->subtarget,
-                              tempmat,
-                              CONSTRAINT_SPACE_WORLD,
-                              ct->space,
-                              con->flag,
-                              con->headtail);
+    /* Skip targets if we're using local float property to set action time */
+    if (data->flag & ACTCON_USE_EVAL_TIME) {
+      s = data->eval_time;
+    } else {
+      /* get the transform matrix of the target */
+      constraint_target_to_mat4(ct->tar,
+                                ct->subtarget,
+                                tempmat,
+                                CONSTRAINT_SPACE_WORLD,
+                                ct->space,
+                                con->flag,
+                                con->headtail);
+
+      /* determine where in transform range target is */
+      /* data->type is mapped as follows for backwards compatibility:
+       * 00,01,02 - rotation (it used to be like this)
+       * 10,11,12 - scaling
+       * 20,21,22 - location
+       */
+      if (data->type < 10) {
+        /* extract rotation (is in whatever space target should be in) */
+        mat4_to_eul(vec, tempmat);
+        mul_v3_fl(vec, RAD2DEGF(1.0f)); /* rad -> deg */
+        axis = data->type;
+      }
+      else if (data->type < 20) {
+        /* extract scaling (is in whatever space target should be in) */
+        mat4_to_size(vec, tempmat);
+        axis = data->type - 10;
+      }
+      else {
+        /* extract location */
+        copy_v3_v3(vec, tempmat[3]);
+        axis = data->type - 20;
+      }
 
-    /* determine where in transform range target is */
-    /* data->type is mapped as follows for backwards compatibility:
-     * 00,01,02 - rotation (it used to be like this)
-     * 10,11,12 - scaling
-     * 20,21,22 - location
-     */
-    if (data->type < 10) {
-      /* extract rotation (is in whatever space target should be in) */
-      mat4_to_eul(vec, tempmat);
-      mul_v3_fl(vec, RAD2DEGF(1.0f)); /* rad -> deg */
-      axis = data->type;
-    }
-    else if (data->type < 20) {
-      /* extract scaling (is in whatever space target should be in) */
-      mat4_to_size(vec, tempmat);
-      axis = data->type - 10;
-    }
-    else {
-      /* extract location */
-      copy_v3_v3(vec, tempmat[3]);
-      axis = data->type - 20;
-    }
+      BLI_assert((unsigned int)axis < 3);
 
-    BLI_assert((unsigned int)axis < 3);
+      /* Target defines the animation */
+      s = (vec[axis] - data->min) / (data->max - data->min);
+    }
 
-    /* Target defines the animation */
-    s = (vec[axis] - data->min) / (data->max - data->min);
     CLAMP(s, 0, 1);
     t = (s * (data->end - data->start)) + data->start;
     const AnimationEvalContext anim_eval_context = BKE_animsys_eval_context_construct(depsgraph,
@@ -2734,7 +2740,7 @@ static void actcon_evaluate(bConstraint *con, bConstraintOb *cob, ListBase *targ
   bActionConstraint *data = con->data;
   bConstraintTarget *ct = targets->first;
 
-  if (VALID_CONS_TARGET(ct)) {
+  if (VALID_CONS_TARGET(ct) || data->flag & ACTCON_USE_EVAL_TIME) {
     switch (data->mix_mode) {
       case ACTCON_MIX_BEFORE:
         mul_m4_m4m4_aligned_scale(cob->matrix, ct->matrix, cob->matrix);