Cleanup: use 'const' arguments in transform calculation

Use const arguments to simplify further optimizations.

Transforming elements shouldn't need to change their containers
data-structures.
ElementResize for grease pencil stroke thickness was
modifying TransInfo.num & TransInfo.values_final.

Now copies are operated on to preserve const correctness although
it's worth investigating if this can be avoided altogether.

7 files changed, 114 insertions, 75 deletions

diff --git a/source/blender/editors/transform/transform.h b/source/blender/editors/transform/transform.h
index 2df0d86d02b..4f97c3b6713 100644
--- a/source/blender/editors/transform/transform.h
+++ b/source/blender/editors/transform/transform.h
@@ -356,22 +356,22 @@ typedef struct TransCon {
 
   /** Apply function pointer for linear vectorial transformation
    * The last three parameters are pointers to the in/out/printable vectors. */
-  void (*applyVec)(struct TransInfo *t,
-                   struct TransDataContainer *tc,
+  void (*applyVec)(const struct TransInfo *t,
+                   const struct TransDataContainer *tc,
                    struct TransData *td,
                    const float in[3],
-                   float out[3]);
+                   float r_out[3]);
   /** Apply function pointer for size transformation. */
-  void (*applySize)(struct TransInfo *t,
-                    struct TransDataContainer *tc,
+  void (*applySize)(const struct TransInfo *t,
+                    const struct TransDataContainer *tc,
                     struct TransData *td,
-                    float smat[3][3]);
+                    float r_smat[3][3]);
   /** Apply function pointer for rotation transformation */
-  void (*applyRot)(struct TransInfo *t,
-                   struct TransDataContainer *tc,
+  void (*applyRot)(const struct TransInfo *t,
+                   const struct TransDataContainer *tc,
                    struct TransData *td,
-                   float vec[3],
-                   float *angle);
+                   float r_axis[3],
+                   float *r_angle);
 } TransCon;
 
 typedef struct MouseInput {
diff --git a/source/blender/editors/transform/transform_constraints.c b/source/blender/editors/transform/transform_constraints.c
index 8c74d5349ba..78fc6575e6e 100644
--- a/source/blender/editors/transform/transform_constraints.c
+++ b/source/blender/editors/transform/transform_constraints.c
@@ -97,7 +97,7 @@ static void view_vector_calc(const TransInfo *t, const float focus[3], float r_v
 /* ************************** CONSTRAINTS ************************* */
 #define CONSTRAIN_EPSILON 0.0001f
 
-static void constraint_plane_calc(TransInfo *t, float r_plane[4])
+static void constraint_plane_calc(const TransInfo *t, float r_plane[4])
 {
   const float *constraint_vector[2];
   int n = 0;
@@ -391,8 +391,11 @@ static void planeProjection(const TransInfo *t, const float in[3], float out[3])
  * projected along the view vector.
  * (in perspective mode, the view vector is relative to the position on screen)
  */
-static void applyAxisConstraintVec(
-    TransInfo *t, TransDataContainer *UNUSED(tc), TransData *td, const float in[3], float out[3])
+static void applyAxisConstraintVec(const TransInfo *t,
+                                   const TransDataContainer *UNUSED(tc),
+                                   TransData *td,
+                                   const float in[3],
+                                   float out[3])
 {
   copy_v3_v3(out, in);
   if (!td && t->con.mode & CON_APPLY) {
@@ -472,8 +475,11 @@ static void applyAxisConstraintVec(
  *
  * Further down, that vector is mapped to each data's space.
  */
-static void applyObjectConstraintVec(
-    TransInfo *t, TransDataContainer *tc, TransData *td, const float in[3], float out[3])
+static void applyObjectConstraintVec(const TransInfo *t,
+                                     const TransDataContainer *tc,
+                                     TransData *td,
+                                     const float in[3],
+                                     float out[3])
 {
   if (!td) {
     applyAxisConstraintVec(t, tc, td, in, out);
@@ -494,36 +500,36 @@ static void applyObjectConstraintVec(
 /**
  * Generic callback for constant spatial constraints applied to resize motion.
  */
-static void applyAxisConstraintSize(TransInfo *t,
-                                    TransDataContainer *UNUSED(tc),
+static void applyAxisConstraintSize(const TransInfo *t,
+                                    const TransDataContainer *UNUSED(tc),
                                     TransData *td,
-                                    float smat[3][3])
+                                    float r_smat[3][3])
 {
   if (!td && t->con.mode & CON_APPLY) {
     float tmat[3][3];
 
     if (!(t->con.mode & CON_AXIS0)) {
-      smat[0][0] = 1.0f;
+      r_smat[0][0] = 1.0f;
     }
     if (!(t->con.mode & CON_AXIS1)) {
-      smat[1][1] = 1.0f;
+      r_smat[1][1] = 1.0f;
     }
     if (!(t->con.mode & CON_AXIS2)) {
-      smat[2][2] = 1.0f;
+      r_smat[2][2] = 1.0f;
     }
 
-    mul_m3_m3m3(tmat, smat, t->spacemtx_inv);
-    mul_m3_m3m3(smat, t->spacemtx, tmat);
+    mul_m3_m3m3(tmat, r_smat, t->spacemtx_inv);
+    mul_m3_m3m3(r_smat, t->spacemtx, tmat);
   }
 }
 
 /**
  * Callback for object based spatial constraints applied to resize motion.
  */
-static void applyObjectConstraintSize(TransInfo *t,
-                                      TransDataContainer *tc,
+static void applyObjectConstraintSize(const TransInfo *t,
+                                      const TransDataContainer *tc,
                                       TransData *td,
-                                      float smat[3][3])
+                                      float r_smat[3][3])
 {
   if (td && t->con.mode & CON_APPLY) {
     float tmat[3][3];
@@ -532,26 +538,26 @@ static void applyObjectConstraintSize(TransInfo *t,
     invert_m3_m3(imat, td->axismtx);
 
     if (!(t->con.mode & CON_AXIS0)) {
-      smat[0][0] = 1.0f;
+      r_smat[0][0] = 1.0f;
     }
     if (!(t->con.mode & CON_AXIS1)) {
-      smat[1][1] = 1.0f;
+      r_smat[1][1] = 1.0f;
     }
     if (!(t->con.mode & CON_AXIS2)) {
-      smat[2][2] = 1.0f;
+      r_smat[2][2] = 1.0f;
     }
 
-    mul_m3_m3m3(tmat, smat, imat);
+    mul_m3_m3m3(tmat, r_smat, imat);
     if (t->flag & T_EDIT) {
-      mul_m3_m3m3(smat, tc->mat3_unit, smat);
+      mul_m3_m3m3(r_smat, tc->mat3_unit, r_smat);
     }
-    mul_m3_m3m3(smat, td->axismtx, tmat);
+    mul_m3_m3m3(r_smat, td->axismtx, tmat);
   }
 }
 
-static void constraints_rotation_impl(TransInfo *t,
+static void constraints_rotation_impl(const TransInfo *t,
                                       const float axismtx[3][3],
-                                      float r_vec[3],
+                                      float r_axis[3],
                                       float *r_angle)
 {
   BLI_assert(t->con.mode & CON_APPLY);
@@ -560,15 +566,15 @@ static void constraints_rotation_impl(TransInfo *t,
   switch (mode) {
     case CON_AXIS0:
     case (CON_AXIS1 | CON_AXIS2):
-      copy_v3_v3(r_vec, axismtx[0]);
+      copy_v3_v3(r_axis, axismtx[0]);
       break;
     case CON_AXIS1:
     case (CON_AXIS0 | CON_AXIS2):
-      copy_v3_v3(r_vec, axismtx[1]);
+      copy_v3_v3(r_axis, axismtx[1]);
       break;
     case CON_AXIS2:
     case (CON_AXIS0 | CON_AXIS1):
-      copy_v3_v3(r_vec, axismtx[2]);
+      copy_v3_v3(r_axis, axismtx[2]);
       break;
   }
   /* don't flip axis if asked to or if num input */
@@ -576,7 +582,7 @@ static void constraints_rotation_impl(TransInfo *t,
       !((mode & CON_NOFLIP) || hasNumInput(&t->num) || (t->flag & T_INPUT_IS_VALUES_FINAL))) {
     float view_vector[3];
     view_vector_calc(t, t->center_global, view_vector);
-    if (dot_v3v3(r_vec, view_vector) > 0.0f) {
+    if (dot_v3v3(r_axis, view_vector) > 0.0f) {
       *r_angle = -(*r_angle);
     }
   }
@@ -595,11 +601,14 @@ static void constraints_rotation_impl(TransInfo *t,
  * This insures that the rotation is always logically following the mouse.
  * (ie: not doing counterclockwise rotations when the mouse moves clockwise).
  */
-static void applyAxisConstraintRot(
-    TransInfo *t, TransDataContainer *UNUSED(tc), TransData *td, float vec[3], float *angle)
+static void applyAxisConstraintRot(const TransInfo *t,
+                                   const TransDataContainer *UNUSED(tc),
+                                   TransData *td,
+                                   float r_axis[3],
+                                   float *r_angle)
 {
   if (!td && t->con.mode & CON_APPLY) {
-    constraints_rotation_impl(t, t->spacemtx, vec, angle);
+    constraints_rotation_impl(t, t->spacemtx, r_axis, r_angle);
   }
 }
 
@@ -616,8 +625,11 @@ static void applyAxisConstraintRot(
  * This insures that the rotation is always logically following the mouse.
  * (ie: not doing counterclockwise rotations when the mouse moves clockwise).
  */
-static void applyObjectConstraintRot(
-    TransInfo *t, TransDataContainer *tc, TransData *td, float vec[3], float *angle)
+static void applyObjectConstraintRot(const TransInfo *t,
+                                     const TransDataContainer *tc,
+                                     TransData *td,
+                                     float r_axis[3],
+                                     float *r_angle)
 {
   if (t->con.mode & CON_APPLY) {
     float tmp_axismtx[3][3];
@@ -638,7 +650,7 @@ static void applyObjectConstraintRot(
       axismtx = td->axismtx;
     }
 
-    constraints_rotation_impl(t, axismtx, vec, angle);
+    constraints_rotation_impl(t, axismtx, r_axis, r_angle);
   }
 }
 
@@ -1164,7 +1176,7 @@ bool isLockConstraint(TransInfo *t)
  * even if they aren't actually used in the callback function.
  * (Which could happen for weird constraints not yet designed. Along a path for example.)
  */
-int getConstraintSpaceDimension(TransInfo *t)
+int getConstraintSpaceDimension(const TransInfo *t)
 {
   int n = 0;
 
diff --git a/source/blender/editors/transform/transform_constraints.h b/source/blender/editors/transform/transform_constraints.h
index ac62c057f9d..cbf6c7bb576 100644
--- a/source/blender/editors/transform/transform_constraints.h
+++ b/source/blender/editors/transform/transform_constraints.h
@@ -47,4 +47,4 @@ void setNearestAxis(TransInfo *t);
 int constraintModeToIndex(const TransInfo *t);
 char constraintModeToChar(const TransInfo *t);
 bool isLockConstraint(TransInfo *t);
-int getConstraintSpaceDimension(TransInfo *t);
+int getConstraintSpaceDimension(const TransInfo *t);
diff --git a/source/blender/editors/transform/transform_mode.c b/source/blender/editors/transform/transform_mode.c
index 6a946994e06..65a673940f8 100644
--- a/source/blender/editors/transform/transform_mode.c
+++ b/source/blender/editors/transform/transform_mode.c
@@ -68,7 +68,7 @@ int transform_mode_really_used(bContext *C, int mode)
   return mode;
 }
 
-bool transdata_check_local_center(TransInfo *t, short around)
+bool transdata_check_local_center(const TransInfo *t, short around)
 {
   return ((around == V3D_AROUND_LOCAL_ORIGINS) &&
           ((t->options & (CTX_OBJECT | CTX_POSE_BONE)) ||
@@ -248,7 +248,7 @@ void protectedSizeBits(short protectflag, float size[3])
 /** \name Transform Limits
  * \{ */
 
-void constraintTransLim(TransInfo *t, TransData *td)
+void constraintTransLim(const TransInfo *t, TransData *td)
 {
   if (td->con) {
     const bConstraintTypeInfo *ctiLoc = BKE_constraint_typeinfo_from_type(
@@ -359,7 +359,7 @@ static void constraintob_from_transdata(bConstraintOb *cob, TransData *td)
   }
 }
 
-static void constraintRotLim(TransInfo *UNUSED(t), TransData *td)
+static void constraintRotLim(const TransInfo *UNUSED(t), TransData *td)
 {
   if (td->con) {
     const bConstraintTypeInfo *cti = BKE_constraint_typeinfo_from_type(CONSTRAINT_TYPE_ROTLIMIT);
@@ -432,7 +432,7 @@ static void constraintRotLim(TransInfo *UNUSED(t), TransData *td)
   }
 }
 
-void constraintSizeLim(TransInfo *t, TransData *td)
+void constraintSizeLim(const TransInfo *t, TransData *td)
 {
   if (td->con && td->ext) {
     const bConstraintTypeInfo *cti = BKE_constraint_typeinfo_from_type(CONSTRAINT_TYPE_SIZELIMIT);
@@ -557,8 +557,8 @@ void headerRotation(TransInfo *t, char *str, const int str_size, float final)
  *
  * Protected axis and other transform settings are taken into account.
  */
-void ElementRotation_ex(TransInfo *t,
-                        TransDataContainer *tc,
+void ElementRotation_ex(const TransInfo *t,
+                        const TransDataContainer *tc,
                         TransData *td,
                         const float mat[3][3],
                         const float *center)
@@ -810,8 +810,11 @@ void ElementRotation_ex(TransInfo *t,
   }
 }
 
-void ElementRotation(
-    TransInfo *t, TransDataContainer *tc, TransData *td, float mat[3][3], const short around)
+void ElementRotation(const TransInfo *t,
+                     const TransDataContainer *tc,
+                     TransData *td,
+                     const float mat[3][3],
+                     const short around)
 {
   const float *center;
 
@@ -921,7 +924,10 @@ static void TransMat3ToSize(const float mat[3][3], const float smat[3][3], float
   }
 }
 
-void ElementResize(TransInfo *t, TransDataContainer *tc, TransData *td, float mat[3][3])
+void ElementResize(const TransInfo *t,
+                   const TransDataContainer *tc,
+                   TransData *td,
+                   const float mat[3][3])
 {
   float tmat[3][3], smat[3][3], center[3];
   float vec[3];
@@ -1014,17 +1020,31 @@ void ElementResize(TransInfo *t, TransDataContainer *tc, TransData *td, float ma
     sub_v3_v3(vec, td->center);
   }
 
-  /* grease pencil falloff */
+  /* Grease pencil falloff.
+   *
+   * FIXME: This is bad on multiple levels!
+   *
+   * - #applyNumInput is not intended to be run for every element,
+   *   this writes back into the number input in a way that doesn't make sense to run many times.
+   *
+   * - Writing into #TransInfo should be avoided since it means order of operations
+   *   may impact the result and isn't thread-safe.
+   *
+   *   Operating on copies as a temporary solution.
+   */
   if (t->options & CTX_GPENCIL_STROKES) {
     bGPDstroke *gps = (bGPDstroke *)td->extra;
     mul_v3_fl(vec, td->factor * gps->runtime.multi_frame_falloff);
 
-    /* scale stroke thickness */
+    /* Scale stroke thickness. */
     if (td->val) {
-      transform_snap_increment(t, t->values_final);
-      applyNumInput(&t->num, t->values_final);
+      NumInput num_evil = t->num;
+      float values_final_evil[4];
+      copy_v4_v4(values_final_evil, t->values_final);
+      transform_snap_increment(t, values_final_evil);
+      applyNumInput(&num_evil, values_final_evil);
 
-      float ratio = t->values_final[0];
+      float ratio = values_final_evil[0];
       *td->val = td->ival * ratio * gps->runtime.multi_frame_falloff;
       CLAMP_MIN(*td->val, 0.001f);
     }
@@ -1044,6 +1064,7 @@ void ElementResize(TransInfo *t, TransDataContainer *tc, TransData *td, float ma
 
   constraintTransLim(t, td);
 }
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
diff --git a/source/blender/editors/transform/transform_mode.h b/source/blender/editors/transform/transform_mode.h
index a2b95eb3de4..027fb6b6982 100644
--- a/source/blender/editors/transform/transform_mode.h
+++ b/source/blender/editors/transform/transform_mode.h
@@ -41,22 +41,28 @@ typedef struct TransDataGenericSlideVert {
 
 /* transform_mode.c */
 int transform_mode_really_used(struct bContext *C, int mode);
-bool transdata_check_local_center(TransInfo *t, short around);
+bool transdata_check_local_center(const TransInfo *t, short around);
 bool transform_mode_is_changeable(const int mode);
 void protectedTransBits(short protectflag, float vec[3]);
 void protectedSizeBits(short protectflag, float size[3]);
-void constraintTransLim(TransInfo *t, TransData *td);
-void constraintSizeLim(TransInfo *t, TransData *td);
+void constraintTransLim(const TransInfo *t, TransData *td);
+void constraintSizeLim(const TransInfo *t, TransData *td);
 void headerRotation(TransInfo *t, char *str, int str_size, float final);
-void ElementRotation_ex(TransInfo *t,
-                        TransDataContainer *tc,
+void ElementRotation_ex(const TransInfo *t,
+                        const TransDataContainer *tc,
                         TransData *td,
                         const float mat[3][3],
                         const float *center);
-void ElementRotation(
-    TransInfo *t, TransDataContainer *tc, TransData *td, float mat[3][3], const short around);
+void ElementRotation(const TransInfo *t,
+                     const TransDataContainer *tc,
+                     TransData *td,
+                     const float mat[3][3],
+                     const short around);
 void headerResize(TransInfo *t, const float vec[3], char *str, int str_size);
-void ElementResize(TransInfo *t, TransDataContainer *tc, TransData *td, float mat[3][3]);
+void ElementResize(const TransInfo *t,
+                   const TransDataContainer *tc,
+                   TransData *td,
+                   const float mat[3][3]);
 short getAnimEdit_SnapMode(TransInfo *t);
 void doAnimEdit_SnapFrame(
     TransInfo *t, TransData *td, TransData2D *td2d, struct AnimData *adt, short autosnap);
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 4ecb9594325..b6e0f07cc70 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -1517,7 +1517,7 @@ bool transform_snap_grid(TransInfo *t, float *val)
   return true;
 }
 
-static void snap_increment_apply_ex(TransInfo *UNUSED(t),
+static void snap_increment_apply_ex(const TransInfo *UNUSED(t),
                                     const int max_index,
                                     const float increment_val,
                                     const float aspect[3],
@@ -1531,8 +1531,8 @@ static void snap_increment_apply_ex(TransInfo *UNUSED(t),
   }
 }
 
-static void snap_increment_apply(TransInfo *t,
-                                 int max_index,
+static void snap_increment_apply(const TransInfo *t,
+                                 const int max_index,
                                  const float increment_dist,
                                  float *r_val)
 {
@@ -1564,7 +1564,7 @@ static void snap_increment_apply(TransInfo *t,
   snap_increment_apply_ex(t, max_index, increment_dist, asp, r_val, r_val);
 }
 
-bool transform_snap_increment_ex(TransInfo *t, bool use_local_space, float *r_val)
+bool transform_snap_increment_ex(const TransInfo *t, bool use_local_space, float *r_val)
 {
   if (!activeSnap(t)) {
     return false;
@@ -1595,7 +1595,7 @@ bool transform_snap_increment_ex(TransInfo *t, bool use_local_space, float *r_va
   return true;
 }
 
-bool transform_snap_increment(TransInfo *t, float *r_val)
+bool transform_snap_increment(const TransInfo *t, float *r_val)
 {
   return transform_snap_increment_ex(t, false, r_val);
 }
diff --git a/source/blender/editors/transform/transform_snap.h b/source/blender/editors/transform/transform_snap.h
index 1632b49fbbf..bf14e564380 100644
--- a/source/blender/editors/transform/transform_snap.h
+++ b/source/blender/editors/transform/transform_snap.h
@@ -54,8 +54,8 @@ void snapFrameTransform(struct TransInfo *t,
 
 bool transformModeUseSnap(const TransInfo *t);
 
-bool transform_snap_increment_ex(TransInfo *t, bool use_local_space, float *r_val);
-bool transform_snap_increment(TransInfo *t, float *val);
+bool transform_snap_increment_ex(const TransInfo *t, bool use_local_space, float *r_val);
+bool transform_snap_increment(const TransInfo *t, float *val);
 bool transform_snap_grid(TransInfo *t, float *val);
 
 void snapSequenceBounds(TransInfo *t, const int mval[2]);