Modifiers: Add normalize weights option to vertex weight modifiers

Original patch by Cody Winchester (@CodyWinch), several fixes and
cleanup by Bastien Montagne (@mont29).

Differential revision: https://developer.blender.org/D7656

5 files changed, 40 insertions, 5 deletions

diff --git a/source/blender/modifiers/intern/MOD_weightvg_util.c b/source/blender/modifiers/intern/MOD_weightvg_util.c
index 5dae6bb8505..1a38787777f 100644
--- a/source/blender/modifiers/intern/MOD_weightvg_util.c
+++ b/source/blender/modifiers/intern/MOD_weightvg_util.c
@@ -272,16 +272,45 @@ void weightvg_update_vg(MDeformVert *dvert,
                         const bool do_add,
                         const float add_thresh,
                         const bool do_rem,
-                        const float rem_thresh)
+                        const float rem_thresh,
+                        const bool do_normalize)
 {
   int i;
 
+  float min_w = weights[0];
+  float norm_fac = 1.0f;
+  if (do_normalize) {
+    float max_w = weights[0];
+    for (i = 1; i < num; i++) {
+      const float w = weights[i];
+
+      /* No need to clamp here, normalization will ensure we stay within [0.0, 1.0] range. */
+      if (w < min_w) {
+        min_w = w;
+      }
+      else if (w > max_w) {
+        max_w = w;
+      }
+    }
+
+    const float range = max_w - min_w;
+    if (fabsf(range) > FLT_EPSILON) {
+      norm_fac = 1.0f / range;
+    }
+    else {
+      min_w = 0.0f;
+    }
+  }
+
   for (i = 0; i < num; i++) {
     float w = weights[i];
     MDeformVert *dv = &dvert[indices ? indices[i] : i];
     MDeformWeight *dw = dws ? dws[i] :
                               ((defgrp_idx >= 0) ? BKE_defvert_find_index(dv, defgrp_idx) : NULL);
 
+    if (do_normalize) {
+      w = (w - min_w) * norm_fac;
+    }
     /* Never allow weights out of [0.0, 1.0] range. */
     CLAMP(w, 0.0f, 1.0f);
 
diff --git a/source/blender/modifiers/intern/MOD_weightvg_util.h b/source/blender/modifiers/intern/MOD_weightvg_util.h
index 09a6a1afb3e..50597d43112 100644
--- a/source/blender/modifiers/intern/MOD_weightvg_util.h
+++ b/source/blender/modifiers/intern/MOD_weightvg_util.h
@@ -86,6 +86,7 @@ void weightvg_update_vg(struct MDeformVert *dvert,
                         const bool do_add,
                         const float add_thresh,
                         const bool do_rem,
-                        const float rem_thresh);
+                        const float rem_thresh,
+                        const bool do_normalize);
 
 #endif /* __MOD_WEIGHTVG_UTIL_H__ */
diff --git a/source/blender/modifiers/intern/MOD_weightvgedit.c b/source/blender/modifiers/intern/MOD_weightvgedit.c
index 1ff8dfbdcca..8ce1aaee942 100644
--- a/source/blender/modifiers/intern/MOD_weightvgedit.c
+++ b/source/blender/modifiers/intern/MOD_weightvgedit.c
@@ -239,6 +239,7 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
 
   /* Do mapping. */
   const bool do_invert_mapping = (wmd->edit_flags & MOD_WVG_INVERT_FALLOFF) != 0;
+  const bool do_normalize = (wmd->edit_flags & MOD_WVG_EDIT_WEIGHTS_NORMALIZE) != 0;
   if (do_invert_mapping || wmd->falloff_type != MOD_WVG_MAPPING_NONE) {
     RNG *rng = NULL;
 
@@ -283,7 +284,8 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
                      do_add,
                      wmd->add_threshold,
                      do_rem,
-                     wmd->rem_threshold);
+                     wmd->rem_threshold,
+                     do_normalize);
 
   /* If weight preview enabled... */
 #if 0 /* XXX Currently done in mod stack :/ */
diff --git a/source/blender/modifiers/intern/MOD_weightvgmix.c b/source/blender/modifiers/intern/MOD_weightvgmix.c
index f1db8502d74..57156aec5ec 100644
--- a/source/blender/modifiers/intern/MOD_weightvgmix.c
+++ b/source/blender/modifiers/intern/MOD_weightvgmix.c
@@ -224,6 +224,7 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
   int numIdx = 0;
   int i;
   const bool invert_vgroup_mask = (wmd->flag & MOD_WVG_MIX_INVERT_VGROUP_MASK) != 0;
+  const bool do_normalize = (wmd->flag & MOD_WVG_MIX_WEIGHTS_NORMALIZE) != 0;
   /* Flags. */
 #if 0
   const bool do_prev = (wmd->modifier.mode & eModifierMode_DoWeightPreview) != 0;
@@ -408,7 +409,7 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
    * XXX Depending on the MOD_WVG_SET_xxx option chosen, we might have to add vertices to vgroup.
    */
   weightvg_update_vg(
-      dvert, defgrp_index, dw1, numIdx, indices, org_w, true, -FLT_MAX, false, 0.0f);
+      dvert, defgrp_index, dw1, numIdx, indices, org_w, true, -FLT_MAX, false, 0.0f, do_normalize);
 
   /* If weight preview enabled... */
 #if 0 /* XXX Currently done in mod stack :/ */
diff --git a/source/blender/modifiers/intern/MOD_weightvgproximity.c b/source/blender/modifiers/intern/MOD_weightvgproximity.c
index 3e746403050..e3f833ff81e 100644
--- a/source/blender/modifiers/intern/MOD_weightvgproximity.c
+++ b/source/blender/modifiers/intern/MOD_weightvgproximity.c
@@ -429,6 +429,7 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
   int i;
   const bool invert_vgroup_mask = (wmd->proximity_flags & MOD_WVG_PROXIMITY_INVERT_VGROUP_MASK) !=
                                   0;
+  const bool do_normalize = (wmd->proximity_flags & MOD_WVG_PROXIMITY_WEIGHTS_NORMALIZE) != 0;
   /* Flags. */
 #if 0
   const bool do_prev = (wmd->modifier.mode & eModifierMode_DoWeightPreview) != 0;
@@ -604,7 +605,8 @@ static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, Mesh *
                    invert_vgroup_mask);
 
   /* Update vgroup. Note we never add nor remove vertices from vgroup here. */
-  weightvg_update_vg(dvert, defgrp_index, dw, numIdx, indices, org_w, false, 0.0f, false, 0.0f);
+  weightvg_update_vg(
+      dvert, defgrp_index, dw, numIdx, indices, org_w, false, 0.0f, false, 0.0f, do_normalize);
 
   /* If weight preview enabled... */
 #if 0 /* XXX Currently done in mod stack :/ */