From 59f9a5e6ac6f5bff914204ef299cba27bb5016eb Mon Sep 17 00:00:00 2001
From: Robert Sheldon <rsheldiii>
Date: Thu, 15 Jul 2021 15:58:34 +0200
Subject: Fix T88188: Allow keyframing vertex mass in cloth sim

Update vertex weights between simulation steps if they have changed.
This allows for animated vertex weights in the cloth sim.

Reviewed By: Sebastian Parborg

Differential Revision: http://developer.blender.org/D11640
---
 source/blender/simulation/SIM_mass_spring.h          | 2 ++
 source/blender/simulation/intern/SIM_mass_spring.cpp | 6 +++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

(limited to 'source/blender/simulation')

diff --git a/source/blender/simulation/SIM_mass_spring.h b/source/blender/simulation/SIM_mass_spring.h
index 43de8b155cf..b3299258209 100644
--- a/source/blender/simulation/SIM_mass_spring.h
+++ b/source/blender/simulation/SIM_mass_spring.h
@@ -45,6 +45,8 @@ void SIM_mass_spring_solver_free(struct Implicit_Data *id);
 int SIM_mass_spring_solver_numvert(struct Implicit_Data *id);
 
 int SIM_cloth_solver_init(struct Object *ob, struct ClothModifierData *clmd);
+void SIM_mass_spring_set_implicit_vertex_mass(struct Implicit_Data *data, int index, float mass);
+
 void SIM_cloth_solver_free(struct ClothModifierData *clmd);
 int SIM_cloth_solve(struct Depsgraph *depsgraph,
                     struct Object *ob,
diff --git a/source/blender/simulation/intern/SIM_mass_spring.cpp b/source/blender/simulation/intern/SIM_mass_spring.cpp
index cf654ebff07..ca01120eecb 100644
--- a/source/blender/simulation/intern/SIM_mass_spring.cpp
+++ b/source/blender/simulation/intern/SIM_mass_spring.cpp
@@ -203,7 +203,7 @@ int SIM_cloth_solver_init(Object *UNUSED(ob), ClothModifierData *clmd)
   cloth->implicit = id = SIM_mass_spring_solver_create(cloth->mvert_num, nondiag);
 
   for (i = 0; i < cloth->mvert_num; i++) {
-    SIM_mass_spring_set_vertex_mass(id, i, verts[i].mass);
+    SIM_mass_spring_set_implicit_vertex_mass(id, i, verts[i].mass);
   }
 
   for (i = 0; i < cloth->mvert_num; i++) {
@@ -213,6 +213,10 @@ int SIM_cloth_solver_init(Object *UNUSED(ob), ClothModifierData *clmd)
   return 1;
 }
 
+void SIM_mass_spring_set_implicit_vertex_mass(Implicit_Data *data, int index, float mass){
+  SIM_mass_spring_set_vertex_mass(data, index, mass);
+}
+
 void SIM_cloth_solver_free(ClothModifierData *clmd)
 {
   Cloth *cloth = clmd->clothObject;
-- 
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