Commit: db2ac79fc7ca7d65a3e2912b4b6b5f1ec3b911fd
Author: Lukas Tönne
Date: Thu Dec 18 13:52:31 2014 +0100
Branches: master
https://developer.blender.org/rBdb2ac79fc7ca7d65a3e2912b4b6b5f1ec3b911fd
Radical simplification of the wind effect on hair, since the previous
approach does not work very well.
Using a cross section estimate still causes large oscillations due to
varying hair force based on angles. It also requires a sensible hair
thickness value (particle radius) which is difficult to control and
visualize at this point.
The new model is based purely on per-vertex forces, which seems to be
much more stable. It's also somewhat justified by the fact that each
hair vertex represents a certain mass.
Conflicts:
source/blender/physics/intern/BPH_mass_spring.cpp
===================================================================
M source/blender/physics/intern/BPH_mass_spring.cpp
M source/blender/physics/intern/implicit.h
M source/blender/physics/intern/implicit_blender.c
===================================================================
diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp
b/source/blender/physics/intern/BPH_mass_spring.cpp
index e9bf376..9e58a13 100644
--- a/source/blender/physics/intern/BPH_mass_spring.cpp
+++ b/source/blender/physics/intern/BPH_mass_spring.cpp
@@ -497,6 +497,7 @@ static void cloth_calc_force(ClothModifierData *clmd, float
UNUSED(frame), ListB
/* Hair has only edges */
if (cloth->numfaces == 0) {
+#if 0
ClothHairData *hairdata = clmd->hairdata;
ClothHairData *hair_ij, *hair_kl;
@@ -508,6 +509,16 @@ static void cloth_calc_force(ClothModifierData *clmd,
float UNUSED(frame), ListB
BPH_mass_spring_force_edge_wind(data,
spring->ij, spring->kl, hair_ij->radius, hair_kl->radius, winvec);
}
}
+#else
+ ClothHairData *hairdata = clmd->hairdata;
+
+ vert = cloth->verts;
+ for (i = 0; i < cloth->numverts; i++, vert++) {
+ ClothHairData *hair = &hairdata[i];
+
+ BPH_mass_spring_force_vertex_wind(data, i,
hair->radius, winvec);
+ }
+#endif
MEM_freeN(winvec);
}
diff --git a/source/blender/physics/intern/implicit.h
b/source/blender/physics/intern/implicit.h
index 1c9dccb..0e2d12b 100644
--- a/source/blender/physics/intern/implicit.h
+++ b/source/blender/physics/intern/implicit.h
@@ -112,6 +112,8 @@ void BPH_mass_spring_force_extern(struct Implicit_Data
*data, int i, const float
void BPH_mass_spring_force_face_wind(struct Implicit_Data *data, int v1, int
v2, int v3, int v4, const float (*winvec)[3]);
/* Wind force, acting on an edge */
void BPH_mass_spring_force_edge_wind(struct Implicit_Data *data, int v1, int
v2, float radius1, float radius2, const float (*winvec)[3]);
+/* Wind force, acting on a vertex */
+void BPH_mass_spring_force_vertex_wind(struct Implicit_Data *data, int v,
float radius, const float (*winvec)[3]);
/* Linear spring force between two points */
bool BPH_mass_spring_force_spring_linear(struct Implicit_Data *data, int i,
int j, float restlen,
float stiffness, float damping, bool
no_compress, float clamp_force,
diff --git a/source/blender/physics/intern/implicit_blender.c
b/source/blender/physics/intern/implicit_blender.c
index e632050..9f43e79 100644
--- a/source/blender/physics/intern/implicit_blender.c
+++ b/source/blender/physics/intern/implicit_blender.c
@@ -1493,11 +1493,22 @@ void BPH_mass_spring_force_edge_wind(Implicit_Data
*data, int v1, int v2, float
add_v3_v3(data->F[v1], f);
world_to_root_v3(data, v2, win, winvec[v2]);
- /* use -length to invert edge direction */
edge_wind_vertex(dir, length, radius2, win, f, dfdx, dfdv);
add_v3_v3(data->F[v2], f);
}
+void BPH_mass_spring_force_vertex_wind(Implicit_Data *data, int v, float
UNUSED(radius), const float (*winvec)[3])
+{
+ const float density = 0.01f; /* XXX arbitrary value, corresponds to
effect of air density */
+
+ float wind[3];
+ float f[3];
+
+ world_to_root_v3(data, v, wind, winvec[v]);
+ mul_v3_v3fl(f, wind, density);
+ add_v3_v3(data->F[v], f);
+}
+
BLI_INLINE void dfdx_spring(float to[3][3], const float dir[3], float length,
float L, float k)
{
// dir is unit length direction, rest is spring's restlength, k is
spring constant.
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