diff options
Diffstat (limited to 'source/blender/physics/intern/implicit_blender.c')
| -rw-r--r-- | source/blender/physics/intern/implicit_blender.c | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/source/blender/physics/intern/implicit_blender.c b/source/blender/physics/intern/implicit_blender.c index cb115a2c10a..e6320507db0 100644 --- a/source/blender/physics/intern/implicit_blender.c +++ b/source/blender/physics/intern/implicit_blender.c @@ -1461,21 +1461,41 @@ void BPH_mass_spring_force_face_wind(Implicit_Data *data, int v1, int v2, int v3 } } -void BPH_mass_spring_force_edge_wind(Implicit_Data *data, int v1, int v2, const float (*winvec)[3]) +static void edge_wind_vertex(const float dir[3], float length, float radius, const float wind[3], float f[3], float UNUSED(dfdx[3][3]), float UNUSED(dfdv[3][3])) { - const float effector_scale = 0.01; - float win[3], dir[3], nor[3], length; + const float density = 0.01f; /* XXX arbitrary value, corresponds to effect of air density */ + float cos_alpha, sin_alpha, cross_section; + float windlen = len_v3(wind); + + if (windlen == 0.0f) { + zero_v3(f); + return; + } + + /* angle of wind direction to edge */ + cos_alpha = dot_v3v3(wind, dir) / windlen; + sin_alpha = sqrt(1.0 - cos_alpha*cos_alpha); + cross_section = radius * (M_PI * radius * sin_alpha + length * cos_alpha); + + mul_v3_v3fl(f, wind, density * cross_section); +} + +void BPH_mass_spring_force_edge_wind(Implicit_Data *data, int v1, int v2, float radius1, float radius2, const float (*winvec)[3]) +{ + float win[3], dir[3], length; + float f[3], dfdx[3][3], dfdv[3][3]; sub_v3_v3v3(dir, data->X[v1], data->X[v2]); length = normalize_v3(dir); world_to_root_v3(data, v1, win, winvec[v1]); - madd_v3_v3v3fl(nor, win, dir, -dot_v3v3(win, dir)); - madd_v3_v3fl(data->F[v1], nor, effector_scale * length); + edge_wind_vertex(dir, length, radius1, win, f, dfdx, dfdv); + add_v3_v3(data->F[v1], f); world_to_root_v3(data, v2, win, winvec[v2]); - madd_v3_v3v3fl(nor, win, dir, -dot_v3v3(win, dir)); - madd_v3_v3fl(data->F[v2], nor, effector_scale * length); + /* use -length to invert edge direction */ + edge_wind_vertex(dir, length, radius2, win, f, dfdx, dfdv); + add_v3_v3(data->F[v2], f); } BLI_INLINE void dfdx_spring(float to[3][3], const float dir[3], float length, float L, float k) |