diff options
Diffstat (limited to 'source/blender/physics/intern')
| -rw-r--r-- | source/blender/physics/intern/BPH_mass_spring.cpp | 29 | ||||
| -rw-r--r-- | source/blender/physics/intern/implicit.h | 5 | ||||
| -rw-r--r-- | source/blender/physics/intern/implicit_blender.c | 63 |
3 files changed, 84 insertions, 13 deletions
diff --git a/source/blender/physics/intern/BPH_mass_spring.cpp b/source/blender/physics/intern/BPH_mass_spring.cpp index 18fab5215a6..3b6e39ef48f 100644 --- a/source/blender/physics/intern/BPH_mass_spring.cpp +++ b/source/blender/physics/intern/BPH_mass_spring.cpp @@ -683,23 +683,42 @@ static void cloth_calc_force( /* handle external forces like wind */ if (effectors) { + bool is_not_hair = (clmd->hairdata == NULL) && (cloth->primitive_num > 0); + bool has_wind = false, has_force = false; + /* cache per-vertex forces to avoid redundant calculation */ - float(*winvec)[3] = (float(*)[3])MEM_callocN(sizeof(float[3]) * mvert_num, "effector forces"); + float(*winvec)[3] = (float(*)[3])MEM_callocN(sizeof(float[3]) * mvert_num * 2, + "effector forces"); + float(*forcevec)[3] = is_not_hair ? winvec + mvert_num : winvec; + for (i = 0; i < cloth->mvert_num; i++) { float x[3], v[3]; EffectedPoint epoint; BPH_mass_spring_get_motion_state(data, i, x, v); pd_point_from_loc(scene, x, v, i, &epoint); - BKE_effectors_apply( - effectors, NULL, clmd->sim_parms->effector_weights, &epoint, winvec[i], NULL); + BKE_effectors_apply(effectors, + NULL, + clmd->sim_parms->effector_weights, + &epoint, + forcevec[i], + winvec[i], + NULL); + + has_wind = has_wind || !is_zero_v3(winvec[i]); + has_force = has_force || !is_zero_v3(forcevec[i]); } /* Hair has only edges. */ - if ((clmd->hairdata == NULL) && (cloth->primitive_num > 0)) { + if (is_not_hair) { for (i = 0; i < cloth->primitive_num; i++) { const MVertTri *vt = &tri[i]; - BPH_mass_spring_force_face_wind(data, vt->tri[0], vt->tri[1], vt->tri[2], winvec); + if (has_wind) { + BPH_mass_spring_force_face_wind(data, vt->tri[0], vt->tri[1], vt->tri[2], winvec); + } + if (has_force) { + BPH_mass_spring_force_face_extern(data, vt->tri[0], vt->tri[1], vt->tri[2], forcevec); + } } } else { diff --git a/source/blender/physics/intern/implicit.h b/source/blender/physics/intern/implicit.h index 69b50f7fa48..8bc09755180 100644 --- a/source/blender/physics/intern/implicit.h +++ b/source/blender/physics/intern/implicit.h @@ -126,9 +126,12 @@ void BPH_mass_spring_force_drag(struct Implicit_Data *data, float drag); /* Custom external force */ void BPH_mass_spring_force_extern( struct Implicit_Data *data, int i, const float f[3], float dfdx[3][3], float dfdv[3][3]); -/* Wind force, acting on a face */ +/* Wind force, acting on a face (only generates pressure from the normal component) */ void BPH_mass_spring_force_face_wind( struct Implicit_Data *data, int v1, int v2, int v3, const float (*winvec)[3]); +/* Arbitrary per-unit-area vector force field acting on a face. */ +void BPH_mass_spring_force_face_extern( + struct Implicit_Data *data, int v1, int v2, int v3, const float (*forcevec)[3]); /* Wind force, acting on an edge */ void BPH_mass_spring_force_edge_wind(struct Implicit_Data *data, int v1, diff --git a/source/blender/physics/intern/implicit_blender.c b/source/blender/physics/intern/implicit_blender.c index 063c224f158..5ec4c750d5d 100644 --- a/source/blender/physics/intern/implicit_blender.c +++ b/source/blender/physics/intern/implicit_blender.c @@ -1469,22 +1469,71 @@ void BPH_mass_spring_force_face_wind( Implicit_Data *data, int v1, int v2, int v3, const float (*winvec)[3]) { const float effector_scale = 0.02f; + int vs[3] = {v1, v2, v3}; float win[3], nor[3], area; - float factor; + float factor, base_force; + float force[3]; /* calculate face normal and area */ area = calc_nor_area_tri(nor, data->X[v1], data->X[v2], data->X[v3]); /* The force is calculated and split up evenly for each of the three face verts */ factor = effector_scale * area / 3.0f; - world_to_root_v3(data, v1, win, winvec[v1]); - madd_v3_v3fl(data->F[v1], nor, factor * dot_v3v3(win, nor)); + /* Calculate wind pressure at each vertex by projecting the wind field on the normal. */ + for (int i = 0; i < 3; i++) { + world_to_root_v3(data, vs[i], win, winvec[vs[i]]); - world_to_root_v3(data, v2, win, winvec[v2]); - madd_v3_v3fl(data->F[v2], nor, factor * dot_v3v3(win, nor)); + force[i] = dot_v3v3(win, nor); + } - world_to_root_v3(data, v3, win, winvec[v3]); - madd_v3_v3fl(data->F[v3], nor, factor * dot_v3v3(win, nor)); + /* Compute per-vertex force values from local pressures. + * From integrating the pressure over the triangle and deriving + * equivalent vertex forces, it follows that: + * + * force[idx] = (sum(pressure) + pressure[idx]) * area / 12 + * + * Effectively, 1/4 of the pressure acts just on its vertex, + * while 3/4 is split evenly over all three. + */ + mul_v3_fl(force, factor / 4.0f); + + base_force = force[0] + force[1] + force[2]; + + /* add pressure to each of the face verts */ + madd_v3_v3fl(data->F[v1], nor, base_force + force[0]); + madd_v3_v3fl(data->F[v2], nor, base_force + force[1]); + madd_v3_v3fl(data->F[v3], nor, base_force + force[2]); +} + +void BPH_mass_spring_force_face_extern( + Implicit_Data *data, int v1, int v2, int v3, const float (*forcevec)[3]) +{ + const float effector_scale = 0.02f; + int vs[3] = {v1, v2, v3}; + float nor[3], area; + float factor, base_force[3]; + float force[3][3]; + + /* calculate face normal and area */ + area = calc_nor_area_tri(nor, data->X[v1], data->X[v2], data->X[v3]); + /* The force is calculated and split up evenly for each of the three face verts */ + factor = effector_scale * area / 3.0f; + + /* Compute common and per-vertex force vectors from the original inputs. */ + zero_v3(base_force); + + for (int i = 0; i < 3; i++) { + world_to_root_v3(data, vs[i], force[i], forcevec[vs[i]]); + + mul_v3_fl(force[i], factor / 4.0f); + add_v3_v3(base_force, force[i]); + } + + /* Apply the common and vertex components to all vertices. */ + for (int i = 0; i < 3; i++) { + add_v3_v3(force[i], base_force); + add_v3_v3(data->F[vs[i]], force[i]); + } } float BPH_tri_tetra_volume_signed_6x(Implicit_Data *data, int v1, int v2, int v3) |