diff options
Diffstat (limited to 'source/blender/blenkernel/intern/particle_system.c')
| -rw-r--r-- | source/blender/blenkernel/intern/particle_system.c | 52 |
1 files changed, 38 insertions, 14 deletions
diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c index 6e4937d11ec..3efe25794e1 100644 --- a/source/blender/blenkernel/intern/particle_system.c +++ b/source/blender/blenkernel/intern/particle_system.c @@ -3028,13 +3028,20 @@ static void basic_rotate(ParticleSettings *part, ParticleData *pa, float dfra, f normalize_qt(pa->state.rot); } -/************************************************/ -/* Collisions */ -/************************************************/ +/************************************************ + * Collisions + * + * The algorithm is roughly: + * 1. Use a BVH tree to search for faces that a particle may collide with. + * 2. Use Newton's method to find the exact time at which the collision occurs. + * http://en.wikipedia.org/wiki/Newton's_method + * + ************************************************/ #define COLLISION_MAX_COLLISIONS 10 #define COLLISION_MIN_RADIUS 0.001f #define COLLISION_MIN_DISTANCE 0.0001f #define COLLISION_ZERO 0.00001f +#define COLLISION_INIT_STEP 0.00008f typedef float (*NRDistanceFunc)(float *p, float radius, ParticleCollisionElement *pce, float *nor); static float nr_signed_distance_to_plane(float *p, float radius, ParticleCollisionElement *pce, float *nor) { @@ -3189,16 +3196,20 @@ static void collision_point_on_surface(float p[3], ParticleCollisionElement *pce /* find first root in range [0-1] starting from 0 */ static float collision_newton_rhapson(ParticleCollision *col, float radius, ParticleCollisionElement *pce, NRDistanceFunc distance_func) { - float t0, t1, d0, d1, dd, n[3]; + float t0, t1, dt_init, d0, d1, dd, n[3]; int iter; pce->inv_nor = -1; + /* Initial step size should be small, but not too small or floating point + * precision errors will appear. - z0r */ + dt_init = COLLISION_INIT_STEP * col->inv_total_time; + /* start from the beginning */ t0 = 0.f; collision_interpolate_element(pce, t0, col->f, col); d0 = distance_func(col->co1, radius, pce, n); - t1 = 0.001f; + t1 = dt_init; d1 = 0.f; for (iter=0; iter<10; iter++) {//, itersum++) { @@ -3208,11 +3219,6 @@ static float collision_newton_rhapson(ParticleCollision *col, float radius, Part d1 = distance_func(pce->p, radius, pce, n); - /* no movement, so no collision */ - if (d1 == d0) { - return -1.f; - } - /* particle already inside face, so report collision */ if (iter == 0 && d0 < 0.f && d0 > -radius) { copy_v3_v3(pce->p, col->co1); @@ -3220,7 +3226,24 @@ static float collision_newton_rhapson(ParticleCollision *col, float radius, Part pce->inside = 1; return 0.f; } - + + /* Zero gradient (no movement relative to element). Can't step from + * here. */ + if (d1 == d0) { + /* If first iteration, try from other end where the gradient may be + * greater. Note: code duplicated below. */ + if (iter == 0) { + t0 = 1.f; + collision_interpolate_element(pce, t0, col->f, col); + d0 = distance_func(col->co2, radius, pce, n); + t1 = 1.0f - dt_init; + d1 = 0.f; + continue; + } + else + return -1.f; + } + dd = (t1-t0)/(d1-d0); t0 = t1; @@ -3228,14 +3251,14 @@ static float collision_newton_rhapson(ParticleCollision *col, float radius, Part t1 -= d1*dd; - /* particle movin away from plane could also mean a strangely rotating face, so check from end */ + /* Particle moving away from plane could also mean a strangely rotating + * face, so check from end. Note: code duplicated above. */ if (iter == 0 && t1 < 0.f) { t0 = 1.f; collision_interpolate_element(pce, t0, col->f, col); d0 = distance_func(col->co2, radius, pce, n); - t1 = 0.999f; + t1 = 1.0f - dt_init; d1 = 0.f; - continue; } else if (iter == 1 && (t1 < -COLLISION_ZERO || t1 > 1.f)) @@ -3683,6 +3706,7 @@ static void collision_check(ParticleSimulationData *sim, int p, float dfra, floa memset(&col, 0, sizeof(ParticleCollision)); col.total_time = timestep * dfra; + col.inv_total_time = 1.0f/col.total_time; col.inv_timestep = 1.0f/timestep; col.cfra = cfra; |