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Particles: Allow python to write hair keys 

Add a function HairKey.co_object_set() which can be used to modify hair
keys positions in a way that hair strands respects the new coordinates,
without doing extra trickery with edit mode toggle. The naming comes
from existing HairKey.co_object().

The usage is a bit tricky:

- The function is to be called on the hair key from an original object.
- The arguments are to be passed from evaluated object.

Basically:

  hair_key_orig.co_object_set(object_eval, modifier_eval, particle_eval)

This is required because coordinate space conversion needs to know
evaluated state of the hair system in order to access hair space
matrix. It is a deliberate choice to not pass dependency graph and not
to do lookup of evaluated ID on every call of co_object_set() to keep
performance on a manageable levels.

One requirement is that the hair strands are to be calculated once, by,
for example, toggling particle edit mode. Without this there will be no
`particles` to access hair keys from in the original object.

Such functionality is something what got lost during 2.80 development
and is something what is needed here at the studio.

Below is the file with more complete example: convert strands from mesh
edges to actual particle system hair strands. The viewport refresh is
sometimes missing, and this does not seem to be related to this specific
change.

{F8858104}

Differential Revision: https://developer.blender.org/D8849
This commit is contained in:
Sergey Sharybin 2020-09-09 15:54:49 +02:00
parent 218e9e76a8
commit 55efa1795f
1 changed files with 109 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

128
source/blender/makesrna/intern/rna_particle.c
View File

@ -243,35 +243,87 @@ static void rna_ParticleHairKey_location_object_get(PointerRNA *ptr, float *valu
}
}
/* Helper function which returns index of the given hair_key in particle which owns it.
* Works with cases when hair_key is coming from the particle which was passed here, and from the
* original particle of the given one.
*
* Such trickery is needed to allow modification of hair keys in the original object using
* evaluated particle and object to access proper hair matrix. */
static int hair_key_index_get(/*const*/ HairKey *hair_key,
/*const*/ ParticleSystemModifierData *modifier,
/*const*/ ParticleData *particle)
{
if (ARRAY_HAS_ITEM(hair_key, particle->hair, particle->totkey)) {
return hair_key - particle->hair;
}
const ParticleSystem *particle_system = modifier->psys;
const int particle_index = particle - particle_system->particles;
const ParticleSystemModifierData *original_modifier = (ParticleSystemModifierData *)
BKE_modifier_get_original(&modifier->modifier);
const ParticleSystem *original_particle_system = original_modifier->psys;
const ParticleData *original_particle = &original_particle_system->particles[particle_index];
if (ARRAY_HAS_ITEM(hair_key, original_particle->hair, original_particle->totkey)) {
return hair_key - original_particle->hair;
}
return -1;
}
/* Set hair_key->co to the given coordinate in object space (the given coordinate will be
* converted to the proper space).
*
* The hair_key can be coming from both original and evaluated object. Object, modifier and
* particle are to be from evaluated object, so that all the data needed for hair matrix is
* present. */
static void hair_key_location_object_set(HairKey *hair_key,
Object *object,
ParticleSystemModifierData *modifier,
ParticleData *particle,
const float src_co[3])
{
Mesh *hair_mesh = (modifier->psys->flag & PSYS_HAIR_DYNAMICS) ? modifier->psys->hair_out_mesh :
NULL;
if (hair_mesh != NULL) {
const int hair_key_index = hair_key_index_get(hair_key, modifier, particle);
if (hair_key_index == -1) {
return;
}
MVert *mvert = &hair_mesh->mvert[particle->hair_index + (hair_key_index)];
copy_v3_v3(mvert->co, src_co);
return;
}
float hairmat[4][4];
psys_mat_hair_to_object(
object, modifier->mesh_final, modifier->psys->part->from, particle, hairmat);
float imat[4][4];
invert_m4_m4(imat, hairmat);
copy_v3_v3(hair_key->co, src_co);
mul_m4_v3(imat, hair_key->co);
}
static void rna_ParticleHairKey_location_object_set(PointerRNA *ptr, const float *values)
{
HairKey *hkey = (HairKey *)ptr->data;
Object *ob = (Object *)ptr->owner_id;
ParticleSystemModifierData *psmd;
ParticleData *pa;
rna_ParticleHairKey_location_object_info(ptr, &psmd, &pa);
if (pa) {
Mesh *hair_mesh = (psmd->psys->flag & PSYS_HAIR_DYNAMICS) ? psmd->psys->hair_out_mesh : NULL;
if (hair_mesh) {
MVert *mvert = &hair_mesh->mvert[pa->hair_index + (hkey - pa->hair)];
copy_v3_v3(mvert->co, values);
}
else {
float hairmat[4][4];
float imat[4][4];
psys_mat_hair_to_object(ob, psmd->mesh_final, psmd->psys->part->from, pa, hairmat);
invert_m4_m4(imat, hairmat);
copy_v3_v3(hkey->co, values);
mul_m4_v3(imat, hkey->co);
}
}
else {
if (pa == NULL) {
zero_v3(hkey->co);
return;
}
hair_key_location_object_set(hkey, ob, psmd, pa, values);
}
static void rna_ParticleHairKey_co_object(HairKey *hairkey,
@ -301,6 +353,31 @@ static void rna_ParticleHairKey_co_object(HairKey *hairkey,
}
}
static void rna_ParticleHairKey_co_object_set(ID *id,
HairKey *hair_key,
Object *object,
ParticleSystemModifierData *modifier,
ParticleData *particle,
float co[3])
{
if (particle == NULL) {
return;
}
/* Mark particle system as edited, so then particle_system_update() does not reset the hair
* keys from path. This behavior is similar to how particle edit mode sets flags. */
ParticleSystemModifierData *orig_modifier = (ParticleSystemModifierData *)
modifier->modifier.orig_modifier_data;
orig_modifier->psys->flag |= PSYS_EDITED;
hair_key_location_object_set(hair_key, object, modifier, particle, co);
/* Tag similar to brushes in particle edit mode, so the modifier stack is properly evaluated
* with the same particle system recalc flags as during combing. */
DEG_id_tag_update(id, ID_RECALC_GEOMETRY | ID_RECALC_PSYS_REDO);
}
static void rna_Particle_uv_on_emitter(ParticleData *particle,
ReportList *reports,
ParticleSystemModifierData *modifier,
@ -1651,6 +1728,19 @@ static void rna_def_particle_hair_key(BlenderRNA *brna)
func, "co", 3, NULL, -FLT_MAX, FLT_MAX, "Co", "Exported hairkey location", -1e4, 1e4);
RNA_def_parameter_flags(parm, PROP_THICK_WRAP, 0);
RNA_def_function_output(func, parm);
func = RNA_def_function(srna, "co_object_set", "rna_ParticleHairKey_co_object_set");
RNA_def_function_flag(func, FUNC_USE_SELF_ID);
RNA_def_function_ui_description(func, "Set hairkey location with particle and modifier data");
parm = RNA_def_pointer(func, "object", "Object", "", "Object");
RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
parm = RNA_def_pointer(func, "modifier", "ParticleSystemModifier", "", "Particle modifier");
RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
parm = RNA_def_pointer(func, "particle", "Particle", "", "hair particle");
RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
parm = RNA_def_float_vector(
func, "co", 3, NULL, -FLT_MAX, FLT_MAX, "Co", "Specified hairkey location", -1e4, 1e4);
RNA_def_parameter_flags(parm, PROP_THICK_WRAP, PARM_REQUIRED);
}
static void rna_def_particle_key(BlenderRNA *brna)