miScalar lume_plane_ray_intersection(miVector *intersection,
miVector *plane_point,
miVector *plane_dir,
miVector *ray_point,
miVector *ray_dir)
{
miScalar q;
miScalar t;
q = mi_vector_dot(plane_dir, ray_dir);
if (fabs(q) < 0.0001)
return 0; /* parallel */
t = (mi_vector_dot(plane_point, plane_dir) -
mi_vector_dot(plane_dir, ray_point)) / q;
*intersection = *ray_dir;
mi_vector_mul(intersection, t);
mi_vector_add(intersection, intersection, ray_point);
return t;
}
static void raymarch(
miColor *result,
miState *state,
struct mrm *p)
{
miVector step, pos, ppos;
miVector old_point, old_normal;
miScalar step_size;
miColor col, prev;
miBoolean has_prev = miFALSE;
int i;
step = state->dir;
step_size = state->dist / ((miScalar)p->num - 1);
mi_vector_mul(&step, step_size);
old_point = state->point;
old_normal = state->normal;
pos = state->org;
/* begin raymarch */
for (i=0; i < p->num; i++) {
state->point = pos;
state->normal = state->dir;
state->pri = 0; /* cats rays from empty space */
mi_call_shader_x(&col, miSHADER_MATERIAL, state, p->s, NULL);
if (has_prev && p->subdiv &&
color_contrast(&prev, &col, &p->contrast))
/* adaptive sampling */
recurse(result, state, ppos, state->dir, step_size,
&prev, &col, 1, p);
result->r += col.r;
result->g += col.g;
result->b += col.b;
result->a += col.a;
prev = col;
ppos = pos;
has_prev = miTRUE;
mi_vector_add(&pos, &pos, &step);
}
state->point = old_point;
state->normal = old_normal;
}
static void recurse(
miColor *result,
miState *state,
miVector from,
miVector dir,
miScalar dist,
miColor *prev,
miColor *next,
miInteger level,
struct mrm *p)
{
miVector step, pos;
miColor col;
if (level > p->subdiv)
return;
step = dir;
mi_vector_mul(&step, dist*0.5);
pos = from;
mi_vector_add(&pos, &pos, &step);
state->point = pos;
state->normal = dir;
state->pri = 0; /* required for ray casting from empty space */
mi_call_shader_x(&col, miSHADER_MATERIAL, state, p->s, NULL);
/* recurse further if necessary */
if (color_contrast(prev, &col, &p->contrast))
recurse(result, state, from, dir, dist*0.5, prev, &col,
level+1, p);
if (color_contrast(next, &col, &p->contrast))
recurse(result, state, pos, dir, dist*0.5, &col, next,
level+1, p);
/* accumulate result */
result->r += 0.5*(col.r - 0.5*(prev->r - next->r)) * dist;
result->g += 0.5*(col.g - 0.5*(prev->g - next->g)) * dist;
result->b += 0.5*(col.b - 0.5*(prev->b - next->b)) * dist;
result->a += 0.5*(col.a - 0.5*(prev->a - next->a)) * dist;
}
miTag createMeshParticles(miState *state, mrParticleGeoShader_paras *paras, PartioContainer& pc)
{
mi_info("Creating mesh particles for cache file: %s", pc.cacheFileName.c_str());
if( ! pc.good())
{
mi_error("Invalid PartioContainer.");
return miNULLTAG;
}
Partio::ParticleAttribute posAttr;
if(!pc.assertAttribute("position", posAttr))
return miNULLTAG;
Partio::ParticleAttribute idAttr;
bool hasId = true;
if(!pc.assertAttribute("id", idAttr))
hasId = false;
Partio::ParticleAttribute radiusPPAttr;
bool hasRadiusPP = true;
if(!pc.assertAttribute("radiusPP", radiusPPAttr))
hasRadiusPP = false;
Partio::ParticleAttribute velocityAttr;
bool hasVelocity = true;
if(!pc.assertAttribute("velocity", velocityAttr))
hasVelocity = false;
miObject *obj = beginObject();
float *fpos;
srand(123345);
int numParticles = pc.data->numParticles();
float sizeMultiplier = *mi_eval_scalar(¶s->sizeMultiplier);
float density = *mi_eval_scalar(¶s->density);
float size = *mi_eval_scalar(¶s->size);
float sizeVariation = *mi_eval_scalar(¶s->sizeVariation);
// particle number can vary because of density value
int numWrittenParticles = 0;
// define vectors
for(int vtxId = 0; vtxId < numParticles; vtxId++)
{
miVector pos;
fpos = (float *)pc.data->data<float>(posAttr, vtxId);
int id = vtxId;
if( hasId)
id = *pc.data->data<int>(idAttr, vtxId);
float radiusPP = 1.0f;
if( hasRadiusPP )
radiusPP = *pc.data->data<float>(radiusPPAttr, vtxId);
miVector vel = {0.0, 0.0, 0.0};
if(hasVelocity)
{
float *v;
v = (float *)pc.data->data<float>(velocityAttr, vtxId);
vel.x = v[0];
vel.y = v[1];
vel.z = v[2];
// velocity ist distance/sekunde, eine velocity von 24 legt also eine Distanz von 1 Einheit pro frame bei 24fps zurück
// zusätzlich muss man noch den shutter angle beachten, bei 140° sind das -.2 -> 0.2 also 0.4 * 1 und damit grob .4 Einheiten
float factor = 1.0f/24.0f * 0.4f;
mi_vector_mul(&vel, factor);
}
pos.x = fpos[0];
pos.y = fpos[1];
pos.z = fpos[2];
miVector camPos = pos;
// ich transformiere das particle in camera space und gehe dann einfach size/2 nach rechts und oben
miMatrix matrix;
mi_matrix_ident(matrix);
miInstance *inst = (miInstance *)mi_db_access(state->instance);
mi_matrix_copy(matrix, inst->tf.global_to_local);
mi_db_unpin(state->instance);
mi_point_from_world(state, &camPos, &pos);
mi_point_from_world(state, &camPos, &camPos);
mi_point_to_camera(state, &camPos, &camPos);
float psize = radiusPP * sizeMultiplier;
int pId = vtxId;
double rndVal = rnd(id * state->camera->frame + 5);
if( rndVal > density)
continue;
float srndVal = (rndVal - 0.5f) * 2.0f;
psize *= size + (size * srndVal * sizeVariation * 0.5f);
psize = fabs(psize);
if(psize == 0.0f)
continue;
miVector upRight, bottomLeft;
upRight = camPos;
upRight.x += psize/2.0f;
upRight.y += psize/2.0f;
bottomLeft = camPos;
bottomLeft.x -= psize/2.0f;
bottomLeft.y -= psize/2.0f;
// checkScreenSpace in Screenspace und testet auf minPixelSize.
if(!checkScreenSpace(state, paras, camPos, bottomLeft, upRight) )
continue;
numWrittenParticles++;
miVector v0, v1, v2, v3;
v0 = bottomLeft;
v2 = upRight;
v1 = bottomLeft;
v1.y = upRight.y;
v3 = upRight;
v3.y = bottomLeft.y;
mi_point_from_camera(state, &v0, &v0);
mi_point_from_camera(state, &v1, &v1);
mi_point_from_camera(state, &v2, &v2);
mi_point_from_camera(state, &v3, &v3);
mi_point_to_world(state, &v0, &v0);
mi_point_to_world(state, &v1, &v1);
mi_point_to_world(state, &v2, &v2);
mi_point_to_world(state, &v3, &v3);
miVector v01, v02, v03;
mi_vector_sub(&v01, &v0, &v1);
mi_vector_sub(&v02, &v0, &v2);
mi_vector_sub(&v03, &v0, &v3);
mi_vector_transform(&v01, &v01, matrix);
mi_vector_transform(&v02, &v02, matrix);
mi_vector_transform(&v03, &v03, matrix);
mi_vector_add(&v1, &v0, &v01);
mi_vector_add(&v2, &v0, &v02);
mi_vector_add(&v3, &v0, &v03);
// add geometry vectors
// e.g. -0.5 -0.5 0.5
add_vector(v0.x, v0.y, v0.z);
add_vector(v1.x, v1.y, v1.z);
add_vector(v2.x, v2.y, v2.z);
add_vector(v3.x, v3.y, v3.z);
// single motion vector per particle
add_vector(vel.x, vel.y, vel.z);
}
// uv coordinates
miVector uvw;
uvw.x = uvw.y = uvw.z = 0.0f;
uvw.z = 123.0f;
mi_api_vector_xyz_add( &uvw );
uvw.x = 1.0;
mi_api_vector_xyz_add( &uvw );
uvw.y = 1.0;
mi_api_vector_xyz_add( &uvw );
uvw.x = 0.0;
mi_api_vector_xyz_add( &uvw );
// define vertices
// depending on the attributes we have x vectors per vertex:
// 0: pos1
// 1: pos2
// 2: pos3
// 3: pos4
// 4: vel
// tex0 = numWrittenParticles * 5 - 4
// num done particles für rnd density
int texIndex = numWrittenParticles * 5;
for(int vtxId = 0; vtxId < numWrittenParticles; vtxId++)
{
int vertexIndex = vtxId * 5;
int mvIndex = vtxId * 5 + 4;
// add vertex definitions
// e.g. v 0 n 8 t 32 m 46
mi_api_vertex_add(vertexIndex);
mi_api_vertex_tex_add( texIndex, -1, -1);
mi_api_vertex_motion_add(mvIndex);
mi_api_vertex_add(vertexIndex + 1);
mi_api_vertex_tex_add( texIndex + 1, -1, -1);
mi_api_vertex_motion_add(mvIndex);
mi_api_vertex_add(vertexIndex + 2);
mi_api_vertex_tex_add( texIndex + 2, -1, -1);
mi_api_vertex_motion_add(mvIndex);
mi_api_vertex_add(vertexIndex + 3);
mi_api_vertex_tex_add( texIndex + 3, -1, -1);
mi_api_vertex_motion_add(mvIndex);
}
// add poly for every particle
for( int pId = 0; pId < numWrittenParticles; pId++)
{
int vtxId = pId * 4;
mi_api_poly_begin_tag(1, miNULLTAG);
mi_api_poly_index_add(vtxId);
mi_api_poly_index_add(vtxId + 1);
mi_api_poly_index_add(vtxId + 2);
mi_api_poly_index_add(vtxId + 3);
mi_api_poly_end();
}
miTag objTag = finishObject();
return objTag;
}
