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use crate::bounding_volume::BoundingVolume;
use crate::math::{IVector, Real, Vector};
use crate::query::{NonlinearRigidMotion, QueryDispatcher, ShapeCastHit};
use crate::shape::{Cuboid, Shape, Voxels};
/// Time Of Impact of a voxels shape with any other shape, under a rigid motion (translation + rotation).
pub fn cast_shapes_nonlinear_voxels_shape<D>(
dispatcher: &D,
motion1: &NonlinearRigidMotion,
g1: &Voxels,
motion2: &NonlinearRigidMotion,
g2: &dyn Shape,
start_time: Real,
end_time: Real,
stop_at_penetration: bool,
) -> Option<ShapeCastHit>
where
D: ?Sized + QueryDispatcher,
{
use num_traits::Bounded;
// HACK: really supporting nonlinear shape-casting on a rotating voxels shape would
// be extremely inefficient without any sort of hierarchical traversal on the voxel.
// So for now we assume that the voxels shape only has a translational motion.
// We can fix that once we introduce a sparse representation (and its accompanying
// acceleration structure) for the voxels shape.
let mut motion2 = *motion2;
let mut motion1 = *motion1;
motion2.linvel -= motion1.linvel;
motion1.freeze(start_time);
let pos1 = motion1.position_at_time(start_time);
// Search for the smallest time of impact.
//
// 1. Check all the cells in the AABB at time `start_time`.
// 2. Check which wall of unchecked voxels is hit first.
// 3. Check one additional layer of voxels behind that wall.
// 4. Continue, with a new AABB taken at the position at the time we hit the
// wall.
// 5. Continue until `curr_t` is bigger than `smallest_t`.
//
// PERF: This will be fairly efficient if the shape being cast has a size in the same order
// of magnitude as the voxels, and if it doesn’t have a significant off-center angular
// motion. Otherwise, this method will be fairly slow, and would require an acceleration
// structure to improve.
let mut hit = None;
let mut smallest_t = end_time;
// NOTE: we approximate the AABB of the shape using its orientation at the start and
// end time. It might miss some cases if the object is rotating fast.
let start_pos2_1 = pos1.inv_mul(&motion2.position_at_time(start_time));
let mut end_pos2_1 = pos1.inv_mul(&motion2.position_at_time(end_time));
end_pos2_1.translation = start_pos2_1.translation;
let start_aabb2_1 = g2
.compute_aabb(&start_pos2_1)
.merged(&g2.compute_aabb(&end_pos2_1));
let mut check_voxels_in_range = |search_domain: [IVector; 2]| {
for vox in g1.voxels_in_range(search_domain[0], search_domain[1]) {
if !vox.state.is_empty() {
// PERF: could we check the canonical shape instead, and deduplicate accordingly?
let center = g1.voxel_center(vox.grid_coords);
let cuboid = Cuboid::new(g1.voxel_size() / 2.0);
let vox_motion1 = motion1.prepend_translation(center);
if let Some(new_hit) = dispatcher
.cast_shapes_nonlinear(
&vox_motion1,
&cuboid,
&motion2,
g2,
start_time,
end_time,
stop_at_penetration,
)
.ok()
.flatten()
{
if new_hit.time_of_impact < smallest_t {
smallest_t = new_hit.time_of_impact;
hit = Some(new_hit);
}
}
}
}
};
let mut search_domain = g1.voxel_range_intersecting_local_aabb(&start_aabb2_1);
check_voxels_in_range(search_domain);
// Run the propagation.
let [domain_mins, domain_maxs] = g1.domain();
loop {
let search_domain_aabb = g1.voxel_range_aabb(search_domain[0], search_domain[1]);
// Figure out if we should move the aabb up/down/right/left.
#[cfg(feature = "dim2")]
let ii = [0, 1];
#[cfg(feature = "dim3")]
let ii = [0, 1, 2];
let toi = ii.map(|i| {
if motion2.linvel[i] > 0.0 {
let t = (search_domain_aabb.maxs[i] - start_aabb2_1.maxs[i]) / motion2.linvel[i];
if t < 0.0 {
(Real::max_value(), true)
} else {
(t, true)
}
} else if motion2.linvel[i] < 0.0 {
let t = (search_domain_aabb.mins[i] - start_aabb2_1.mins[i]) / motion2.linvel[i];
if t < 0.0 {
(Real::max_value(), false)
} else {
(t, false)
}
} else {
(Real::max_value(), false)
}
});
#[cfg(feature = "dim2")]
if toi[0].0 > end_time && toi[1].0 > end_time {
break;
}
#[cfg(feature = "dim3")]
if toi[0].0 > end_time && toi[1].0 > end_time && toi[2].0 > end_time {
break;
}
let imin = Vector::from(toi.map(|t| t.0)).min_position();
if toi[imin].1 {
search_domain[0][imin] += 1;
search_domain[1][imin] += 1;
if search_domain[1][imin] <= domain_maxs[imin] {
// Check the voxels on the added row.
let mut prev_row = search_domain[0];
prev_row[imin] = search_domain[1][imin] - 1;
let range_to_check = [prev_row, search_domain[1]];
check_voxels_in_range(range_to_check);
} else if search_domain[0][imin] >= domain_maxs[imin] {
// Leaving the shape’s bounds.
break;
}
} else {
search_domain[0][imin] -= 1;
search_domain[1][imin] -= 1;
if search_domain[0][imin] >= domain_mins[imin] {
// Check the voxels on the added row.
let mut next_row = search_domain[1];
next_row[imin] = search_domain[0][imin] + 1;
let range_to_check = [search_domain[0], next_row];
check_voxels_in_range(range_to_check);
} else if search_domain[1][imin] <= domain_mins[imin] {
// Leaving the shape’s bounds.
break;
}
}
}
hit
}
/// Time Of Impact of any shape with a composite shape, under a rigid motion (translation + rotation).
pub fn cast_shapes_nonlinear_shape_voxels<D>(
dispatcher: &D,
motion1: &NonlinearRigidMotion,
g1: &dyn Shape,
motion2: &NonlinearRigidMotion,
g2: &Voxels,
start_time: Real,
end_time: Real,
stop_at_penetration: bool,
) -> Option<ShapeCastHit>
where
D: ?Sized + QueryDispatcher,
{
cast_shapes_nonlinear_voxels_shape(
dispatcher,
motion2,
g2,
motion1,
g1,
start_time,
end_time,
stop_at_penetration,
)
.map(|hit| hit.swapped())
}