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#include "shared/pch.hh"
#include "shared/collision.hh"
#include "core/constexpr.hh"
#include "shared/coord.hh"
#include "shared/dimension.hh"
#include "shared/globals.hh"
#include "shared/gravity.hh"
#include "shared/grounded.hh"
#include "shared/transform.hh"
#include "shared/velocity.hh"
#include "shared/voxel_registry.hh"
static int vgrid_collide(const Dimension* dimension, int d, CollisionComponent& collision, TransformComponent& transform,
VelocityComponent& velocity, voxel_surface& touch_surface)
{
const auto move = globals::fixed_frametime * velocity.value[d];
const auto move_sign = vx::sign<int>(move);
const auto& ref_aabb = collision.aabb;
const auto current_aabb = ref_aabb.push(transform.local);
auto next_aabb = AABB(current_aabb);
next_aabb.min[d] += move;
next_aabb.max[d] += move;
local_pos lpos_min;
lpos_min.x = vx::floor<local_pos::value_type>(next_aabb.min.x);
lpos_min.y = vx::floor<local_pos::value_type>(next_aabb.min.y);
lpos_min.z = vx::floor<local_pos::value_type>(next_aabb.min.z);
local_pos lpos_max;
lpos_max.x = vx::ceil<local_pos::value_type>(next_aabb.max.x);
lpos_max.y = vx::ceil<local_pos::value_type>(next_aabb.max.y);
lpos_max.z = vx::ceil<local_pos::value_type>(next_aabb.max.z);
// Other axes
const int u = (d + 1) % 3;
const int v = (d + 2) % 3;
local_pos::value_type ddir;
local_pos::value_type dmin;
local_pos::value_type dmax;
if(move < 0.0f) {
ddir = local_pos::value_type(+1);
dmin = lpos_min[d];
dmax = lpos_max[d];
} else {
ddir = local_pos::value_type(-1);
dmin = lpos_max[d];
dmax = lpos_min[d];
}
voxel_touch latch_touch = voxel_touch::NOTHING;
glm::fvec3 latch_values = glm::fvec3(0.0f, 0.0f, 0.0f);
voxel_surface latch_surface = voxel_surface::UNKNOWN;
AABB latch_vbox;
for(auto i = dmin; i != dmax; i += ddir) {
for(auto j = lpos_min[u]; j < lpos_max[u]; ++j)
for(auto k = lpos_min[v]; k < lpos_max[v]; ++k) {
local_pos lpos;
lpos[d] = i;
lpos[u] = j;
lpos[v] = k;
const auto vpos = coord::to_voxel(transform.chunk, lpos);
const auto info = voxel_registry::find(dimension->get_voxel(vpos));
if(info == nullptr) {
// Don't collide with something
// that we assume to be nothing
continue;
}
AABB vbox;
vbox.min = glm::fvec3(lpos);
vbox.max = glm::fvec3(lpos) + 1.0f;
if(!next_aabb.intersect(vbox)) {
// No intersection between the voxel
// and the entity's collision hull
continue;
}
if(info->touch_type == voxel_touch::SOLID) {
// Solid touch type makes a collision
// response whenever it is encountered
velocity.value[d] = 0.0f;
touch_surface = info->surface;
return move_sign;
}
// In case of other touch types, they
// are latched and the last ever touch
// type is then responded to
if(info->touch_type != voxel_touch::NOTHING) {
latch_touch = info->touch_type;
latch_values = info->touch_values;
latch_surface = info->surface;
latch_vbox = vbox;
continue;
}
}
}
if(latch_touch != voxel_touch::NOTHING) {
if(latch_touch == voxel_touch::BOUNCE) {
const auto move_distance = vx::abs(current_aabb.min[d] - next_aabb.min[d]);
const auto threshold = 2.0f * globals::fixed_frametime;
if(move_distance > threshold) {
velocity.value[d] *= -latch_values[d];
} else {
velocity.value[d] = 0.0f;
}
touch_surface = latch_surface;
return move_sign;
}
if(latch_touch == voxel_touch::SINK) {
velocity.value[d] *= latch_values[d];
touch_surface = latch_surface;
return move_sign;
}
}
return 0;
}
void CollisionComponent::fixed_update(Dimension* dimension)
{
// FIXME: this isn't particularly accurate considering
// some voxels might be passable and some other voxels
// might apply some slowing factor; what I might do in the
// future is to add a specific value to the voxel registry
// entries that would specify the amount of force we apply
// to prevent player movement inside a specific voxel, plus
// we shouldn't treat all voxels as full cubes if we want
// to support slabs, stairs and non-full liquid voxels in the future
auto group = dimension->entities.group<CollisionComponent>(entt::get<TransformComponent, VelocityComponent>);
for(auto [entity, collision, transform, velocity] : group.each()) {
auto surface = voxel_surface::UNKNOWN;
auto vertical_move = vgrid_collide(dimension, 1, collision, transform, velocity, surface);
if(dimension->entities.any_of<GravityComponent>(entity)) {
if(vertical_move == vx::sign<int>(dimension->get_gravity())) {
dimension->entities.emplace_or_replace<GroundedComponent>(entity, GroundedComponent { surface });
} else {
dimension->entities.remove<GroundedComponent>(entity);
}
} else {
// The entity cannot be grounded because the component
// setup of said entity should not let it comprehend the
// concept of resting on the ground (it flies around)
dimension->entities.remove<GroundedComponent>(entity);
}
vgrid_collide(dimension, 0, collision, transform, velocity, surface);
vgrid_collide(dimension, 2, collision, transform, velocity, surface);
}
}
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