Add whatever I was working on for the last month

1 files changed, 160 insertions, 0 deletions

diff --git a/game/shared/collision.cc b/game/shared/collision.cc
new file mode 100644
index 0000000..126d3bb
--- /dev/null
+++ b/game/shared/collision.cc
@@ -0,0 +1,160 @@
+#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/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 = cxpr::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 = cxpr::floor<local_pos::value_type>(next_aabb.min.x);
+    lpos_min.y = cxpr::floor<local_pos::value_type>(next_aabb.min.y);
+    lpos_min.z = cxpr::floor<local_pos::value_type>(next_aabb.min.z);
+
+    local_pos lpos_max;
+    lpos_max.x = cxpr::ceil<local_pos::value_type>(next_aabb.max.x);
+    lpos_max.y = cxpr::ceil<local_pos::value_type>(next_aabb.max.y);
+    lpos_max.z = cxpr::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 = cxpr::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(vertical_move == cxpr::sign<int>(dimension->get_gravity())) {
+            auto &component = dimension->entities.get_or_emplace<GroundedComponent>(entity);
+            component.surface = surface;
+        }
+        else {
+            dimension->entities.remove<GroundedComponent>(entity);
+        }
+
+        vgrid_collide(dimension, 0, collision, transform, velocity, surface);
+        vgrid_collide(dimension, 2, collision, transform, velocity, surface);
+    }
+}