Add interpolation to Velocity component; fixes #20

- Also disabled snapping to grid for sideways movement as it was somehow
  messing with player_move code and was making you slide on voxels as if
  you were on ice (not good)

6 files changed, 38 insertions, 11 deletions

diff --git a/src/game/client/entity/camera.cc b/src/game/client/entity/camera.cc
index 2009066..27603cf 100644
--- a/src/game/client/entity/camera.cc
+++ b/src/game/client/entity/camera.cc
@@ -8,6 +8,7 @@
 
 #include "core/math/angles.hh"
 
+#include "shared/entity/grounded.hh"
 #include "shared/entity/head.hh"
 #include "shared/entity/transform.hh"
 #include "shared/entity/velocity.hh"
@@ -87,7 +88,7 @@ void camera::update(void)
 
     const auto& head = globals::dimension->entities.get<client::HeadIntr>(globals::player);
     const auto& transform = globals::dimension->entities.get<client::TransformIntr>(globals::player);
-    const auto& velocity = globals::dimension->entities.get<Velocity>(globals::player);
+    const auto& velocity = globals::dimension->entities.get<client::VelocityIntr>(globals::player);
 
     camera::angles = transform.angles + head.angles;
     camera::position_chunk = transform.chunk;
@@ -98,8 +99,7 @@ void camera::update(void)
 
     auto client_angles = camera::angles;
 
-    if(!toggles::get(TOGGLE_PM_FLIGHT)) {
-        // Apply the quake-like view rolling
+    if(!toggles::get(TOGGLE_PM_FLIGHT) && globals::dimension->entities.try_get<Grounded>(globals::player)) {
         client_angles[2] = math::radians(-camera::roll_angle.get_value() * glm::dot(velocity.value / PMOVE_MAX_SPEED_GROUND, right_vector));
     }
 
diff --git a/src/game/client/entity/factory.cc b/src/game/client/entity/factory.cc
index f4724c5..94a9698 100644
--- a/src/game/client/entity/factory.cc
+++ b/src/game/client/entity/factory.cc
@@ -5,6 +5,7 @@
 #include "shared/entity/factory.hh"
 #include "shared/entity/head.hh"
 #include "shared/entity/transform.hh"
+#include "shared/entity/velocity.hh"
 
 #include "shared/world/dimension.hh"
 
@@ -24,6 +25,10 @@ void client::create_player(Dimension* dimension, entt::entity entity)
     dimension->entities.emplace_or_replace<client::TransformIntr>(entity, transform);
     dimension->entities.emplace_or_replace<client::TransformPrev>(entity, transform);
 
+    const auto& velocity = dimension->entities.get<Velocity>(entity);
+    dimension->entities.emplace_or_replace<client::VelocityIntr>(entity, velocity);
+    dimension->entities.emplace_or_replace<client::VelocityPrev>(entity, velocity);
+
     if(globals::sound_ctx) {
         dimension->entities.emplace_or_replace<SoundEmitter>(entity);
     }
diff --git a/src/game/client/entity/interpolation.cc b/src/game/client/entity/interpolation.cc
index 69fd487..86af971 100644
--- a/src/game/client/entity/interpolation.cc
+++ b/src/game/client/entity/interpolation.cc
@@ -6,6 +6,7 @@
 
 #include "shared/entity/head.hh"
 #include "shared/entity/transform.hh"
+#include "shared/entity/velocity.hh"
 
 #include "shared/world/dimension.hh"
 
@@ -53,11 +54,23 @@ static void head_interpolate(float alpha)
     }
 }
 
+static void velocity_interpolate(float alpha)
+{
+    auto group = globals::dimension->entities.group<client::VelocityIntr>(entt::get<Velocity, client::VelocityPrev>);
+
+    for(auto [entity, interp, current, previous] : group.each()) {
+        interp.value[0] = glm::mix(previous.value[0], current.value[0], alpha);
+        interp.value[1] = glm::mix(previous.value[1], current.value[1], alpha);
+        interp.value[2] = glm::mix(previous.value[2], current.value[2], alpha);
+    }
+}
+
 void interpolation::update(void)
 {
     if(globals::dimension) {
         auto alpha = static_cast<float>(globals::fixed_accumulator) / static_cast<float>(globals::fixed_frametime_us);
         transform_interpolate(alpha);
         head_interpolate(alpha);
+        velocity_interpolate(alpha);
     }
 }
\ No newline at end of file
diff --git a/src/game/client/entity/player_move.cc b/src/game/client/entity/player_move.cc
index 14d64cc..edf9150 100644
--- a/src/game/client/entity/player_move.cc
+++ b/src/game/client/entity/player_move.cc
@@ -161,6 +161,7 @@ void player_move::fixed_update(void)
 
     // Interpolation - preserve current component states
     globals::dimension->entities.emplace_or_replace<client::TransformPrev>(globals::player, transform);
+    globals::dimension->entities.emplace_or_replace<client::VelocityPrev>(globals::player, velocity);
 
     glm::fvec3 forward, right;
     math::vectors(glm::fvec3(0.0f, head.angles[1], 0.0f), &forward, &right, nullptr);
diff --git a/src/game/shared/entity/collision.cc b/src/game/shared/entity/collision.cc
index 1be1ded..8da6405 100644
--- a/src/game/shared/entity/collision.cc
+++ b/src/game/shared/entity/collision.cc
@@ -16,7 +16,7 @@
 #include "shared/globals.hh"
 
 static int vgrid_collide(const Dimension* dimension, int d, Collision& collision, Transform& transform, Velocity& velocity,
-    VoxelMaterial& touch_surface)
+    VoxelMaterial& touch_surface, bool enable_snapping_to_grid)
 {
     auto movespeed = globals::fixed_frametime * velocity.value[d];
     auto movesign = math::sign<int>(movespeed);
@@ -135,15 +135,15 @@ static int vgrid_collide(const Dimension* dimension, int d, Collision& collision
             snap_to_closest_vbox = true;
         }
 
-        if(snap_to_closest_vbox) {
+        if(snap_to_closest_vbox && enable_snapping_to_grid) {
             auto vbox_center = 0.5f * closest_vbox.min[d] + 0.5f * closest_vbox.max[d];
             auto vbox_halfsize = 0.5f * closest_vbox.max[d] - 0.5f * closest_vbox.min[d];
 
             if(movesign < 0) {
-                transform.local[d] = vbox_center + vbox_halfsize + ref_halfsize[d] - ref_center[d] + 0.01f;
+                transform.local[d] = vbox_center + vbox_halfsize + ref_halfsize[d] - ref_center[d] + 0.01f * globals::fixed_frametime;
             }
             else {
-                transform.local[d] = vbox_center - vbox_halfsize - ref_halfsize[d] - ref_center[d] - 0.01f;
+                transform.local[d] = vbox_center - vbox_halfsize - ref_halfsize[d] - ref_center[d] - 0.01f * globals::fixed_frametime;
             }
         }
 
@@ -162,10 +162,11 @@ void Collision::fixed_update(Dimension* dimension)
 
     for(auto [entity, collision, transform, velocity] : group.each()) {
         auto surface = VMAT_UNKNOWN;
-        auto vertical_move = vgrid_collide(dimension, 1, collision, transform, velocity, surface);
+        auto vertical_move = vgrid_collide(dimension, 1, collision, transform, velocity, surface, true);
 
         if(dimension->entities.any_of<Gravity>(entity)) {
             if(vertical_move == math::sign<int>(dimension->get_gravity())) {
+                spdlog::info("grounded");
                 dimension->entities.emplace_or_replace<Grounded>(entity, Grounded { surface });
             }
             else {
@@ -179,7 +180,7 @@ void Collision::fixed_update(Dimension* dimension)
             dimension->entities.remove<Grounded>(entity);
         }
 
-        vgrid_collide(dimension, 0, collision, transform, velocity, surface);
-        vgrid_collide(dimension, 2, collision, transform, velocity, surface);
+        vgrid_collide(dimension, 0, collision, transform, velocity, surface, false);
+        vgrid_collide(dimension, 2, collision, transform, velocity, surface, false);
     }
 }
diff --git a/src/game/shared/entity/velocity.hh b/src/game/shared/entity/velocity.hh
index 69fce9e..0266bd0 100644
--- a/src/game/shared/entity/velocity.hh
+++ b/src/game/shared/entity/velocity.hh
@@ -2,7 +2,7 @@
 
 class Dimension;
 
-struct Velocity final {
+struct Velocity {
     glm::fvec3 value;
 
 public:
@@ -11,3 +11,10 @@ public:
     // NOTE: This system was previously called inertial
     static void fixed_update(Dimension* dimension);
 };
+
+namespace client
+{
+// Client-side only - interpolated and previous velocity
+struct VelocityIntr final : public Velocity {};
+struct VelocityPrev final : public Velocity {};
+} // namespace client