From 6cb677d3490c7a2a3882f2e034353b7b28d3cbc8 Mon Sep 17 00:00:00 2001
From: Jan Hohenheim <jan@hohenheim.ch>
Date: Thu, 22 Aug 2024 01:07:28 +0200
Subject: [PATCH] Use shape cast for more accuracy

---
 examples/full_setup.rs         |  2 +-
 src/interaction/hold/update.rs | 52 +++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 21 deletions(-)

diff --git a/examples/full_setup.rs b/examples/full_setup.rs
index dccc90a..310ac9c 100644
--- a/examples/full_setup.rs
+++ b/examples/full_setup.rs
@@ -11,7 +11,7 @@ fn main() {
             DefaultPlugins,
             WorldInspectorPlugin::new(),
             PhysicsPlugins::default(),
-            //PhysicsDebugPlugin::default(),
+            PhysicsDebugPlugin::default(),
             AvianPickupPlugin::default(),
         ))
         .add_systems(Startup, setup)
diff --git a/src/interaction/hold/update.rs b/src/interaction/hold/update.rs
index de5757f..1ceb5a6 100644
--- a/src/interaction/hold/update.rs
+++ b/src/interaction/hold/update.rs
@@ -133,19 +133,48 @@ pub(super) fn update_object(
         // actor's origins if possible instead.
         let max_distance = preferred_distance.max(min_distance);
 
-        let terrain_hit = spatial_query.cast_ray(
+        let Some(actor_space_rotation) = preferred_rotation
+            .map(|preferred| preferred.0)
+            .or_else(|| pre_pickup_rotation.map(|pre| pre.0))
+        else {
+            error!("Held prop does not have a preferred or pre-pickup rotation. Ignoring.");
+            continue;
+        };
+        // orient the prop wrt the actor
+        // The 2013 code uses the non-clamped code here, resulting in the prop
+        // rotating when looking further up than the clamp allows.
+        // Looks weird imo, so we use the clamped rotation.
+        let clamped_actor_transform = actor_transform.with_rotation(clamped_rotation);
+        let target_rotation =
+            prop_rotation_from_actor_space(actor_space_rotation, clamped_actor_transform);
+
+        shadow.target_rotation = target_rotation;
+
+        // The cast needs to be longer to account for the fact that
+        // the prop might hit terrain with the side that is not facing
+        // the player. We are assuming the prop has the same radius
+        // "behind" it as it has in front of it. Also add a bit of
+        // padding to be safe.
+        let max_cast_toi = max_distance + min_distance + 0.5;
+
+        let terrain_hit = spatial_query.cast_shape(
+            &prop_collider,
             actor_transform.translation,
+            target_rotation,
             forward,
-            max_distance,
+            max_cast_toi,
             true,
             &config.terrain_filter,
         );
         let distance = if let Some(terrain_hit) = terrain_hit {
             let fraction = terrain_hit.time_of_impact / max_distance;
+            info!("fraction: {}", fraction);
             if fraction < 0.5 {
+                info!("min distance");
                 min_distance
             } else {
-                max_distance
+                info!("far terrain hit");
+                max_distance.min(terrain_hit.time_of_impact)
             }
         } else {
             max_distance
@@ -155,23 +184,6 @@ pub(super) fn update_object(
         // distance
         let target_position = actor_transform.translation + forward * distance;
         shadow.target_position = target_position;
-
-        let Some(actor_space_rotation) = preferred_rotation
-            .map(|preferred| preferred.0)
-            .or_else(|| pre_pickup_rotation.map(|pre| pre.0))
-        else {
-            error!("Held prop does not have a preferred or pre-pickup rotation. Ignoring.");
-            continue;
-        };
-        // orient the prop wrt the actor
-        // The 2013 code uses the non-clamped code here, resulting in the prop
-        // rotating when looking further up than the clamp allows.
-        // Looks weird imo, so we use the clamped rotation.
-        let clamped_actor_transform = actor_transform.with_rotation(clamped_rotation);
-        let target_rotation =
-            prop_rotation_from_actor_space(actor_space_rotation, clamped_actor_transform);
-
-        shadow.target_rotation = target_rotation;
     }
 }