fix: raycast traversal (#647)

`Ray::voxel_traversal` and `get_direction_from_rotation` were
implemented wrong.

Author: Tebarem

.cargo/config.toml

@@ -1,2 +1,5 @@
 [build]
 rustflags = ["--cfg", "tokio_unstable", "-Ctarget-cpu=native"]
+
+[env]
+RUST_LOG="debug"

crates/geometry/src/ray.rs

@@ -42,11 +42,20 @@ impl Ray {
         self.origin + self.direction * t
     }
 
-    /// Efficiently traverse through grid cells that the ray intersects.
+    /// Efficiently traverse through grid cells that the ray intersects using an optimized DDA algorithm.
     /// Returns an iterator over the grid cells ([`IVec3`]) that the ray passes through.
     pub fn voxel_traversal(&self, bounds_min: IVec3, bounds_max: IVec3) -> VoxelTraversal {
-        // Convert ray origin to grid coordinates
-        let current_pos = self.origin.floor().as_ivec3();
+        // Convert ray origin to grid coordinates and handle negative coordinates correctly
+        #[allow(clippy::cast_possible_truncation)]
+        let current_pos = if self.origin.x < 0.0 || self.origin.y < 0.0 || self.origin.z < 0.0 {
+            IVec3::new(
+                self.origin.x.floor() as i32,
+                self.origin.y.floor() as i32,
+                self.origin.z.floor() as i32,
+            )
+        } else {
+            self.origin.as_ivec3()
+        };
 
         // Calculate step direction for each axis
         let step = IVec3::new(
@@ -73,42 +82,56 @@ impl Ray {
             },
         );
 
-        // Calculate initial t_max values (distance to next voxel boundary for each axis)
-        let next_voxel = current_pos + step;
+        // Calculate t_max - distance to next voxel boundary for each axis
         let t_max = Vec3::new(
             if self.direction.x == 0.0 {
                 f32::INFINITY
             } else {
-                ((next_voxel.x as f32) - self.origin.x) * self.inv_direction.x
+                let next_x = if self.direction.x > 0.0 {
+                    current_pos.x as f32 + 1.0 - self.origin.x
+                } else {
+                    self.origin.x - current_pos.x as f32
+                };
+                next_x * self.inv_direction.x.abs()
             },
             if self.direction.y == 0.0 {
                 f32::INFINITY
             } else {
-                ((next_voxel.y as f32) - self.origin.y) * self.inv_direction.y
+                let next_y = if self.direction.y > 0.0 {
+                    current_pos.y as f32 + 1.0 - self.origin.y
+                } else {
+                    self.origin.y - current_pos.y as f32
+                };
+                next_y * self.inv_direction.y.abs()
             },
             if self.direction.z == 0.0 {
                 f32::INFINITY
             } else {
-                ((next_voxel.z as f32) - self.origin.z) * self.inv_direction.z
+                let next_z = if self.direction.z > 0.0 {
+                    current_pos.z as f32 + 1.0 - self.origin.z
+                } else {
+                    self.origin.z - current_pos.z as f32
+                };
+                next_z * self.inv_direction.z.abs()
             },
         );
 
-        // Calculate t_delta values (distance between voxel boundaries)
+        // Calculate t_delta - distance between voxel boundaries
         let t_delta = Vec3::new(
             if self.direction.x == 0.0 {
                 f32::INFINITY
             } else {
-                step.x as f32 * self.inv_direction.x
+                self.inv_direction.x.abs()
             },
             if self.direction.y == 0.0 {
                 f32::INFINITY
             } else {
-                step.y as f32 * self.inv_direction.y
+                self.inv_direction.y.abs()
             },
             if self.direction.z == 0.0 {
                 f32::INFINITY
             } else {
-                step.z as f32 * self.inv_direction.z
+                self.inv_direction.z.abs()
             },
         );
 

crates/hyperion/src/simulation/blocks/mod.rs

@@ -99,16 +99,18 @@ impl Blocks {
 
     #[must_use]
     pub fn first_collision(&self, ray: Ray, distance_limit: f32) -> Option<RayCollision> {
-        let a = ray.origin();
-        let b = ray.origin() + ray.direction() * distance_limit;
+        // Calculate exact start position (the block we're in)
+        let start_pos = ray.origin();
 
-        let min = a.min(b);
-        let max = a.max(b);
+        // Calculate end position with a small offset to handle edge cases
+        let end_pos = ray.origin() + ray.direction() * (distance_limit + 0.0001);
 
-        let min = min.floor().as_ivec3();
-        let max = max.ceil().as_ivec3();
+        // Convert to block coordinates, expanding bounds to ensure we catch all blocks
+        let min_block = start_pos.min(end_pos).floor().as_ivec3();
+        let max_block = start_pos.max(end_pos).ceil().as_ivec3();
 
-        let traversal = ray.voxel_traversal(min, max);
+        // Set up voxel traversal through the blocks
+        let traversal = ray.voxel_traversal(min_block, max_block);
 
         let mut min: Option<RayCollision> = None;
 

events/tag/src/command/raycast.rs

@@ -30,16 +30,14 @@ pub struct RaycastCommand;
 /// A normalized Vec3 representing the look direction
 pub fn get_direction_from_rotation(yaw: f32, pitch: f32) -> Vec3 {
     // Convert angles from degrees to radians
-    let yaw_rad = (yaw + 90.0).to_radians(); // Add 90° to match Minecraft's coordinate system
-    let pitch_rad = (-pitch).to_radians(); // Negate pitch because Minecraft's pitch is inverted
+    let yaw_rad = yaw.to_radians();
+    let pitch_rad = pitch.to_radians();
 
-    // Calculate direction vector components
     Vec3::new(
-        pitch_rad.cos() * yaw_rad.cos(), // X component
-        pitch_rad.sin(),                 // Y component
-        pitch_rad.cos() * yaw_rad.sin(), // Z component
+        -pitch_rad.cos() * yaw_rad.sin(), // x = -cos(pitch) * sin(yaw)
+        -pitch_rad.sin(),                 // y = -sin(pitch)
+        pitch_rad.cos() * yaw_rad.cos(),  // z = cos(pitch) * cos(yaw)
     )
-    .normalize()
 }
 
 impl MinecraftCommand for RaycastCommand {