Place the cylinder at the center of the coordinates

shaders/terrain-draw.wgsl

@@ -47,7 +47,7 @@ fn cartesian_to_radial(p: vec3f) -> RadialCoordinates {
 }
 
 fn sample_map(rc: RadialCoordinates) -> vec4f {
-    let tc = vec2f(rc.alpha / (2.0 * PI), rc.depth / g_terrain_params.length);
+    let tc = vec2f(rc.alpha / (2.0 * PI), rc.depth / g_terrain_params.length + 0.5);
     return textureSampleLevel(g_terrain, g_terrain_sampler, tc, 0.0);
 }
 
@@ -70,7 +70,7 @@ fn intersect_ray_with_map_radius(dir: vec2f, radius: f32) -> vec2f {
 fn compute_ray_distance(dir: vec3f) -> vec2f {
     var result = vec2f(g_camera.clip_near, g_camera.clip_far);
     // intersect with bottom or top
-    let limit = (select(0.0, g_terrain_params.length, dir.z > 0.0) - g_camera.pos.z) / dir.z;
+    let limit = (g_terrain_params.length * select(-0.5, 0.5, dir.z > 0.0) - g_camera.pos.z) / dir.z;
     result.y = min(result.y, limit);
     if (result.x >= result.y) {
         // outside of the cylinder length

src/physics.rs

@@ -219,10 +219,17 @@ impl rapier3d::geometry::RayCast for TerrainShape {
 
 impl rapier3d::geometry::Shape for TerrainShape {
     fn compute_local_aabb(&self) -> rapier3d::parry::bounding_volume::Aabb {
-        self.cylinder(1.0).compute_local_aabb()
+        let r = self.radius.end;
+        rapier3d::parry::bounding_volume::Aabb {
+            mins: nalgebra::Point3::new(-r, -r, -0.5 * self.length),
+            maxs: nalgebra::Point3::new(r, r, 0.5 * self.length),
+        }
     }
     fn compute_local_bounding_sphere(&self) -> rapier3d::parry::bounding_volume::BoundingSphere {
-        self.cylinder(1.0).compute_local_bounding_sphere()
+        rapier3d::parry::bounding_volume::BoundingSphere {
+            center: nalgebra::Point3::default(),
+            radius: nalgebra::Vector2::new(self.radius.end, 0.5 * self.length).norm(),
+        }
     }
     fn clone_dyn(&self) -> Box<dyn rapier3d::geometry::Shape> {
         Box::new(self.clone())