EntityCollider

cajphrase

Jul 31st, 2024

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public struct EntityCollider
{
public enum Type
{
box,
capsule,
sphere,
}
public Type type;
public float3 size; //use xy to store radius / height for capsule
public Pose localTransform;
public EntityCollider(BoxCollider b, EntityTransform localTransform)
{
type = EntityCollider.Type.box,
size = b.size * localTransform.scale,
this.localTransform = (Pose)localTransform,
}
public EntityCollider(CapsuleCollider c, EntityTransform localTransform)
{
type = EntityCollider.Type.capsule,
size = new float3(c.radius, c.height, 0) * localTransform.scale,
this.localTransform = (Pose)localTransform,
}
public EntityCollider(SphereCollider s, EntityTransform localTransform)
{
type = EntityCollider.Type.sphere,
size = new float3(s.radius, 0, 0) * localTransform.scale,
this.localTransform = (Pose)localTransform,
}
}
public static class EntityCollisionUtility
{
public class Loader : ILoader
{
public bool IsComplete => true;
public int progress => 1;
public int totalCount => 1;
public void Load()
{
EntityCollisionUtility.Initialize();
}
}
public static NativeParallelMultiHashMap<PrefabReference, EntityCollider> entityColliders;
public static void Initialize()
{
entityColliders = new(PrefabList.prefabs.Count, Allocator.Persistent);
Lifecycle.onShutDown += Dispose;
foreach (var prefab in PrefabList.prefabs)
{
var rootTx = new EntityTransform(prefab.transform);
var colliders = prefab.GetComponentsInChildren<Collider>();
foreach (var collider in colliders)
{
if (collider.IsTrigger)
continue;
var localTx = rootTx / new EntityTransform(collider.transform);
switch (collider)
{
case BoxCollider b:
entityColliders.Add(prefab, new(b));
break;
case CapsuleCollider c:
entityColliders.Add(prefab, new(c));
break;
case SphereCollider s:
entityColliders.Add(prefab, new(s));
break;
default: // fail silently on mesh colliders, not supported
break;
}
}
}
}
public static void Dispose()
{
entityColliders.Dispose();
}
public static bool CalculateCollision(EntityCollider a, EntityTransform aTransform, EntityCollider b, EntityTransform bTransform, out float penetrationDepth, out float3 penetrationNormal)
{
switch (a.type)
{
case EntityCollider.Type.box:
var aBox = a.AsBox(aTransform);
switch (b.type)
{
case EntityCollider.Type.box:
break;
case EntityCollider.Type.capsule:
return CollisionUtils.CapsuleBoxIntersection(b.AsCapsule(bTransform), aBox, out penetrationDepth, out penetrationNormal);
case EntityCollider.Type.sphere:
return CollisionUtils.SphereBoxIntersection(b.AsSphere(bTransform), aBox, out penetrationDepth, out penetrationNormal);
}
break;
case EntityCollider.Type.capsule:
switch (b.type)
{
case EntityCollider.Type.box:
break;
case EntityCollider.Type.capsule:
break:
case EntityCollider.Type.sphere:
break:
}
break;
case EntityCollider.Type.sphere:
switch (b.type)
{
case EntityCollider.Type.box:
break;
case EntityCollider.Type.capsule:
break:
case EntityCollider.Type.sphere:
break:
}
break;
}
}
}
public static bool SphereBoxIntersection(float3 sphereCenter, float radius, box box, out float3 penetrationNormal, out float penetrationDepth)
{
penetrationNormal = default;
penetrationDepth = default;
var localCenter = sphereCenter / box.localTransform;
var aabb = new AABB(0, box.halfExtents);
var cp = ClosestPointOnOrInAABB(localCenter, aabb);
var dist = mafs.distance(localCenter, cp);
if (dist > radius)
return false;
if (cp == localCenter) // center of sphere is inside the box
{
var edgePt = ClosestPointOnAABB(localCenter, aabb);
penetrationNormal = mafs.normalize(localCenter - edgePt);
penetrationDepth = mafs.distance(localCenter, edgePt) + radius;
}
else // center of sphere is outside the box
{
penetrationNormal = mafs.normalize(cp - localCenter);
penetrationDepth = dist;
}
return true;
}
public static bool CapsuleBoxIntersection(capsule cap, box box, out float3 penetrationNormal, out float penetrationDepth)
{
penetrationNormal = default;
penetrationDepth = default;
// transform the capsule into box space so the box becomes an AABB
var localCapTx = box.transform / cap.transform;
AABB aabb = new AABB(0, box.halfExtents);
var localCap = new capsule(localCapTx, cap.height, cap.radius);
// Expand the AABB by the radius. This will give false positives on the corners which we will find later.
var expandedAABB = new AABB(0, box.halfExtents + cap.radius);
// Check if the ray intersects the box
var rayHit = RayBoxIntersection(
in localCap.baseCenter,
in localCap.normal * localCap.height,
in expandedAABB.halfExtents,
out float2 hits,
out float3 normal);
// return early if there is no chance of intersection
if (!rayHit)
return false;
hits = mafs.clamp01(hits);
var pointA = localCap.baseCenter + localCap.normal * hits.x;
var cpA = ClosestPointOnOrInAABB(pointA, aabb);
var distA = mafs.distance(pointA, cpA);
if (distA < cap.radius)
{
penetrationDepth = distA;
penetrationNormal = normal;
return true;
}
var pointB = localCap.baseCenter + localCap.normal * hits.y;
var cpB = ClosestPointOnOrInAABB(pointB, aabb);
var distB = mafs.distance(pointA, cpA);
if (distB < cap.radius)
{
penetrationDepth = distB;
penetrationNormal = normal;
return true;
}
return false;
}

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