{"id":2003,"date":"2019-01-21T16:17:12","date_gmt":"2019-01-21T08:17:12","guid":{"rendered":"http:\/\/www.clonefactor.com\/wordpress\/?p=2003"},"modified":"2019-01-21T16:31:39","modified_gmt":"2019-01-21T08:31:39","slug":"%e7%ad%86%e8%a8%98-%e8%87%aa%e5%ae%9a%e7%be%a9%e7%89%a9%e7%90%86-physics-computepenetration","status":"publish","type":"post","link":"https:\/\/www.clonefactor.com\/wordpress\/program\/c\/2003\/","title":{"rendered":"\u7b46\u8a18: \u81ea\u5b9a\u7fa9\u7269\u7406 Physics.ComputePenetration"},"content":{"rendered":"\n

\u5728\u7de8\u5beb\u904a\u6232\u6642\u7d93\u5e38\u9700\u8981\u505a\u4e00\u4e9b\u9055\u8fd4\u7269\u7406\u7684\u4e8b.
\u9019\u6642\u5019\u5f88\u5bb9\u6613\u7684\u5c31\u60f3\u7528 tweening \u6216\u8005\u81ea\u5df1\u8a08\u7b97\u7684\u8def\u7d93\u4f86\u8986\u5beb\u7269\u7406\u5f15\u64ce\u7684\u7d50\u679c.\u4f46\u662f\u5728\u5be6\u969b\u904b\u4f5c\u6642\u53c8\u6703\u9677\u5165\u60f3\u4f7f\u7528\u7269\u7406\u5f15\u64ce\u7684\u60c5\u6cc1.
\u9019\u6642\u5019\u5c31\u6703\u60f3 : “\u5982\u679c\u6709\u65b9\u6cd5\u53ef\u4ee5\u5f97\u77e5\u7269\u7406\u5f15\u64ce\u7684\u904b\u7b97\u7d50\u679c\u5c31\u597d\u4e86.” \u7684\u60f3\u6cd5<\/p>\n\n\n\n

We always want to redefine physics during game development.
usually implement it by tweening or custom path to complete ignore the physic engine result.
however at some point we still wanted to respect the result from physic engine.
<\/p>\n\n\n\n

\u5728 Unity3D \u88e1\u7684 Physics.ComputePenetration \u5c31\u662f\u4e00\u500b\u5c0d\u9019\u60c5\u6cc1\u4f7f\u7528\u7684\u63a5\u53e3.
Ref : https:\/\/docs.unity3d.com\/ScriptReference\/Physics.ComputePenetration.html<\/a>
\u5728\u5b98\u65b9\u7684\u6587\u4ef6\u4e2d\u6709\u6a19\u660e\u9019\u662f\u500b\u4f54\u7528\u8cc7\u6e90\u7684 API,
\u4e26\u5efa\u8b70\u5118\u91cf\u65bc Physics.Overlap \u5f8c\u4f7f\u7528.

\u4ee5\u4e0b\u70ba\u6211\u6240\u505a\u7684\u5c0f\u6e2c\u8a66, \u65b9\u4fbf\u660e\u767d\u9019\u500b API \u5728\u505a\u751a\u9ebc.<\/p>\n\n\n\n

in Unity3D, there is an API : Physics.ComputePentration to handle this situation.
Ref : https:\/\/docs.unity3d.com\/ScriptReference\/Physics.ComputePenetration.html<\/a>
<\/p>\n\n\n\n

In official document, there is a warning about this API.<\/p>This function is useful to write custom depenetration functions. One particular example is an implementation of a character controller where a specific reaction to collision with the surrounding physics objects is required. In this case, one would first query for the colliders nearby using OverlapSphere and then adjust the character’s position using the data returned by ComputePenetration.
<\/cite><\/blockquote>\n\n\n\n

\"\"
PhysicsComputePenetration test (red arrow represent the final result of all overlap object vector(s))<\/figcaption><\/figure>\n\n\n\n

\u53ef\u4ee5\u770b\u898b\u96a8\u8457 Capsule \u7684\u4f4d\u7f6e\u6539\u8b8a, ComputePenetration \u7684\u7d50\u679c\u7e3d\u662f\u6307\u5411\u6c92\u6709\u969c\u7919\u7269\u7684\u7a7a\u9593.
\u90a3\u662f\u7269\u7406\u5f15\u64ce\u907f\u514d\u7269\u4ef6\u4e92\u76f8\u4ea4\u758a\u800c\u6307\u51fa\u7684\u5efa\u8b70\u8def\u7d93.
\u6e2c\u8a66\u4e2d, \u7531\u65bc\u6bcf\u652f\u5411\u91cf\u662f\u55ae\u7368\u5c0d\u65bc\u8a72 Collider \u7684\u6240\u4ee5\u6700\u5f8c\u7684\u6307\u5411\u53ca\u8ddd\u96e2\u9700\u8981\u81ea\u5df1\u4f86\u7b97.<\/p>\n\n\n\n

As you can see based on the capsule position changed, the result from ComputePenetration are always pointing to the avoid collision direction.
that’s what physic engine will do on your object to avoid those collide overlap each others.
however you need to handle each collision vector by yourself, it return direction<\/code> and distance<\/code> and only able to return one object,
so for multiple objects you will need to calculate the final direction & distance after combine all of it.<\/p>\n\n\n\n

Here is the implement of above test script.<\/p>\n\n\n\n

using UnityEngine;\nusing Kit;\n\n[RequireComponent(typeof(CapsuleCollider))]\npublic class PhyTest : MonoBehaviour\n{\n\t[SerializeField] CapsuleCollider m_Self = null;\n\t[SerializeField, Range(0f, 89f)] float m_Angle = 3f;\n\t[SerializeField, Range(0f, 1f)] float m_Length = .3f;\n\t[SerializeField] Color m_DebugColor = Color.yellow;\n\n\t[SerializeField] Color m_Color = new Color(1f, 1f, 1f, 0.3f);\n\t[SerializeField] Color m_HitColor = new Color(1f, 0f, 0f, 0.4f);\n\tprivate Collider[] m_OverlapColliders = new Collider[128];\n\tprivate int HitCount { get; set; } = 0;\n\n\tprivate Vector3 SuggestedDirectionFromEngine(Collider[] objArr, int validRange)\n\t{\n\t\tVector3 finalVector = Vector3.zero;\n\t\tfloat distance = 0f;\n\t\tint total = 0;\n\t\tfor (int i = 0; i < validRange; i++)\n\t\t{\n\t\t\tCollider obstacle = objArr[i];\n\t\t\tif (obstacle == m_Self)\n\t\t\t\tcontinue;\n\t\t\tVector3 pushBackDirection;\n\t\t\tfloat pushBackDistance;\n\t\t\tbool isCollision = Physics.ComputePenetration(m_Self, transform.position, transform.rotation,\n\t\t\t\tobstacle, obstacle.transform.position, obstacle.transform.rotation, out pushBackDirection, out pushBackDistance);\n\t\t\tif (!isCollision)\n\t\t\t\tcontinue;\n\n\t\t\ttotal++;\n\t\t\tdistance += pushBackDistance;\n\t\t\tfinalVector += pushBackDirection;\n\n\t\t\tDebug.DrawRay(transform.position, pushBackDirection * pushBackDistance, Color.magenta, 0f, false);\n\t\t}\n\n\t\treturn finalVector.normalized * (distance \/ (float)total);\n\t}\n\n\tprivate void Reset()\n\t{\n\t\tif (m_Self == null)\n\t\t\tm_Self = GetComponent<CapsuleCollider>();\n\t}\n\n\tprivate void OnDrawGizmos()\n\t{\n\t\tif (KitBox.IsEditorMode)\n\t\t{\n\t\t\tMatrix4x4 matrix = Matrix4x4.TRS(transform.position, transform.rotation, transform.lossyScale);\n\t\t\tfloat half = Mathf.Clamp((m_Self.height \/ 2f) - m_Self.radius, 0f, float.PositiveInfinity);\n\t\t\tVector3 p0 = matrix.MultiplyPoint3x4(m_Self.center + new Vector3(0f, half, 0f));\n\t\t\tVector3 p1 = matrix.MultiplyPoint3x4(m_Self.center + new Vector3(0f, -half, 0f));\n\t\t\tHitCount = Physics.OverlapCapsuleNonAlloc(p0, p1, m_Self.radius, m_OverlapColliders);\n\t\t}\n\t\t\n\t\tVector3 dir = SuggestedDirectionFromEngine(m_OverlapColliders, HitCount);\n\t\tGizmosExtend.DrawRay(transform.position, dir, Color.green);\n\n\t\tGizmosExtend.DrawArrow(transform.position, dir, m_DebugColor, m_Angle, m_Length);\n\t}\n}<\/pre>\n","protected":false},"excerpt":{"rendered":"
\u5728\u7de8\u5beb\u904a\u6232\u6642\u7d93\u5e38\u9700\u8981\u505a\u4e00\u4e9b\u9055\u8fd4\u7269\u7406\u7684\u4e8b. \u9019\u6642\u5019\u5f88\u5bb9\u6613\u7684\u5c31\u60f3\u7528 tweening \u6216\u8005\u81ea\u5df1\u8a08\u7b97\u7684\u8def\u7d93 …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,78,11],"tags":[79,43],"class_list":["post-2003","post","type-post","status-publish","format-standard","hentry","category-c","category-math","category-unity3d","tag-physical","tag-unity3d-2"],"_links":{"self":[{"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/posts\/2003","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/comments?post=2003"}],"version-history":[{"count":0,"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/posts\/2003\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/media?parent=2003"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/categories?post=2003"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.clonefactor.com\/wordpress\/wp-json\/wp\/v2\/tags?post=2003"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}