113 lines
4.5 KiB
C++
113 lines
4.5 KiB
C++
// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
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#include "InverseKinematics.h"
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void InverseKinematics::SolveAimIK(const Transform& node, const Vector3& target, Quaternion& outNodeCorrection)
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{
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Vector3 toTarget = target - node.Translation;
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toTarget.Normalize();
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const Vector3 fromNode = Vector3::Forward;
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Quaternion::FindBetween(fromNode, toTarget, outNodeCorrection);
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}
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void InverseKinematics::SolveTwoBoneIK(Transform& rootNode, Transform& jointNode, Transform& targetNode, const Vector3& target, const Vector3& jointTarget, bool allowStretching, float maxStretchScale)
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{
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float lowerLimbLength = (targetNode.Translation - jointNode.Translation).Length();
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float upperLimbLength = (jointNode.Translation - rootNode.Translation).Length();
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Vector3 jointPos = jointNode.Translation;
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Vector3 desiredDelta = target - rootNode.Translation;
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float desiredLength = desiredDelta.Length();
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float maxLimbLength = lowerLimbLength + upperLimbLength;
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Vector3 desiredDir;
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if (desiredLength < ZeroTolerance)
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{
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desiredLength = ZeroTolerance;
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desiredDir = Vector3(1, 0, 0);
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}
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else
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{
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desiredDir = desiredDelta.GetNormalized();
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}
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Vector3 jointTargetDelta = jointTarget - rootNode.Translation;
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const float jointTargetLengthSqr = jointTargetDelta.LengthSquared();
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Vector3 jointPlaneNormal, jointBendDir;
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if (jointTargetLengthSqr < ZeroTolerance * ZeroTolerance)
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{
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jointBendDir = Vector3::Forward;
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jointPlaneNormal = Vector3::Up;
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}
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else
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{
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jointPlaneNormal = desiredDir ^ jointTargetDelta;
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if (jointPlaneNormal.LengthSquared() < ZeroTolerance * ZeroTolerance)
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{
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desiredDir.FindBestAxisVectors(jointPlaneNormal, jointBendDir);
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}
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else
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{
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jointPlaneNormal.Normalize();
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jointBendDir = jointTargetDelta - (jointTargetDelta | desiredDir) * desiredDir;
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jointBendDir.Normalize();
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}
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}
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if (allowStretching)
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{
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const float startStretchRatio = 1.0f;
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const float scaleRange = maxStretchScale - startStretchRatio;
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if (scaleRange > ZeroTolerance && maxLimbLength > ZeroTolerance)
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{
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const float reachRatio = desiredLength / maxLimbLength;
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const float scalingFactor = (maxStretchScale - 1.0f) * Math::Saturate((reachRatio - startStretchRatio) / scaleRange);
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if (scalingFactor > ZeroTolerance)
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{
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lowerLimbLength *= 1.0f + scalingFactor;
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upperLimbLength *= 1.0f + scalingFactor;
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maxLimbLength *= 1.0f + scalingFactor;
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}
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}
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}
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Vector3 resultEndPos = target;
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Vector3 resultJointPos = jointPos;
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if (desiredLength >= maxLimbLength)
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{
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resultEndPos = rootNode.Translation + maxLimbLength * desiredDir;
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resultJointPos = rootNode.Translation + upperLimbLength * desiredDir;
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}
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else
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{
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const float twoAb = 2.0f * upperLimbLength * desiredLength;
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const float cosAngle = twoAb > ZeroTolerance ? (upperLimbLength * upperLimbLength + desiredLength * desiredLength - lowerLimbLength * lowerLimbLength) / twoAb : 0.0f;
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const bool reverseUpperBone = cosAngle < 0.0f;
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const float angle = Math::Acos(cosAngle);
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const float jointLineDist = upperLimbLength * Math::Sin(angle);
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const float projJointDistSqr = upperLimbLength * upperLimbLength - jointLineDist * jointLineDist;
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float projJointDist = projJointDistSqr > 0.0f ? Math::Sqrt(projJointDistSqr) : 0.0f;
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if (reverseUpperBone)
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projJointDist *= -1.0f;
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resultJointPos = rootNode.Translation + projJointDist * desiredDir + jointLineDist * jointBendDir;
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}
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{
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const Vector3 oldDir = (jointPos - rootNode.Translation).GetNormalized();
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const Vector3 newDir = (resultJointPos - rootNode.Translation).GetNormalized();
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const Quaternion deltaRotation = Quaternion::FindBetween(oldDir, newDir);
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rootNode.Orientation = deltaRotation * rootNode.Orientation;
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}
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{
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const Vector3 oldDir = (targetNode.Translation - jointPos).GetNormalized();
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const Vector3 newDir = (resultEndPos - resultJointPos).GetNormalized();
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const Quaternion deltaRotation = Quaternion::FindBetween(oldDir, newDir);
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jointNode.Orientation = deltaRotation * jointNode.Orientation;
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jointNode.Translation = resultJointPos;
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}
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targetNode.Translation = resultEndPos;
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}
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