摄像机平滑移动

摄像机移动大概的思路：/*
场景新位置 = 场景当前位置 *(1-smooth) + 场景目标位置*smooth
每一帧 都调用这个 公式 修正 场景的位置即可
smooth 是0 -1 的数字 用于 控制场景移动的 光滑程度
*/

//更新镜头
Vec2 vec2 = GetCameraPostion(_pCameraTarget->getPosition());
float smooth = 0.1f;
Vec2 newPos = getPosition()*(1-smooth) + vec2*smooth;

//===================================
float damping = 0.1;
float lookAheadFactor = 3;
float lookAheadReturnSpeed = 680.5f;
float lookAheadMoveThreshold = 0.1f;

float m_OffsetZ;
Vector3 m_LastTargetPosition;
Vector3 m_CurrentVelocity;
Vector3 m_LookAheadPos;

<span style="font-family: Arial, Helvetica, sans-serif;">//目的地位置</span>

Vec2 vec2 = GetCameraPostion(_pCameraTarget->getPosition());
Vector3 position = Vector3::ConvertVec2(vec2);

if (getPosition().x > position.x) {
m_CurrentVelocity.x = -GM()->m_fCameraSpeed;
if (getPosition().x + m_CurrentVelocity.x < position.x) {
m_CurrentVelocity.x = position.x - getPosition().x;
}
}
else
{
m_CurrentVelocity.x = GM()->m_fCameraSpeed;
if (getPosition().x + m_CurrentVelocity.x > position.x) {
m_CurrentVelocity.x = position.x - getPosition().x;
}
}
if (getPosition().y > position.y) {
m_CurrentVelocity.y = -GM()->m_fCameraSpeed;
if (getPosition().y + m_CurrentVelocity.y < position.y) {
m_CurrentVelocity.y = position.y - getPosition().y;
}
}
else
{
m_CurrentVelocity.y = GM()->m_fCameraSpeed;
if (getPosition().y + m_CurrentVelocity.y > position.y) {
m_CurrentVelocity.y = position.y - getPosition().y;
}
}

// only update lookahead pos if accelerating or changed direction
float xMoveDelta = (position - m_LastTargetPosition).x;

bool updateLookAheadTarget = abs(xMoveDelta) > lookAheadMoveThreshold;

if (updateLookAheadTarget)
{
m_LookAheadPos = lookAheadFactor*Vector3::right()*signbit(xMoveDelta);
}
else
{

m_LookAheadPos = Vector3::MoveTowards(m_LookAheadPos, Vector3::ZERO, dt*lookAheadReturnSpeed);
}
Vector3 transformPos = Vector3::ConvertVec2(getPosition());

Vector3 aheadTargetPos = position;// + m_LookAheadPos + Vector3()*m_OffsetZ;
Vector3 newPos = Vector3::SmoothDamp(transformPos, aheadTargetPos,m_CurrentVelocity, damping,GM()->m_fCameraSpeed*10,dt);
//        log("newPos(%f,%f,%f)",newPos.x,newPos.y,newPos.z);
float speedX = newPos.x - getPositionX();
float speedY = newPos.y - getPositionY();
//更新镜头
setPosition(Vec2(newPos.x, newPos.y));

//记录上一个目标位置
m_LastTargetPosition = Vector3::ConvertVec2(GetCameraPostion(_pCameraTarget->getPosition()));