剑气追魂：影子追到哪砍到哪

 fx-swordchase

local SwordChase = {}
local KEY = { SPD = 280, TURN_RATE = 5 }

local qi = nil

function SC.Cast(self_, target)
    qi = {
        x = SL:GetValue("actorX", self_) + 24,
        y = SL:GetValue("actorY", self_) - 58,
        vx = 280, vy = -60,
        trail = {}, target = target
    }
    SL:PlayActorAct(self_, "cast")
    SL:Schedule(function(dt)
        if not qi then SL:UnSchedule("scRun") return end
        -- 追踪: 速度向量朝目标渐进旋转
        local dx = SL:GetValue("actorX", qi.target) - qi.x
        local dy = SL:GetValue("actorY", qi.target) - 58 - qi.y
        local wantA = math.atan2(dy, dx)
        local curA = math.atan2(qi.vy, qi.vx)
        local diff = wantA - curA
        -- 归一化到 -PI 到 PI
        while diff > math.pi do diff = diff - 2 * math.pi end
        while diff < -math.pi do diff = diff + 2 * math.pi end
        local maxTurn = KEY.TURN_RATE * dt
        local turn = math.max(-maxTurn, math.min(maxTurn, diff))
        local newA = curA + turn
        qi.vx = math.cos(newA) * KEY.SPD
        qi.vy = math.sin(newA) * KEY.SPD
        qi.x = qi.x + qi.vx * dt
        qi.y = qi.y + qi.vy * dt
        -- 拖尾
        qi.trail[#qi.trail + 1] = { x = qi.x, y = qi.y }
        if #qi.trail > 8 then table.remove(qi.trail, 1) end
        -- 命中判定
        local tx = SL:GetValue("actorX", qi.target)
        local ty = SL:GetValue("actorY", qi.target) - 58
        local d = math.sqrt((qi.x - tx) ^ 2 + (qi.y - ty) ^ 2)
        if d < 26 then
            SL:UnSchedule("scRun")
            SL:PlayFxAt("qi_hit", tx, ty)
            SL:DeductHp(qi.target, 34)
            SL:ShowHitNum(qi.target, 34, "chase_hit")
            SL:PlayActorAct(qi.target, "stuck")
            qi = nil
        end
    end, 0.016, "scRun")
end

return SC