火焰粒子：三属性耦合的温度感

fx-phoenix

local FireParticle = {}
local CONST = { KEY = "FireParticle", LIFETIME = 0.8 }

function FireParticle.Spawn(x, y)
    local p = {
        x = x, y = y,
        vx = (math.random() - 0.5) * 30,
        vy = -20 - math.random() * 40,
        size = 3 + math.random() * 4,
        life = CONST.LIFETIME,
        maxLife = CONST.LIFETIME
    }
end

function FireParticle:Update(dt)
    self.life = self.life - dt
    if self.life <= 0 then self.dead = true return end
    local ratio = self.life / self.maxLife
    self.x = self.x + self.vx * dt
    self.y = self.y + self.vy * dt
    self.vy = self.vy - 8 * dt                      -- 上升浮力
    self.size = self.size * (1 - dt * 0.5)           -- 大小衰减
    self.color = InterpolateColor(ratio)             -- 颜色插值
end

return FireParticle