using UnityEngine;
using UnityStandardAssets.ImageEffects;

public class WaterWaveOnUI : PostEffectBase
{
    //距离系数
    public float distanceFactor = 60.0f;
    //时间系数
    public float timeFactor = -30.0f;
    //sin函数结果系数
    public float totalFactor = 1.0f;

    //波纹宽度
    public float waveWidth = 0.3f;
    //波纹扩散的速度
    public float waveSpeed = 0.3f;

    private float waveStartTime;

    public void StartWave()
    {
        enabled = true;
        //设置startTime
        waveStartTime = Time.time;
    }

    void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        if (Time.time - waveStartTime > 1)
        {
            //如果时间超过1s，关闭波纹效果
            enabled = false;
            return;
        }
        //计算波纹移动的距离，根据enable到目前的时间*速度求解
        float curWaveDistance = (Time.time - waveStartTime) * waveSpeed;
        //设置一系列参数
        _Material.SetFloat("_distanceFactor", distanceFactor);
        _Material.SetFloat("_timeFactor", timeFactor);
        _Material.SetFloat("_totalFactor", totalFactor);
        _Material.SetFloat("_waveWidth", waveWidth);
        _Material.SetFloat("_curWaveDis", curWaveDistance);

        Graphics.Blit(source, destination, _Material);
    }

}