PROS的不妙冒险（七） 实现《英雄联盟》中的视野迷雾效果

今天，我们来一起学习下，如何给MOBA或RTS游戏添加视野迷雾效果。

那么看完视频没怎么懂的同学也不要急，下面是我经过改进与优化的版本的详细讲解。

private void GetCache()
{
    ……
    //使用广度优先搜索算法，缓存所有视野范围内的小格坐标相对于该视野单元坐标的偏移
    for (int a = 0; a < offsetCacheList.Count; ++a)
    {
        int x = offsetCacheList[a].x;
        int y = offsetCacheList[a].y;
        distance = (x - 1) * (x - 1) + y * y;
        offset = _offsets[_halfOffsetLength + x - 1, _halfOffsetLength + y];
        if (distance < targetDistance && !offset.isVisited)
        {
            offset.distance = distance;
            offset.isVisited = true;
            offsetCacheList.Add(offset);
        }
        distance = (x + 1) * (x + 1) + y * y;
        offset = _offsets[_halfOffsetLength + x + 1, _halfOffsetLength + y];
        if (distance < targetDistance && !offset.isVisited)
        {
            offset.distance = distance;
            offset.isVisited = true;
            offsetCacheList.Add(offset);
        }
        distance = x * x + (y - 1) * (y - 1);
        offset = _offsets[_halfOffsetLength + x, _halfOffsetLength + y - 1];
        if (distance < targetDistance && !offset.isVisited)
        {
            offset.distance = distance;
            offset.isVisited = true;
            offsetCacheList.Add(offset);
        }
        distance = x * x + (y + 1) * (y + 1);
        offset = _offsets[_halfOffsetLength + x, _halfOffsetLength + y + 1];
        if (distance < targetDistance && !offset.isVisited)
        {
            offset.distance = distance;
            offset.isVisited = true;
            offsetCacheList.Add(offset);
        }
    }
    offsetCacheList = offsetCacheList.OrderByDescending(item => item.distance).ToList();
    ……
}

private void GetCache()
{
    ……
    //缓存1/8个圆内障碍物产生迷雾的情况
    fogCacheList = new List<FogCache>();
    for (int a = 0; a < offsetCacheList.Count - 1; ++a)
    {
        offset = offsetCacheList[a];
        if (offset.x >= offset.y && offset.y >= 0)
        {
            FogCache fogCache = new FogCache {obstructionCoordinate = offset};
            float slopeLeftBottom = (offset.y - 0.5f) / (offset.x - 0.5f);
            float slopeLeftUp = (offset.y + 0.5f) / (offset.x - 0.5f);
            float slopeRightBottom = (offset.y - 0.5f) / (offset.x + 0.5f);
            float maxSlope = Mathf.Max(slopeLeftBottom, slopeLeftUp, slopeRightBottom);
            float minSlope = Mathf.Min(slopeLeftBottom, slopeLeftUp, slopeRightBottom);
            for (int b = 0; b < a; ++b)
            {
                Coordinate fog = offsetCacheList[b];
                if (fog.x > 0)
                {
                    float slope = (float) fog.y / fog.x;
                    if (maxSlope > slope && minSlope < slope)
                    {
                        fogCache.fogCoordinateList.Add(fog);
                    }
                }
            }
            fogCacheList.Add(fogCache);
        }
    }
    ……
}

fixed4 fragBlur(v2f i) : SV_Target
{
    fixed4 col = fixed4(0, 0, 0, 0);
    float2 offset = _BlurRadius * _MainTex_TexelSize;
    half gau[9] = {1, 2, 1, 2, 4, 2, 1, 2, 1};
    for (int x = 0; x < 3; ++x)
    {
        for (int y = 0; y < 3; ++y)
        {
            col += tex2D(_MainTex, fixed2(x - 1, y - 1) * offset + i.uv) * gau[x * 3 + y];
        }
    }
    return col / 16;
}

fixed4 fragLerp(v2f i) : SV_Target
{
    half4 lastCol = tex2D(_LastTex, i.uv);
    half4 col = tex2D(_MainTex, i.uv);
    return lerp(lastCol, col, unity_DeltaTime.x * 5);
}

完工！让我们来看一看最终的效果如何：

最后，感谢认真读完的你。这一期的内容制作耗费了笔者极大的精力与时间，如果您觉得有所收获，或是想要直接获取完整的源码，请一定要<font color="#ff0000">点赞+收藏</font>支持一下我！如果需要的人多的话，我会在下一期附上源码文件及说明。下期再见~