Bump改进

Shader
1.8k words

Desc:

记录法线贴图的变更

法线映射

非移动平台上，Unity会把法线贴图转换成 DXRT5nm 格式，只有两个有效通道 GA ，节省空间的优化
移动平台上，RGB 通道

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fixed3 UnpackNormalmapRGorAG(fixed4 packednormal)
{
    // This do the trick
   packednormal.x *= packednormal.w;

    fixed3 normal;
    normal.xy = packednormal.xy * 2 - 1;
    normal.z = sqrt(1 - saturate(dot(normal.xy, normal.xy)));
    return normal;
}
inline fixed3 UnpackNormal(fixed4 packednormal)
{
#if defined(UNITY_NO_DXT5nm)
    return packednormal.xyz * 2 - 1;
#else
    return UnpackNormalmapRGorAG(packednormal);
#endif
}

视察映射

知乎

Image text

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//视差映射
float2 ParallaxMapping(float2 Huv, real3 viewDirTS)
{
    float height = tex2D(_HeightMap, Huv).r;
    float2 offuv = viewDirTS.xy / viewDirTS.z * height * _HeightScale;
    return offuv;
}

陡视差映射

Image text
//陡峭视差映射

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float2 SteepParallaxMapping(float2 uv, real3 viewDirTS)
{
    float numLayers = 20.0;
    float layerHeight = 1.0 / numLayers;
    float currentLayerHeight = 0.0;
    float2 offlayerUV = viewDirTS.xy / viewDirTS.z * _HeightScale;
    float2 Stepping = offlayerUV / numLayers;
    float2 currentUV = uv;
    float2 AddUV = float2(0, 0);
    float currentHeightMapValue = tex2D(_HeightMap, currentUV + AddUV).r;
    for (int i = 0; i < numLayers; i++)
    {
        if (currentLayerHeight > currentHeightMapValue)
        {
            return AddUV;
        }
        AddUV += Stepping;
        currentHeightMapValue = tex2D(_HeightMap, currentUV + AddUV).r;
        currentLayerHeight += layerHeight;
    }
    return AddUV;
}

视差遮蔽映射

Image text

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// get texture coordinates before collision (reverse operations)
float2 prevTexCoords = currentTexCoords + deltaTexCoords;

// get depth after and before collision for linear interpolation
float afterDepth  = currentDepthMapValue - currentLayerDepth;
float beforeDepth = texture(depthMap, prevTexCoords).r - currentLayerDepth + layerDepth;
 
// interpolation of texture coordinates
float weight = afterDepth / (afterDepth - beforeDepth);
float2 finalTexCoords = prevTexCoords * weight + currentTexCoords * (1.0 - weight);

return finalTexCoords;

浮雕映射

Image text
Image text
二分查找的操作存在性能开销，优化方法，视差闭塞贴图（pom）

链接

github