轉載請注明出處：http://blog.csdn.net/tianhai110

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Hatching（素描）渲染——通過光照的強弱，用不同深淺的紋理，實現一種類似素描效果。

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Hatching的實現原理是：通過N.L計算點受光的強弱，將該值分成不同的段，不同的光照強度對應不同深淺的素描貼圖

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算法對應的VS如下：

VS_OUTPUT vs_main( VS_INPUT Input ) {VS_OUTPUT Output;Output.Position = mul( Input.Position, matViewProjection );Output.Texcoord = Input.Texcoord;float3 normalW = mul( Input.Normal, matView);float diffuse = min( 1, max(0, dot( vecLightDir, normalW)));//把diffuse平方兩次是為了，把亮度降低點，把整體亮度向暗方向偏移，以得到更好的視覺效果。diffuse = diffuse * diffuse;diffuse = diffuse * diffuse;float factor = diffuse * 6.0; // 通過兩個weight,來記錄權值，減少傳入ps的變量數。float3 weight0 = 0.0;float3 weight1 = 0.0;// 不同光照強度，對應不同的權值，及不同的紋理貼圖if( factor > 5.0){weight0.x = 1;}else if( factor > 4.0){weight0.x = factor - 4.0;weight0.y = 1.0 - weight0.x;}else if( factor > 3.0){weight0.y = factor - 3.0;weight0.z = 1.0 - weight0.y;}else if( factor > 2.0){weight0.z = factor - 2.0;weight1.x = 1.0 - weight0.z;}else if( factor > 1.0){weight1.x = factor - 1.0;weight1.y = 1.0 - weight1.x; }else if( factor > 0.0){weight1.y = factor;weight1.z = 1.0 - weight1.y;}Output.Weight0 = weight0;Output.Weight1 = weight1;return( Output );}

PS為：

struct PS_INPUT {float2 tex : TEXCOORD0;float3 weight0 : TEXCOORD1;float3 weight1 : TEXCOORD2; };float4 ps_main( PS_INPUT input) : COLOR0 { float4 hattch0 = tex2D(hattch0Map, input.tex)*input.weight0.x;float4 hattch1 = tex2D(hattch1Map, input.tex)*input.weight0.y;float4 hattch2 = tex2D(hattch2Map, input.tex)*input.weight0.z;float4 hattch3 = tex2D(hattch3Map, input.tex)*input.weight1.x;float4 hattch4 = tex2D(hattch4Map, input.tex)*input.weight1.y;float4 hattch5 = tex2D(hattch5Map, input.tex)*input.weight1.z;return hattch0 + hattch1 + hattch2+ hattch3 + hattch4 + hattch5;}

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最終效果

總結

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