//-----------------------------------------------------------------------------// Name: Sobel.fx// // Description: // //-----------------------------------------------------------------------------//-----------------------------------------------------------------------------// Effect File Variables//-----------------------------------------------------------------------------float4x4 worldViewProj : WorldViewProjection; // This matrix will be loaded by the applicationtexture testTexture; // This texture will be loaded by the applicationconst float Brightness = 1.0f;sampler Sampler = sampler_state
...{
Texture = (testTexture); MipFilter = LINEAR; MinFilter = LINEAR; MagFilter = LINEAR;
};//-----------------------------------------------------------------------------// Vertex Definitions//-----------------------------------------------------------------------------// Our sample application will send vertices // down the pipeline laid-out like this...struct VS_INPUT...{ float3 position : POSITION; float2 texture0 : TEXCOORD0;};// Once the vertex shader is finished, it will // pass the vertices on to the pixel shader like this...struct VS_OUTPUT...{ float4 hposition : POSITION; float2 texture0 : TEXCOORD0; float4 color : COLOR0;};// And finally, the pixel shader will send a single // color value to the frame buffer like this...struct PS_OUTPUT...{ float4 color : COLOR;};//-----------------------------------------------------------------------------// Simple Vertex Shader//-----------------------------------------------------------------------------VS_OUTPUT myvs( VS_INPUT IN )...{ VS_OUTPUT OUT; OUT.hposition = mul( worldViewProj, float4(IN.position, 1) ); OUT.color = float4( 1.0, 1.0, 1.0, 1.0 ); // Pass white as a default color //OUT.color = float4( 0.0, 1.0, 0.0, 1.0 ); // Pass green to test vertex shader OUT.texture0 = IN.texture0; return OUT;}//-----------------------------------------------------------------------------// Simple Pixel Shader//-----------------------------------------------------------------------------PS_OUTPUT myps( VS_OUTPUT IN )...{ PS_OUTPUT OUT;// OUT.color = tex2D( Sampler, IN.texture0 ) * IN.color; // If you uncomment the next line, the color passed to us by our // vertex shader and the selected texture sampler will be ignored // completely and all output to the frame buffer will be blue regardless. //OUT.color = float4( 0.0, 0.0, 1.0, 1.0); const int NUM = 9; const float threshold = 0.09; const float texW = 140.f; const float texH = 140.f;//round texels
const float2 c[NUM] =...{ float2( -1/texW,1/texH), float2( 0.00, 1/texH), float2( 1/texW, 1/texH), float2( -1/texW,0.00), float2( 0.00, 0.00), float2( 1/texW, 1/texH ), float2(-1/texW, -1/texH), float2( 0.00 , -1/texH), float2( 1/texW, -1/texH),
}; float3 col[NUM]; int i;//it stores the samples of texture to col array. for (i=0; i < NUM; i++) ...{ col[i] = tex2D(Sampler, IN.texture0 + c[i]); }//now we start to compute the luminance with dot product and store them in lum array.//lum = 0.30r + 0.59g + 0.11b; float3 rgb2lum = float3( 0.30, 0.59, 0.11); float lum[NUM]; for (i = 0; i < NUM; i++) ...{ lum[i] = dot(col[i].xyz, rgb2lum); }//Sobel filter computes new value at the central position by sum the weighted neighbors. float x = lum[2]+ lum[8]+2*lum[5]-lum[0]-2*lum[3]-lum[6]; float y = lum[6]+2*lum[7]+ lum[8]-lum[0]-2*lum[1]-lum[2];//show the points which values are over the threshold and hide others. Final result is the //product of col[5] and edge detector value. Brightness adjusts the brightness of the image. float edge =(x*x + y*y < threshold)? 1.0:0.0;//final output OUT.color.xyz = Brightness * col[5].xyz * edge; OUT.color.w = 1.0; return OUT;}//-----------------------------------------------------------------------------// Simple Effect (1 technique with 1 pass)//-----------------------------------------------------------------------------technique Technique0...{ pass Pass0 ...{ Lighting = FALSE; Sampler[0] = (Sampler); // Needed by pixel shader VertexShader = compile vs_2_0 myvs(); PixelShader = compile ps_2_0 myps(); }}效果图：
参考文档：
http://homepages.inf.ed.ac.uk/rbf/HIPR2/sobel.htm