Vertical Blur in Microsoft Word

Generator Data Matrix ECC200 in Microsoft Word Vertical Blur

Now that you have the horizontal blur, it s quite easy to create the vertical blur. Instead of adding the value from the positions array to the horizontal texture coordinate, you should add it to the vertical texture coordinate, selecting the pixels on the same column as the pixel of interest:

//------- PP Technique: VerBlur -------PPPixelToFrame VerBlurPS(PPVertexToPixel PSIn) : COLOR0 { PPPixelToFrame Output = (PPPixelToFrame)0; for (int i = 0; i < 8; i++) { float4 samplePos = tex2D(textureSampler, PSIn.TexCoord + float2(0, positions[i])*xBlurSize); samplePos *= weights[i]; float4 sampleNeg = tex2D(textureSampler, PSIn.TexCoord - float2(0, positions[i])*xBlurSize); sampleNeg *= weights[i]; Output.Color += samplePos + sampleNeg; } return Output; } technique VerBlur { pass Pass0 { VertexShader = compile vs_1_1 PassThroughVertexShader(); PixelShader = compile ps_2_0 VerBlurPS(); } } You will get a nicely blurred image by combining the horizontal and vertical blurs: List<string> ppEffectsList = new List<string>(); ppEffectsList.Add("HorBlur"); ppEffectsList.Add("VerBlur"); postProcessor.Parameters["xBlurSize"].SetValue(0.5f); postProcessor.PostProcess(ppEffectsList);

As explained in the introduction of this recipe, you can obtain a glow effect by starting from the blended image and blending in the original image a bit. This way, the original contours will be sharpened. This requires you to have the blurred image present in the back buffer, so during a second pass, you can blend in the original image. Therefore, you will define a new technique, a glow, that has as a first pass the vertical blur and as a second pass a blend-in pass:

technique VerBlurAndGlow { pass Pass0 { VertexShader = compile vs_1_1 PassThroughVertexShader(); PixelShader = compile ps_2_0 VerBlurPS(); } pass Pass1 { AlphaBlendEnable = true; SrcBlend = SrcAlpha; DestBlend = InvSrcAlpha; PixelShader = compile ps_2_0 BlendInPS(); } } The second pass is new. You can see three render states are changed at the beginning of the pass: you enable alpha blending and set the alpha function. You ll learn more about this alpha function in a few minutes. The effect will start with the first pass, so the blurred image will be present in the back buffer. Next, the second pass will be started, allowing you to blend in the original image over the image in the back buffer. This is the pixel shader for the second pass: //------- PP Technique: VerBlurAndGlow -------PPPixelToFrame BlendInPS(PPVertexToPixel PSIn) : COLOR0 { PPPixelToFrame Output = (PPPixelToFrame)0; float4 finalColor = tex2D(originalSampler, PSIn.TexCoord); finalColor.a = 0.3f; Output.Color = finalColor; return Output; } Here, you sample the color of the pixel of the original image and adjust its alpha (transparency) value. When blending in XNA, the final color is found using this rule: finalColor=sourceBlend*sourceColor+destBlend*destColor In the technique definition, you ve set sourceBlend to SourceAlpha. This means sourceBlend equals the alpha value of the color you want to blend in, which is 0.3f, as you ve defined in the previous code. Furthermore, you ve set destBlend to InvSourceAlpha, meaning 1 SourceAlpha. So, destBlend will be 1 0.3f = 0.7f. In summary, 70 percent of the final color will be taken from the color already present in the back buffer (in which the blurred image of the first pass is stored). The remaining 30 percent will be taken from the new color you want to write to the back buffer, which, in this case, is sampled from the original image. You haven t yet defined the originalSampler. Add it to the top of your effect file:

texture originalImage; sampler originalSampler = sampler_state { texture = <originalImage>; magfilter = LINEAR; minfilter = LINEAR; mipfilter = LINEAR; }; In your XNA project, you should store the original image that you hijacked from the back buffer into this originalImage variable. Luckily, using the framework created in the previous chapter, you can do this easily during the first effect: if (currentTechnique == 0) { device.ResolveBackBuffer(resolveTexture, 0); textureRenderedTo = resolveTexture; ppEffect.Parameters["originalImage"].SetValue(textureRenderedTo); } The last line sends the original image to your HLSL effect. Now that all your effects are ready, this code will first blur your image vertically. Afterward, this result will first be horizontally blurred by the first pass of the VerBlurAndGlow effect. After the first pass, the blurred image will remain inside the frame buffer, allowing you to blend in the original image! List<string> ppEffectsList = new List<string>(); ppEffectsList.Add("HorBlur"); ppEffectsList.Add("VerBlurAndGlow"); postProcessor.Parameters["xBlurSize"].SetValue(0.5f); postProcessor.PostProcess(ppEffectsList);