kaminari - Developer IT

HLSL, Program pixel shader with different Texture2D downscaling algorithms

- by Kaminari

I'm trying to port some image interpolation algorithms into HLSL code, for now i got: float2 texSize; float scale; int method; sampler TextureSampler : register(s0); float4 PixelShader(float4 color : COLOR0, float2 texCoord : TEXCOORD0) : COLOR0 { float2 newTexSize = texSize * scale; float4 tex2; if(texCoord[0] * texSize[0] > newTexSize[0] || texCoord[1] * texSize[1] > newTexSize[1]) { tex2 = float4( 0, 0, 0, 0 ); } else { if (method == 0) { tex2 = tex2D(TextureSampler, float2(texCoord[0]/scale, texCoord[1]/scale)); } else { float2 step = float2(1/texSize[0], 1/texSize[1]); float4 px1 = tex2D(TextureSampler, float2(texCoord[0]/scale-step[0], texCoord[1]/scale-step[1])); float4 px2 = tex2D(TextureSampler, float2(texCoord[0]/scale , texCoord[1]/scale-step[1])); float4 px3 = tex2D(TextureSampler, float2(texCoord[0]/scale+step[0], texCoord[1]/scale-step[1])); float4 px4 = tex2D(TextureSampler, float2(texCoord[0]/scale-step[0], texCoord[1]/scale )); float4 px5 = tex2D(TextureSampler, float2(texCoord[0]/scale+step[0], texCoord[1]/scale )); float4 px6 = tex2D(TextureSampler, float2(texCoord[0]/scale-step[0], texCoord[1]/scale+step[1])); float4 px7 = tex2D(TextureSampler, float2(texCoord[0]/scale , texCoord[1]/scale+step[1])); float4 px8 = tex2D(TextureSampler, float2(texCoord[0]/scale+step[0], texCoord[1]/scale+step[1])); tex2 = (px1+px2+px3+px4+px5+px6+px7+px8)/8; tex2.a = 1; } } return tex2; } technique Resample { pass Pass1 { PixelShader = compile ps_2_0 PixelShader(); } } The problem is that programming pixel shader requires different approach because we don't have the control of current position, only the 'inner' part of actual loop through pixels. I've been googling for about whole day and found none open source library with scaling algoriths used in loop. Is there such library from wich i could port some methods? I found http://www.codeproject.com/KB/GDI-plus/imgresizoutperfgdiplus.aspx but I really don't understand His approach to the problem, and porting it will be a pain in the ... Wikipedia tells a matematic approach. So my question is: Where can I find easy-to-port graphic open source library wich includes simple scaling algorithms? Of course if such library even exists :)

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C#, XNA, How to select image minialization filter in 2D mode?

- by Kaminari

The problem is that I can't select minimalization filter for Texture2D scaling. There is MinFilter GraphicsDevice.SamplerStates[0].MinFilter But it's not working. When I try to assign some filter it just changes back to the Linear. Is there a way to implement my own filter or how to select one of the available?

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How to download file into string with progress callback?

- by Kaminari

I would like to use the WebClient (or there is another better option?) but there is a problem. I understand that opening up the stream takes some time and this can not be avoided. However, reading it takes a strangely much more amount of time compared to read it entirely immediately. Is there a best way to do this? I mean two ways, to string and to file. Progress is my own delegate and it's working good. FIFTH UPDATE: Finally, I managed to do it. In the meantime I checked out some solutions what made me realize that the problem lies elsewhere. I've tested custom WebResponse and WebRequest objects, library libCURL.NET and even Sockets. The difference in time was gzip compression. Compressed stream lenght was simply half the normal stream lenght and thus download time was less than 3 seconds with the browser. I put some code if someone will want to know how i solved this: (some headers are not needed) public static string DownloadString(string URL) { WebClient client = new WebClient(); client.Headers["User-Agent"] = "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1045 Safari/532.5"; client.Headers["Accept"] = "application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5"; client.Headers["Accept-Encoding"] = "gzip,deflate,sdch"; client.Headers["Accept-Charset"] = "ISO-8859-2,utf-8;q=0.7,*;q=0.3"; Stream inputStream = client.OpenRead(new Uri(URL)); MemoryStream memoryStream = new MemoryStream(); const int size = 32 * 4096; byte[] buffer = new byte[size]; if (client.ResponseHeaders["Content-Encoding"] == "gzip") { inputStream = new GZipStream(inputStream, CompressionMode.Decompress); } int count = 0; do { count = inputStream.Read(buffer, 0, size); if (count > 0) { memoryStream.Write(buffer, 0, count); } } while (count > 0); string result = Encoding.Default.GetString(memoryStream.ToArray()); memoryStream.Close(); inputStream.Close(); return result; } I think that asyncro functions will be almost the same. But i will simply use another thread to fire this function. I dont need percise progress indication.

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Using Custom Generic Collection faster with objects than List

- by Kaminari

I'm iterating through a List<> to find a matching element. The problem is that object has only 2 significant values, Name and Link (both strings), but has some other values which I don't want to compare. I'm thinking about using something like HashSet (which is exactly what I'm searching for -- fast) from .NET 3.5 but target framework has to be 2.0. There is something called Power Collections here: http://powercollections.codeplex.com/, should I use that? But maybe there is other way? If not, can you suggest me a suitable custom collection?

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C#, How to download file into string with progress callback?

- by Kaminari

I would like to use the WebClient (or there is another better option?) but there is a problem. I understand that opening up the stream takes some time and this can not be avoided. However, reading it takes a strangely much more amount of time compared to read it entirely immediately. Of course it's not working good because i'm not so familiar with streams. Is there a best way to do this? I mean two ways, to string and to file. Progress is my own delegate and it's working good. FIRST UPDATE: Ok, now i got something like this and it seems to work but still slow: System.Net.WebClient client = new System.Net.WebClient(); System.IO.Stream streamRemote = client.OpenRead(new Uri(URL)); if (savePath == null) { StreamReader reader = new StreamReader(streamRemote); int iByteSize = 0; byte[] byteBuffer = new byte[iSize]; char[] charBuffer = new char[iSize]; StringBuilder sb = new StringBuilder(); while ((iByteSize = reader.Read(charBuffer, 0, iSize)) > 0) { sb.Append(charBuffer, 0, iByteSize); iRunningByteTotal += iByteSize; float dIndex = (float)(iRunningByteTotal); float dTotal = (float)byteBuffer.Length; float dProgressPercentage = (dIndex / dTotal); float iProgressPercentage = (dProgressPercentage * 100); if (Progress != null) Progress(iProgressPercentage); } result = sb.ToString(); } Im wondering about DownloadStringAsync method?

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C#, Using Custom Generic Collection faster with objects than List

- by Kaminari

Hello, I'm using for now List< to iterate through some object collection and find matching element, The problem is that object has only 2 significant values Name and Link (strings) but has some other values wich I dont want to compare. I'm thinkig about using something like HashSet (wich is exactly what I'm searching for - fast) from .NET 3.5 but target framework has to be 2.0. There is something called Power Collections here: http://powercollections.codeplex.com/ But maybe there is other way? If not, can you suggest me a suitable custom collection?

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Speed of interpolation algorithms, C# and C++ working together.

- by Kaminari

Hello. I need fast implementation of popular interpolation algorithms. I figured it out that C# in such simple algorithms will be much slower than C++ so i think of writing some native code and using it in my C# GUI. First of all i run some tests and few operations on 1024x1024x3 matrix took 32ms in C# and 4ms in C++ and that's what i basicly need. Interpolation however is not a good word because i need them only for downscaling. But the question is: Will it be faster than C# methods in Drawing2D Image outputImage = new Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb); Graphics grPhoto = Graphics.FromImage(outputImage); grPhoto.InterpolationMode = InterpolationMode.*; //all of them grPhoto.DrawImage(bmp, new Rectangle(0, 0, destWidth, destHeight), Rectangle(0, 0, sourceWidth, sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); Some of these method run in 20ms and some in 80. Is there a way to do it faster?

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