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DX11 Getting bitmap from multisampled backbuffer

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Hi Everyone,


In my desktop application (using SlimDX & DX11 ) I need to make a snapshot of a rendered window. I use the following code to save the bitmap of the current back buffer:

            var context = device.ImmediateContext;            
            var srcTex = renderTarget.Resource as Texture2D;
            var desc = srcTex.Description;
            desc.BindFlags = BindFlags.None;
            desc.Usage = ResourceUsage.Staging;
            desc.CpuAccessFlags = CpuAccessFlags.Read;
            desc.SampleDescription = new SampleDescription(1, 0);
            Texture2D staging = new Texture2D(device, desc);
            context.CopyResource(srcTex, staging);
            Texture2D.ToFile(context, staging, ImageFileFormat.Png, "c:/Temp/Screenshot.png");

This code works fine, if my renderTarget is not multisampled. If the renderTarget is multisampled ( as needed for anti-aliasing) I got blank image. Does anybody know a way to get a bitmap snapshot from a multisampled render target?





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Thank you very much for the quick response. It solves the problem completely. Just for people who might be encounter the same problem, my code to get a bitmap from current back-buffer looks as following:

        public Bitmap GetBitmap() {
            var ctx = device.ImmediateContext;
            var srcTex = renderTarget.Resource as Texture2D;
            var desc = srcTex.Description;
            desc.BindFlags = BindFlags.None;
            desc.Usage = ResourceUsage.Staging;
            desc.CpuAccessFlags = CpuAccessFlags.Read;
            desc.SampleDescription = new SampleDescription(1, 0);
            Texture2D staging = new Texture2D(device, desc);

            desc.Usage = ResourceUsage.Default;
            desc.CpuAccessFlags = CpuAccessFlags.None;
            Texture2D resolved = new Texture2D(device, desc);

            ctx.ResolveSubresource(srcTex, 0, resolved, 0, desc.Format);
            ctx.CopyResource(resolved, staging);

            using (Surface surface = staging.AsSurface()) {
                var rect = surface.Map(SlimDX.DXGI.MapFlags.Read);
                Bitmap bm = new Bitmap(desc.Width, desc.Height,
                            rect.Pitch, PixelFormat.Format32bppArgb, rect.Data.DataPointer);
                return bm;
Edited by jamesxli

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