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POTrying to pass struct with Vector4 array to cbuffer
 

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  1. POTrying to pass struct with Vector4 array to cbuffer
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    <p>I'm playing around with SlimDX (with DX10/11) a bit and I got some nice results so far, but I'm stuck on passing an array of Vector4s to the shaders.</p> <p>If I try the following struct:</p> <pre><code>[StructLayout(LayoutKind.Sequential)] public struct PerFrameBuffer { public Vector4 Position; public Matrix World; public Matrix View; public Matrix Projection; [MarshalAs( UnmanagedType.ByValArray, SizeConst=2)] public Vector4[] Lights; } </code></pre> <p>and try to store it in the following cbuffer:</p> <pre><code>cbuffer cPerFrame : register( b0 ) { float4 xPosition; matrix xWorld; matrix xView; matrix xProjection; float4 pointLights[2]; } </code></pre> <p>I don't get any errors, but the values in the matrices are broken.</p> <p>However when I declare my struct in c# as follows:</p> <pre><code>[StructLayout(LayoutKind.Sequential)] public struct PerFrameBuffer { public Vector4 Position; public Matrix World; public Matrix View; public Matrix Projection; public Vector4 Light1; public Vector4 Light2; } </code></pre> <p>Then everything works fine as expected.</p> <p>I don't really want to make 64 fields in the struct and fill them up like that (I could with reflection but still). How can I use an array to pass the Vector4's to my constantbuffer?</p> <p>If by any means this is a dumb idea and should be done in another way, please let me know. It's my first time programming directx and shader related stuff.</p> <p>To be complete:</p> <p>Declaration of the buffer in C#</p> <pre><code> cPerFrameBuffer = new SlimDX.Direct3D11.Buffer(device, new BufferDescription { Usage = ResourceUsage.Default, SizeInBytes = Marshal.SizeOf(typeof(PerFrameBuffer)), BindFlags = BindFlags.ConstantBuffer }); context.VertexShader.SetConstantBuffer(cPerFrameBuffer, 0); </code></pre> <p>How I'm updating the buffer:</p> <pre><code>var cb = new AbstractDXManager.PerFrameBuffer() { Position = new Vector4(camera.Position, 1.0f), Projection = Matrix.Transpose(camera.ProjectionMatrix), View = Matrix.Transpose(camera.ViewMatrix), World = Matrix.Transpose(Matrix.Identity), }; cb.Lights = new Vector4[2]; cb.Lights[0] = cb.Position; cb.Lights[1] = new Vector4(20, 20, 20, 1); var context = device.ImmediateContext; using (DataStream data = new DataStream(Marshal.SizeOf(typeof(PerFrameBuffer)), true, true)) { data.Write(cb); data.Position = 0; context.UpdateSubresource(new DataBox(0, 0, data), cPerFrameBuffer, 0); } </code></pre> <p>Thanks in advance</p>
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