/// <summary>
/// Sets a callback to be used whenever texture data is requested by a shader.
/// The callback will be passed the u, v and w coordinates.
/// </summary>
/// <typeparam name="TColor">Color type, i.e. Vector4.</typeparam>
/// <param name="name">Name of the resource.</param>
/// <param name="callback">The callback will be executed once for each texture fetch,
/// and will be passed the u, v and w coordinates.</param>
public void SetResource <TColor>(string name, ResourceCallback <TColor> callback)
where TColor : struct
{
// Validate.
var resourceIndex = _resourceBindings.FindIndex(x => x.Name == name);
if (resourceIndex == -1)
{
throw new ArgumentException("Could not find resource named '" + name + "'", "name");
}
if (StructUtility.SizeOf <TColor>() != Number4.SizeInBytes)
{
throw new ArgumentException(string.Format("Expected color struct to be {0} bytes, but was {1}'",
Number4.SizeInBytes, StructUtility.SizeOf <TColor>()));
}
// Set resource into virtual machine. We also set a default sampler state.
var registerIndex = new RegisterIndex((ushort)resourceIndex);
_virtualMachine.SetSampler(registerIndex, new SamplerState());
_virtualMachine.SetTexture(registerIndex,
new FakeTexture((u, v, w, i) =>
{
var bytes = StructUtility.ToBytes(callback(u, v, w, i));
return(Number4.FromByteArray(bytes, 0));
}));
}
/// <summary>
/// Executes the shader. First, the input value is set into the input registers.
/// Then the shader is executed. Finally, the output value is extracted from
/// the output registers.
/// </summary>
/// <typeparam name="TInput">Input type. This must be a struct whose byte count
/// exactly matches the shader input.</typeparam>
/// <typeparam name="TOutput">Output type. This must be a struct whose byte count
/// exactly matches the shader output.</typeparam>
/// <param name="input">Input to the shader.</param>
/// <returns>Shader output.</returns>
public TOutput Execute <TInput, TOutput>(TInput input)
where TInput : struct
where TOutput : struct
{
// Validate.
if (StructUtility.SizeOf <TInput>() != _inputSignatureSize)
{
throw new ArgumentException(string.Format("Expected input struct to be {0} bytes, but was {1}'",
_inputSignatureSize, StructUtility.SizeOf <TInput>()));
}
// Set input parameters into virtual machine registers. Use knowledge of byte size of each
// parameter to extract the right values from the input.
var inputBytes = StructUtility.ToBytes(input);
var inputByteIndex = 0;
for (int i = 0; i < _inputSignature.Parameters.Count; i++)
{
var inputParameter = _inputSignature.Parameters[i];
var registerBytes = new byte[Number4.SizeInBytes];
Array.Copy(inputBytes, inputByteIndex, registerBytes, 0, inputParameter.ByteCount);
_virtualMachine.SetInputRegisterValue(ContextIndex, 0, i, Number4.FromByteArray(registerBytes, 0));
inputByteIndex += inputParameter.ByteCount;
}
// Execute shader.
_virtualMachine.Execute();
// Get output parameters from virtual machine registers.
var outputBytes = new byte[_outputSignatureSize];
var outputByteIndex = 0;
for (var i = 0; i < _outputSignature.Parameters.Count; i++)
{
var outputParameter = _outputSignature.Parameters[i];
var registerBytes = _virtualMachine.GetOutputRegisterValue(ContextIndex, i).RawBytes;
Array.Copy(registerBytes, 0, outputBytes, outputByteIndex, outputParameter.ByteCount);
outputByteIndex += outputParameter.ByteCount;
}
return(StructUtility.FromBytes <TOutput>(outputBytes));
}
