/// <summary>
/// Registers are effectively shared between outputs of the previous stage
/// and inputs of the next stage, so we don't need to do any mapping. We only
/// need to keep track of the interpolation mode, and system value semantic,
/// of the inputs.
/// <seealso cref="http://msdn.microsoft.com/en-us/library/windows/desktop/bb509650(v=vs.85).aspx"/>
///
/// TODO: Add some sort of runtime validation that signatures match. Direct3D
/// does this, but only when debugging.
/// </summary>
public static ShaderOutputInputBindings FromShaderSignatures(
OutputSignatureChunk outputSignature,
BytecodeContainer inputShader)
{
var inputRegisterDeclarations = inputShader.Shader.DeclarationTokens
.OfType<PixelShaderInputRegisterDeclarationToken>()
.ToList();
// Only create a binding if the value is actually used in the next shader.
// We can gather this information from the declaration tokens. If there is
// no declaration token for an item, then it isn't used.
var bindings = new List<ShaderOutputInputBinding>();
foreach (var inputParameter in inputShader.InputSignature.Parameters)
{
// Get register declaration for this parameter. If there is no register
// declaration, then it isn't used, and we can move on.
var inputRegisterDeclaration = FindInputRegisterDeclaration(
inputRegisterDeclarations, inputParameter);
if (inputRegisterDeclaration == null)
continue;
bindings.Add(new ShaderOutputInputBinding
{
Register = (int) inputParameter.Register,
ComponentMask = inputParameter.Mask,
InterpolationMode = inputRegisterDeclaration.InterpolationMode,
SystemValueType = inputParameter.SystemValueType
});
}
return new ShaderOutputInputBindings
{
Bindings = bindings.ToArray()
};
}
internal IEnumerable<FragmentQuad> Execute(
IEnumerable<InputAssemblerPrimitiveOutput> inputs,
PrimitiveTopology primitiveTopology,
OutputSignatureChunk previousStageOutputSignature,
BytecodeContainer pixelShader,
int multiSampleCount)
{
// TODO: Allow selection of different viewport.
var viewport = _viewports[0];
var outputInputBindings = ShaderOutputInputBindings.FromShaderSignatures(
previousStageOutputSignature, pixelShader);
var rasterizer = PrimitiveRasterizerFactory.CreateRasterizer(
primitiveTopology, State.Description, multiSampleCount,
outputInputBindings, ref viewport, FragmentFilter);
foreach (var primitive in inputs)
{
// Frustum culling.
if (ViewportCuller.ShouldCullTriangle(primitive.Vertices))
continue;
// TODO: Clipping.
// http://simonstechblog.blogspot.tw/2012/04/software-rasterizer-part-2.html#softwareRasterizerDemo
// Perspective divide.
for (int i = 0; i < primitive.Vertices.Length; i++)
PerspectiveDivide(ref primitive.Vertices[i].Position);
// Backface culling.
if (State.Description.CullMode != CullMode.None && rasterizer.ShouldCull(primitive.Vertices))
continue;
// Transform from clip space to screen space.
for (int i = 0; i < primitive.Vertices.Length; i++)
viewport.MapClipSpaceToScreenSpace(ref primitive.Vertices[i].Position);
// Rasterize.
foreach (var fragmentQuad in rasterizer.Rasterize(primitive))
yield return fragmentQuad;
}
}
public ShaderBase(Device device, byte[] shaderBytecode)
: base(device)
{
_shaderBytecode = BytecodeContainer.Parse(shaderBytecode);
}
