private Number4[] CreatePixelShaderInput(ref BarycentricCoordinates coordinates)
{
float w = InterpolationUtility.PrecalculateW(
coordinates.Alpha, coordinates.Beta, coordinates.Gamma,
_p0.W, _p1.W, _p2.W);
var v0Data = _primitive.Vertices[0].OutputData;
var v1Data = _primitive.Vertices[1].OutputData;
var v2Data = _primitive.Vertices[2].OutputData;
// Calculate interpolated attribute values for this fragment.
// TODO: Optimize this.
var result = new Number4[_primitive.Vertices[0].OutputData.Length];
foreach (var outputInputBinding in OutputInputBindings.Bindings)
{
var v0Value = v0Data[outputInputBinding.Register];
var v1Value = v1Data[outputInputBinding.Register];
var v2Value = v2Data[outputInputBinding.Register];
if (outputInputBinding.SystemValueType != Name.Undefined)
{
throw new NotImplementedException();
}
// Create input values. Normally, this will require interpolation
// of the vertex attributes.
Number4 inputValue;
switch (outputInputBinding.InterpolationMode)
{
case InterpolationMode.Constant:
inputValue = v0Value;
break;
case InterpolationMode.Linear:
inputValue = InterpolationUtility.Perspective(
coordinates.Alpha, coordinates.Beta, coordinates.Gamma,
ref v0Value, ref v1Value, ref v2Value,
_p0.W, _p1.W, _p2.W, w);
break;
case InterpolationMode.LinearNoPerspective:
inputValue = InterpolationUtility.Linear(
coordinates.Alpha, coordinates.Beta, coordinates.Gamma,
ref v0Value, ref v1Value, ref v2Value);
break;
default:
throw new InvalidOperationException("Unrecognised interpolation mode: " + outputInputBinding.InterpolationMode);
}
// Apply component mask so that we don't overwrite other values in this register.
result[outputInputBinding.Register].WriteMaskedValue(
inputValue, outputInputBinding.ComponentMask);
}
return(result);
}
private bool IsSampleInsideTriangle(ref BarycentricCoordinates coordinates, out float depth)
{
// TODO: Use fill convention.
// If any of these tests fails, the current pixel is not inside the triangle.
if (coordinates.IsOutsideTriangle)
{
depth = 0;
return(false);
}
// Calculate depth.
depth = InterpolationUtility.Linear(coordinates.Alpha, coordinates.Beta, coordinates.Gamma, _p0.Z, _p1.Z, _p2.Z);
//// Clip to near and far planes.
//if (depth < 0 || depth > 1)
// return false;
//// Clip to 0 < w.
//// TODO: Is this right?
//// TODO: We do the same thing later on for attribute interpolations, can it be optimised?
//var w = InterpolationUtility.Linear(coordinates.Alpha, coordinates.Beta, coordinates.Gamma, _p0.W, _p1.W, _p2.W);
//if (w <= 0)
// return false;
// The exact value to compare against depends on fill mode - if we're rendering wireframe,
// then check whether sample position is within the "wireframe threshold" (i.e. 1 pixel) of an edge.
switch (RasterizerState.FillMode)
{
case FillMode.Solid:
return(true);
case FillMode.Wireframe:
// TODO: This threshold thing is not correct.
const float wireframeThreshold = 0.1f;
return(coordinates.Alpha < wireframeThreshold || coordinates.Beta < wireframeThreshold || coordinates.Gamma < wireframeThreshold);
default:
throw new NotSupportedException();
}
}