/// <summary>
/// Creates a transfer function from RGB and alpha cubic splines.
/// </summary>
/// <param name="tcp">Transfer control points to use.</param>
/// <returns>An array of RGBA colors corresponding to each isovalue 0-255.</returns>
public static Color[] CreateTransferFunction(TransferControlPoints tcp)
{
Debug.Assert(tcp.rgbPoints.Count == tcp.rgbIsoValues.Count);
Debug.Assert(tcp.alphaPoints.Count == tcp.alphaIsoValues.Count);
Debug.Assert(tcp.rgbIsoValues[0] == 0 && tcp.rgbIsoValues[tcp.rgbIsoValues.Count - 1] == 255,
"The first and last isovalues must be 0 and 255, respectively.");
Debug.Assert(tcp.alphaIsoValues[0] == 0 && tcp.alphaIsoValues[tcp.alphaIsoValues.Count - 1] == 255,
"The first and last isovalues must be 0 and 255, respectively.");
// Calculate the cubic splines for the RGB and alpha values.
CubicSpline <Cubic3> rgbSpline = new CubicSpline <Cubic3>();
CubicSpline <Cubic1> alphaSpline = new CubicSpline <Cubic1>();
rgbSpline.Calculate(tcp.rgbPoints);
alphaSpline.Calculate(tcp.alphaPoints);
// Create the transfer function from the two splines.
Color[] transferFunc = new Color[256];
// ...RGB portion.
int index = 0;
for (int i = 0; i < rgbSpline.Count; ++i)
{
int interval = tcp.rgbIsoValues[i + 1] - tcp.rgbIsoValues[i];
Debug.Assert(interval > 0, "Isovalues must be incremental by at least 1/increment.");
// Fill in the color at the isovalues covered by the current spline segment.
for (int j = 0; j < interval; ++j)
{
float position = j / (float)interval;
transferFunc[index++] = rgbSpline.GetPointOnSpline(i, position).ToColor();
}
}
transferFunc[index] = rgbSpline.GetPointOnSpline(rgbSpline.Count - 1, 1f).ToColor();
// ...alpha portion.
index = 0;
for (int i = 0; i < alphaSpline.Count; ++i)
{
int interval = tcp.alphaIsoValues[i + 1] - tcp.alphaIsoValues[i];
Debug.Assert(interval > 0, "Isovalues must be incremental by at least 1/increment.");
// Fill in the alpha at the isovalues covered by the current spline segment.
for (int j = 0; j < interval; ++j)
{
float position = j / (float)interval;
transferFunc[index++].A = alphaSpline.GetPointOnSpline(i, position).ToByte();
}
}
transferFunc[index].A = alphaSpline.GetPointOnSpline(alphaSpline.Count - 1, 1f).ToByte();
return(transferFunc);
}
/// <summary>
/// Creates a transfer function from RGB and alpha cubic splines.
/// </summary>
/// <param name="tcp">Transfer control points to use.</param>
/// <returns>An array of RGBA colors corresponding to each isovalue 0-255.</returns>
public static Color[] CreateTransferFunction(TransferControlPoints tcp)
{
Debug.Assert(tcp.rgbPoints.Count == tcp.rgbIsoValues.Count);
Debug.Assert(tcp.alphaPoints.Count == tcp.alphaIsoValues.Count);
Debug.Assert(tcp.rgbIsoValues[0] == 0 && tcp.rgbIsoValues[tcp.rgbIsoValues.Count - 1] == 255,
"The first and last isovalues must be 0 and 255, respectively.");
Debug.Assert(tcp.alphaIsoValues[0] == 0 && tcp.alphaIsoValues[tcp.alphaIsoValues.Count - 1] == 255,
"The first and last isovalues must be 0 and 255, respectively.");
// Calculate the cubic splines for the RGB and alpha values.
CubicSpline<Cubic3> rgbSpline = new CubicSpline<Cubic3>();
CubicSpline<Cubic1> alphaSpline = new CubicSpline<Cubic1>();
rgbSpline.Calculate(tcp.rgbPoints);
alphaSpline.Calculate(tcp.alphaPoints);
// Create the transfer function from the two splines.
Color[] transferFunc = new Color[256];
// ...RGB portion.
int index = 0;
for (int i = 0; i < rgbSpline.Count; ++i)
{
int interval = tcp.rgbIsoValues[i + 1] - tcp.rgbIsoValues[i];
Debug.Assert(interval > 0, "Isovalues must be incremental by at least 1/increment.");
// Fill in the color at the isovalues covered by the current spline segment.
for (int j = 0; j < interval; ++j)
{
float position = j / (float)interval;
transferFunc[index++] = rgbSpline.GetPointOnSpline(i, position).ToColor();
}
}
transferFunc[index] = rgbSpline.GetPointOnSpline(rgbSpline.Count - 1, 1f).ToColor();
// ...alpha portion.
index = 0;
for (int i = 0; i < alphaSpline.Count; ++i)
{
int interval = tcp.alphaIsoValues[i + 1] - tcp.alphaIsoValues[i];
Debug.Assert(interval > 0, "Isovalues must be incremental by at least 1/increment.");
// Fill in the alpha at the isovalues covered by the current spline segment.
for (int j = 0; j < interval; ++j)
{
float position = j / (float)interval;
transferFunc[index++].A = alphaSpline.GetPointOnSpline(i, position).ToByte();
}
}
transferFunc[index].A = alphaSpline.GetPointOnSpline(alphaSpline.Count - 1, 1f).ToByte();
return transferFunc;
}
