|
public static CreateVertexColor ( byte r, byte g, byte b, byte a ) : |
||
| r | byte | |
| g | byte | |
| b | byte | |
| a | byte | |
| return | ||
/// <summary>
/// Multiplies a range of alpha values with a certain factor.
/// </summary>
public void ScaleAlphaBy(float factor, int index, int numVertices)
{
if (index < 0 || index >= _numVertices)
{
throw new IndexOutOfRangeException("Invalid vertex index");
}
if (factor == 1.0f)
{
return;
}
int minAlpha = _premultipliedAlpha ? (int)(MIN_ALPHA * 255.0f) : 0;
for (int i = index; i < index + numVertices; ++i)
{
VertexColor vertexColor = _vertexColors[i];
byte newAlpha = Convert.ToByte(NumberUtil.Clamp(vertexColor.A * factor, minAlpha, 255));
if (_premultipliedAlpha)
{
vertexColor = VertexColorHelper.UnmultiplyAlpha(vertexColor);
vertexColor.A = newAlpha;
_vertexColors[i] = VertexColorHelper.PremultiplyAlpha(vertexColor);
}
else
{
_vertexColors[i] = VertexColorHelper.CreateVertexColor(vertexColor.R, vertexColor.G, vertexColor.B, newAlpha);
}
}
}
/// <summary>
/// Updates the color of a vertex. The method always expects non-premultiplied alpha values.
/// </summary>
public void SetColor(uint color, float alpha, int atIndex)
{
if (atIndex < 0 || atIndex >= _numVertices)
{
throw new IndexOutOfRangeException("Invalid vertex index");
}
alpha = NumberUtil.Clamp(alpha, _premultipliedAlpha ? MIN_ALPHA : 0.0f, 1.0f);
VertexColor vertexColor = VertexColorHelper.CreateVertexColor(color, alpha);
_vertexColors[atIndex] = _premultipliedAlpha ? VertexColorHelper.PremultiplyAlpha(vertexColor) : vertexColor;
}