/// <summary>
/// Adds a varying particle parameter.
/// </summary>
/// <typeparam name="T">The type of the parameter value.</typeparam>
/// <param name="name">The name of the parameter (e.g. "Color", "Position", etc.).</param>
/// <returns>The existing or newly created particle parameter.</returns>
/// <remarks>
/// If the collection does not contain a particle parameter with the given
/// <paramref name="name"/>, a new varying particle parameter is added. If the collection
/// contains a varying particle parameter with the given <paramref name="name"/>, then only the
/// existing particle parameter is returned. If the collection contains a uniform particle
/// parameter with the given <paramref name="name"/>, then the existing particle parameter is
/// removed and replaced by a new varying particle parameter.
/// </remarks>
/// <exception cref="ArgumentNullException">
/// <paramref name="name"/> is <see langword="null"/>.
/// </exception>
/// <exception cref="ArgumentException">
/// <paramref name="name"/> is empty.
/// </exception>
/// <exception cref="ParticleSystemException">
/// A particle parameter with the given name was found but the parameter type cannot be cast to
/// type <typeparamref name="T"/>.
/// </exception>
public IParticleParameter <T> AddVarying <T>(string name)
{
if (name == null)
{
throw new ArgumentNullException("name");
}
if (name.Length == 0)
{
throw new ArgumentException("The particle parameter name must not be empty.", "name");
}
IParticleParameter <T> parameter = Get <T>(name, true);
T defaultValue = default(T);
if (parameter is UniformParticleParameter <T> )
{
// Remove uniform parameter, but keep default value.
defaultValue = parameter.DefaultValue;
_collection.Remove(name);
}
else if (parameter != null)
{
return(parameter);
}
parameter = new VaryingParticleParameter <T>(name, ParticleSystem.MaxNumberOfParticles);
parameter.DefaultValue = defaultValue;
_collection.Add(parameter);
OnChanged(EventArgs.Empty);
return(parameter);
}
