/// <summary>
/// Sets the default value for the specified field.
/// </summary>
/// <typeparam name="T">The field type.</typeparam>
/// <param name="particleField">The field.</param>
/// <param name="defaultValue">The new field default value.</param>
internal void SetDefaultValue <T>(ParticleField particleField, T defaultValue) where T : struct
{
if (particleDefaultValue == IntPtr.Zero)
{
throw new InvalidOperationException();
}
// Write new default value for the field
Utilities.Write(particleDefaultValue + particleField.Offset, ref defaultValue);
}
/// <summary>
/// Adds a new field to the particle system.
/// </summary>
/// <typeparam name="T">The field type.</typeparam>
/// <param name="fieldDesc">The field description.</param>
/// <returns>The field.</returns>
/// <exception cref="System.ArgumentException">Particle field size must be a multiple of 4;size</exception>
internal ParticleField AddField <T>(ParticleFieldDescription <T> fieldDesc) where T : struct
{
ParticleField existingField;
if (fields.TryGetValue(fieldDesc, out existingField))
{
return(existingField);
}
var size = Utilities.SizeOf <T>();
// Only accept 4-byte multiples.
if (size % 4 != 0)
{
throw new ArgumentException("Particle field size must be a multiple of 4", "size");
}
var newParticleSize = particleSize + size;
// Update default value
var newParticleDefaultValue = Utilities.AllocateMemory(newParticleSize);
if (particleDefaultValue != IntPtr.Zero)
{
Utilities.CopyMemory(newParticleDefaultValue, particleDefaultValue, particleSize);
Utilities.FreeMemory(particleDefaultValue);
}
particleDefaultValue = newParticleDefaultValue;
// Write default value for new field
var defaultValue = fieldDesc.DefaultValue;
Utilities.Write(newParticleDefaultValue + particleSize, ref defaultValue);
// Check if there is enough space to do the conversion in-place
if (particleData != IntPtr.Zero && particleCapacity * particleSize < newParticleSize * particleCount)
{
// Copy in-place, particles from back to front (so that there is no memory overlap)
// i.e.
// AAABBBCCCDDD gets copied that way:
// --------------D-
// -------------DD-
// ------------DDD-
// ----------C-DDD-
// ................
// AAA-BBB-CCC-DDD-
var particleSizeInDword = particleSize / 4;
unsafe
{
var particleEnd = (int *)(particleData + particleCount * particleSize);
var newParticleEnd = (int *)(particleData + particleCount * newParticleSize - size);
for (int i = particleCount - 1; i >= 0; --i)
{
// Copy one particle, from back to end (no overlap)
for (int j = 0; j < particleSizeInDword; ++j)
{
*--newParticleEnd = *--particleEnd;
}
// Leave space for the newly added field.
newParticleEnd -= size;
// Write default value for new field
Utilities.Write((IntPtr)newParticleEnd, ref defaultValue);
}
}
// Update capacity
particleCapacity = particleCapacity * particleSize / newParticleSize;
}
else if (particleCapacity > 0)
{
var newParticleData = Utilities.AllocateMemory(particleCapacity * newParticleSize);
// Copy previous data to the new buffer, interleaved with space for the new field
if (particleData != IntPtr.Zero)
{
var newParticleDataPtr = newParticleData;
var particleDataPtr = particleData;
for (int i = 0; i < particleCount; ++i)
{
// Copy particle values
Utilities.CopyMemory(newParticleDataPtr, particleDataPtr, particleSize);
// Write default value for new field
Utilities.Write(newParticleDataPtr + particleSize, ref defaultValue);
particleDataPtr += particleSize;
newParticleDataPtr += newParticleSize;
}
Utilities.FreeMemory(particleData);
}
particleData = newParticleData;
}
// Add the field
var field = new ParticleField {
Offset = particleSize, Size = size
};
fields.Add(fieldDesc, field);
// Update particle size
particleSize = newParticleSize;
return(field);
}
