int ComponentSize(glTFLoader.Schema.Accessor.ComponentTypeEnum componentType)
{
switch (componentType)
{
case glTFLoader.Schema.Accessor.ComponentTypeEnum.BYTE:
return(sizeof(sbyte));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.SHORT:
return(sizeof(short));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_BYTE:
return(sizeof(byte));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_SHORT:
return(sizeof(ushort));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_INT:
return(sizeof(uint));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.FLOAT:
return(sizeof(float));
default:
return(sizeof(byte));
}
}
private int GetTypeSize(glTFLoader.Schema.Accessor.ComponentTypeEnum componentType)
{
switch (componentType)
{
case glTFLoader.Schema.Accessor.ComponentTypeEnum.BYTE:
return(sizeof(sbyte));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_BYTE:
return(sizeof(byte));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.SHORT:
return(sizeof(short));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_SHORT:
return(sizeof(ushort));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_INT:
return(sizeof(uint));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.FLOAT:
return(sizeof(float));
default:
throw new InvalidOperationException($"Invalid component type ({componentType})");
}
}
private object GetElement(glTFLoader.Schema.Accessor.ComponentTypeEnum componentType, byte[] buffer, int index)
{
switch (componentType)
{
case glTFLoader.Schema.Accessor.ComponentTypeEnum.BYTE:
return((sbyte)buffer[index]);
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_BYTE:
return(buffer[index]);
case glTFLoader.Schema.Accessor.ComponentTypeEnum.SHORT:
return(BitConverter.ToInt16(buffer, index));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_SHORT:
return(BitConverter.ToUInt16(buffer, index));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.UNSIGNED_INT:
return(BitConverter.ToUInt32(buffer, index));
case glTFLoader.Schema.Accessor.ComponentTypeEnum.FLOAT:
return(BitConverter.ToSingle(buffer, index));
default:
throw new InvalidOperationException($"Invalid component type ({componentType})");
}
}
private int AddIndices(List <int> indices)
{
// evaulate min max
//
var MinMaxV = indices.Aggregate(new
{
MinV = int.MaxValue,
MaxV = int.MinValue
},
(accumulator, o) => new
{
MinV = Math.Min(o, accumulator.MinV),
MaxV = Math.Max(o, accumulator.MaxV)
});
gltf.Accessor.ComponentTypeEnum ct = gltf.Accessor.ComponentTypeEnum.BYTE;
// depending on the count of positions and normals, we determine the index type
//
Func <int, byte[]> ToBits;
var size = 0;
if (!Prevent8bitIndices && MinMaxV.MaxV <= Math.Pow(2, 8))
{
ct = gltf.Accessor.ComponentTypeEnum.UNSIGNED_BYTE;
size = sizeof(byte);
ToBits = x => new byte[] { (byte)x };
}
else if (MinMaxV.MaxV <= Math.Pow(2, 16))
{
ct = gltf.Accessor.ComponentTypeEnum.UNSIGNED_SHORT;
size = sizeof(short);
ToBits = x => BitConverter.GetBytes((short)x);
}
else
{
ct = gltf.Accessor.ComponentTypeEnum.UNSIGNED_INT;
size = sizeof(int);
ToBits = x => BitConverter.GetBytes((int)x);
}
// the offset position needs to be a multiple of the size
// (this is from a warning we received in beta testing)
// so we inject some padding when needed
//
var padding = _indicesBuffer.Count % size;
for (int i = 0; i < padding; i++)
{
_indicesBuffer.Add(0);
}
var indAccessor = new gltf.Accessor
{
BufferView = 0,
ComponentType = ct,
ByteOffset = _indicesBuffer.Count,
Normalized = false,
Type = gltf.Accessor.TypeEnum.SCALAR,
Count = indices.Count,
Min = new float[] { MinMaxV.MinV },
Max = new float[] { MinMaxV.MaxV }
};
var IndexSize = indices.Count * size;
List <byte> indicesBufferData = new List <byte>(IndexSize);
foreach (var index in indices)
{
var lst = ToBits(index);
indicesBufferData.AddRange(lst);
}
_indicesBuffer.AddRange(indicesBufferData);
var thisIndex = _accessors.Count;
_accessors.Add(indAccessor);
return(thisIndex);
}
int TotalStride(glTFLoader.Schema.Accessor.ComponentTypeEnum componentType, glTFLoader.Schema.Accessor.TypeEnum type)
{
return(ComponentSize(componentType) * ComponentsCount(type));
}