private static int ComputeAttributeStride(IEnumerable <VertexAttribute> attributes)
{
var stride = 0;
foreach (var attr in attributes)
{
stride += VertexAttribute.GetSizeInBytes(attr.Type, attr.Size);
}
return(stride);
}
internal static VertexAttribute[] GenerateAttributes(Type type)
{
// Get all fields w/ attribute defs
var fields = type.GetFields()
.Where(x => x.GetCustomAttribute <VertexAttributeAttribute>() != null)
.ToArray();
// Must have at least one attribute defined
if (fields.Length == 0)
{
throw new InvalidOperationException("Must have at least one field with a vertex attribute defined.");
}
// Console.WriteLine($"Attribute Layout: {type}");
// Create attribute list (one attributed per field)
var attributes = new List <VertexAttribute>();
// For each field
for (var f = 0; f < fields.Length; f++)
{
var attribute = fields[f].GetCustomAttribute <VertexAttributeAttribute>();
var field = fields[f];
// Number of attributes needed to describe this data, most attributes will be one.
var attributeCount = GetAttributeCount(field.FieldType);
// Get offset and usable size
var nextOffset = f != (fields.Length - 1) ? OffsetOf(fields[f + 1]) : Marshal.SizeOf(type);
var currOffset = OffsetOf(field);
var size = nextOffset - currOffset;
// Gather respective field type
var attr = GetAttributeType(field.FieldType);
var step = GetSizeInBytes(attr, 1) * attributeCount;
var count = size / step;
var waste = size % step;
if (waste != 0)
{
throw new Exception($"Vertex attribute defined in struct has unattributed space after '{attr}'.");
}
// Store extracted attribute data
for (var o = 0u; o < attributeCount; o++)
{
var _attribute = new VertexAttribute(attribute.Attribute, count, attr, attribute.Normalize, o);
// Console.WriteLine($" {attribute.Attribute} ({_attribute.Index}): {count} x {attr}");
attributes.Add(_attribute);
}
}
return(attributes.ToArray());
