/// <summary>
/// Creates a default delegate for an OpenGL function in the event that it is not implemented by the driver.
/// </summary>
/// <param name="type">The OpenGL delegate type.</param>
/// <param name="function">The name of the OpenGL function.</param>
/// <param name="requirements">The OpenGL function's specified requirements.</param>
/// <returns>The default delegate that was created.</returns>
private static Delegate CreateDefaultDelegate(Type type, String function, RequireAttribute requirements)
{
var valFunction = Expression.Constant(function);
var valHasReqs = Expression.Constant(requirements != null);
var valIsCore = Expression.Constant(requirements != null && requirements.IsCore(majorVersion, minorVersion, isGLES));
var valExt = Expression.Constant(requirements == null ? null : requirements.Extension);
var valExtFn = Expression.Constant(requirements == null ? null : requirements.ExtensionFunction);
var delegateInvoke = type.GetMethod("Invoke");
var delegateParameters = delegateInvoke.GetParameters().Select(x => Expression.Parameter(x.ParameterType, x.Name));
var throwExpression = Expression.Throw(Expression.Call(miCreateDefaultDelegateException,
valFunction,
valIsCore,
valHasReqs,
Expression.Convert(valExt, typeof(String)),
Expression.Convert(valExtFn, typeof(String))), delegateInvoke.ReturnType);
var throwLambda = Expression.Lambda(type, throwExpression, delegateParameters);
return(throwLambda.Compile());
}
/// <summary>
/// Loads the default delegate for the specified field.
/// </summary>
/// <param name="field">The field for which to load a default delegate.</param>
/// <param name="requirements">The OpenGL function's specified requirements.</param>
private static void LoadDefaultDelegate(FieldInfo field, RequireAttribute requirements)
{
var fndefault = CreateDefaultDelegate(field.FieldType, field.Name, requirements);
field.SetValue(null, fndefault);
}