/// <summary>
/// Gets the version attribute of an enumeration value <paramref name="enumeration"/>.
/// </summary>
/// <param name="enumeration">The enumeration.</param>
/// <returns>The <see cref="VersionAttribute"/> defined on <paramref name="enumeration "/>, or null of none exists.</returns>
public static VersionAttribute GetVersionAttribute(Enum enumeration)
{
// Get the attribute from the enumeration value (if it exists).
Type type = enumeration.GetType();
string str = enumeration.ToString();
MemberInfo[] members = type.GetMember(str);
MemberInfo member = members.Single();
object[] objs = member.GetCustomAttributes(typeof(VersionAttribute), false);
IEnumerable <VersionAttribute> attributes = objs.OfType <VersionAttribute>();
VersionAttribute firstOrDefault = attributes.FirstOrDefault();
return(firstOrDefault);
}
/// <summary>
/// Only valid to be called after the render context is created, this function attempts to
/// move the render context to the OpenGL version originally requested. If this is > 2.1, this
/// means building a new context. If this fails, we'll have to make do with 2.1.
/// </summary>
/// <param name="gl">The OpenGL instance.</param>
protected void UpdateContextVersion()
{
// If the request version number is anything up to and including 2.1, standard render contexts
// will provide what we need (as long as the graphics card drivers are up to date).
var requestedVersionNumber = VersionAttribute.GetVersionAttribute(RequestedGLVersion);
if (requestedVersionNumber.IsAtLeastVersion(3, 0) == false)
{
CreatedGLVersion = RequestedGLVersion;
return;
}
// Now the none-trivial case. We must use the WGL_ARB_create_context extension to
// attempt to create a 3.0+ context.
try
{
int[] attributes =
{
GL.WGL_CONTEXT_MAJOR_VERSION_ARB, requestedVersionNumber.Major,
GL.WGL_CONTEXT_MINOR_VERSION_ARB, requestedVersionNumber.Minor,
GL.WGL_CONTEXT_FLAGS_ARB, GL.WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB, // compatible profile
#if DEBUG
GL.WGL_CONTEXT_FLAGS_ARB, GL.WGL_CONTEXT_DEBUG_BIT_ARB, // this is a debug context
#endif
0
};
IntPtr hrc = GL.CreateContextAttribsARB(this.DeviceContextHandle, IntPtr.Zero, attributes);
Win32.wglMakeCurrent(IntPtr.Zero, IntPtr.Zero);
Win32.wglDeleteContext(RenderContextHandle);
Win32.wglMakeCurrent(DeviceContextHandle, hrc);
RenderContextHandle = hrc;
}
catch (Exception)
{
// TODO: can we actually get the real version?
CreatedGLVersion = GLVersion.OpenGL2_1;
}
}