public void BeginObject(string objectName)
{
if (modelRoot != null && currentObject == null)
{
throw new InvalidOperationException("Attempting to start a root object, when one was already created and finished.");
}
if (currentObjectHasOwnCommands)
{
throw new InvalidOperationException("Objects containing both own commands and nested objects are not allowed.");
}
// Create the display list and the tree node associated with the object
int objectDisplayList = GL.GenLists(1);
try
{
OpenGlModelObjectInformation objectInfo = new OpenGlModelObjectInformation(objectName, objectDisplayList);
Tree <OpenGlModelObjectInformation> objectNode = new Tree <OpenGlModelObjectInformation>(objectInfo);
if (currentObject != null)
{
// Add the new object node as a children of the current object
currentObject.Add(objectNode);
}
else // (modelRoot = null here)
{
// First object being created, set it as the root node
modelRoot = objectNode;
}
// Set the new node as the current object and start its display list
currentObject = objectNode;
currentObjectHasOwnCommands = false;
}
catch
{
GL.DeleteLists(objectDisplayList, 1);
throw;
}
}
/// <summary>
/// Render the model at position "index" in OpenGL.
/// </summary>
public void CallDisplayList(OpenGlModelObjectInformation model)
{
GL.CallList(model.DisplayListIndex);
}