// The issue with using a single render id to order commands is the handling of
// depth which is a floating point number that can't simply be cast as an int value
// due to the potential of overflow/rounding errors
// So instead we first perform the layer group, group, depth and arrival index comparisons individually
// and then package any remaining traits for comparison (e.g. Material) into the RenderFlags
public int CompareTo(CCRenderCommand otherCommand)
{
// Sort groups in descending order
// This is because the typical use case is to group nodes into a render texture
// Then the render texture's corresponding sprite is then rendered to the scene
// So the render texture needs to be filled beforehand or else we will have a corrupted sprite
int compare = Group.CompareTo(otherCommand.Group) * -1;
if (compare == 0)
{
// Only sort by depth if depth testing is used by both commands
// Main issue is that oftentimes a pure 2d game will typically have all nodes with vertex z = 0
// Normally, sorting by depth wouldn't be a problem - depths are equal so compare using other traits below
// However, if a 3d effect (e.g. orbit camera) is used then vertex z of nodes will be altered
// Here, floating-point errors plus the inprecision of the depth-buffer the further a node is from a camera
// means that two nodes originally with vertex z = 0 may not have the exact same vertex z post-effect
compare = UsingDepthTest && otherCommand.UsingDepthTest ? GlobalDepth.CompareTo(otherCommand.GlobalDepth) : 0;
// If all traits are equal, then use the arrival index to differentiate
// This is necessary because we rely on quick sort to sort our command queue which is
// an unstable sorting algorithm
// i.e. Does not guarantee to presever order between two equal elements
if (compare == 0)
{
compare = ArrivalIndex.CompareTo(otherCommand.ArrivalIndex);
if (compare == 0)
{
compare = RenderFlags.CompareTo(otherCommand.RenderFlags);
}
}
}
return(compare);
}
public override string ToString()
{
return(string.Concat("[CCQuadCommand: Group ", Group.ToString(), " Depth ", GlobalDepth.ToString(),
" QuadCount ", QuadCount,
" MaterialId ", MaterialId.ToString(), "]"));
}
public override string ToString()
{
return(string.Concat("[CCCustomCommand: Group ", Group.ToString(), " Depth ", GlobalDepth.ToString(), "]"));
}