HardwareOcclusionQuery.hs

module Graphics.LambdaCube.HardwareOcclusionQuery where

-- | This is a abstract class that that provides the interface for the query class for hardware occlusion.
class HardwareOcclusionQuery a where
    {-| Starts the hardware occlusion query
        @Remarks	Simple usage: Create one or more OcclusionQuery object one per outstanding query or one per tested object 
       				OcclusionQuery* m_pOcclusionQuery;
       				createOcclusionQuery( &m_pOcclusionQuery );
       				In the rendering loop:
       				Draw all occluders
       				m_pOcclusionQuery->startOcclusionQuery();
       				Draw the polygons to be tested
       				m_pOcclusionQuery->endOcclusionQuery();
       
       				Results must be pulled using:
       				UINT	m_uintNumberOfPixelsVisable;
       				pullOcclusionQuery( &m_dwNumberOfPixelsVisable );
    -}
    beginOcclusionQuery     :: a -> IO ()
    endOcclusionQuery       :: a -> IO ()   -- ^ Ends the hardware occlusion test

    {-| Pulls the hardware occlusion query.
        @note Waits until the query result is available; use isStillOutstanding
       		if just want to test if the result is available.
        @retval NumOfFragments will get the resulting number of fragments.
        @return True if success or false if not.
    -}
    pullOcclusionQuery      :: a -> IO Int

    {-| Let's you get the last pixel count with out doing the hardware occlusion test
        @return The last fragment count from the last test.
        Remarks This function won't give you new values, just the old value.
    -}
--    getLastQuerysPixelcount :: a -> IO Int

    {-| Lets you know when query is done, or still be processed by the Hardware
        @return true if query isn't finished.
    -}
    isStillOutstanding      :: a -> IO Bool