-- #hide -------------------------------------------------------------------------------- -- | -- Module : Graphics.Rendering.OGL.GL.PrimitiveMode -- Copyright : (c) Sven Panne 2002-2006 -- License : BSD-style (see the file libraries/OpenGL/LICENSE) -- -- Maintainer : sven.panne@aedion.de -- Stability : stable -- Portability : portable -- -- This is a purely internal module for (un-)marshaling PrimitiveMode. -- -------------------------------------------------------------------------------- module Graphics.Rendering.OGL.GL.PrimitiveMode ( PrimitiveMode(..), marshalPrimitiveMode, unmarshalPrimitiveMode ) where import Graphics.Rendering.OGL.GL.BasicTypes ( GLenum ) -------------------------------------------------------------------------------- -- | Specification of the way the vertices given during 'renderPrimitive' are -- interpreted. In the description of the constructors, /n/ is an integer count -- starting at one, and /N/ is the total number of vertices specified. data PrimitiveMode = Points -- ^ Treats each vertex as a single point. Vertex /n/ defines point /n/. -- /N/ points are drawn. | Lines -- ^ Treats each pair of vertices as an independent line segment. Vertices -- 2/n/-1 and 2/n/ define line /n/. /N/\/2 lines are drawn. | LineLoop -- ^ Draws a connected group of line segments from the first vertex to the -- last, then back to the first. Vertices /n/ and /n/+1 define line /n/. -- The last line, however, is defined by vertices /N/ and 1. /N/ lines -- are drawn. | LineStrip -- ^ Draws a connected group of line segments from the first vertex to the -- last. Vertices /n/ and /n/+1 define line /n/. /N/-1 lines are drawn. | Triangles -- ^ Treats each triplet of vertices as an independent triangle. Vertices -- /3n-2/, /3n-1/, and /3n/ define triangle /n/. /N\/3/ triangles are drawn. | TriangleStrip -- ^ Draws a connected group of triangles. One triangle is defined for each -- vertex presented after the first two vertices. For odd /n/, vertices -- /n/, /n/+1, and /n/+2 define triangle /n/. For even /n/, vertices /n/+1, -- /n/, and /n/+2 define triangle /n/. /N/-2 triangles are drawn. | TriangleFan -- ^ Draws a connected group of triangles. One triangle is defined for each -- vertex presented after the first two vertices. Vertices 1, /n/+1, and -- /n/+2 define triangle /n/. /N/-2 triangles are drawn. | Quads -- ^ Treats each group of four vertices as an independent quadrilateral. -- Vertices 4/n/-3, 4/n/-2, 4/n/-1, and 4/n/ define quadrilateral /n/. -- /N/\/4 quadrilaterals are drawn. | QuadStrip -- ^ Draws a connected group of quadrilaterals. One quadrilateral is --defined for each pair of vertices presented after the first pair. -- Vertices 2/n/-1, 2/n/, 2/n/+2, and 2/n/+1 define quadrilateral /n/. -- /N/\/2-1 quadrilaterals are drawn. Note that the order in which vertices -- are used to construct a quadrilateral from strip data is different from -- that used with independent data. | Polygon -- ^ Draws a single, convex polygon. Vertices 1 through /N/ define this -- polygon. deriving ( Eq, Ord, Show ) marshalPrimitiveMode :: PrimitiveMode -> GLenum marshalPrimitiveMode x = case x of Points -> 0x0 Lines -> 0x1 LineLoop -> 0x2 LineStrip -> 0x3 Triangles -> 0x4 TriangleStrip -> 0x5 TriangleFan -> 0x6 Quads -> 0x7 QuadStrip -> 0x8 Polygon -> 0x9 unmarshalPrimitiveMode :: GLenum -> PrimitiveMode unmarshalPrimitiveMode x | x == 0x0 = Points | x == 0x1 = Lines | x == 0x2 = LineLoop | x == 0x3 = LineStrip | x == 0x4 = Triangles | x == 0x5 = TriangleStrip | x == 0x6 = TriangleFan | x == 0x7 = Quads | x == 0x8 = QuadStrip | x == 0x9 = Polygon | otherwise = error ("unmarshalPrimitiveMode: illegal value " ++ show x)