Copyright | (c) Sven Panne 2002-2019 |
---|---|

License | BSD3 |

Maintainer | Sven Panne <svenpanne@gmail.com> |

Stability | stable |

Portability | portable |

Safe Haskell | None |

Language | Haskell2010 |

This module corresponds to section 10.8 (Drawing Commands Using Begin and End) of the OpenGL 4.4 specs.

## Synopsis

- renderPrimitive :: PrimitiveMode -> IO a -> IO a
- unsafeRenderPrimitive :: PrimitiveMode -> IO a -> IO a
- primitiveRestart :: IO ()
- data EdgeFlag
- edgeFlag :: StateVar EdgeFlag

# Begin and End Objects

renderPrimitive :: PrimitiveMode -> IO a -> IO a Source #

Delimit the vertices that define a primitive or a group of like primitives.

Only a subset of GL commands can be used in the delimited action:
Those for specifying vertex coordinates
(`vertex`

,
`vertexv`

),
vertex colors
(`color`

,
`colorv`

,
`secondaryColor`

,
`secondaryColorv`

,
`index`

,
`indexv`

),
normal
(`normal`

,
`normalv`

),
texture coordinates
(`texCoord`

,
`texCoordv`

,
`multiTexCoord`

,
`multiTexCoordv`

),
and fog coordinates
(`fogCoord`

,
`fogCoordv`

).
Additionally,
`evalPoint1`

,
`evalPoint2`

,
`evalCoord1`

,
`evalCoord1v`

,
`evalCoord2`

,
`evalCoord2v`

,
`materialAmbient`

,
`materialDiffuse`

,
`materialAmbientAndDiffuse`

,
`materialSpecular`

,
`materialEmission`

,
`materialShininess`

,
`callList`

,
`callLists`

,
and setting `edgeFlag`

are allowed. Writing the respective state variables
is allowed in the delimited action, too.

Regardless of the chosen `PrimitiveMode`

, there is no limit to the number of
vertices that can be defined during a single `renderPrimitive`

. Lines,
triangles, quadrilaterals, and polygons that are incompletely specified are
not drawn. Incomplete specification results when either too few vertices are
provided to specify even a single primitive or when an incorrect multiple of
vertices is specified. The incomplete primitive is ignored; the rest are
drawn.

The minimum specification of vertices for each primitive is as follows: 1
for a point, 2 for a line, 3 for a triangle, 4 for a quadrilateral, and 3 for
a polygon. Modes that require a certain multiple of vertices are `Lines`

(2),
`Triangles`

(3), `Quads`

(4), and `QuadStrip`

(2).

unsafeRenderPrimitive :: PrimitiveMode -> IO a -> IO a Source #

A more efficient, but potentially dangerous version of `renderPrimitive`

:
The given action is not allowed to throw an exception.

primitiveRestart :: IO () Source #

# Polygon Edges

A vertex can begin an edge which lies in the interior of its polygon or on the polygon's boundary.

edgeFlag :: StateVar EdgeFlag Source #

Each vertex of a polygon, separate triangle, or separate quadrilateral
specified during `renderPrimitive`

is marked as the start of either a boundary
or nonboundary (interior) edge.

The vertices of connected triangles and connected quadrilaterals are always marked as boundary, regardless of the value of the edge flag.

Boundary and nonboundary edge flags on vertices are significant only if
`polygonMode`

is set to
`Point`

or
`Line`

.

Note that the current edge flag can be updated at any time, in particular
during `renderPrimitive`

.