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</script></head><body><div id="package-header"><ul class="links" id="page-menu"><li><a href="src/Graphics-Rendering-OpenGL-GL-BeginEnd.html">Source</a></li><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">OpenGL-2.2.3.0: A binding for the OpenGL graphics system</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Portability</th><td>portable</td></tr><tr><th>Stability</th><td>stable</td></tr><tr><th>Maintainer</th><td>sven.panne@aedion.de</td></tr></table><p class="caption">Graphics.Rendering.OpenGL.GL.BeginEnd</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">Begin and End Objects
</a></li><li><a href="#g:2">Polygon Edges
</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>This module corresponds to section 2.6 (Begin/End Paradigm) of the
OpenGL 2.1 specs.
</p></div></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short"><span class="keyword">data</span> <a href="#t:PrimitiveMode">PrimitiveMode</a> <ul class="subs"><li>= <a href="#v:Points">Points</a> </li><li>| <a href="#v:Lines">Lines</a> </li><li>| <a href="#v:LineLoop">LineLoop</a> </li><li>| <a href="#v:LineStrip">LineStrip</a> </li><li>| <a href="#v:Triangles">Triangles</a> </li><li>| <a href="#v:TriangleStrip">TriangleStrip</a> </li><li>| <a href="#v:TriangleFan">TriangleFan</a> </li><li>| <a href="#v:Quads">Quads</a> </li><li>| <a href="#v:QuadStrip">QuadStrip</a> </li><li>| <a href="#v:Polygon">Polygon</a> </li></ul></li><li class="src short"><a href="#v:renderPrimitive">renderPrimitive</a> :: <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a> -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a</li><li class="src short"><a href="#v:unsafeRenderPrimitive">unsafeRenderPrimitive</a> :: <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a> -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a</li><li class="src short"><a href="#v:primitiveRestart">primitiveRestart</a> :: <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> <a href="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t:-40--41-">()</a></li><li class="src short"><span class="keyword">data</span> <a href="#t:EdgeFlag">EdgeFlag</a> <ul class="subs"><li>= <a href="#v:BeginsInteriorEdge">BeginsInteriorEdge</a> </li><li>| <a href="#v:BeginsBoundaryEdge">BeginsBoundaryEdge</a> </li></ul></li><li class="src short"><a href="#v:edgeFlag">edgeFlag</a> :: <a href="Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:EdgeFlag">EdgeFlag</a></li></ul></div><div id="interface"><h1 id="g:1">Begin and End Objects
</h1><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:PrimitiveMode" class="def">PrimitiveMode</a> <a href="src/Graphics-Rendering-OpenGL-GL-PrimitiveMode.html#PrimitiveMode" class="link">Source</a></p><div class="doc"><p>Specification of the way the vertices given during <code>renderPrimitive</code> are
interpreted. In the description of the constructors, <em>n</em> is an integer count
starting at one, and <em>N</em> is the total number of vertices specified.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:Points" class="def">Points</a></td><td class="doc"><p>Treats each vertex as a single point. Vertex <em>n</em> defines point <em>n</em>.
<em>N</em> points are drawn.
</p></td></tr><tr><td class="src"><a name="v:Lines" class="def">Lines</a></td><td class="doc"><p>Treats each pair of vertices as an independent line segment. Vertices
2<em>n</em>-1 and 2<em>n</em> define line <em>n</em>. <em>N</em>/2 lines are drawn.
</p></td></tr><tr><td class="src"><a name="v:LineLoop" class="def">LineLoop</a></td><td class="doc"><p>Draws a connected group of line segments from the first vertex to the
last, then back to the first. Vertices <em>n</em> and <em>n</em>+1 define line <em>n</em>.
The last line, however, is defined by vertices <em>N</em> and 1. <em>N</em> lines
are drawn.
</p></td></tr><tr><td class="src"><a name="v:LineStrip" class="def">LineStrip</a></td><td class="doc"><p>Draws a connected group of line segments from the first vertex to the
last. Vertices <em>n</em> and <em>n</em>+1 define line <em>n</em>. <em>N</em>-1 lines are drawn.
</p></td></tr><tr><td class="src"><a name="v:Triangles" class="def">Triangles</a></td><td class="doc"><p>Treats each triplet of vertices as an independent triangle. Vertices
<em>3n-2</em>, <em>3n-1</em>, and <em>3n</em> define triangle <em>n</em>. <em>N\</em>3/ triangles are drawn.
</p></td></tr><tr><td class="src"><a name="v:TriangleStrip" class="def">TriangleStrip</a></td><td class="doc"><p>Draws a connected group of triangles. One triangle is defined for each
vertex presented after the first two vertices. For odd <em>n</em>, vertices
<em>n</em>, <em>n</em>+1, and <em>n</em>+2 define triangle <em>n</em>. For even <em>n</em>, vertices <em>n</em>+1,
<em>n</em>, and <em>n</em>+2 define triangle <em>n</em>. <em>N</em>-2 triangles are drawn.
</p></td></tr><tr><td class="src"><a name="v:TriangleFan" class="def">TriangleFan</a></td><td class="doc"><p>Draws a connected group of triangles. One triangle is defined for each
vertex presented after the first two vertices. Vertices 1, <em>n</em>+1, and
<em>n</em>+2 define triangle <em>n</em>. <em>N</em>-2 triangles are drawn.
</p></td></tr><tr><td class="src"><a name="v:Quads" class="def">Quads</a></td><td class="doc"><p>Treats each group of four vertices as an independent quadrilateral.
Vertices 4<em>n</em>-3, 4<em>n</em>-2, 4<em>n</em>-1, and 4<em>n</em> define quadrilateral <em>n</em>.
<em>N</em>/4 quadrilaterals are drawn.
</p></td></tr><tr><td class="src"><a name="v:QuadStrip" class="def">QuadStrip</a></td><td class="doc"><p>Draws a connected group of quadrilaterals. One quadrilateral is
defined for each pair of vertices presented after the first pair.
Vertices 2<em>n</em>-1, 2<em>n</em>, 2<em>n</em>+2, and 2<em>n</em>+1 define quadrilateral <em>n</em>.
<em>N</em>/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.
</p></td></tr><tr><td class="src"><a name="v:Polygon" class="def">Polygon</a></td><td class="doc"><p>Draws a single, convex polygon. Vertices 1 through <em>N</em> define this
polygon.
</p></td></tr></table></div><div class="subs instances"><p id="control.i:PrimitiveMode" class="caption collapser" onclick="toggleSection('i:PrimitiveMode')">Instances</p><div id="section.i:PrimitiveMode" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a></td><td class="doc empty"> </td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:renderPrimitive" class="def">renderPrimitive</a> :: <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a> -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a<a href="src/Graphics-Rendering-OpenGL-GL-BeginEnd.html#renderPrimitive" class="link">Source</a></p><div class="doc"><p>Delimit the vertices that define a primitive or a group of like primitives.
</p><p>Only a subset of GL commands can be used in the delimited action:
Those for specifying vertex coordinates
(<code>Graphics.Rendering.OpenGL.GL.VertexSpec.vertex</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.vertexv</code>),
vertex colors
(<code>Graphics.Rendering.OpenGL.GL.VertexSpec.color</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.colorv</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.secondaryColor</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.secondaryColorv</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.index</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.indexv</code>),
normal
(<code>Graphics.Rendering.OpenGL.GL.VertexSpec.normal</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.normalv</code>),
texture coordinates
(<code>Graphics.Rendering.OpenGL.GL.VertexSpec.texCoord</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.texCoordv</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.multiTexCoord</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.multiTexCoordv</code>),
and fog coordinates
(<code>Graphics.Rendering.OpenGL.GL.VertexSpec.fogCoord</code>,
<code>Graphics.Rendering.OpenGL.GL.VertexSpec.fogCoordv</code>).
Additionally,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalPoint1</code>,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalPoint2</code>,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalCoord1</code>,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalCoord1v</code>,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalCoord2</code>,
<code>Graphics.Rendering.OpenGL.GL.Evaluators.evalCoord2v</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialAmbient</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialDiffuse</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialAmbientAndDiffuse</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialSpecular</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialEmission</code>,
<code>Graphics.Rendering.OpenGL.GL.Colors.materialShininess</code>,
<code>Graphics.Rendering.OpenGL.GL.DisplayLists.callList</code>,
<code>Graphics.Rendering.OpenGL.GL.DisplayLists.callLists</code>,
and setting <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:edgeFlag">edgeFlag</a></code> are allowed. Writing the respective state variables
is allowed in the delimited action, too.
</p><p>Regardless of the chosen <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a></code>, there is no limit to the number of
vertices that can be defined during a single <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:renderPrimitive">renderPrimitive</a></code>. 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.
</p><p>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 <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:Lines">Lines</a></code> (2),
<code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:Triangles">Triangles</a></code> (3), <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:Quads">Quads</a></code> (4), and <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:QuadStrip">QuadStrip</a></code> (2).
</p></div></div><div class="top"><p class="src"><a name="v:unsafeRenderPrimitive" class="def">unsafeRenderPrimitive</a> :: <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:PrimitiveMode">PrimitiveMode</a> -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a -> <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> a<a href="src/Graphics-Rendering-OpenGL-GL-BeginEnd.html#unsafeRenderPrimitive" class="link">Source</a></p><div class="doc"><p>A more efficient, but potentially dangerous version of <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:renderPrimitive">renderPrimitive</a></code>:
The given action is not allowed to throw an exception.
</p></div></div><div class="top"><p class="src"><a name="v:primitiveRestart" class="def">primitiveRestart</a> :: <a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/System-IO.html#t:IO">IO</a> <a href="/usr/share/doc/ghc/html/libraries/ghc-prim-0.2.0.0/GHC-Unit.html#t:-40--41-">()</a><a href="src/Graphics-Rendering-OpenGL-GL-BeginEnd.html#primitiveRestart" class="link">Source</a></p></div><h1 id="g:2">Polygon Edges
</h1><div class="top"><p class="src"><span class="keyword">data</span> <a name="t:EdgeFlag" class="def">EdgeFlag</a> <a href="src/Graphics-Rendering-OpenGL-GL-EdgeFlag.html#EdgeFlag" class="link">Source</a></p><div class="doc"><p>A vertex can begin an edge which lies in the interior of its polygon or on
the polygon's boundary.
</p></div><div class="subs constructors"><p class="caption">Constructors</p><table><tr><td class="src"><a name="v:BeginsInteriorEdge" class="def">BeginsInteriorEdge</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a name="v:BeginsBoundaryEdge" class="def">BeginsBoundaryEdge</a></td><td class="doc empty"> </td></tr></table></div><div class="subs instances"><p id="control.i:EdgeFlag" class="caption collapser" onclick="toggleSection('i:EdgeFlag')">Instances</p><div id="section.i:EdgeFlag" class="show"><table><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Eq.html#t:Eq">Eq</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:EdgeFlag">EdgeFlag</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Data-Ord.html#t:Ord">Ord</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:EdgeFlag">EdgeFlag</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="/usr/share/doc/ghc/html/libraries/base-4.3.1.0/Text-Show.html#t:Show">Show</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:EdgeFlag">EdgeFlag</a></td><td class="doc empty"> </td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:edgeFlag" class="def">edgeFlag</a> :: <a href="Graphics-Rendering-OpenGL-GL-StateVar.html#t:StateVar">StateVar</a> <a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#t:EdgeFlag">EdgeFlag</a><a href="src/Graphics-Rendering-OpenGL-GL-BeginEnd.html#edgeFlag" class="link">Source</a></p><div class="doc"><p>Each vertex of a polygon, separate triangle, or separate quadrilateral
specified during <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:renderPrimitive">renderPrimitive</a></code> is marked as the start of either a boundary
or nonboundary (interior) edge.
</p><p>The vertices of connected triangles and connected quadrilaterals are always
marked as boundary, regardless of the value of the edge flag.
</p><p>Boundary and nonboundary edge flags on vertices are significant only if
<code>Graphics.Rendering.OpenGL.GL.Polygons.polygonMode</code> is set to
<code>Graphics.Rendering.OpenGL.GL.Polygons.Point</code> or
<code>Graphics.Rendering.OpenGL.GL.Polygons.Line</code>.
</p><p>Note that the current edge flag can be updated at any time, in particular
during <code><a href="Graphics-Rendering-OpenGL-GL-BeginEnd.html#v:renderPrimitive">renderPrimitive</a></code>.
</p></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.9.2</p></div></body></html>
