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><head><title>glShadeModel</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GL.xml" title="GL"/><link rel="previous" href="glSeparableFilter2D.3G.xml" title="glSeparableFilter2D"/><link rel="next" href="glStencilFunc.3G.xml" title="glStencilFunc"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">glShadeModel</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="glSeparableFilter2D.3G.xml">Prev</a> </td><th width="60%" align="center">GL</th><td width="20%" align="right"> <a accesskey="n" href="glStencilFunc.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="glShadeModel.3G"/><div class="titlepage"/><div class="refnamediv"><a name="glShadeModel.3G-name"/><h2>Name</h2><p>glShadeModel &#8212; select flat or smooth shading</p></div><div class="refsynopsisdiv"><a name="glShadeModel.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void <tt>glShadeModel</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLenum <i><tt>mode</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="glShadeModel.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>glShadeModel</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>mode</tt></i>) &#8594; <tt>None</tt></code></td></tr></table></div><div class="refsect1" lang="en"><a name="glShadeModel.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>mode</tt></i></span></dt><dd>
						Specifies a symbolic value representing a shading technique. Accepted values are
						<tt>GL_FLAT</tt> and <tt>GL_SMOOTH</tt>. The initial value is
						<tt>GL_SMOOTH</tt>.
					</dd></dl></div></div><div class="refsect1" lang="en"><a name="glShadeModel.3G-description"/><h2>Description</h2><p>
			GL primitives can have either flat or smooth shading. Smooth shading, the default, causes the computed colors of
			vertices to be interpolated as the primitive is rasterized, typically assigning different colors to each resulting
			pixel fragment. Flat shading selects the computed color of just one vertex and assigns it to all the pixel fragments
			generated by rasterizing a single primitive. In either case, the computed color of a vertex is the result of lighting
			if lighting is enabled, or it is the current color at the time the vertex was specified if lighting is disabled.
		</p><p>
			Flat and smooth shading are indistinguishable for points. Starting when <a href="glBegin.3G.xml"><tt>glBegin</tt></a> is issued and counting vertices and primitives from 1, the GL gives each
			flat-shaded line segment <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
					<mml:mi>i</mml:mi>
				</mml:math> the computed color of vertex <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
					<mml:mrow>
						<mml:mi>i</mml:mi>
						<mml:mo>+</mml:mo>
						<mml:mn>1</mml:mn>
					</mml:mrow>
				</mml:math>, its second vertex. Counting similarly from 1, the GL gives each flat-shaded polygon the computed
			color of the vertex listed in the following table. This is the last vertex to specify the polygon in all cases except
			single polygons, where the first vertex specifies the flat-shaded color.
		</p><div class="informaltable"><table border="1"><colgroup><col/><col/></colgroup><tbody><tr><td><span class="bold"><b>Primitive Type of Polygon</b></span><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mi>i</mml:mi>
							</mml:math></td><td align="center"><span class="bold"><b>Vertex</b></span></td></tr><tr><td>Single polygon (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mi>i</mml:mi>
									<mml:mo>&#8801;</mml:mo>
									<mml:mn>1</mml:mn>
								</mml:mrow>
							</mml:math>)</td><td align="center">1</td></tr><tr><td>Triangle strip</td><td align="center"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mi>i</mml:mi>
									<mml:mo>+</mml:mo>
									<mml:mn>2</mml:mn>
								</mml:mrow>
							</mml:math></td></tr><tr><td>Triangle fan</td><td align="center"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mi>i</mml:mi>
									<mml:mo>+</mml:mo>
									<mml:mn>2</mml:mn>
								</mml:mrow>
							</mml:math></td></tr><tr><td>Independent triangle</td><td align="center"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mn>3</mml:mn>
									<mml:mi>i</mml:mi>
								</mml:mrow>
							</mml:math></td></tr><tr><td>Quad strip</td><td align="center"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mn>2</mml:mn>
									<mml:mi>i</mml:mi>
									<mml:mo>+</mml:mo>
									<mml:mn>2</mml:mn>
								</mml:mrow>
							</mml:math></td></tr><tr><td>Independent quad</td><td align="center"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
								<mml:mrow>
									<mml:mn>4</mml:mn>
									<mml:mi>i</mml:mi>
								</mml:mrow>
							</mml:math></td></tr></tbody></table></div><p>
			Flat and smooth shading are specified by <tt>glShadeModel</tt> with <i><tt>mode</tt></i> set to
			<tt>GL_FLAT</tt> and <tt>GL_SMOOTH</tt>, respectively.
		</p></div><div class="refsect1" lang="en"><a name="glShadeModel.3G-errors"/><h2>Errors</h2><p>
			<tt>GL_INVALID_ENUM</tt> is generated if <i><tt>mode</tt></i> is any value other than
			<tt>GL_FLAT</tt> or <tt>GL_SMOOTH</tt>.
		</p><p>
			<tt>GL_INVALID_OPERATION</tt> is generated if <tt>glShadeModel</tt> is executed between the
			execution of <a href="glBegin.3G.xml"><tt>glBegin</tt></a> and the corresponding execution of <a href="glBegin.3G.xml"><tt>glEnd</tt></a>.
		</p></div><div class="refsect1" lang="en"><a name="glShadeModel.3G-associated_gets"/><h2>Associated Gets</h2><p>
			<tt>glGet</tt> with argument <tt>GL_SHADE_MODEL</tt>
		</p></div><div class="refsect1" lang="en"><a name="glShadeModel.3G-see_also"/><h2>See Also</h2><p>
			<span class="simplelist"><a href="glBegin.3G.xml">glBegin</a>, <a href="glColor.3G.xml">glColor</a>, <a href="glLight.3G.xml">glLight</a>, <a href="glLightModel.3G.xml">glLightModel</a></span>
		</p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="glSeparableFilter2D.3G.xml">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference-GL.xml">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="glStencilFunc.3G.xml">Next</a></td></tr><tr><td width="40%" align="left" valign="top">glSeparableFilter2D </td><td width="20%" align="center"><a accesskey="h" href="index.xml">Home</a></td><td width="40%" align="right" valign="top"> glStencilFunc</td></tr></table></div></body></html>