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<h2><span class="refentrytitle"><a name="cogl-Matrices.top_of_page"></a>Matrices</span></h2>
<p>Matrices — Fuctions for initializing and manipulating 4x4 matrices</p>
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<div class="refsynopsisdiv">
<a name="cogl-Matrices.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis"> <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix">CoglMatrix</a>;
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-init-identity" title="cogl_matrix_init_identity ()">cogl_matrix_init_identity</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
<a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="returnvalue">CoglMatrix</span></a> * <a class="link" href="cogl-Matrices.html#cogl-matrix-copy" title="cogl_matrix_copy ()">cogl_matrix_copy</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
<span class="returnvalue">gboolean</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-equal" title="cogl_matrix_equal ()">cogl_matrix_equal</a> (<em class="parameter"><code><span class="type">gconstpointer</span> v1</code></em>,
<em class="parameter"><code><span class="type">gconstpointer</span> v2</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-free" title="cogl_matrix_free ()">cogl_matrix_free</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-frustum" title="cogl_matrix_frustum ()">cogl_matrix_frustum</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> left</code></em>,
<em class="parameter"><code><span class="type">float</span> right</code></em>,
<em class="parameter"><code><span class="type">float</span> bottom</code></em>,
<em class="parameter"><code><span class="type">float</span> top</code></em>,
<em class="parameter"><code><span class="type">float</span> z_near</code></em>,
<em class="parameter"><code><span class="type">float</span> z_far</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-ortho" title="cogl_matrix_ortho ()">cogl_matrix_ortho</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> left</code></em>,
<em class="parameter"><code><span class="type">float</span> right</code></em>,
<em class="parameter"><code><span class="type">float</span> bottom</code></em>,
<em class="parameter"><code><span class="type">float</span> top</code></em>,
<em class="parameter"><code><span class="type">float</span> near</code></em>,
<em class="parameter"><code><span class="type">float</span> far</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-perspective" title="cogl_matrix_perspective ()">cogl_matrix_perspective</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> fov_y</code></em>,
<em class="parameter"><code><span class="type">float</span> aspect</code></em>,
<em class="parameter"><code><span class="type">float</span> z_near</code></em>,
<em class="parameter"><code><span class="type">float</span> z_far</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-multiply" title="cogl_matrix_multiply ()">cogl_matrix_multiply</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *result</code></em>,
<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *a</code></em>,
<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *b</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-rotate" title="cogl_matrix_rotate ()">cogl_matrix_rotate</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> angle</code></em>,
<em class="parameter"><code><span class="type">float</span> x</code></em>,
<em class="parameter"><code><span class="type">float</span> y</code></em>,
<em class="parameter"><code><span class="type">float</span> z</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-translate" title="cogl_matrix_translate ()">cogl_matrix_translate</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> x</code></em>,
<em class="parameter"><code><span class="type">float</span> y</code></em>,
<em class="parameter"><code><span class="type">float</span> z</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-scale" title="cogl_matrix_scale ()">cogl_matrix_scale</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> sx</code></em>,
<em class="parameter"><code><span class="type">float</span> sy</code></em>,
<em class="parameter"><code><span class="type">float</span> sz</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-transpose" title="cogl_matrix_transpose ()">cogl_matrix_transpose</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-init-from-array" title="cogl_matrix_init_from_array ()">cogl_matrix_init_from_array</a> (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code>const <span class="type">float</span> *array</code></em>);
const <span class="returnvalue">float</span> * <a class="link" href="cogl-Matrices.html#cogl-matrix-get-array" title="cogl_matrix_get_array ()">cogl_matrix_get_array</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
<span class="returnvalue">gboolean</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-get-inverse" title="cogl_matrix_get_inverse ()">cogl_matrix_get_inverse</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *inverse</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-transform-point" title="cogl_matrix_transform_point ()">cogl_matrix_transform_point</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> *x</code></em>,
<em class="parameter"><code><span class="type">float</span> *y</code></em>,
<em class="parameter"><code><span class="type">float</span> *z</code></em>,
<em class="parameter"><code><span class="type">float</span> *w</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-project-points" title="cogl_matrix_project_points ()">cogl_matrix_project_points</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">int</span> n_components</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_in</code></em>,
<em class="parameter"><code>const <span class="type">void</span> *points_in</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_out</code></em>,
<em class="parameter"><code><span class="type">void</span> *points_out</code></em>,
<em class="parameter"><code><span class="type">int</span> n_points</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-transform-points" title="cogl_matrix_transform_points ()">cogl_matrix_transform_points</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">int</span> n_components</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_in</code></em>,
<em class="parameter"><code>const <span class="type">void</span> *points_in</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_out</code></em>,
<em class="parameter"><code><span class="type">void</span> *points_out</code></em>,
<em class="parameter"><code><span class="type">int</span> n_points</code></em>);
<span class="returnvalue">gboolean</span> <a class="link" href="cogl-Matrices.html#cogl-matrix-is-identity" title="cogl_matrix_is_identity ()">cogl_matrix_is_identity</a> (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);
</pre>
</div>
<div class="refsect1">
<a name="cogl-Matrices.description"></a><h2>Description</h2>
<p>
Matrices are used in Cogl to describe affine model-view transforms, texture
transforms, and projective transforms. This exposes a utility API that can
be used for direct manipulation of these matrices.
</p>
</div>
<div class="refsect1">
<a name="cogl-Matrices.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="CoglMatrix"></a><h3>CoglMatrix</h3>
<pre class="programlisting">typedef struct {
/* column 0 */
float xx;
float yx;
float zx;
float wx;
/* column 1 */
float xy;
float yy;
float zy;
float wy;
/* column 2 */
float xz;
float yz;
float zz;
float wz;
/* column 3 */
float xw;
float yw;
float zw;
float ww;
} CoglMatrix;
</pre>
<p>
A CoglMatrix holds a 4x4 transform matrix. This is a single precision,
column-major matrix which means it is compatible with what OpenGL expects.
</p>
<p>
A CoglMatrix can represent transforms such as, rotations, scaling,
translation, sheering, and linear projections. You can combine these
transforms by multiplying multiple matrices in the order you want them
applied.
</p>
<p>
The transformation of a vertex (x, y, z, w) by a CoglMatrix is given by:
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
x_new = xx * x + xy * y + xz * z + xw * w
y_new = yx * x + yy * y + yz * z + yw * w
z_new = zx * x + zy * y + zz * z + zw * w
w_new = wx * x + wy * y + wz * z + ww * w
</pre></div>
<p>
</p>
<p>
Where w is normally 1
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>You must consider the members of the CoglMatrix structure read only,
and all matrix modifications must be done via the cogl_matrix API. This
allows Cogl to annotate the matrices internally. Violation of this will give
undefined results. If you need to initialize a matrix with a constant other
than the identity matrix you can use <a class="link" href="cogl-Matrices.html#cogl-matrix-init-from-array" title="cogl_matrix_init_from_array ()"><code class="function">cogl_matrix_init_from_array()</code></a>.</div>
<p>
</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-init-identity"></a><h3>cogl_matrix_init_identity ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_init_identity (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Resets matrix to the identity matrix:
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
.xx=1; .xy=0; .xz=0; .xw=0;
.yx=0; .yy=1; .yz=0; .yw=0;
.zx=0; .zy=0; .zz=1; .zw=0;
.wx=0; .wy=0; .wz=0; .ww=1;
</pre></div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-copy"></a><h3>cogl_matrix_copy ()</h3>
<pre class="programlisting"><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="returnvalue">CoglMatrix</span></a> * cogl_matrix_copy (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Allocates a new <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> on the heap and initializes it with
the same values as <em class="parameter"><code>matrix</code></em>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix you want to copy</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>A newly allocated <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> which should be freed using
<a class="link" href="cogl-Matrices.html#cogl-matrix-free" title="cogl_matrix_free ()"><code class="function">cogl_matrix_free()</code></a>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.6</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-equal"></a><h3>cogl_matrix_equal ()</h3>
<pre class="programlisting"><span class="returnvalue">gboolean</span> cogl_matrix_equal (<em class="parameter"><code><span class="type">gconstpointer</span> v1</code></em>,
<em class="parameter"><code><span class="type">gconstpointer</span> v2</code></em>);</pre>
<p>
Compares two matrices to see if they represent the same
transformation. Although internally the matrices may have different
annotations associated with them and may potentially have a cached
inverse matrix these are not considered in the comparison.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>v1</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>v2</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.4</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-free"></a><h3>cogl_matrix_free ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_free (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Frees a <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> that was previously allocated via a call to
<a class="link" href="cogl-Matrices.html#cogl-matrix-copy" title="cogl_matrix_copy ()"><code class="function">cogl_matrix_copy()</code></a>.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix you want to free</td>
</tr></tbody>
</table></div>
<p class="since">Since 1.6</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-frustum"></a><h3>cogl_matrix_frustum ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_frustum (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> left</code></em>,
<em class="parameter"><code><span class="type">float</span> right</code></em>,
<em class="parameter"><code><span class="type">float</span> bottom</code></em>,
<em class="parameter"><code><span class="type">float</span> top</code></em>,
<em class="parameter"><code><span class="type">float</span> z_near</code></em>,
<em class="parameter"><code><span class="type">float</span> z_far</code></em>);</pre>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> by the given frustum perspective matrix.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>left</code></em> :</span></p></td>
<td>X position of the left clipping plane where it
intersects the near clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>right</code></em> :</span></p></td>
<td>X position of the right clipping plane where it
intersects the near clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>bottom</code></em> :</span></p></td>
<td>Y position of the bottom clipping plane where it
intersects the near clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>top</code></em> :</span></p></td>
<td>Y position of the top clipping plane where it intersects
the near clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z_near</code></em> :</span></p></td>
<td>The distance to the near clipping plane (Must be positive)</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z_far</code></em> :</span></p></td>
<td>The distance to the far clipping plane (Must be positive)</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-ortho"></a><h3>cogl_matrix_ortho ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_ortho (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> left</code></em>,
<em class="parameter"><code><span class="type">float</span> right</code></em>,
<em class="parameter"><code><span class="type">float</span> bottom</code></em>,
<em class="parameter"><code><span class="type">float</span> top</code></em>,
<em class="parameter"><code><span class="type">float</span> near</code></em>,
<em class="parameter"><code><span class="type">float</span> far</code></em>);</pre>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Warning</h3>
<p><code class="literal">cogl_matrix_ortho</code> has been deprecated since version 1.10 and should not be used in newly-written code. Use <code class="function">cogl_matrix_orthographic()</code></p>
</div>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> by a parallel projection matrix.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>left</code></em> :</span></p></td>
<td>The coordinate for the left clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>right</code></em> :</span></p></td>
<td>The coordinate for the right clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>bottom</code></em> :</span></p></td>
<td>The coordinate for the bottom clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>top</code></em> :</span></p></td>
<td>The coordinate for the top clipping plane</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>near</code></em> :</span></p></td>
<td>The <span class="emphasis"><em>distance</em></span> to the near clipping
plane (will be <span class="emphasis"><em>negative</em></span> if the plane is
behind the viewer)</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>far</code></em> :</span></p></td>
<td>The <span class="emphasis"><em>distance</em></span> to the far clipping
plane (will be <span class="emphasis"><em>negative</em></span> if the plane is
behind the viewer)</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-perspective"></a><h3>cogl_matrix_perspective ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_perspective (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> fov_y</code></em>,
<em class="parameter"><code><span class="type">float</span> aspect</code></em>,
<em class="parameter"><code><span class="type">float</span> z_near</code></em>,
<em class="parameter"><code><span class="type">float</span> z_far</code></em>);</pre>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> by the described perspective matrix
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>You should be careful not to have to great a <em class="parameter"><code>z_far</code></em> / <em class="parameter"><code>z_near</code></em>
ratio since that will reduce the effectiveness of depth testing
since there wont be enough precision to identify the depth of
objects near to each other.</div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>fov_y</code></em> :</span></p></td>
<td>Vertical field of view angle in degrees.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>aspect</code></em> :</span></p></td>
<td>The (width over height) aspect ratio for display</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z_near</code></em> :</span></p></td>
<td>The distance to the near clipping plane (Must be positive,
and must not be 0)</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z_far</code></em> :</span></p></td>
<td>The distance to the far clipping plane (Must be positive)</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-multiply"></a><h3>cogl_matrix_multiply ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_multiply (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *result</code></em>,
<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *a</code></em>,
<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *b</code></em>);</pre>
<p>
Multiplies the two supplied matrices together and stores
the resulting matrix inside <em class="parameter"><code>result</code></em>.
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>It is possible to multiply the <em class="parameter"><code>a</code></em> matrix in-place, so
<em class="parameter"><code>result</code></em> can be equal to <em class="parameter"><code>a</code></em> but can't be equal to <em class="parameter"><code>b</code></em>.</div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>result</code></em> :</span></p></td>
<td>The address of a 4x4 matrix to store the result in</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>a</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>b</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-rotate"></a><h3>cogl_matrix_rotate ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_rotate (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> angle</code></em>,
<em class="parameter"><code><span class="type">float</span> x</code></em>,
<em class="parameter"><code><span class="type">float</span> y</code></em>,
<em class="parameter"><code><span class="type">float</span> z</code></em>);</pre>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> with a rotation matrix that applies a rotation
of <em class="parameter"><code>angle</code></em> degrees around the specified 3D vector.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>angle</code></em> :</span></p></td>
<td>The angle you want to rotate in degrees</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>X component of your rotation vector</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>Y component of your rotation vector</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>Z component of your rotation vector</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-translate"></a><h3>cogl_matrix_translate ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_translate (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> x</code></em>,
<em class="parameter"><code><span class="type">float</span> y</code></em>,
<em class="parameter"><code><span class="type">float</span> z</code></em>);</pre>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> with a transform matrix that translates along
the X, Y and Z axis.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>The X translation you want to apply</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>The Y translation you want to apply</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>The Z translation you want to apply</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-scale"></a><h3>cogl_matrix_scale ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_scale (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> sx</code></em>,
<em class="parameter"><code><span class="type">float</span> sy</code></em>,
<em class="parameter"><code><span class="type">float</span> sz</code></em>);</pre>
<p>
Multiplies <em class="parameter"><code>matrix</code></em> with a transform matrix that scales along the X,
Y and Z axis.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>sx</code></em> :</span></p></td>
<td>The X scale factor</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>sy</code></em> :</span></p></td>
<td>The Y scale factor</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>sz</code></em> :</span></p></td>
<td>The Z scale factor</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-transpose"></a><h3>cogl_matrix_transpose ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_transpose (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Replaces <em class="parameter"><code>matrix</code></em> with its transpose. Ie, every element (i,j) in the
new matrix is taken from element (j,i) in the old matrix.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a>
</td>
</tr></tbody>
</table></div>
<p class="since">Since 1.10</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-init-from-array"></a><h3>cogl_matrix_init_from_array ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_init_from_array (<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code>const <span class="type">float</span> *array</code></em>);</pre>
<p>
Initializes <em class="parameter"><code>matrix</code></em> with the contents of <em class="parameter"><code>array</code></em>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>array</code></em> :</span></p></td>
<td>A linear array of 16 floats (column-major order)</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-get-array"></a><h3>cogl_matrix_get_array ()</h3>
<pre class="programlisting">const <span class="returnvalue">float</span> * cogl_matrix_get_array (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Casts <em class="parameter"><code>matrix</code></em> to a float array which can be directly passed to OpenGL.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>a pointer to the float array</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-get-inverse"></a><h3>cogl_matrix_get_inverse ()</h3>
<pre class="programlisting"><span class="returnvalue">gboolean</span> cogl_matrix_get_inverse (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *inverse</code></em>);</pre>
<p>
Gets the inverse transform of a given matrix and uses it to initialize
a new <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a>.
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>Although the first parameter is annotated as const to indicate
that the transform it represents isn't modified this function may
technically save a copy of the inverse transform within the given
<a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> so that subsequent requests for the inverse transform may
avoid costly inversion calculations.</div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>inverse</code></em> :</span></p></td>
<td>The destination for a 4x4 inverse transformation matrix. <span class="annotation">[<acronym title="Parameter for returning results. Default is transfer full."><span class="acronym">out</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>
<code class="literal">TRUE</code> if the inverse was successfully calculated or <code class="literal">FALSE</code>
for degenerate transformations that can't be inverted (in this case the
<em class="parameter"><code>inverse</code></em> matrix will simply be initialized with the identity matrix)</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.2</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-transform-point"></a><h3>cogl_matrix_transform_point ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_transform_point (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">float</span> *x</code></em>,
<em class="parameter"><code><span class="type">float</span> *y</code></em>,
<em class="parameter"><code><span class="type">float</span> *z</code></em>,
<em class="parameter"><code><span class="type">float</span> *w</code></em>);</pre>
<p>
Transforms a point whos position is given and returned as four float
components.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A 4x4 transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>x</code></em> :</span></p></td>
<td>The X component of your points position. <span class="annotation">[<acronym title="Parameter for input and for returning results. Default is transfer full."><span class="acronym">inout</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>y</code></em> :</span></p></td>
<td>The Y component of your points position. <span class="annotation">[<acronym title="Parameter for input and for returning results. Default is transfer full."><span class="acronym">inout</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>z</code></em> :</span></p></td>
<td>The Z component of your points position. <span class="annotation">[<acronym title="Parameter for input and for returning results. Default is transfer full."><span class="acronym">inout</span></acronym>]</span>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>w</code></em> :</span></p></td>
<td>The W component of your points position. <span class="annotation">[<acronym title="Parameter for input and for returning results. Default is transfer full."><span class="acronym">inout</span></acronym>]</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-project-points"></a><h3>cogl_matrix_project_points ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_project_points (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">int</span> n_components</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_in</code></em>,
<em class="parameter"><code>const <span class="type">void</span> *points_in</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_out</code></em>,
<em class="parameter"><code><span class="type">void</span> *points_out</code></em>,
<em class="parameter"><code><span class="type">int</span> n_points</code></em>);</pre>
<p>
Projects an array of input points and writes the result to another
array of output points. The input points can either have 2, 3 or 4
components each. The output points always have 4 components (known
as homogenous coordinates). The output array can simply point to
the input array to do the transform in-place.
</p>
<p>
Here's an example with differing input/output strides:
</p>
<div class="informalexample"><pre class="programlisting">
typedef struct {
float x,y;
guint8 r,g,b,a;
float s,t,p;
} MyInVertex;
typedef struct {
guint8 r,g,b,a;
float x,y,z;
} MyOutVertex;
MyInVertex vertices[N_VERTICES];
MyOutVertex results[N_VERTICES];
CoglMatrix matrix;
my_load_vertices (vertices);
my_get_matrix (&matrix);
cogl_matrix_project_points (&matrix,
2,
sizeof (MyInVertex),
&vertices[0].x,
sizeof (MyOutVertex),
&results[0].x,
N_VERTICES);
</pre></div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A projection matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_components</code></em> :</span></p></td>
<td>The number of position components for each input point.
(either 2, 3 or 4)</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>stride_in</code></em> :</span></p></td>
<td>The stride in bytes between input points.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>points_in</code></em> :</span></p></td>
<td>A pointer to the first component of the first input point.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>stride_out</code></em> :</span></p></td>
<td>The stride in bytes between output points.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>points_out</code></em> :</span></p></td>
<td>A pointer to the first component of the first output point.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_points</code></em> :</span></p></td>
<td>The number of points to transform.</td>
</tr>
</tbody>
</table></div>
<p class="stability">Stability Level: Unstable</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-transform-points"></a><h3>cogl_matrix_transform_points ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_matrix_transform_points (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>,
<em class="parameter"><code><span class="type">int</span> n_components</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_in</code></em>,
<em class="parameter"><code>const <span class="type">void</span> *points_in</code></em>,
<em class="parameter"><code><span class="type">size_t</span> stride_out</code></em>,
<em class="parameter"><code><span class="type">void</span> *points_out</code></em>,
<em class="parameter"><code><span class="type">int</span> n_points</code></em>);</pre>
<p>
Transforms an array of input points and writes the result to
another array of output points. The input points can either have 2
or 3 components each. The output points always have 3 components.
The output array can simply point to the input array to do the
transform in-place.
</p>
<p>
If you need to transform 4 component points see
<a class="link" href="cogl-Matrices.html#cogl-matrix-project-points" title="cogl_matrix_project_points ()"><code class="function">cogl_matrix_project_points()</code></a>.
</p>
<p>
Here's an example with differing input/output strides:
</p>
<div class="informalexample"><pre class="programlisting">
typedef struct {
float x,y;
guint8 r,g,b,a;
float s,t,p;
} MyInVertex;
typedef struct {
guint8 r,g,b,a;
float x,y,z;
} MyOutVertex;
MyInVertex vertices[N_VERTICES];
MyOutVertex results[N_VERTICES];
CoglMatrix matrix;
my_load_vertices (vertices);
my_get_matrix (&matrix);
cogl_matrix_transform_points (&matrix,
2,
sizeof (MyInVertex),
&vertices[0].x,
sizeof (MyOutVertex),
&results[0].x,
N_VERTICES);
</pre></div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A transformation matrix</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_components</code></em> :</span></p></td>
<td>The number of position components for each input point.
(either 2 or 3)</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>stride_in</code></em> :</span></p></td>
<td>The stride in bytes between input points.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>points_in</code></em> :</span></p></td>
<td>A pointer to the first component of the first input point.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>stride_out</code></em> :</span></p></td>
<td>The stride in bytes between output points.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>points_out</code></em> :</span></p></td>
<td>A pointer to the first component of the first output point.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>n_points</code></em> :</span></p></td>
<td>The number of points to transform.</td>
</tr>
</tbody>
</table></div>
<p class="stability">Stability Level: Unstable</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-matrix-is-identity"></a><h3>cogl_matrix_is_identity ()</h3>
<pre class="programlisting"><span class="returnvalue">gboolean</span> cogl_matrix_is_identity (<em class="parameter"><code>const <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a> *matrix</code></em>);</pre>
<p>
Determines if the given matrix is an identity matrix.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>matrix</code></em> :</span></p></td>
<td>A <a class="link" href="cogl-Matrices.html#CoglMatrix" title="CoglMatrix"><span class="type">CoglMatrix</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>
<code class="literal">TRUE</code> if <em class="parameter"><code>matrix</code></em> is an identity matrix else <code class="literal">FALSE</code>
</td>
</tr>
</tbody>
</table></div>
<p class="since">Since 1.8</p>
</div>
</div>
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