/usr/share/gtk-doc/html/cogl/cogl-Offscreen-Buffers.html is in libcogl-doc 1.10.0-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Offscreen Buffers</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.76.1">
<link rel="home" href="index.html" title="Cogl Reference Manual">
<link rel="up" href="ch01.html" title="Cogl - a modern 3D graphics API">
<link rel="prev" href="cogl-Shaders-and-Programmable-Pipeline.html" title="Shaders and Programmable Pipeline">
<link rel="next" href="cogl-Bitmaps.html" title="Bitmaps">
<meta name="generator" content="GTK-Doc V1.18 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2">
<tr valign="middle">
<td><a accesskey="p" href="cogl-Shaders-and-Programmable-Pipeline.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td>
<td><a accesskey="u" href="ch01.html"><img src="up.png" width="24" height="24" border="0" alt="Up"></a></td>
<td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td>
<th width="100%" align="center">Cogl Reference Manual</th>
<td><a accesskey="n" href="cogl-Bitmaps.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td>
</tr>
<tr><td colspan="5" class="shortcuts">
<a href="#cogl-Offscreen-Buffers.synopsis" class="shortcut">Top</a>
|
<a href="#cogl-Offscreen-Buffers.description" class="shortcut">Description</a>
</td></tr>
</table>
<div class="refentry">
<a name="cogl-Offscreen-Buffers"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="cogl-Offscreen-Buffers.top_of_page"></a>Offscreen Buffers</span></h2>
<p>Offscreen Buffers — Fuctions for creating and manipulating offscreen
framebuffers.</p>
</td>
<td valign="top" align="right"></td>
</tr></table></div>
<div class="refsynopsisdiv">
<a name="cogl-Offscreen-Buffers.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis"><span class="returnvalue">CoglOffscreen</span> * <a class="link" href="cogl-Offscreen-Buffers.html#cogl-offscreen-new-to-texture" title="cogl_offscreen_new_to_texture ()">cogl_offscreen_new_to_texture</a> (<em class="parameter"><code><span class="type">CoglTexture</span> *texture</code></em>);
<span class="returnvalue">gboolean</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-is-offscreen" title="cogl_is_offscreen ()">cogl_is_offscreen</a> (<em class="parameter"><code><span class="type">void</span> *object</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-set-framebuffer" title="cogl_set_framebuffer ()">cogl_set_framebuffer</a> (<em class="parameter"><code><span class="type">CoglFramebuffer</span> *buffer</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-push-framebuffer" title="cogl_push_framebuffer ()">cogl_push_framebuffer</a> (<em class="parameter"><code><span class="type">CoglFramebuffer</span> *buffer</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-pop-framebuffer" title="cogl_pop_framebuffer ()">cogl_pop_framebuffer</a> (<em class="parameter"><code><span class="type">void</span></code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-set-draw-buffer" title="cogl_set_draw_buffer ()">cogl_set_draw_buffer</a> (<em class="parameter"><code><a class="link" href="cogl-General-API.html#CoglBufferTarget" title="enum CoglBufferTarget"><span class="type">CoglBufferTarget</span></a> target</code></em>,
<em class="parameter"><code><a class="link" href="cogl-General-API.html#CoglHandle" title="CoglHandle"><span class="type">CoglHandle</span></a> offscreen</code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-pop-draw-buffer" title="cogl_pop_draw_buffer ()">cogl_pop_draw_buffer</a> (<em class="parameter"><code><span class="type">void</span></code></em>);
<span class="returnvalue">void</span> <a class="link" href="cogl-Offscreen-Buffers.html#cogl-push-draw-buffer" title="cogl_push_draw_buffer ()">cogl_push_draw_buffer</a> (<em class="parameter"><code><span class="type">void</span></code></em>);
</pre>
</div>
<div class="refsect1">
<a name="cogl-Offscreen-Buffers.description"></a><h2>Description</h2>
<p>
Cogl allows creating and operating on offscreen framebuffers.
</p>
</div>
<div class="refsect1">
<a name="cogl-Offscreen-Buffers.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="cogl-offscreen-new-to-texture"></a><h3>cogl_offscreen_new_to_texture ()</h3>
<pre class="programlisting"><span class="returnvalue">CoglOffscreen</span> * cogl_offscreen_new_to_texture (<em class="parameter"><code><span class="type">CoglTexture</span> *texture</code></em>);</pre>
<p>
This creates an offscreen buffer object using the given <em class="parameter"><code>texture</code></em> as the
primary color buffer. It doesn't just initialize the contents of the
offscreen buffer with the <em class="parameter"><code>texture</code></em>; they are tightly bound so that
drawing to the offscreen buffer effectivly updates the contents of the
given texture. You don't need to destroy the offscreen buffer before
you can use the <em class="parameter"><code>texture</code></em> again.
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>This only works with low-level <span class="type">CoglTexture</span> types such as
<span class="type">CoglTexture2D</span>, <span class="type">CoglTexture3D</span> and <span class="type">CoglTextureRectangle</span>, and not
with meta-texture types such as <span class="type">CoglTexture2DSliced</span>.</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>texture</code></em> :</span></p></td>
<td>A <span class="type">CoglTexture</span> pointer</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>a newly instantiated <span class="type">CoglOffscreen</span>
framebuffer or <code class="literal">NULL</code> if it wasn't possible to create the
buffer. <span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-is-offscreen"></a><h3>cogl_is_offscreen ()</h3>
<pre class="programlisting"><span class="returnvalue">gboolean</span> cogl_is_offscreen (<em class="parameter"><code><span class="type">void</span> *object</code></em>);</pre>
<p>
Determines whether the given <a class="link" href="cogl-General-API.html#CoglObject" title="CoglObject"><span class="type">CoglObject</span></a> references an offscreen
framebuffer object.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>object</code></em> :</span></p></td>
<td>A pointer to a <a class="link" href="cogl-General-API.html#CoglObject" title="CoglObject"><span class="type">CoglObject</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>object</code></em> is a <span class="type">CoglOffscreen</span> framebuffer,
<code class="literal">FALSE</code> otherwise</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-set-framebuffer"></a><h3>cogl_set_framebuffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_set_framebuffer (<em class="parameter"><code><span class="type">CoglFramebuffer</span> *buffer</code></em>);</pre>
<p>
This redirects all subsequent drawing to the specified framebuffer. This can
either be an offscreen buffer created with <a class="link" href="cogl-Offscreen-Buffers.html#cogl-offscreen-new-to-texture" title="cogl_offscreen_new_to_texture ()"><code class="function">cogl_offscreen_new_to_texture()</code></a>
or in the future it may be an onscreen framebuffers too.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term"><em class="parameter"><code>buffer</code></em> :</span></p></td>
<td>A <span class="type">CoglFramebuffer</span> object, either onscreen or offscreen.</td>
</tr></tbody>
</table></div>
<p class="since">Since 1.2</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-push-framebuffer"></a><h3>cogl_push_framebuffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_push_framebuffer (<em class="parameter"><code><span class="type">CoglFramebuffer</span> *buffer</code></em>);</pre>
<p>
Redirects all subsequent drawing to the specified framebuffer. This can
either be an offscreen buffer created with <a class="link" href="cogl-Offscreen-Buffers.html#cogl-offscreen-new-to-texture" title="cogl_offscreen_new_to_texture ()"><code class="function">cogl_offscreen_new_to_texture()</code></a>
or in the future it may be an onscreen framebuffer too.
</p>
<p>
You should understand that a framebuffer owns the following state:
</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">The projection matrix</li>
<li class="listitem">The modelview matrix stack</li>
<li class="listitem">The viewport</li>
<li class="listitem">The clip stack</li>
</ul></div>
<p>
So these items will automatically be saved and restored when you
push and pop between different framebuffers.
</p>
<p>
Also remember a newly allocated framebuffer will have an identity matrix for
the projection and modelview matrices which gives you a coordinate space
like OpenGL with (-1, -1) corresponding to the top left of the viewport,
(1, 1) corresponding to the bottom right and +z coming out towards the
viewer.
</p>
<p>
If you want to set up a coordinate space like Clutter does with (0, 0)
corresponding to the top left and (framebuffer_width, framebuffer_height)
corresponding to the bottom right you can do so like this:
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
static void
setup_viewport (unsigned int width,
unsigned int height,
float fovy,
float aspect,
float z_near,
float z_far)
{
float z_camera;
CoglMatrix projection_matrix;
CoglMatrix mv_matrix;
cogl_set_viewport (0, 0, width, height);
cogl_perspective (fovy, aspect, z_near, z_far);
cogl_get_projection_matrix (&projection_matrix);
z_camera = 0.5 * projection_matrix.xx;
cogl_matrix_init_identity (&mv_matrix);
cogl_matrix_translate (&mv_matrix, -0.5f, -0.5f, -z_camera);
cogl_matrix_scale (&mv_matrix, 1.0f / width, -1.0f / height, 1.0f / width);
cogl_matrix_translate (&mv_matrix, 0.0f, -1.0 * height, 0.0f);
cogl_set_modelview_matrix (&mv_matrix);
}
static void
my_init_framebuffer (ClutterStage *stage,
CoglFramebuffer *framebuffer,
unsigned int framebuffer_width,
unsigned int framebuffer_height)
{
ClutterPerspective perspective;
clutter_stage_get_perspective (stage, &perspective);
cogl_push_framebuffer (framebuffer);
setup_viewport (framebuffer_width,
framebuffer_height,
perspective.fovy,
perspective.aspect,
perspective.z_near,
perspective.z_far);
}
</pre></div>
<p>
</p>
<p>
The previous framebuffer can be restored by calling <a class="link" href="cogl-Offscreen-Buffers.html#cogl-pop-framebuffer" title="cogl_pop_framebuffer ()"><code class="function">cogl_pop_framebuffer()</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>buffer</code></em> :</span></p></td>
<td>A <span class="type">CoglFramebuffer</span> object, either onscreen or offscreen.</td>
</tr></tbody>
</table></div>
<p class="since">Since 1.2</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-pop-framebuffer"></a><h3>cogl_pop_framebuffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_pop_framebuffer (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>
Restores the framebuffer that was previously at the top of the stack.
All subsequent drawing will be redirected to this framebuffer.
</p>
<p class="since">Since 1.2</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-set-draw-buffer"></a><h3>cogl_set_draw_buffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_set_draw_buffer (<em class="parameter"><code><a class="link" href="cogl-General-API.html#CoglBufferTarget" title="enum CoglBufferTarget"><span class="type">CoglBufferTarget</span></a> target</code></em>,
<em class="parameter"><code><a class="link" href="cogl-General-API.html#CoglHandle" title="CoglHandle"><span class="type">CoglHandle</span></a> offscreen</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_set_draw_buffer</code> has been deprecated since version 1.2 and should not be used in newly-written code. The target argument was redundant since we could look at
the type of CoglHandle given instead.</p>
</div>
<p>
Redirects all subsequent drawing to the specified framebuffer. This
can either be an offscreen buffer created with
<a class="link" href="cogl-Offscreen-Buffers.html#cogl-offscreen-new-to-texture" title="cogl_offscreen_new_to_texture ()"><code class="function">cogl_offscreen_new_to_texture()</code></a> or you can revert to your original
on screen window buffer.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>target</code></em> :</span></p></td>
<td>A <a class="link" href="cogl-General-API.html#CoglBufferTarget" title="enum CoglBufferTarget"><span class="type">CoglBufferTarget</span></a> that specifies what kind of framebuffer you
are setting as the render target.</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>offscreen</code></em> :</span></p></td>
<td>If you are setting a framebuffer of type COGL_OFFSCREEN_BUFFER
then this is a CoglHandle for the offscreen buffer.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="cogl-pop-draw-buffer"></a><h3>cogl_pop_draw_buffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_pop_draw_buffer (<em class="parameter"><code><span class="type">void</span></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_pop_draw_buffer</code> has been deprecated since version 1.2 and should not be used in newly-written code. The draw buffer API was replaced with a framebuffer API</p>
</div>
<p>
Restore <a class="link" href="cogl-Offscreen-Buffers.html#cogl-set-draw-buffer" title="cogl_set_draw_buffer ()"><code class="function">cogl_set_draw_buffer()</code></a> state.
</p>
</div>
<hr>
<div class="refsect2">
<a name="cogl-push-draw-buffer"></a><h3>cogl_push_draw_buffer ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> cogl_push_draw_buffer (<em class="parameter"><code><span class="type">void</span></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_push_draw_buffer</code> has been deprecated since version 1.2 and should not be used in newly-written code. The draw buffer API was replaced with a framebuffer API</p>
</div>
<p>
Save <a class="link" href="cogl-Offscreen-Buffers.html#cogl-set-draw-buffer" title="cogl_set_draw_buffer ()"><code class="function">cogl_set_draw_buffer()</code></a> state.
</p>
</div>
</div>
</div>
<div class="footer">
<hr>
Generated by GTK-Doc V1.18</div>
</body>
</html>
|