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authorBrian Paul <brianp@vmware.com>2009-04-07 11:09:53 -0600
committerBrian Paul <brianp@vmware.com>2009-04-07 11:09:53 -0600
commit439909a87d50723c2dba0ee1539467f1f4bf8bf0 (patch)
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docs: document the MESA_GLSL env var, other misc GLSL updates
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@@ -22,6 +22,7 @@ Last updated on 15 December 2008.
Contents
</p>
<ul>
+<li><a href="#envvars">Environment variables</a>
<li><a href="#120">GLSL 1.20 support</a>
<li><a href="#unsup">Unsupported Features</a>
<li><a href="#notes">Implementation Notes</a>
@@ -33,11 +34,32 @@ Contents
+<a name="envvars">
+<h2>Environment Variables</h2>
+
+<p>
+The <b>MESA_GLSL</b> environment variable can be set to a comma-separated
+list of keywords to control some aspects of the GLSL compiler:
+</p>
+<ul>
+<li>dump - print GLSL shader code to stdout at link time
+<li>log - log all GLSL shaders to files.
+ The filenames will be "shader_X.vert" or "shader_X.frag" where X
+ the shader ID.
+<li>nopt - disable compiler optimizations
+<li>opt - force compiler optimizations
+<li>uniform - print message to stdout when glUniform is called
+</ul>
+<p>
+Example: export MESA_GLSL=dump,nopt
+</p>
+
+
<a name="120">
<h2>GLSL 1.20 support</h2>
<p>
-GLSL version 1.20 is supported in Mesa 7.3.
+GLSL version 1.20 is supported in Mesa 7.3 and later.
Among the features/differences of GLSL 1.20 are:
<ul>
<li><code>mat2x3, mat2x4</code>, etc. types and functions
@@ -59,12 +81,14 @@ Among the features/differences of GLSL 1.20 are:
<h2>Unsupported Features</h2>
<p>
-The following features of the shading language are not yet supported
+The following features of the shading language are not yet fully supported
in Mesa:
</p>
<ul>
-<li>Linking of multiple shaders is not supported
+<li>Linking of multiple shaders does not always work. Currently, linking
+ is implemented through shader concatenation and re-compiling. This
+ doesn't always work because of some #pragma and preprocessor issues.
<li>gl_ClipVertex
<li>The gl_Color and gl_SecondaryColor varying vars are interpolated
without perspective correction
@@ -177,6 +201,8 @@ This tool is useful for:
After building Mesa, the glslcompiler can be built by manually running:
</p>
<pre>
+ make realclean
+ make linux
cd src/mesa/drivers/glslcompiler
make
</pre>