</p>
<p>
-Last updated on 28 March 2007.
+Last updated on 15 December 2008.
</p>
<p>
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>
<li><a href="#hints">Programming Hints</a>
<li><a href="#standalone">Stand-alone GLSL Compiler</a>
<li><a href="#implementation">Compiler Implementation</a>
<li><a href="#validation">Compiler Validation</a>
-<li><a href="#120">GLSL 1.20 support</a>
</ul>
+
+<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 and shader
+execution. These are generally used for debugging.
+</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
+<li>nopvert - force vertex shaders to be a simple shader that just transforms
+ the vertex position with ftransform() and passes through the color and
+ texcoord[0] attributes.
+<li>nopfrag - force fragment shader to be a simple shader that passes
+ through the color attribute.
+<li>useprog - log glUseProgram calls to stderr
+</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 and later.
+Among the features/differences of GLSL 1.20 are:
+<ul>
+<li><code>mat2x3, mat2x4</code>, etc. types and functions
+<li><code>transpose(), outerProduct(), matrixCompMult()</code> functions
+(but untested)
+<li>precision qualifiers (lowp, mediump, highp)
+<li><code>invariant</code> qualifier
+<li><code>array.length()</code> method
+<li><code>float[5] a;</code> array syntax
+<li><code>centroid</code> qualifier
+<li>unsized array constructors
+<li>initializers for uniforms
+<li>const initializers calling built-in functions
+</ul>
+
+
+
<a name="unsup">
<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>Dereferencing arrays with non-constant indexes
-<li>Comparison of user-defined structs
-<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 derivative functions such as dFdx() are not implemented
-<li>The inverse trig functions asin(), acos(), and atan() are not implemented
<li>The gl_Color and gl_SecondaryColor varying vars are interpolated
without perspective correction
-<li>Floating point literal suffixes 'f' and 'F' aren't allowed.
</ul>
<p>
After building Mesa, the glslcompiler can be built by manually running:
</p>
<pre>
+ make realclean
+ make linux
cd src/mesa/drivers/glslcompiler
make
</pre>
<h2>Compiler Validation</h2>
<p>
-A
new <a href="http://glean.sf.net" target="_parent">Glean</a> test has
+A <a href="http://glean.sf.net" target="_parent">Glean</a> test has
been create to exercise the GLSL compiler.
</p>
<p>
-The <em>glsl1</em> test runs over 150 sub-tests to check that the language
+The <em>glsl1</em> test runs over 170 sub-tests to check that the language
features and built-in functions work properly.
This test should be run frequently while working on the compiler to catch
regressions.
</p>
-
-<a name="120">
-<h2>GLSL 1.20 support</h2>
-
-<p>
-Support for GLSL version 1.20 is underway. Status as follows.
-</p>
-
-<h3>Supported</h3>
-<ul>
-<li><code>mat2x3, mat2x4</code>, etc. types and functions
-<li><code>transpose(), outerProduct(), matrixCompMult()</code> functions
-(but untested)
-<li>precision qualifiers (lowp, mediump, highp)
-</ul>
-
-<h3>Partially Complete</h3>
-<ul>
-<li><code>invariant</code> qualifier
-</ul>
-
-<h3>Not Completed</h3>
-<ul>
-<li><code>array.length()</code> method
-<li><code>float[5] a;</code> array syntax
-<li><code>centroid</code> qualifier
-<li>unsized array constructors
-<li>initializers for uniforms
-<li>const initializers calling built-in functions
-</ul>
-
-
-
-
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