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diff --git a/mesalib/docs/shading.html b/mesalib/docs/shading.html index c41d4a9be..cc1f9f1ec 100644 --- a/mesalib/docs/shading.html +++ b/mesalib/docs/shading.html @@ -1,268 +1,268 @@ -<HTML> - -<TITLE>Shading Language Support</TITLE> - -<link rel="stylesheet" type="text/css" href="mesa.css"></head> - -<BODY> - -<H1>Shading Language Support</H1> - -<p> -This page describes the features and status of Mesa's support for the -<a href="http://opengl.org/documentation/glsl/" target="_parent"> -OpenGL Shading Language</a>. -</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> -</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><b>dump</b> - print GLSL shader code to stdout at link time -<li><b>log</b> - log all GLSL shaders to files. - The filenames will be "shader_X.vert" or "shader_X.frag" where X - the shader ID. -<li><b>nopt</b> - disable compiler optimizations -<li><b>opt</b> - force compiler optimizations -<li><b>uniform</b> - print message to stdout when glUniform is called -<li><b>nopvert</b> - 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><b>nopfrag</b> - force fragment shader to be a simple shader that passes - through the color attribute. -<li><b>useprog</b> - log glUseProgram calls to stderr -</ul> -<p> -Example: export MESA_GLSL=dump,nopt -</p> - - -<a name="120"> -<h2>GLSL Version</h2> - -<p> -The GLSL compiler currently supports version 1.20 of the shading language. -</p> - -<p> -Several GLSL extensions are also supported: -</p> -<ul> -<li>GL_ARB_draw_buffers -<li>GL_ARB_texture_rectangle -<li>GL_ARB_fragment_coord_conventions -<li>GL_EXT_texture_array -</ul> - - -<a name="unsup"> -<h2>Unsupported Features</h2> - -<p>XXX update this section</p> - -<p> -The following features of the shading language are not yet fully supported -in Mesa: -</p> - -<ul> -<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 -</ul> - -<p> -All other major features of the shading language should function. -</p> - - -<a name="notes"> -<h2>Implementation Notes</h2> - -<ul> -<li>Shading language programs are compiled into low-level programs - very similar to those of GL_ARB_vertex/fragment_program. -<li>All vector types (vec2, vec3, vec4, bvec2, etc) currently occupy full - float[4] registers. -<li>Float constants and variables are packed so that up to four floats - can occupy one program parameter/register. -<li>All function calls are inlined. -<li>Shaders which use too many registers will not compile. -<li>The quality of generated code is pretty good, register usage is fair. -<li>Shader error detection and reporting of errors (InfoLog) is not - very good yet. -<li>The ftransform() function doesn't necessarily match the results of - fixed-function transformation. -</ul> - -<p> -These issues will be addressed/resolved in the future. -</p> - - -<a name="hints"> -<h2>Programming Hints</h2> - -<ul> -<li>Use the built-in library functions whenever possible. - For example, instead of writing this: -<pre> - float x = 1.0 / sqrt(y); -</pre> - Write this: -<pre> - float x = inversesqrt(y); -</pre> -</li> -</ul> - - -<a name="standalone"> -<h2>Stand-alone GLSL Compiler</h2> - -<p> -The stand-alone GLSL compiler program can be used to compile GLSL shaders -into low-level GPU code. -</p> - -<p> -This tool is useful for: -<p> -<ul> -<li>Inspecting GPU code to gain insight into compilation -<li>Generating initial GPU code for subsequent hand-tuning -<li>Debugging the GLSL compiler itself -</ul> - -<p> -After building Mesa, the compiler can be found at src/glsl/glsl_compiler -</p> - -<p> -Here's an example of using the compiler to compile a vertex shader and -emit GL_ARB_vertex_program-style instructions: -</p> -<pre> - src/glsl/glslcompiler --dump-ast myshader.vert -</pre> - -Options include -<ul> -<li><b>--dump-ast</b> - dump GPU code -<li><b>--dump-hir</b> - dump high-level IR code -<li><b>--dump-lir</b> - dump low-level IR code -<li><b>--link</b> - ??? -</ul> - - - - -<a name="implementation"> -<h2>Compiler Implementation</h2> - -<p> -The source code for Mesa's shading language compiler is in the -<code>src/glsl/</code> directory. -</p> - -<p> -XXX provide some info about the compiler.... -</p> - -<p> -The final vertex and fragment programs may be interpreted in software -(see prog_execute.c) or translated into a specific hardware architecture -(see drivers/dri/i915/i915_fragprog.c for example). -</p> - -<h3>Code Generation Options</h3> - -<p> -Internally, there are several options that control the compiler's code -generation and instruction selection. -These options are seen in the gl_shader_state struct and may be set -by the device driver to indicate its preferences: - -<pre> -struct gl_shader_state -{ - ... - /** Driver-selectable options: */ - GLboolean EmitHighLevelInstructions; - GLboolean EmitCondCodes; - GLboolean EmitComments; -}; -</pre> - -<ul> -<li>EmitHighLevelInstructions -<br> -This option controls instruction selection for loops and conditionals. -If the option is set high-level IF/ELSE/ENDIF, LOOP/ENDLOOP, CONT/BRK -instructions will be emitted. -Otherwise, those constructs will be implemented with BRA instructions. -</li> - -<li>EmitCondCodes -<br> -If set, condition codes (ala GL_NV_fragment_program) will be used for -branching and looping. -Otherwise, ordinary registers will be used (the IF instruction will -examine the first operand's X component and do the if-part if non-zero). -This option is only relevant if EmitHighLevelInstructions is set. -</li> - -<li>EmitComments -<br> -If set, instructions will be annoted with comments to help with debugging. -Extra NOP instructions will also be inserted. -</br> - -</ul> - - -<a name="validation"> -<h2>Compiler Validation</h2> - -<p> -Developers working on the GLSL compiler should test frequently to avoid -regressions. -</p> - -<p> -The <a href="http://people.freedesktop.org/~nh/piglit/">Piglit</a> project -has many GLSL tests and the -<a href="http://glean.sf.net" target="_parent">Glean</a> glsl1 test -tests GLSL features. -</p> - -<p> -The Mesa demos repository also has some good GLSL tests. -</p> - -</BODY> -</HTML> +<HTML>
+
+<TITLE>Shading Language Support</TITLE>
+
+<link rel="stylesheet" type="text/css" href="mesa.css"></head>
+
+<BODY>
+
+<H1>Shading Language Support</H1>
+
+<p>
+This page describes the features and status of Mesa's support for the
+<a href="http://opengl.org/documentation/glsl/" target="_parent">
+OpenGL Shading Language</a>.
+</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>
+</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><b>dump</b> - print GLSL shader code to stdout at link time
+<li><b>log</b> - log all GLSL shaders to files.
+ The filenames will be "shader_X.vert" or "shader_X.frag" where X
+ the shader ID.
+<li><b>nopt</b> - disable compiler optimizations
+<li><b>opt</b> - force compiler optimizations
+<li><b>uniform</b> - print message to stdout when glUniform is called
+<li><b>nopvert</b> - 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><b>nopfrag</b> - force fragment shader to be a simple shader that passes
+ through the color attribute.
+<li><b>useprog</b> - log glUseProgram calls to stderr
+</ul>
+<p>
+Example: export MESA_GLSL=dump,nopt
+</p>
+
+
+<a name="120">
+<h2>GLSL Version</h2>
+
+<p>
+The GLSL compiler currently supports version 1.20 of the shading language.
+</p>
+
+<p>
+Several GLSL extensions are also supported:
+</p>
+<ul>
+<li>GL_ARB_draw_buffers
+<li>GL_ARB_texture_rectangle
+<li>GL_ARB_fragment_coord_conventions
+<li>GL_EXT_texture_array
+</ul>
+
+
+<a name="unsup">
+<h2>Unsupported Features</h2>
+
+<p>XXX update this section</p>
+
+<p>
+The following features of the shading language are not yet fully supported
+in Mesa:
+</p>
+
+<ul>
+<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
+</ul>
+
+<p>
+All other major features of the shading language should function.
+</p>
+
+
+<a name="notes">
+<h2>Implementation Notes</h2>
+
+<ul>
+<li>Shading language programs are compiled into low-level programs
+ very similar to those of GL_ARB_vertex/fragment_program.
+<li>All vector types (vec2, vec3, vec4, bvec2, etc) currently occupy full
+ float[4] registers.
+<li>Float constants and variables are packed so that up to four floats
+ can occupy one program parameter/register.
+<li>All function calls are inlined.
+<li>Shaders which use too many registers will not compile.
+<li>The quality of generated code is pretty good, register usage is fair.
+<li>Shader error detection and reporting of errors (InfoLog) is not
+ very good yet.
+<li>The ftransform() function doesn't necessarily match the results of
+ fixed-function transformation.
+</ul>
+
+<p>
+These issues will be addressed/resolved in the future.
+</p>
+
+
+<a name="hints">
+<h2>Programming Hints</h2>
+
+<ul>
+<li>Use the built-in library functions whenever possible.
+ For example, instead of writing this:
+<pre>
+ float x = 1.0 / sqrt(y);
+</pre>
+ Write this:
+<pre>
+ float x = inversesqrt(y);
+</pre>
+</li>
+</ul>
+
+
+<a name="standalone">
+<h2>Stand-alone GLSL Compiler</h2>
+
+<p>
+The stand-alone GLSL compiler program can be used to compile GLSL shaders
+into low-level GPU code.
+</p>
+
+<p>
+This tool is useful for:
+<p>
+<ul>
+<li>Inspecting GPU code to gain insight into compilation
+<li>Generating initial GPU code for subsequent hand-tuning
+<li>Debugging the GLSL compiler itself
+</ul>
+
+<p>
+After building Mesa, the compiler can be found at src/glsl/glsl_compiler
+</p>
+
+<p>
+Here's an example of using the compiler to compile a vertex shader and
+emit GL_ARB_vertex_program-style instructions:
+</p>
+<pre>
+ src/glsl/glsl_compiler --dump-ast myshader.vert
+</pre>
+
+Options include
+<ul>
+<li><b>--dump-ast</b> - dump GPU code
+<li><b>--dump-hir</b> - dump high-level IR code
+<li><b>--dump-lir</b> - dump low-level IR code
+<li><b>--link</b> - ???
+</ul>
+
+
+
+
+<a name="implementation">
+<h2>Compiler Implementation</h2>
+
+<p>
+The source code for Mesa's shading language compiler is in the
+<code>src/glsl/</code> directory.
+</p>
+
+<p>
+XXX provide some info about the compiler....
+</p>
+
+<p>
+The final vertex and fragment programs may be interpreted in software
+(see prog_execute.c) or translated into a specific hardware architecture
+(see drivers/dri/i915/i915_fragprog.c for example).
+</p>
+
+<h3>Code Generation Options</h3>
+
+<p>
+Internally, there are several options that control the compiler's code
+generation and instruction selection.
+These options are seen in the gl_shader_state struct and may be set
+by the device driver to indicate its preferences:
+
+<pre>
+struct gl_shader_state
+{
+ ...
+ /** Driver-selectable options: */
+ GLboolean EmitHighLevelInstructions;
+ GLboolean EmitCondCodes;
+ GLboolean EmitComments;
+};
+</pre>
+
+<ul>
+<li>EmitHighLevelInstructions
+<br>
+This option controls instruction selection for loops and conditionals.
+If the option is set high-level IF/ELSE/ENDIF, LOOP/ENDLOOP, CONT/BRK
+instructions will be emitted.
+Otherwise, those constructs will be implemented with BRA instructions.
+</li>
+
+<li>EmitCondCodes
+<br>
+If set, condition codes (ala GL_NV_fragment_program) will be used for
+branching and looping.
+Otherwise, ordinary registers will be used (the IF instruction will
+examine the first operand's X component and do the if-part if non-zero).
+This option is only relevant if EmitHighLevelInstructions is set.
+</li>
+
+<li>EmitComments
+<br>
+If set, instructions will be annoted with comments to help with debugging.
+Extra NOP instructions will also be inserted.
+</br>
+
+</ul>
+
+
+<a name="validation">
+<h2>Compiler Validation</h2>
+
+<p>
+Developers working on the GLSL compiler should test frequently to avoid
+regressions.
+</p>
+
+<p>
+The <a href="http://people.freedesktop.org/~nh/piglit/">Piglit</a> project
+has many GLSL tests and the
+<a href="http://glean.sf.net" target="_parent">Glean</a> glsl1 test
+tests GLSL features.
+</p>
+
+<p>
+The Mesa demos repository also has some good GLSL tests.
+</p>
+
+</BODY>
+</HTML>
|