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1 files changed, 268 insertions, 268 deletions
diff --git a/mesalib/docs/shading.html b/mesalib/docs/shading.html index cc1f9f1ec..aba395974 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/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>
+<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> |