mutter/cogl/cogl-snippet.h
Neil Roberts 7590fc3ec3 snippet: Add a hook for the vertex transform
This adds a hook to wrap or replace the vertex transform stage.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
2011-12-06 19:02:06 +00:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2011 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
*
*
* Authors:
* Neil Roberts <neil@linux.intel.com>
*/
#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_SNIPPET_H__
#define __COGL_SNIPPET_H__
#include <glib.h>
G_BEGIN_DECLS
/**
* SECTION:cogl-snippet
* @short_description: Functions for creating and manipulating shader snippets
*
* ...
*/
typedef struct _CoglSnippet CoglSnippet;
#define COGL_SNIPPET(OBJECT) ((CoglSnippet *)OBJECT)
/* Enumeration of all the hook points that a snippet can be attached
to within a pipeline. */
/**
* CoglSnippetHook:
* @COGL_SNIPPET_HOOK_VERTEX: A hook for the entire vertex processing
* stage of the pipeline.
* @COGL_SNIPPET_HOOK_VERTEX_TRANSFORM: A hook for the vertex transformation.
* @COGL_SNIPPET_HOOK_FRAGMENT: A hook for the entire fragment
* processing stage of the pipeline.
* @COGL_SNIPPET_HOOK_TEXTURE_COORD_TRANSFORM: A hook for applying the
* layer matrix to a texture coordinate for a layer.
* @COGL_SNIPPET_HOOK_LAYER_FRAGMENT: A hook for the fragment
* processing of a particular layer.
* @COGL_SNIPPET_HOOK_TEXTURE_LOOKUP: A hook for the texture lookup
* stage of a given layer in a pipeline.
*
* #CoglSnippetHook is used to specify a location within a
* #CoglPipeline where the code of the snippet should be used when it
* is attached to a pipeline.
*
* <glosslist>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_VERTEX</glossterm>
* <glossdef>
* <para>
* Adds a shader snippet that will hook on to the vertex processing
* stage of the pipeline. This gives a chance for the application to
* modify the vertex attributes generated by the shader. Typically the
* snippet will modify cogl_color_out or cogl_position_out builtins.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted at the top of the
* main() function before any vertex processing is done.
* </para>
* <para>
* The replace string in @snippet will be used instead of the
* generated vertex processing if it is present. This can be used if
* the application wants to provide a complete vertex shader and
* doesn't need the generated output from Cogl.
* </para>
* <para>
* The post string in @snippet will be inserted after all of the
* standard vertex processing is done. This can be used to modify the
* outputs.
* </para>
* </glossdef>
* </glossentry>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_VERTEX_TRANSFORM</glossterm>
* <glossdef>
* <para>
* Adds a shader snippet that will hook on to the vertex transform stage.
* Typically the snippet will use the cogl_modelview_matrix,
* cogl_projection_matrix and cogl_modelview_projection_matrix matrices and the
* cogl_position_in attribute. The hook must write to cogl_position_out.
* The default processing for this hook will multiply cogl_position_in by
* the combined modelview-projection matrix and store it on cogl_position_out.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted at the top of the
* main() function before the vertex transform is done.
* </para>
* <para>
* The replace string in @snippet will be used instead of the
* generated vertex transform if it is present.
* </para>
* <para>
* The post string in @snippet will be inserted after all of the
* standard vertex transformation is done. This can be used to modify the
* cogl_position_out in addition to the default processing.
* </para>
* </glossdef>
* </glossentry>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_FRAGMENT</glossterm>
* <glossdef>
* <para>
* Adds a shader snippet that will hook on to the fragment processing
* stage of the pipeline. This gives a chance for the application to
* modify the fragment color generated by the shader. Typically the
* snippet will modify cogl_color_out.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted at the top of the
* main() function before any fragment processing is done.
* </para>
* <para>
* The replace string in @snippet will be used instead of the
* generated fragment processing if it is present. This can be used if
* the application wants to provide a complete fragment shader and
* doesn't need the generated output from Cogl.
* </para>
* <para>
* The post string in @snippet will be inserted after all of the
* standard fragment processing is done. At this point the generated
* value for the rest of the pipeline state will already be in
* cogl_color_out so the application can modify the result by altering
* this variable.
* </para>
* </glossdef>
* </glossentry>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_TEXTURE_COORD_TRANSFORM</glossterm>
* Adds a shader snippet that will hook on to the texture coordinate
* transformation of a particular layer. This can be used to replace
* the processing for a layer or to modify the results.
* </para>
* <para>
* Within the snippet code for this hook there are two extra
* variables. The first is a mat4 called cogl_matrix which represents
* the user matrix for this layer. The second is called cogl_tex_coord
* and represents the incoming and outgoing texture coordinate. On
* entry to the hook, cogl_tex_coord contains the value of the
* corresponding texture coordinate attribute for this layer. The hook
* is expected to modify this variable. The output will be passed as a
* varying to the fragment processing stage. The default code will
* just multiply cogl_matrix by cogl_tex_coord and store the result in
* cogl_tex_coord.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted just before the
* fragment processing for this layer. At this point cogl_tex_coord
* still contains the value of the texture coordinate attribute.
* </para>
* <para>
* If a replace string is given then this will be used instead of
* the default fragment processing for this layer. The snippet can
* modify cogl_tex_coord or leave it as is to apply no transformation.
* </para>
* <para>
* The post string in @snippet will be inserted just after the
* transformation. At this point cogl_tex_coord will contain the
* results of the transformation but it can be further modified by the
* snippet.
* </para>
* </glossentry>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_LAYER_FRAGMENT</glossterm>
* Adds a shader snippet that will hook on to the fragment processing
* of a particular layer. This can be used to replace the processing
* for a layer or to modify the results.
* </para>
* <para>
* Within the snippet code for this hook there is an extra vec4
* variable called cogl_layer. This contains the resulting color
* that will be used for the layer. This can be modified in the post
* section or it the default processing can be replaced entirely using
* the replace section.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted just before the
* fragment processing for this layer.
* </para>
* <para>
* If a replace string is given then this will be used instead of
* the default fragment processing for this layer. The snippet must write to
* the cogl_layer variable in that case.
* </para>
* <para>
* The post string in @snippet will be inserted just after the
* fragment processing for the layer. The results can be modified by changing
* the value of the cogl_layer variable.
* </para>
* </glossentry>
* <glossentry>
* <glossterm>%COGL_SNIPPET_HOOK_TEXTURE_LOOKUP</glossterm>
* Adds a shader snippet that will hook on to the texture lookup part
* of a given layer. This gives a chance for the application to modify
* the coordinates that will be used for the texture lookup or to
* alter the returned texel.
* </para>
* <para>
* Within the snippet code for this hook there are two extra variables
* available. cogl_tex_coord is a vec4 which contains the texture
* coordinates that will be used for the texture lookup this can be
* modified. cogl_texel will contain the result of the texture
* lookup. This can be modified.
* </para>
* <para>
* The declarations string in @snippet will be inserted in the
* global scope of the shader. Use this to declare any uniforms,
* attributes or functions that the snippet requires.
* </para>
* <para>
* The pre string in @snippet will be inserted at the top of the
* main() function before any fragment processing is done. This is a
* good place to modify the cogl_tex_coord variable.
* </para>
* <para>
* If a replace string is given then this will be used instead of a
* the default texture lookup. The snippet would typically use its own
* sampler in this case.
* </para>
* <para>
* The post string in @snippet will be inserted after texture lookup
* has been preformed. Here the snippet can modify the cogl_texel
* variable to alter the returned texel.
* </para>
* </glossentry>
* </glosslist>
*
* Since: 1.10
* Stability: Unstable
*/
typedef enum {
/* Per pipeline vertex hooks */
COGL_SNIPPET_HOOK_VERTEX = 0,
COGL_SNIPPET_HOOK_VERTEX_TRANSFORM,
/* Per pipeline fragment hooks */
COGL_SNIPPET_HOOK_FRAGMENT = 2048,
/* Per layer vertex hooks */
COGL_SNIPPET_HOOK_TEXTURE_COORD_TRANSFORM = 4096,
/* Per layer fragment hooks */
COGL_SNIPPET_HOOK_LAYER_FRAGMENT = 6144,
COGL_SNIPPET_HOOK_TEXTURE_LOOKUP
} CoglSnippetHook;
#define cogl_snippet_new cogl_snippet_new_EXP
/**
* cogl_snippet_new:
* @hook: The point in the pipeline that this snippet will wrap around
* or replace.
* @declarations: The source code for the declarations for this
* snippet or %NULL. See cogl_snippet_set_declarations().
* @post: The source code to run after the hook point where this
* shader snippet is attached or %NULL. See cogl_snippet_set_post().
*
* Allocates and initializes a new snippet with the given source strings.
*
* Return value: a pointer to a new #CoglSnippet
*
* Since: 1.10
* Stability: Unstable
*/
CoglSnippet *
cogl_snippet_new (CoglSnippetHook hook,
const char *declarations,
const char *post);
#define cogl_snippet_get_hook cogl_snipet_get_hook_EXP
/**
* cogl_snippet_get_hook:
* @snippet: A #CoglSnippet
*
* Return value: the hook that was set when cogl_snippet_new() was
* called.
*/
CoglSnippetHook
cogl_snippet_get_hook (CoglSnippet *snippet);
#define cogl_is_snippet cogl_is_snippet_EXP
/**
* cogl_is_snippet:
* @handle: A CoglHandle
*
* Gets whether the given handle references an existing snippet object.
*
* Return value: %TRUE if the handle references a #CoglSnippet,
* %FALSE otherwise
*
* Since: 1.10
* Stability: Unstable
*/
gboolean
cogl_is_snippet (void *object);
#define cogl_snippet_set_declarations cogl_snippet_set_declarations_EXP
/**
* cogl_snippet_set_declarations:
* @snippet: A #CoglSnippet
* @declarations: The new source string for the declarations section
* of this snippet.
*
* Sets a source string that will be inserted in the global scope of
* the generated shader when this snippet is used on a pipeline. This
* string is typically used to declare uniforms, attributes or
* functions that will be used by the other parts of the snippets.
*
* This function should only be called before the snippet is attached
* to its first pipeline. After that the snippet should be considered
* immutable.
*
* Since: 1.10
* Stability: Unstable
*/
void
cogl_snippet_set_declarations (CoglSnippet *snippet,
const char *declarations);
#define cogl_snippet_get_declarations cogl_snippet_get_declarations_EXP
/**
* cogl_snippet_get_declarations:
* @snippet: A #CoglSnippet
*
* Return value: the source string that was set with
* cogl_snippet_set_declarations() or %NULL if none was set.
*
* Since: 1.10
* Stability: Unstable
*/
const char *
cogl_snippet_get_declarations (CoglSnippet *snippet);
#define cogl_snippet_set_pre cogl_snippet_set_pre_EXP
/**
* cogl_snippet_set_pre:
* @snippet: A #CoglSnippet
* @pre: The new source string for the pre section of this snippet.
*
* Sets a source string that will be inserted before the hook point in
* the generated shader for the pipeline that this snippet is attached
* to. Please see the documentation of each hook point in
* #CoglPipeline for a description of how this string should be used.
*
* This function should only be called before the snippet is attached
* to its first pipeline. After that the snippet should be considered
* immutable.
*
* Since: 1.10
* Stability: Unstable
*/
void
cogl_snippet_set_pre (CoglSnippet *snippet,
const char *pre);
#define cogl_snippet_get_pre cogl_snippet_get_pre_EXP
/**
* cogl_snippet_get_pre:
* @snippet: A #CoglSnippet
*
* Return value: the source string that was set with
* cogl_snippet_set_pre() or %NULL if none was set.
*
* Since: 1.10
* Stability: Unstable
*/
const char *
cogl_snippet_get_pre (CoglSnippet *snippet);
#define cogl_snippet_set_replace cogl_snippet_set_replace_EXP
/**
* cogl_snippet_set_replace:
* @snippet: A #CoglSnippet
* @replace: The new source string for the replace section of this snippet.
*
* Sets a source string that will be used instead of any generated
* source code or any previous snippets for this hook point. Please
* see the documentation of each hook point in #CoglPipeline for a
* description of how this string should be used.
*
* This function should only be called before the snippet is attached
* to its first pipeline. After that the snippet should be considered
* immutable.
*
* Since: 1.10
* Stability: Unstable
*/
void
cogl_snippet_set_replace (CoglSnippet *snippet,
const char *replace);
#define cogl_snippet_get_replace cogl_snippet_get_replace_EXP
/**
* cogl_snippet_get_replace:
* @snippet: A #CoglSnippet
*
* Return value: the source string that was set with
* cogl_snippet_set_replace() or %NULL if none was set.
*
* Since: 1.10
* Stability: Unstable
*/
const char *
cogl_snippet_get_replace (CoglSnippet *snippet);
#define cogl_snippet_set_post cogl_snippet_set_post_EXP
/**
* cogl_snippet_set_post:
* @snippet: A #CoglSnippet
* @post: The new source string for the post section of this snippet.
*
* Sets a source string that will be inserted after the hook point in
* the generated shader for the pipeline that this snippet is attached
* to. Please see the documentation of each hook point in
* #CoglPipeline for a description of how this string should be used.
*
* This function should only be called before the snippet is attached
* to its first pipeline. After that the snippet should be considered
* immutable.
*
* Since: 1.10
* Stability: Unstable
*/
void
cogl_snippet_set_post (CoglSnippet *snippet,
const char *post);
#define cogl_snippet_get_post cogl_snippet_get_post_EXP
/**
* cogl_snippet_get_post:
* @snippet: A #CoglSnippet
*
* Return value: the source string that was set with
* cogl_snippet_set_post() or %NULL if none was set.
*
* Since: 1.10
* Stability: Unstable
*/
const char *
cogl_snippet_get_post (CoglSnippet *snippet);
G_END_DECLS
#endif /* __COGL_SNIPPET_H__ */