This file is indexed.

/usr/include/cogl/cogl/cogl-snippet.h is in libcogl-dev 1.22.2-3.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
/*
 * Cogl
 *
 * A Low Level GPU Graphics and Utilities API
 *
 * Copyright (C) 2011, 2013 Intel Corporation.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 *
 *
 * Authors:
 *   Neil Roberts <neil@linux.intel.com>
 */

#if !defined(__COGL_H_INSIDE__) && !defined(COGL_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif

#ifndef __COGL_SNIPPET_H__
#define __COGL_SNIPPET_H__

COGL_BEGIN_DECLS

/**
 * SECTION:cogl-snippet
 * @short_description: Functions for creating and manipulating shader snippets
 *
 * #CoglSnippet<!-- -->s are used to modify or replace parts of a
 * #CoglPipeline using GLSL. GLSL is a programming language supported
 * by OpenGL on programmable hardware to provide a more flexible
 * description of what should be rendered. A description of GLSL
 * itself is outside the scope of this documentation but any good
 * OpenGL book should help to describe it.
 *
 * Unlike in OpenGL, when using GLSL with Cogl it is possible to write
 * short snippets to replace small sections of the pipeline instead of
 * having to replace the whole of either the vertex or fragment
 * pipelines. Of course it is also possible to replace the whole of
 * the pipeline if needed.
 *
 * Each snippet is a standalone chunk of code which would attach to
 * the pipeline at a particular point. The code is split into four
 * separate strings (all of which are optional):
 *
 * <glosslist>
 *  <glossentry>
 *   <glossterm>declarations</glossterm>
 *   <glossdef><para>
 * The code in this string will be inserted outside of any function in
 * the global scope of the shader. This can be used to declare
 * uniforms, attributes, varyings and functions to be used by the
 * snippet.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>pre</glossterm>
 *   <glossdef><para>
 * The code in this string will be inserted before the hook point.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>post</glossterm>
 *   <glossdef><para>
 * The code in this string will be inserted after the hook point. This
 * can be used to modify the results of the builtin generated code for
 * that hook point.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>replace</glossterm>
 *   <glossdef><para>
 * If present the code in this string will replace the generated code
 * for the hook point.
 *   </para></glossdef>
 *  </glossentry>
 * </glosslist>
 *
 * All of the strings apart from the declarations string of a pipeline
 * are generated in a single function so they can share variables
 * declared from one string in another. The scope of the code is
 * limited to each snippet so local variables declared in the snippet
 * will not collide with variables declared in another
 * snippet. However, code in the 'declarations' string is global to
 * the shader so it is the application's responsibility to ensure that
 * variables declared here will not collide with those from other
 * snippets.
 *
 * The snippets can be added to a pipeline with
 * cogl_pipeline_add_snippet() or
 * cogl_pipeline_add_layer_snippet(). Which function to use depends on
 * which hook the snippet is targetting. The snippets are all
 * generated in the order they are added to the pipeline. That is, the
 * post strings are executed in the order they are added to the
 * pipeline and the pre strings are executed in reverse order. If any
 * replace strings are given for a snippet then any other snippets
 * with the same hook added before that snippet will be ignored. The
 * different hooks are documented under #CoglSnippetHook.
 *
 * For portability with GLES2, it is recommended not to use the GLSL
 * builtin names such as gl_FragColor. Instead there are replacement
 * names under the cogl_* namespace which can be used instead. These
 * are:
 *
 * <glosslist>
 *  <glossentry>
 *   <glossterm>uniform mat4
 *         <emphasis>cogl_modelview_matrix</emphasis></glossterm>
 *   <glossdef><para>
 *    The current modelview matrix. This is equivalent to
 *    #gl_ModelViewMatrix.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>uniform mat4
 *         <emphasis>cogl_projection_matrix</emphasis></glossterm>
 *   <glossdef><para>
 *    The current projection matrix. This is equivalent to
 *    #gl_ProjectionMatrix.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>uniform mat4
 *         <emphasis>cogl_modelview_projection_matrix</emphasis></glossterm>
 *   <glossdef><para>
 *    The combined modelview and projection matrix. A vertex shader
 *    would typically use this to transform the incoming vertex
 *    position. The separate modelview and projection matrices are
 *    usually only needed for lighting calculations. This is
 *    equivalent to #gl_ModelViewProjectionMatrix.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>uniform mat4
 *         <emphasis>cogl_texture_matrix</emphasis>[]</glossterm>
 *   <glossdef><para>
 *    An array of matrices for transforming the texture
 *    coordinates. This is equivalent to #gl_TextureMatrix.
 *   </para></glossdef>
 *  </glossentry>
 * </glosslist>
 *
 * In a vertex shader, the following are also available:
 *
 * <glosslist>
 *  <glossentry>
 *   <glossterm>attribute vec4
 *         <emphasis>cogl_position_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The incoming vertex position. This is equivalent to #gl_Vertex.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>attribute vec4
 *         <emphasis>cogl_color_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The incoming vertex color. This is equivalent to #gl_Color.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>attribute vec4
 *         <emphasis>cogl_tex_coord_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The texture coordinate for layer 0. This is an alternative name
 *    for #cogl_tex_coord0_in.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>attribute vec4
 *         <emphasis>cogl_tex_coord0_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The texture coordinate for the layer 0. This is equivalent to
 *    #gl_MultiTexCoord0. There will also be #cogl_tex_coord1_in and
 *    so on if more layers are added to the pipeline.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>attribute vec3
 *         <emphasis>cogl_normal_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The normal of the vertex. This is equivalent to #gl_Normal.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>vec4
 *         <emphasis>cogl_position_out</emphasis></glossterm>
 *   <glossdef><para>
 *    The calculated position of the vertex. This must be written to
 *    in all vertex shaders. This is equivalent to #gl_Position.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>float
 *         <emphasis>cogl_point_size_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The incoming point size from the cogl_point_size_in attribute.
 *    This is only available if
 *    cogl_pipeline_set_per_vertex_point_size() is set on the
 *    pipeline.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>float
 *         <emphasis>cogl_point_size_out</emphasis></glossterm>
 *   <glossdef><para>
 *    The calculated size of a point. This is equivalent to #gl_PointSize.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>varying vec4
 *         <emphasis>cogl_color_out</emphasis></glossterm>
 *   <glossdef><para>
 *    The calculated color of a vertex. This is equivalent to #gl_FrontColor.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>varying vec4
 *         <emphasis>cogl_tex_coord0_out</emphasis></glossterm>
 *   <glossdef><para>
 *    The calculated texture coordinate for layer 0 of the pipeline.
 *    This is equivalent to #gl_TexCoord[0]. There will also be
 *    #cogl_tex_coord1_out and so on if more layers are added to the
 *    pipeline. In the fragment shader, this varying is called
 *    #cogl_tex_coord0_in.
 *   </para></glossdef>
 *  </glossentry>
 * </glosslist>
 *
 * In a fragment shader, the following are also available:
 *
 * <glosslist>
 *  <glossentry>
 *   <glossterm>varying vec4 <emphasis>cogl_color_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The calculated color of a vertex. This is equivalent to #gl_FrontColor.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>varying vec4
 *              <emphasis>cogl_tex_coord0_in</emphasis></glossterm>
 *   <glossdef><para>
 *    The texture coordinate for layer 0. This is equivalent to
 *    #gl_TexCoord[0]. There will also be #cogl_tex_coord1_in and so
 *    on if more layers are added to the pipeline.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>vec4 <emphasis>cogl_color_out</emphasis></glossterm>
 *   <glossdef><para>
 *    The final calculated color of the fragment. All fragment shaders
 *    must write to this variable. This is equivalent to
 *    #gl_FrontColor.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>float <emphasis>cogl_depth_out</emphasis></glossterm>
 *   <glossdef><para>
 *    An optional output variable specifying the depth value to use
 *    for this fragment. This is equivalent to #gl_FragDepth.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>bool <emphasis>cogl_front_facing</emphasis></glossterm>
 *   <glossdef><para>
 *    A readonly variable that will be true if the current primitive
 *    is front facing. This can be used to implement two-sided
 *    coloring algorithms. This is equivalent to #gl_FrontFacing.
 *   </para></glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>vec2 <emphasis>cogl_point_coord</emphasis></glossterm>
 *   <glossdef><para>
 *    When rendering points, this will contain a vec2 which represents
 *    the position within the point of the current fragment.
 *    vec2(0.0,0.0) will be the topleft of the point and vec2(1.0,1.0)
 *    will be the bottom right. Note that there is currently a bug in
 *    Cogl where when rendering to an offscreen buffer these
 *    coordinates will be upside-down. The value is undefined when not
 *    rendering points. This builtin can only be used if the
 *    %COGL_FEATURE_ID_POINT_SPRITE feature is available.
 *   </para></glossdef>
 *  </glossentry>
 * </glosslist>
 *
 * Here is an example of using a snippet to add a desaturate effect to the
 * generated color on a pipeline.
 *
 * <programlisting>
 *   CoglPipeline *pipeline = cogl_pipeline_new ();
 *
 *   /<!-- -->* Set up the pipeline here, ie by adding a texture or other
 *      layers *<!-- -->/
 *
 *   /<!-- -->* Create the snippet. The first string is the declarations which
 *      we will use to add a uniform. The second is the 'post' string which
 *      will contain the code to perform the desaturation. *<!-- -->/
 *   CoglSnippet *snippet =
 *     cogl_snippet_new (COGL_SNIPPET_HOOK_FRAGMENT,
 *                       "uniform float factor;",
 *                       "float gray = dot (vec3 (0.299, 0.587, 0.114), "
 *                       "                  cogl_color_out.rgb);"
 *                       "cogl_color_out.rgb = mix (vec3 (gray),"
 *                       "                          cogl_color_out.rgb,"
 *                       "                          factor);");
 *
 *   /<!-- -->* Add it to the pipeline *<!-- -->/
 *   cogl_pipeline_add_snippet (pipeline, snippet);
 *   /<!-- -->* The pipeline keeps a reference to the snippet
 *      so we don't need to *<!-- -->/
 *   cogl_object_unref (snippet);
 *
 *   /<!-- -->* Update the custom uniform on the pipeline *<!-- -->/
 *   int location = cogl_pipeline_get_uniform_location (pipeline, "factor");
 *   cogl_pipeline_set_uniform_1f (pipeline, location, 0.5f);
 *
 *   /<!-- -->* Now we can render with the snippet as usual *<!-- -->/
 *   cogl_push_source (pipeline);
 *   cogl_rectangle (0, 0, 10, 10);
 *   cogl_pop_source ();
 * </programlisting>
 */
typedef struct _CoglSnippet CoglSnippet;

#define COGL_SNIPPET(OBJECT) ((CoglSnippet *)OBJECT)

#ifdef COGL_HAS_GTYPE_SUPPORT
/**
 * cogl_snippet_get_gtype:
 *
 * Returns: a #GType that can be used with the GLib type system.
 */
GType cogl_snippet_get_gtype (void);
#endif

/* Enumeration of all the hook points that a snippet can be attached
   to within a pipeline. */
/**
 * CoglSnippetHook:
 * @COGL_SNIPPET_HOOK_VERTEX_GLOBALS: A hook for declaring global data
 *   that can be shared with all other snippets that are on a vertex
 *   hook.
 * @COGL_SNIPPET_HOOK_FRAGMENT_GLOBALS: A hook for declaring global
 *   data wthat can be shared with all other snippets that are on a
 *   fragment hook.
 * @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_POINT_SIZE: A hook for manipulating the point
 *   size of a vertex. This is only used if
 *   cogl_pipeline_set_per_vertex_point_size() is enabled on the
 *   pipeline.
 * @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_GLOBALS</glossterm>
 *   <glossdef>
 * <para>
 * Adds a shader snippet at the beginning of the global section of the
 * shader for the vertex processing. Any declarations here can be
 * shared with all other snippets that are attached to a vertex hook.
 * Only the ‘declarations’ string is used and the other strings are
 * ignored.
 * </para>
 *   </glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>%COGL_SNIPPET_HOOK_FRAGMENT_GLOBALS</glossterm>
 *   <glossdef>
 * <para>
 * Adds a shader snippet at the beginning of the global section of the
 * shader for the fragment processing. Any declarations here can be
 * shared with all other snippets that are attached to a fragment
 * hook. Only the ‘declarations’ string is used and the other strings
 * are ignored.
 * </para>
 *   </glossdef>
 *  </glossentry>
 *  <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_POINT_SIZE</glossterm>
 *   <glossdef>
 * <para>
 * Adds a shader snippet that will hook on to the point size
 * calculation step within the vertex shader stage. The snippet should
 * write to the builtin cogl_point_size_out with the new point size.
 * The snippet can either read cogl_point_size_in directly and write a
 * new value or first read an existing value in cogl_point_size_out
 * that would be set by a previous snippet. Note that this hook is
 * only used if cogl_pipeline_set_per_vertex_point_size() is enabled
 * on the pipeline.
 * </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
 * calculating the point size.
 * </para>
 * <para>
 * The ‘replace’ string in @snippet will be used instead of the
 * generated point size calculation if it is present.
 * </para>
 * <para>
 * The ‘post’ string in @snippet will be inserted after the
 * standard point size calculation is done. This can be used to modify
 * cogl_point_size_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>
 *    <glossdef>
 * <para>
 * 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>
 *   </glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>%COGL_SNIPPET_HOOK_LAYER_FRAGMENT</glossterm>
 *    <glossdef>
 * <para>
 * 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>
 *   </glossdef>
 *  </glossentry>
 *  <glossentry>
 *   <glossterm>%COGL_SNIPPET_HOOK_TEXTURE_LOOKUP</glossterm>
 *   <glossdef>
 * <para>
 * 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 three extra
 * variables available. ‘cogl_sampler’ is a sampler object
 * representing the sampler for the layer where the snippet is
 * attached. ‘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 also 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>
 *   </glossdef>
 *  </glossentry>
 * </glosslist>
 *
 * Since: 1.10
 * Stability: Unstable
 */
typedef enum {
  /* Per pipeline vertex hooks */
  COGL_SNIPPET_HOOK_VERTEX = 0,
  COGL_SNIPPET_HOOK_VERTEX_TRANSFORM,
  COGL_SNIPPET_HOOK_VERTEX_GLOBALS,
  COGL_SNIPPET_HOOK_POINT_SIZE,

  /* Per pipeline fragment hooks */
  COGL_SNIPPET_HOOK_FRAGMENT = 2048,
  COGL_SNIPPET_HOOK_FRAGMENT_GLOBALS,

  /* 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;

/**
 * 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);

/**
 * cogl_snippet_get_hook:
 * @snippet: A #CoglSnippet
 *
 * Return value: the hook that was set when cogl_snippet_new() was
 *   called.
 * Since: 1.10
 * Stability: Unstable
 */
CoglSnippetHook
cogl_snippet_get_hook (CoglSnippet *snippet);

/**
 * cogl_is_snippet:
 * @object: A #CoglObject pointer
 *
 * Gets whether the given @object references an existing snippet object.
 *
 * Return value: %TRUE if the @object references a #CoglSnippet,
 *   %FALSE otherwise
 *
 * Since: 1.10
 * Stability: Unstable
 */
CoglBool
cogl_is_snippet (void *object);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

/**
 * 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);

COGL_END_DECLS

#endif /* __COGL_SNIPPET_H__ */