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mutter/cogl/cogl-context-private.h
Robert Bragg e3d6bc36d3 Re-design the matrix stack using a graph of ops 
This re-designs the matrix stack so we now keep track of each separate
operation such as rotating, scaling, translating and multiplying as
immutable, ref-counted nodes in a graph.

Being a "graph" here means that different transformations composed of
a sequence of linked operation nodes may share nodes.

The first node in a matrix-stack is always a LOAD_IDENTITY operation.

As an example consider if an application where to draw three rectangles
A, B and C something like this:

cogl_framebuffer_scale (fb, 2, 2, 2);
cogl_framebuffer_push_matrix(fb);

  cogl_framebuffer_translate (fb, 10, 0, 0);

  cogl_framebuffer_push_matrix(fb);

    cogl_framebuffer_rotate (fb, 45, 0, 0, 1);
    cogl_framebuffer_draw_rectangle (...); /* A */

  cogl_framebuffer_pop_matrix(fb);

  cogl_framebuffer_draw_rectangle (...); /* B */

cogl_framebuffer_pop_matrix(fb);

cogl_framebuffer_push_matrix(fb);
  cogl_framebuffer_set_modelview_matrix (fb, &mv);
  cogl_framebuffer_draw_rectangle (...); /* C */
cogl_framebuffer_pop_matrix(fb);

That would result in a graph of nodes like this:

LOAD_IDENTITY
      |
    SCALE
    /     \
SAVE       LOAD
  |           |
TRANSLATE    RECTANGLE(C)
  |     \
SAVE    RECTANGLE(B)
  |
ROTATE
  |
RECTANGLE(A)

Each push adds a SAVE operation which serves as a marker to rewind too
when a corresponding pop is issued and also each SAVE node may also
store a cached matrix representing the composition of all its ancestor
nodes. This means if we repeatedly need to resolve a real CoglMatrix
for a given node then we don't need to repeat the composition.

Some advantages of this design are:
- A single pointer to any node in the graph can now represent a
  complete, immutable transformation that can be logged for example
  into a journal. Previously we were storing a full CoglMatrix in
  each journal entry which is 16 floats for the matrix itself as well
  as space for flags and another 16 floats for possibly storing a
  cache of the inverse. This means that we significantly reduce
  the size of the journal when drawing lots of primitives and we also
  avoid copying over 128 bytes per entry.
- It becomes much cheaper to check for equality. In cases where some
  (unlikely) false negatives are allowed simply comparing the pointers
  of two matrix stack graph entries is enough. Previously we would use
  memcmp() to compare matrices.
- It becomes easier to do comparisons of transformations. By looking
  for the common ancestry between nodes we can determine the operations
  that differentiate the transforms and use those to gain a high level
  understanding of the differences. For example we use this in the
  journal to be able to efficiently determine when two rectangle
  transforms only differ by some translation so that we can perform
  software clipping.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit f75aee93f6b293ca7a7babbd8fcc326ee6bf7aef)
2012-08-06 14:27:40 +01:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009 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/>.
*
*
*/
#ifndef __COGL_CONTEXT_PRIVATE_H
#define __COGL_CONTEXT_PRIVATE_H
#include "cogl-internal.h"
#include "cogl-context.h"
#include "cogl-winsys-private.h"
#include "cogl-flags.h"
#ifdef COGL_HAS_XLIB_SUPPORT
#include "cogl-xlib-private.h"
#endif
#include "cogl-display-private.h"
#include "cogl-primitives.h"
#include "cogl-clip-stack.h"
#include "cogl-matrix-stack.h"
#include "cogl-pipeline-private.h"
#include "cogl-buffer-private.h"
#include "cogl-bitmask.h"
#include "cogl-atlas.h"
#include "cogl-driver.h"
#include "cogl-texture-driver.h"
#include "cogl-pipeline-cache.h"
#include "cogl-texture-2d.h"
#include "cogl-texture-3d.h"
#include "cogl-texture-rectangle.h"
#include "cogl-sampler-cache-private.h"
#include "cogl-gpu-info-private.h"
#include "cogl-gl-header.h"
typedef struct
{
GLfloat v[3];
GLfloat t[2];
GLubyte c[4];
} CoglTextureGLVertex;
struct _CoglContext
{
CoglObject _parent;
CoglDisplay *display;
CoglDriver driver;
/* Information about the GPU and driver which we can use to
determine certain workarounds */
CoglGpuInfo gpu;
/* vtables for the driver functions */
const CoglDriverVtable *driver_vtable;
const CoglTextureDriver *texture_driver;
/* Features cache */
unsigned long features[COGL_FLAGS_N_LONGS_FOR_SIZE (_COGL_N_FEATURE_IDS)];
CoglFeatureFlags feature_flags; /* legacy/deprecated feature flags */
CoglPrivateFeatureFlags private_feature_flags;
CoglPipeline *default_pipeline;
CoglPipelineLayer *default_layer_0;
CoglPipelineLayer *default_layer_n;
CoglPipelineLayer *dummy_layer_dependant;
GHashTable *attribute_name_states_hash;
GArray *attribute_name_index_map;
int n_attribute_names;
CoglBitmask enabled_builtin_attributes;
CoglBitmask enabled_texcoord_attributes;
CoglBitmask enabled_custom_attributes;
/* These are temporary bitmasks that are used when disabling
* builtin,texcoord and custom attribute arrays. They are here just
* to avoid allocating new ones each time */
CoglBitmask enable_builtin_attributes_tmp;
CoglBitmask enable_texcoord_attributes_tmp;
CoglBitmask enable_custom_attributes_tmp;
CoglBitmask changed_bits_tmp;
CoglBool legacy_backface_culling_enabled;
/* A few handy matrix constants */
CoglMatrix identity_matrix;
CoglMatrix y_flip_matrix;
/* Value that was last used when calling glMatrixMode to avoid
calling it multiple times */
CoglMatrixMode flushed_matrix_mode;
/* The matrix stack entries that should be flushed during the next
* pipeline state flush */
CoglMatrixEntry *current_projection_entry;
CoglMatrixEntry *current_modelview_entry;
CoglMatrixEntry identity_entry;
/* A cache of the last (immutable) matrix stack entries that were
* flushed to the GL matrix builtins */
CoglMatrixEntryCache builtin_flushed_projection;
CoglMatrixEntryCache builtin_flushed_modelview;
GArray *texture_units;
int active_texture_unit;
CoglPipelineFogState legacy_fog_state;
/* Pipelines */
CoglPipeline *opaque_color_pipeline; /* used for set_source_color */
CoglPipeline *blended_color_pipeline; /* used for set_source_color */
CoglPipeline *texture_pipeline; /* used for set_source_texture */
GString *codegen_header_buffer;
GString *codegen_source_buffer;
GList *source_stack;
int legacy_state_set;
CoglPipelineCache *pipeline_cache;
/* Textures */
CoglTexture2D *default_gl_texture_2d_tex;
CoglTexture3D *default_gl_texture_3d_tex;
CoglTextureRectangle *default_gl_texture_rect_tex;
/* Central list of all framebuffers so all journals can be flushed
* at any time. */
GList *framebuffers;
/* Global journal buffers */
GArray *journal_flush_attributes_array;
GArray *journal_clip_bounds;
GArray *polygon_vertices;
/* Some simple caching, to minimize state changes... */
CoglPipeline *current_pipeline;
unsigned long current_pipeline_changes_since_flush;
CoglBool current_pipeline_skip_gl_color;
unsigned long current_pipeline_age;
CoglBool gl_blend_enable_cache;
CoglBool depth_test_enabled_cache;
CoglDepthTestFunction depth_test_function_cache;
CoglBool depth_writing_enabled_cache;
float depth_range_near_cache;
float depth_range_far_cache;
CoglBool legacy_depth_test_enabled;
CoglBuffer *current_buffer[COGL_BUFFER_BIND_TARGET_COUNT];
/* Framebuffers */
GSList *framebuffer_stack;
CoglFramebuffer *window_buffer;
unsigned long current_draw_buffer_state_flushed;
unsigned long current_draw_buffer_changes;
CoglFramebuffer *current_draw_buffer;
CoglFramebuffer *current_read_buffer;
/* Primitives */
CoglPath *current_path;
CoglPipeline *stencil_pipeline;
/* Pre-generated VBOs containing indices to generate GL_TRIANGLES
out of a vertex array of quads */
CoglIndices *quad_buffer_indices_byte;
unsigned int quad_buffer_indices_len;
CoglIndices *quad_buffer_indices;
CoglIndices *rectangle_byte_indices;
CoglIndices *rectangle_short_indices;
int rectangle_short_indices_len;
CoglBool in_begin_gl_block;
CoglPipeline *texture_download_pipeline;
CoglPipeline *blit_texture_pipeline;
GSList *atlases;
GHookList atlas_reorganize_callbacks;
/* This debugging variable is used to pick a colour for visually
displaying the quad batches. It needs to be global so that it can
be reset by cogl_clear. It needs to be reset to increase the
chances of getting the same colour during an animation */
uint8_t journal_rectangles_color;
/* Cached values for GL_MAX_TEXTURE_[IMAGE_]UNITS to avoid calling
glGetInteger too often */
GLint max_texture_units;
GLint max_texture_image_units;
GLint max_activateable_texture_units;
/* Fragment processing programs */
CoglHandle current_program;
CoglPipelineProgramType current_fragment_program_type;
CoglPipelineProgramType current_vertex_program_type;
GLuint current_gl_program;
CoglBool current_gl_dither_enabled;
CoglColorMask current_gl_color_mask;
/* List of types that will be considered a subclass of CoglTexture in
cogl_is_texture */
GSList *texture_types;
/* List of types that will be considered a subclass of CoglBuffer in
cogl_is_buffer */
GSList *buffer_types;
/* Clipping */
/* TRUE if we have a valid clipping stack flushed. In that case
current_clip_stack will describe what the current state is. If
this is FALSE then the current clip stack is completely unknown
so it will need to be reflushed. In that case current_clip_stack
doesn't need to be a valid pointer. We can't just use NULL in
current_clip_stack to mark a dirty state because NULL is a valid
stack (meaning no clipping) */
CoglBool current_clip_stack_valid;
/* The clip state that was flushed. This isn't intended to be used
as a stack to push and pop new entries. Instead the current stack
that the user wants is part of the framebuffer state. This is
just used to record the flush state so we can avoid flushing the
same state multiple times. When the clip state is flushed this
will hold a reference */
CoglClipStack *current_clip_stack;
/* Whether the stencil buffer was used as part of the current clip
state. If TRUE then any further use of the stencil buffer (such
as for drawing paths) would need to be merged with the existing
stencil buffer */
CoglBool current_clip_stack_uses_stencil;
/* This is used as a temporary buffer to fill a CoglBuffer when
cogl_buffer_map fails and we only want to map to fill it with new
data */
GByteArray *buffer_map_fallback_array;
CoglBool buffer_map_fallback_in_use;
CoglWinsysRectangleState rectangle_state;
CoglSamplerCache *sampler_cache;
/* FIXME: remove these when we remove the last xlib based clutter
* backend. they should be tracked as part of the renderer but e.g.
* the eglx backend doesn't yet have a corresponding Cogl winsys
* and so we wont have a renderer in that case. */
#ifdef COGL_HAS_XLIB_SUPPORT
int damage_base;
/* List of callback functions that will be given every Xlib event */
GSList *event_filters;
/* Current top of the XError trap state stack. The actual memory for
these is expected to be allocated on the stack by the caller */
CoglXlibTrapState *trap_state;
#endif
unsigned long winsys_features
[COGL_FLAGS_N_LONGS_FOR_SIZE (COGL_WINSYS_FEATURE_N_FEATURES)];
void *winsys;
/* Array of names of uniforms. These are used like quarks to give a
unique number to each uniform name except that we ensure that
they increase sequentially so that we can use the id as an index
into a bitfield representing the uniforms that a pipeline
overrides from its parent. */
GPtrArray *uniform_names;
/* A hash table to quickly get an index given an existing name. The
name strings are owned by the uniform_names array. The values are
the uniform location cast to a pointer. */
GHashTable *uniform_name_hash;
int n_uniform_names;
/* This defines a list of function pointers that Cogl uses from
either GL or GLES. All functions are accessed indirectly through
these pointers rather than linking to them directly */
#ifndef APIENTRY
#define APIENTRY
#endif
#define COGL_EXT_BEGIN(name, \
min_gl_major, min_gl_minor, \
gles_availability, \
extension_suffixes, extension_names)
#define COGL_EXT_FUNCTION(ret, name, args) \
ret (APIENTRY * name) args;
#define COGL_EXT_END()
#include "gl-prototypes/cogl-all-functions.h"
#undef COGL_EXT_BEGIN
#undef COGL_EXT_FUNCTION
#undef COGL_EXT_END
};
CoglContext *
_cogl_context_get_default ();
const CoglWinsysVtable *
_cogl_context_get_winsys (CoglContext *context);
/* Query the GL extensions and lookup the corresponding function
* pointers. Theoretically the list of extensions can change for
* different GL contexts so it is the winsys backend's responsiblity
* to know when to re-query the GL extensions. The backend should also
* check whether the GL context is supported by Cogl. If not it should
* return FALSE and set @error */
CoglBool
_cogl_context_update_features (CoglContext *context,
GError **error);
/* Obtains the context and returns retval if NULL */
#define _COGL_GET_CONTEXT(ctxvar, retval) \
CoglContext *ctxvar = _cogl_context_get_default (); \
if (ctxvar == NULL) return retval;
#define NO_RETVAL
void
_cogl_context_set_current_projection_entry (CoglContext *context,
CoglMatrixEntry *entry);
void
_cogl_context_set_current_modelview_entry (CoglContext *context,
CoglMatrixEntry *entry);
#endif /* __COGL_CONTEXT_PRIVATE_H */
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