/*
 * Cogl
 *
 * An object oriented GL/GLES Abstraction/Utility Layer
 *
 * Copyright (C) 2008,2009,2010 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:
 *   Robert Bragg <robert@linux.intel.com>
 */

#ifndef __COGL_MATERIAL_PRIVATE_H
#define __COGL_MATERIAL_PRIVATE_H

#include "cogl.h"

#include "cogl-material.h"
#include "cogl-matrix.h"
#include "cogl-matrix-stack.h"
#include "cogl-handle.h"

#include <glib.h>

/*
 * cogl-material.c owns the GPU's texture unit state so we have some
 * private structures for describing the current state of a texture
 * unit that we track in a per context array (ctx->texture_units) that
 * grows according to the largest texture unit used so far...
 *
 * Roughly speaking the members in this structure are of two kinds:
 * either they are a low level reflection of the state we send to
 * OpenGL or they are for high level meta data assoicated with the
 * texture unit when flushing CoglMaterialLayers that is typically
 * used to optimize subsequent re-flushing of the same layer.
 *
 * The low level members are at the top, and the high level members
 * start with the .layer member.
 */
typedef struct _CoglTextureUnit
{
  /* The base 0 texture unit index which can be used with
   * glActiveTexture () */
  int                index;

  /* Whether or not the corresponding gl_target has been glEnabled */
  gboolean           enabled;

  /* The GL target currently glEnabled or the target last enabled
   * if .enabled == FALSE */
  GLenum             current_gl_target;

  /* The raw GL texture object name for which we called glBindTexture when
   * we flushed the last layer. (NB: The CoglTexture associated
   * with a layer may represent more than one GL texture) */
  GLuint             gl_texture;

  /* Foreign textures are those not created or deleted by Cogl. If we ever
   * call glBindTexture for a foreign texture then the next time we are
   * asked to glBindTexture we can't try and optimize a redundant state
   * change because we don't know if the original texture name was deleted
   * and now we are being asked to bind a recycled name. */
  gboolean           is_foreign;

  /* We have many components in Cogl that need to temporarily bind arbitrary
   * textures e.g. to query texture object parameters and since we don't
   * want that to result in too much redundant reflushing of layer state
   * when all that's needed is to re-bind the layer's gl_texture we use this
   * to track when the unit->gl_texture state is out of sync with the GL
   * texture object really bound too (GL_TEXTURE0+unit->index).
   *
   * XXX: as a further optimization cogl-material.c uses a convention
   * of always using texture unit 1 for these transient bindings so we
   * can assume this is only ever TRUE for unit 1.
   */
  gboolean           dirty_gl_texture;

  /* A matrix stack giving us the means to associate a texture
   * transform matrix with the texture unit. */
  CoglMatrixStack   *matrix_stack;

  /*
   * Higher level layer state associated with the unit...
   */

  /* The CoglMaterialLayer whos state was flushed to update this
   * texture unit last.
   *
   * This will be set to NULL if the layer is modified or freed which
   * means when we come to flush a layer; if this pointer is still
   * valid and == to the layer being flushed we don't need to update
   * any texture unit state. */
  CoglMaterialLayer *layer;

  /* To help minimize the state changes required we track the
   * difference flags associated with the layer whos state was last
   * flushed to update this texture unit.
   *
   * Note: we track this explicitly because .layer may get invalidated
   * if that layer is modified or deleted. Even if the layer is
   * invalidated though these flags can be used to optimize the state
   * flush of the next layer
   */
  unsigned long      layer_changes_since_flush;

  /* Whenever a CoglTexture's internal GL texture storage changes
   * cogl-material.c is notified with a call to
   * _cogl_material_texture_storage_change_notify which inturn sets
   * this to TRUE for each texture unit that it is currently bound
   * too. When we later come to flush some material state then we will
   * always check this to potentially force an update of the texture
   * state even if the material hasn't changed. */
  gboolean           texture_storage_changed;

} CoglTextureUnit;

CoglTextureUnit *
_cogl_get_texture_unit (int index_);

void
_cogl_destroy_texture_units (void);

void
_cogl_bind_gl_texture_transient (GLenum gl_target,
                                 GLuint gl_texture,
                                 gboolean is_foreign);

#if defined (HAVE_COGL_GL)

/* NB: material->backend is currently a 3bit unsigned int bitfield */
#define COGL_MATERIAL_BACKEND_GLSL       0
#define COGL_MATERIAL_BACKEND_GLSL_MASK  (1L<<0)
#define COGL_MATERIAL_BACKEND_ARBFP      1
#define COGL_MATERIAL_BACKEND_ARBFP_MASK (1L<<1)
#define COGL_MATERIAL_BACKEND_FIXED      2
#define COGL_MATERIAL_BACKEND_FIXED_MASK (1L<<2)

#define COGL_MATERIAL_N_BACKENDS         3

#elif defined (HAVE_COGL_GLES2)

#define COGL_MATERIAL_BACKEND_GLSL       0
#define COGL_MATERIAL_BACKEND_GLSL_MASK  (1L<<0)
#define COGL_MATERIAL_BACKEND_FIXED      1
#define COGL_MATERIAL_BACKEND_FIXED_MASK (1L<<1)

#define COGL_MATERIAL_N_BACKENDS         2

#else /* HAVE_COGL_GLES */

#define COGL_MATERIAL_BACKEND_FIXED      0
#define COGL_MATERIAL_BACKEND_FIXED_MASK (1L<<0)

#define COGL_MATERIAL_N_BACKENDS         1

#endif

#define COGL_MATERIAL_BACKEND_DEFAULT    0
#define COGL_MATERIAL_BACKEND_UNDEFINED  3

typedef enum
{
  COGL_MATERIAL_LAYER_STATE_UNIT             = 1L<<0,
  COGL_MATERIAL_LAYER_STATE_TEXTURE          = 1L<<1,
  COGL_MATERIAL_LAYER_STATE_FILTERS          = 1L<<2,
  COGL_MATERIAL_LAYER_STATE_WRAP_MODES       = 1L<<3,

  COGL_MATERIAL_LAYER_STATE_COMBINE          = 1L<<4,
  COGL_MATERIAL_LAYER_STATE_COMBINE_CONSTANT = 1L<<5,
  COGL_MATERIAL_LAYER_STATE_USER_MATRIX      = 1L<<6,

  COGL_MATERIAL_LAYER_STATE_POINT_SPRITE_COORDS = 1L<<7,

  /* COGL_MATERIAL_LAYER_STATE_TEXTURE_INTERN   = 1L<<8, */

  COGL_MATERIAL_LAYER_STATE_ALL_SPARSE =
    COGL_MATERIAL_LAYER_STATE_UNIT |
    COGL_MATERIAL_LAYER_STATE_TEXTURE |
    COGL_MATERIAL_LAYER_STATE_FILTERS |
    COGL_MATERIAL_LAYER_STATE_WRAP_MODES |
    COGL_MATERIAL_LAYER_STATE_COMBINE |
    COGL_MATERIAL_LAYER_STATE_COMBINE_CONSTANT |
    COGL_MATERIAL_LAYER_STATE_USER_MATRIX |
    COGL_MATERIAL_LAYER_STATE_POINT_SPRITE_COORDS,

  COGL_MATERIAL_LAYER_STATE_NEEDS_BIG_STATE =
    COGL_MATERIAL_LAYER_STATE_COMBINE |
    COGL_MATERIAL_LAYER_STATE_COMBINE_CONSTANT |
    COGL_MATERIAL_LAYER_STATE_USER_MATRIX |
    COGL_MATERIAL_LAYER_STATE_POINT_SPRITE_COORDS,

} CoglMaterialLayerState;

typedef struct
{
  /* The texture combine state determines how the color of individual
   * texture fragments are calculated. */
  GLint texture_combine_rgb_func;
  GLint texture_combine_rgb_src[3];
  GLint texture_combine_rgb_op[3];

  GLint texture_combine_alpha_func;
  GLint texture_combine_alpha_src[3];
  GLint texture_combine_alpha_op[3];

  float texture_combine_constant[4];

  /* The texture matrix dscribes how to transform texture coordinates */
  CoglMatrix matrix;

  gboolean point_sprite_coords;

} CoglMaterialLayerBigState;

/* Materials and layers represent their state in a tree structure where
 * some of the state relating to a given material or layer may actually
 * be owned by one if is ancestors in the tree. We have a common data
 * type to track the tree heirachy so we can share code... */
typedef struct _CoglMaterialNode CoglMaterialNode;
struct _CoglMaterialNode
{
  /* the parent in terms of class hierarchy, so anything inheriting
   * from CoglMaterialNode also inherits from CoglObject. */
  CoglObject _parent;

  /* The parent material/layer */
  CoglMaterialNode *parent;

  /* As an optimization for creating leaf node materials/layers (the
   * most common) we don't require any list node allocations to link
   * to a single descendant. */
  CoglMaterialNode *first_child;

  /* Determines if node->first_child and node->children are
   * initialized pointers. */
  gboolean has_children;

  /* Materials and layers are sparse structures defined as a diff
   * against their parent and may have multiple children which depend
   * on them to define the values of properties which they don't
   * change. */
  GList *children;
};

#define COGL_MATERIAL_NODE(X) ((CoglMaterialNode *)(X))

typedef void (*CoglMaterialNodeUnparentVFunc) (CoglMaterialNode *node);

typedef gboolean (*CoglMaterialNodeChildCallback) (CoglMaterialNode *child,
                                                   void *user_data);

void
_cogl_material_node_foreach_child (CoglMaterialNode *node,
                                   CoglMaterialNodeChildCallback callback,
                                   void *user_data);

struct _CoglMaterialLayer
{
  /* XXX: Please think twice about adding members that *have* be
   * initialized during a _cogl_material_layer_copy. We are aiming
   * to have copies be as cheap as possible and copies may be
   * done by the primitives APIs which means they may happen
   * in performance critical code paths.
   *
   * XXX: If you are extending the state we track please consider if
   * the state is expected to vary frequently across many materials or
   * if the state can be shared among many derived materials instead.
   * This will determine if the state should be added directly to this
   * structure which will increase the memory overhead for *all*
   * layers or if instead it can go under ->big_state.
   */

  /* Layers represent their state in a tree structure where some of
   * the state relating to a given material or layer may actually be
   * owned by one if is ancestors in the tree. We have a common data
   * type to track the tree heirachy so we can share code... */
  CoglMaterialNode _parent;

  /* Some layers have a material owner, which is to say that the layer
   * is referenced in that materials->layer_differences list.  A layer
   * doesn't always have an owner and may simply be an ancestor for
   * other layers that keeps track of some shared state. */
  CoglMaterial      *owner;

  /* The lowest index is blended first then others on top */
  int	             index;

  /* Different material backends (GLSL/ARBfp/Fixed Function) may
   * want to associate private data with a layer...
   *
   * NB: we have per backend pointers because a layer may be
   * associated with multiple materials with different backends.
   */
  void              *backend_priv[COGL_MATERIAL_N_BACKENDS];

  /* A mask of which state groups are different in this layer
   * in comparison to its parent. */
  unsigned long             differences;

  /* Common differences
   *
   * As a basic way to reduce memory usage we divide the layer
   * state into two groups; the minimal state modified in 90% of
   * all layers and the rest, so that the second group can
   * be allocated dynamically when required.
   */

  /* Each layer is directly associated with a single texture unit */
  int                        unit_index;

  /* The texture for this layer, or COGL_INVALID_HANDLE for an empty
   * layer */
  CoglHandle                 texture;
  gboolean                   texture_overridden;
  /* If ->texture_overridden == TRUE then the texture is instead
   * defined by these... */
  GLuint                     slice_gl_texture;
  GLenum                     slice_gl_target;

  CoglMaterialFilter         mag_filter;
  CoglMaterialFilter         min_filter;

  CoglMaterialWrapMode       wrap_mode_s;
  CoglMaterialWrapMode       wrap_mode_t;
  CoglMaterialWrapMode       wrap_mode_p;

  /* Infrequent differences aren't currently tracked in
   * a separate, dynamically allocated structure as they are
   * for materials... */
  CoglMaterialLayerBigState *big_state;

  /* bitfields */

  /* Determines if layer->big_state is valid */
  unsigned int          has_big_state:1;

};

/* Used in material->differences masks and for notifying material
 * state changes... */
typedef enum _CoglMaterialState
{
  COGL_MATERIAL_STATE_COLOR             = 1L<<0,
  COGL_MATERIAL_STATE_BLEND_ENABLE      = 1L<<1,
  COGL_MATERIAL_STATE_LAYERS            = 1L<<2,

  COGL_MATERIAL_STATE_LIGHTING          = 1L<<3,
  COGL_MATERIAL_STATE_ALPHA_FUNC        = 1L<<4,
  COGL_MATERIAL_STATE_BLEND             = 1L<<5,
  COGL_MATERIAL_STATE_USER_SHADER       = 1L<<6,
  COGL_MATERIAL_STATE_DEPTH             = 1L<<7,
  COGL_MATERIAL_STATE_FOG               = 1L<<8,
  COGL_MATERIAL_STATE_POINT_SIZE        = 1L<<9,

  COGL_MATERIAL_STATE_REAL_BLEND_ENABLE = 1L<<10,

  COGL_MATERIAL_STATE_ALL_SPARSE =
    COGL_MATERIAL_STATE_COLOR |
    COGL_MATERIAL_STATE_BLEND_ENABLE |
    COGL_MATERIAL_STATE_LAYERS |
    COGL_MATERIAL_STATE_LIGHTING |
    COGL_MATERIAL_STATE_ALPHA_FUNC |
    COGL_MATERIAL_STATE_BLEND |
    COGL_MATERIAL_STATE_USER_SHADER |
    COGL_MATERIAL_STATE_DEPTH |
    COGL_MATERIAL_STATE_FOG |
    COGL_MATERIAL_STATE_POINT_SIZE,

  COGL_MATERIAL_STATE_AFFECTS_BLENDING =
    COGL_MATERIAL_STATE_COLOR |
    COGL_MATERIAL_STATE_BLEND_ENABLE |
    COGL_MATERIAL_STATE_LAYERS |
    COGL_MATERIAL_STATE_LIGHTING |
    COGL_MATERIAL_STATE_BLEND |
    COGL_MATERIAL_STATE_USER_SHADER,

  COGL_MATERIAL_STATE_NEEDS_BIG_STATE =
    COGL_MATERIAL_STATE_LIGHTING |
    COGL_MATERIAL_STATE_ALPHA_FUNC |
    COGL_MATERIAL_STATE_BLEND |
    COGL_MATERIAL_STATE_USER_SHADER |
    COGL_MATERIAL_STATE_DEPTH |
    COGL_MATERIAL_STATE_FOG |
    COGL_MATERIAL_STATE_POINT_SIZE

} CoglMaterialState;

typedef enum
{
  COGL_MATERIAL_LIGHTING_STATE_PROPERTY_AMBIENT = 1,
  COGL_MATERIAL_LIGHTING_STATE_PROPERTY_DIFFUSE,
  COGL_MATERIAL_LIGHTING_STATE_PROPERTY_SPECULAR,
  COGL_MATERIAL_LIGHTING_STATE_PROPERTY_EMISSION,
  COGL_MATERIAL_LIGHTING_STATE_PROPERTY_SHININESS
} CoglMaterialLightingStateProperty;

typedef struct
{
  /* Standard OpenGL lighting model attributes */
  float ambient[4];
  float diffuse[4];
  float specular[4];
  float emission[4];
  float shininess;
} CoglMaterialLightingState;

typedef struct
{
  /* Determines what fragments are discarded based on their alpha */
  CoglMaterialAlphaFunc alpha_func;
  GLfloat		alpha_func_reference;
} CoglMaterialAlphaFuncState;

typedef enum _CoglMaterialBlendEnable
{
  /* XXX: we want to detect users mistakenly using TRUE or FALSE
   * so start the enum at 2. */
  COGL_MATERIAL_BLEND_ENABLE_ENABLED = 2,
  COGL_MATERIAL_BLEND_ENABLE_DISABLED,
  COGL_MATERIAL_BLEND_ENABLE_AUTOMATIC
} CoglMaterialBlendEnable;

typedef struct
{
  /* Determines how this material is blended with other primitives */
#ifndef HAVE_COGL_GLES
  GLenum    blend_equation_rgb;
  GLenum    blend_equation_alpha;
  GLint     blend_src_factor_alpha;
  GLint     blend_dst_factor_alpha;
  CoglColor blend_constant;
#endif
  GLint     blend_src_factor_rgb;
  GLint     blend_dst_factor_rgb;
} CoglMaterialBlendState;

typedef struct
{
  gboolean              depth_test_enabled;
  CoglDepthTestFunction depth_test_function;
  gboolean              depth_writing_enabled;
  float                 depth_range_near;
  float                 depth_range_far;
} CoglMaterialDepthState;

typedef struct
{
  gboolean        enabled;
  CoglColor       color;
  CoglFogMode     mode;
  float           density;
  float           z_near;
  float           z_far;
} CoglMaterialFogState;

typedef struct
{
  CoglMaterialLightingState lighting_state;
  CoglMaterialAlphaFuncState alpha_state;
  CoglMaterialBlendState blend_state;
  CoglHandle user_program;
  CoglMaterialDepthState depth_state;
  CoglMaterialFogState fog_state;
  float point_size;
} CoglMaterialBigState;

typedef enum
{
  COGL_MATERIAL_FLAG_DIRTY_LAYERS_CACHE     = 1L<<0,
  COGL_MATERIAL_FLAG_DIRTY_GET_LAYERS_LIST  = 1L<<1
} CoglMaterialFlag;

typedef struct
{
  CoglMaterial *owner;
  CoglMaterialLayer *layer;
} CoglMaterialLayerCacheEntry;

struct _CoglMaterial
{
  /* XXX: Please think twice about adding members that *have* be
   * initialized during a cogl_material_copy. We are aiming to have
   * copies be as cheap as possible and copies may be done by the
   * primitives APIs which means they may happen in performance
   * critical code paths.
   *
   * XXX: If you are extending the state we track please consider if
   * the state is expected to vary frequently across many materials or
   * if the state can be shared among many derived materials instead.
   * This will determine if the state should be added directly to this
   * structure which will increase the memory overhead for *all*
   * materials or if instead it can go under ->big_state.
   */

  /* Layers represent their state in a tree structure where some of
   * the state relating to a given material or layer may actually be
   * owned by one if is ancestors in the tree. We have a common data
   * type to track the tree heirachy so we can share code... */
  CoglMaterialNode _parent;

  /* We need to track if a material is referenced in the journal
   * because we can't allow modification to these materials without
   * flushing the journal first */
  unsigned long    journal_ref_count;

  /* A mask of which sparse state groups are different in this
   * material in comparison to its parent. */
  unsigned long    differences;

  /* The fragment processing backends can associate private data with a
   * material. */
  void		  *backend_privs[COGL_MATERIAL_N_BACKENDS];

  /* Whenever a material is modified we increment the age. There's no
   * guarantee that it won't wrap but it can nevertheless be a
   * convenient mechanism to determine when a material has been
   * changed to you can invalidate some some associated cache that
   * depends on the old state. */
  unsigned long    age;

  /* This is the primary color of the material.
   *
   * This is a sparse property, ref COGL_MATERIAL_STATE_COLOR */
  CoglColor        color;

  /* A material may be made up with multiple layers used to combine
   * textures together.
   *
   * This is sparse state, ref COGL_MATERIAL_STATE_LAYERS */
  GList	          *layer_differences;
  unsigned int     n_layers;

  /* As a basic way to reduce memory usage we divide the material
   * state into two groups; the minimal state modified in 90% of
   * all materials and the rest, so that the second group can
   * be allocated dynamically when required... */
  CoglMaterialBigState *big_state;

  /* For debugging purposes it's possible to associate a static const
   * string with a material which can be an aid when trying to trace
   * where the material originates from */
  const char      *static_breadcrumb;

  /* Cached state... */

  /* A cached, complete list of the layers this material depends
   * on sorted by layer->unit_index. */
  CoglMaterialLayer   **layers_cache;
  /* To avoid a separate ->layers_cache allocation for common
   * materials with only a few layers... */
  CoglMaterialLayer    *short_layers_cache[3];

  /* The deprecated cogl_material_get_layers() API returns a
   * const GList of layers, which we track here... */
  GList                *deprecated_get_layers_list;

  /* XXX: consider adding an authorities cache to speed up sparse
   * property value lookups:
   * CoglMaterial *authorities_cache[COGL_MATERIAL_N_SPARSE_PROPERTIES];
   * and corresponding authorities_cache_dirty:1 bitfield
   */

  /* bitfields */

  /* A material can have private data associated with it for multiple
   * fragment processing backends. Although only one backend is
   * associated with a material the backends may want to cache private
   * state with the ancestors of other materials and those ancestors
   * could currently be associated with different backends.
   *
   * Each set bit indicates if the correspondong ->backend_privs[]
   * entry is valid.
   */
  unsigned int          backend_priv_set_mask:COGL_MATERIAL_N_BACKENDS;

  /* Weak materials don't count as dependants on their parents which
   * means that the parent material can be modified without
   * considering how the modifications may affect the weak material.
   */
  unsigned int          is_weak:1;

  /* Determines if material->big_state is valid */
  unsigned int          has_big_state:1;

  /* By default blending is enabled automatically depending on the
   * unlit color, the lighting colors or the texture format. The user
   * can override this to explicitly enable or disable blending.
   *
   * This is a sparse property */
  unsigned int          blend_enable:3;

  /* There are many factors that can determine if we need to enable
   * blending, this holds our final decision */
  unsigned int          real_blend_enable:1;

  unsigned int          layers_cache_dirty:1;
  unsigned int          deprecated_get_layers_list_dirty:1;

  /* For debugging purposes it's possible to associate a static const
   * string with a material which can be an aid when trying to trace
   * where the material originates from */
  unsigned int          has_static_breadcrumb:1;

  /* There are multiple fragment processing backends for CoglMaterial,
   * glsl, arbfp and fixed. This identifies the backend being used for
   * the material and any private state the backend has associated
   * with the material. */
  unsigned int          backend:3;
};

typedef struct _CoglMaterialBackend
{
  int (*get_max_texture_units) (void);

  gboolean (*start) (CoglMaterial *material,
                     int n_layers,
                     unsigned long materials_difference);
  gboolean (*add_layer) (CoglMaterial *material,
                         CoglMaterialLayer *layer,
                         unsigned long layers_difference);
  gboolean (*passthrough) (CoglMaterial *material);
  gboolean (*end) (CoglMaterial *material,
                   unsigned long materials_difference);

  void (*material_pre_change_notify) (CoglMaterial *material,
                                      CoglMaterialState change,
                                      const CoglColor *new_color);
  void (*material_set_parent_notify) (CoglMaterial *material);
  void (*layer_pre_change_notify) (CoglMaterialLayer *layer,
                                   CoglMaterialLayerState change);

  void (*free_priv) (CoglMaterial *material);
  void (*free_layer_priv) (CoglMaterialLayer *layer);
} CoglMaterialBackend;

typedef enum
{
  COGL_MATERIAL_PROGRAM_TYPE_GLSL = 1,
  COGL_MATERIAL_PROGRAM_TYPE_ARBFP,
  COGL_MATERIAL_PROGRAM_TYPE_FIXED
} CoglMaterialProgramType;

void
_cogl_material_init_default_material (void);

void
_cogl_material_init_default_layers (void);

/*
 * SECTION:cogl-material-internals
 * @short_description: Functions for creating custom primitives that make use
 *    of Cogl materials for filling.
 *
 * Normally you shouldn't need to use this API directly, but if you need to
 * developing a custom/specialised primitive - probably using raw OpenGL - then
 * this API aims to expose enough of the material internals to support being
 * able to fill your geometry according to a given Cogl material.
 */

gboolean
_cogl_material_get_real_blend_enabled (CoglMaterial *material);

gboolean
_cogl_material_layer_has_user_matrix (CoglMaterialLayer *layer);

/*
 * Calls the pre_paint method on the layer texture if there is
 * one. This will determine whether mipmaps are needed based on the
 * filter settings.
 */
void
_cogl_material_layer_pre_paint (CoglMaterialLayer *layerr);

/*
 * CoglMaterialFlushFlag:
 * @COGL_MATERIAL_FLUSH_FALLBACK_MASK: The fallback_layers member is set to
 *      a guint32 mask of the layers that can't be supported with the user
 *      supplied texture and need to be replaced with fallback textures. (1 =
 *      fallback, and the least significant bit = layer 0)
 * @COGL_MATERIAL_FLUSH_DISABLE_MASK: The disable_layers member is set to
 *      a guint32 mask of the layers that you want to completly disable
 *      texturing for (1 = fallback, and the least significant bit = layer 0)
 * @COGL_MATERIAL_FLUSH_LAYER0_OVERRIDE: The layer0_override_texture member is
 *      set to a GLuint OpenGL texture name to override the texture used for
 *      layer 0 of the material. This is intended for dealing with sliced
 *      textures where you will need to point to each of the texture slices in
 *      turn when drawing your geometry.  Passing a value of 0 is the same as
 *      not passing the option at all.
 * @COGL_MATERIAL_FLUSH_SKIP_GL_COLOR: When flushing the GL state for the
 *      material don't call glColor.
 * @COGL_MATERIAL_FLUSH_WRAP_MODE_OVERRIDES: Specifies that a bitmask
 *      of overrides for the wrap modes for some or all layers is
 *      given.
 */
typedef enum _CoglMaterialFlushFlag
{
  COGL_MATERIAL_FLUSH_FALLBACK_MASK       = 1L<<0,
  COGL_MATERIAL_FLUSH_DISABLE_MASK        = 1L<<1,
  COGL_MATERIAL_FLUSH_LAYER0_OVERRIDE     = 1L<<2,
  COGL_MATERIAL_FLUSH_SKIP_GL_COLOR       = 1L<<3,
  COGL_MATERIAL_FLUSH_WRAP_MODE_OVERRIDES = 1L<<4
} CoglMaterialFlushFlag;

/* This isn't defined in the GLES headers */
#ifndef GL_CLAMP_TO_BORDER
#define GL_CLAMP_TO_BORDER 0x812d
#endif

/* GL_ALWAYS is just used here as a value that is known not to clash
 * with any valid GL wrap modes.
 *
 * XXX: keep the values in sync with the CoglMaterialWrapMode enum
 * so no conversion is actually needed.
 */
typedef enum _CoglMaterialWrapModeInternal
{
  COGL_MATERIAL_WRAP_MODE_INTERNAL_REPEAT = GL_REPEAT,
  COGL_MATERIAL_WRAP_MODE_INTERNAL_CLAMP_TO_EDGE = GL_CLAMP_TO_EDGE,
  COGL_MATERIAL_WRAP_MODE_INTERNAL_CLAMP_TO_BORDER = GL_CLAMP_TO_BORDER,
  COGL_MATERIAL_WRAP_MODE_INTERNAL_AUTOMATIC = GL_ALWAYS
} CoglMaterialWrapModeInternal;

typedef enum _CoglMaterialWrapModeOverride
{
  COGL_MATERIAL_WRAP_MODE_OVERRIDE_NONE = 0,
  COGL_MATERIAL_WRAP_MODE_OVERRIDE_REPEAT =
    COGL_MATERIAL_WRAP_MODE_INTERNAL_REPEAT,
  COGL_MATERIAL_WRAP_MODE_OVERRIDE_CLAMP_TO_EDGE =
    COGL_MATERIAL_WRAP_MODE_INTERNAL_CLAMP_TO_EDGE,
  COGL_MATERIAL_WRAP_MODE_OVERRIDE_CLAMP_TO_BORDER =
    COGL_MATERIAL_WRAP_MODE_INTERNAL_CLAMP_TO_BORDER,
} CoglMaterialWrapModeOverride;

/* There can't be more than 32 layers because we need to fit a bitmask
   of the layers into a guint32 */
#define COGL_MATERIAL_MAX_LAYERS 32

typedef struct _CoglMaterialWrapModeOverrides
{
  struct
  {
    CoglMaterialWrapModeOverride s;
    CoglMaterialWrapModeOverride t;
    CoglMaterialWrapModeOverride p;
  } values[COGL_MATERIAL_MAX_LAYERS];
} CoglMaterialWrapModeOverrides;

/*
 * CoglMaterialFlushOptions:
 *
 */
typedef struct _CoglMaterialFlushOptions
{
  CoglMaterialFlushFlag         flags;

  guint32                       fallback_layers;
  guint32                       disable_layers;
  GLuint                        layer0_override_texture;
  CoglMaterialWrapModeOverrides wrap_mode_overrides;
} CoglMaterialFlushOptions;


void
_cogl_set_active_texture_unit (int unit_index);

void
_cogl_delete_gl_texture (GLuint gl_texture);

int
_cogl_get_max_texture_image_units (void);


void
_cogl_use_program (CoglHandle program_handle, CoglMaterialProgramType type);

unsigned int
_cogl_get_n_args_for_combine_func (GLint func);


CoglMaterial *
_cogl_material_get_parent (CoglMaterial *material);

void
_cogl_material_get_colorubv (CoglMaterial *material,
                             guint8       *color);

void
_cogl_material_flush_gl_state (CoglMaterial *material,
                               gboolean skip_gl_state);

gboolean
_cogl_material_equal (CoglMaterial *material0,
                      CoglMaterial *material1,
                      gboolean skip_gl_color);

CoglMaterial *
_cogl_material_journal_ref (CoglMaterial *material);

void
_cogl_material_journal_unref (CoglMaterial *material);

void
_cogl_material_set_user_program (CoglMaterial *material,
                                 CoglHandle program);

void
_cogl_material_texture_storage_change_notify (CoglHandle texture);

void
_cogl_material_apply_legacy_state (CoglMaterial *material);

void
_cogl_gl_use_program_wrapper (GLuint program);

void
_cogl_material_apply_overrides (CoglMaterial *material,
                                CoglMaterialFlushOptions *options);

CoglMaterialBlendEnable
_cogl_material_get_blend_enabled (CoglMaterial *material);

void
_cogl_material_set_blend_enabled (CoglMaterial *material,
                                  CoglMaterialBlendEnable enable);

void
_cogl_material_set_static_breadcrumb (CoglMaterial *material,
                                      const char *breadcrumb);

unsigned long
_cogl_material_get_age (CoglMaterial *material);

CoglMaterial *
_cogl_material_get_authority (CoglMaterial *material,
                              unsigned long difference);

unsigned long
_cogl_material_layer_compare_differences (CoglMaterialLayer *layer0,
                                          CoglMaterialLayer *layer1);

CoglMaterialLayer *
_cogl_material_layer_get_authority (CoglMaterialLayer *layer,
                                    unsigned long difference);

CoglHandle
_cogl_material_layer_get_texture (CoglMaterialLayer *layer);

typedef gboolean (*CoglMaterialLayerCallback) (CoglMaterialLayer *layer,
                                               void *user_data);

void
_cogl_material_foreach_layer (CoglMaterial *material,
                              CoglMaterialLayerCallback callback,
                              void *user_data);

int
_cogl_material_layer_get_unit_index (CoglMaterialLayer *layer);

#endif /* __COGL_MATERIAL_PRIVATE_H */