/*************************************************************************
 * Copyright (C) 2009-2014 Tavian Barnes <tavianator@tavianator.com>     *
 *                                                                       *
 * This file is part of The Dimension Library.                           *
 *                                                                       *
 * The Dimension 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 3 of the *
 * License, or (at your option) any later version.                       *
 *                                                                       *
 * The Dimension 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 program.  If not, see                         *
 * <http://www.gnu.org/licenses/>.                                       *
 *************************************************************************/

/**
 * @file
 * Object finishes.
 */

// Ambient component

/// Ambient finish component.
typedef struct dmnsn_ambient {
  dmnsn_color ambient; ///< Ambient light.
} dmnsn_ambient;

/// Allocate an ambient component.
dmnsn_ambient *dmnsn_new_ambient(dmnsn_pool *pool, dmnsn_color ambient);

// Diffuse component

typedef struct dmnsn_diffuse dmnsn_diffuse;

/**
 * Diffuse reflection callback.
 * @param[in] diffuse  The diffuse object itself.
 * @param[in] light    The color of the light illuminating the object.
 * @param[in] color    The pigment of the object.
 * @param[in] ray      The direction of the light source.
 * @param[in] normal   The normal vector of the surface.
 * @return The diffuse reflection component of the object's color.
 */
typedef dmnsn_color dmnsn_diffuse_fn(const dmnsn_diffuse *diffuse,
                                     dmnsn_color light, dmnsn_color color,
                                     dmnsn_vector ray, dmnsn_vector normal);

/// Diffuse finish component.
struct dmnsn_diffuse {
  dmnsn_diffuse_fn *diffuse_fn; ///< Diffuse callback.
};

/// Allocate a dummy diffuse component.
dmnsn_diffuse *dmnsn_new_diffuse(dmnsn_pool *pool);
/// Initialize a dmnsn_diffuse field.
void dmnsn_init_diffuse(dmnsn_diffuse *diffuse);

// Specular component

typedef struct dmnsn_specular dmnsn_specular;

/**
 * Specular highlight callback.
 * @param[in] specular  The specular object itself.
 * @param[in] light     The color of the light illuminating the object.
 * @param[in] color     The pigment of the object.
 * @param[in] ray       The direction of the light source.
 * @param[in] normal    The normal vector of the surface.
 * @param[in] viewer    The direction of the viewer.
 * @return The specular reflection component of the object's color.
 */
typedef dmnsn_color dmnsn_specular_fn(const dmnsn_specular *specular,
                                      dmnsn_color light, dmnsn_color color,
                                      dmnsn_vector ray, dmnsn_vector normal,
                                      dmnsn_vector viewer);

/// Specular finish component.
struct dmnsn_specular {
  dmnsn_specular_fn *specular_fn; ///< Specular callback.
};

/// Allocate a dummy specular component.
dmnsn_specular *dmnsn_new_specular(dmnsn_pool *pool);
/// Initialize a dmnsn_specular field.
void dmnsn_init_specular(dmnsn_specular *specular);

// Reflection component

typedef struct dmnsn_reflection dmnsn_reflection;

/**
 * Reflected light callback.
 * @param[in] reflection  The reflection object itself.
 * @param[in] reflect     The color of the reflected ray.
 * @param[in] color       The pigment of the object.
 * @param[in] ray         The direction of the reflected ray.
 * @param[in] normal      The normal vector of the surface.
 * @return The contribution of the reflected ray to the object's color.
 */
typedef dmnsn_color dmnsn_reflection_fn(const dmnsn_reflection *reflection,
                                        dmnsn_color reflect, dmnsn_color color,
                                        dmnsn_vector ray, dmnsn_vector normal);

/// The reflection component.
struct dmnsn_reflection {
  dmnsn_reflection_fn *reflection_fn; ///< Reflection callback.
};

/// Allocate a dummy reflection component.
dmnsn_reflection *dmnsn_new_reflection(dmnsn_pool *pool);
/// Initialize a dmnsn_reflection field.
void dmnsn_init_reflection(dmnsn_reflection *reflection);

// Entire finishes

/// A finish.
typedef struct dmnsn_finish {
  dmnsn_ambient *ambient; ///< Ambient component.
  dmnsn_diffuse *diffuse; ///< Diffuse component.
  dmnsn_specular *specular; ///< Specular component.
  dmnsn_reflection *reflection; ///< Reflection component.
} dmnsn_finish;

/**
 * Create a new blank finish.
 * @return The new finish.
 */
dmnsn_finish dmnsn_new_finish(void);

/**
 * Fill missing finish properties from a default finish.
 * @param[in]     default_finish  The default finish.
 * @param[in,out] finish          The finish to fill.
 */
void dmnsn_finish_cascade(const dmnsn_finish *default_finish,
                          dmnsn_finish *finish);