/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2018 by Blender Foundation.
 * All rights reserved.
 *
 * Contributor(s): Sergey Sharybin.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file BKE_subdiv_eval.h
 *  \ingroup bke
 *  \since September 2018
 *  \author Sergey Sharybin
 */

#ifndef __BKE_SUBDIV_EVAL_H__
#define __BKE_SUBDIV_EVAL_H__

#include "BLI_sys_types.h"

struct Mesh;
struct Subdiv;

/* Returns true if evaluator is ready for use. */
bool BKE_subdiv_eval_begin(struct Subdiv *subdiv);
bool BKE_subdiv_eval_update_from_mesh(struct Subdiv *subdiv,
                                      const struct Mesh *mesh);

/* Makes sure displacement evaluator is initialized.
 *
 * NOTE: This function must be called once before evaluating displacement or
 * final surface position. */
void BKE_subdiv_eval_init_displacement(struct Subdiv *subdiv);

/* Single point queries. */

void BKE_subdiv_eval_limit_point(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        float r_P[3]);
void BKE_subdiv_eval_limit_point_and_derivatives(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        float r_P[3], float r_dPdu[3], float r_dPdv[3]);
void BKE_subdiv_eval_limit_point_and_normal(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        float r_P[3], float r_N[3]);
void BKE_subdiv_eval_limit_point_and_short_normal(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        float r_P[3], short r_N[3]);

void BKE_subdiv_eval_face_varying(
        struct Subdiv *subdiv,
        const int face_varying_channel,
        const int ptex_face_index,
        const float u, const float v,
        float r_varying[2]);

/* NOTE: Expects derivatives to be correct.
 *
 * TODO(sergey): This is currently used together with
 * BKE_subdiv_eval_final_point() which cas easily evaluate derivatives.
 * Would be nice to have dispalcement evaluation function which does not require
 * knowing derivatives ahead of a time. */
void BKE_subdiv_eval_displacement(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        const float dPdu[3], const float dPdv[3],
        float r_D[3]);

void BKE_subdiv_eval_final_point(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const float u, const float v,
        float r_P[3]);

/* Patch queries at given resolution.
 *
 * Will evaluate patch at uniformly distributed (u, v) coordinates on a grid
 * of given resolution, producing resolution^2 evaluation points. The order
 * goes as u in rows, v in columns. */

void BKE_subdiv_eval_limit_patch_resolution_point(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const int resolution,
        void *buffer, const int offset, const int stride);
void BKE_subdiv_eval_limit_patch_resolution_point_and_derivatives(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const int resolution,
        void *point_buffer, const int point_offset, const int point_stride,
        void *du_buffer, const int du_offset, const int du_stride,
        void *dv_buffer, const int dv_offset, const int dv_stride);
void BKE_subdiv_eval_limit_patch_resolution_point_and_normal(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const int resolution,
        void *point_buffer, const int point_offset, const int point_stride,
        void *normal_buffer, const int normal_offset, const int normal_stride);
void BKE_subdiv_eval_limit_patch_resolution_point_and_short_normal(
        struct Subdiv *subdiv,
        const int ptex_face_index,
        const int resolution,
        void *point_buffer, const int point_offset, const int point_stride,
        void *normal_buffer, const int normal_offset, const int normal_stride);

#endif  /* __BKE_SUBDIV_EVAL_H__ */