specbuf.cpp

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/* ResidualVM - A 3D game interpreter
 *
 * ResidualVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the AUTHORS
 * file distributed with this source distribution.
 *
 * 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.
 *
 */

/*
 * This file is based on, or a modified version of code from TinyGL (C) 1997-1998 Fabrice Bellard,
 * which is licensed under the zlib-license (see LICENSE).
 * It also has modifications by the ResidualVM-team, which are covered under the GPLv2 (or later).
 */

#include "graphics/tinygl/zgl.h"

namespace TinyGL {

static void calc_buf(GLSpecBuf *buf, const float shininess) {
    float val, inc;
    val = 0.0f;
    inc = 1.0f / SPECULAR_BUFFER_SIZE;
    for (int i = 0; i <= SPECULAR_BUFFER_SIZE; i++) {
        buf->buf[i] = pow(val, shininess);
        val += inc;
    }
}

GLSpecBuf *specbuf_get_buffer(GLContext *c, const int shininess_i, const float shininess) {
    GLSpecBuf *found, *oldest;
    found = oldest = c->specbuf_first;
    while (found && found->shininess_i != shininess_i) {
        if (found->last_used < oldest->last_used) {
            oldest = found;
        }
        found = found->next;
    }
    if (found) {
        found->last_used = c->specbuf_used_counter++;
        return found;
    }
    if (!oldest || c->specbuf_num_buffers < MAX_SPECULAR_BUFFERS) {
        // create new buffer
        GLSpecBuf *buf = (GLSpecBuf *)gl_malloc(sizeof(GLSpecBuf));
        if (!buf)
            error("could not allocate specular buffer");
        c->specbuf_num_buffers++;
        buf->next = c->specbuf_first;
        c->specbuf_first = buf;
        buf->last_used = c->specbuf_used_counter++;
        buf->shininess_i = shininess_i;
        calc_buf(buf, shininess);
        return buf;
    }
    //overwrite the lru buffer
    oldest->shininess_i = shininess_i;
    oldest->last_used = c->specbuf_used_counter++;
    calc_buf(oldest, shininess);
    return oldest;
}

void specbuf_cleanup(GLContext *c) {
    GLSpecBuf *buf, *next;
    buf = c->specbuf_first;
    for (int i = 0; i < c->specbuf_num_buffers; ++i) {
        next = buf->next;
        gl_free(buf);
        buf = next;
    }
}

} // end of namespace TinyGL