texture.cpp

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/*
    Sheep - A Rigid Body Dynamics Engine
    Copyright (C) 2001-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of Sheep.

    Sheep 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.

    Sheep 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 Sheep; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "texture.h"    // include first
#include "common/math/real.h"

#include <cassert>
#include <GL/glut.h>
#include <IL/il.h>

using namespace sheep;
using namespace std;

Texture::Texture(int width, int height, const unsigned char *texels) {
    assert(texels);
    set_texture(width, height, texels);
}

Texture::Texture(const string &filename) {
    ILuint image_id;

    ilGenImages(1, &image_id);
    ilBindImage(image_id);

    const ILboolean success = ilLoadImage((/*const*/ ILstring)filename.c_str());
    assert(success);

    const int width = ilGetInteger(IL_IMAGE_WIDTH);
    const int height = ilGetInteger(IL_IMAGE_HEIGHT);

    GLubyte *texels = new GLubyte[width * height * 3];

    ilCopyPixels(0, 0, 0, width, height, 1, IL_RGB, IL_UNSIGNED_BYTE, texels);
    ilDeleteImages(1, &image_id);

    set_texture(width, height, texels);

    delete [] texels;
}

Texture::~Texture() {
    glDeleteTextures(1, &m_name);
}

void Texture::set_texture(int img_width, int img_height, const unsigned char *img_bits) {
    glGenTextures(1, &m_name);
    glBindTexture(GL_TEXTURE_2D, m_name);

    GLint max_tex_size;
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_tex_size);

    int tex_width = min(max_tex_size, NextPowerOfTwo(img_width));
    int tex_height = min(max_tex_size, NextPowerOfTwo(img_height));

    while(true) {
        GLint format = 0;   // must be initialized to zero

        glTexImage2D(GL_PROXY_TEXTURE_2D, 0, GL_RGB, tex_width, tex_height, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
        glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0, GL_TEXTURE_INTERNAL_FORMAT, &format);

        if(format == GL_RGB)
            break;

        // Cannot accommodate such a texture. Reduce the texture size.

        if(tex_width > tex_height) {
            assert(tex_width > 1);
            tex_width /= 2;
        } else {
            assert(tex_height > 1);
            tex_height /= 2;
        }
    }

    unsigned char *tex_bits = new unsigned char[tex_width * tex_height * 3];

    //!\todo Implement a better scaling scheme.
    gluScaleImage(
        GL_RGB,
        img_width, img_height, GL_UNSIGNED_BYTE, img_bits,  // in
        tex_width, tex_height, GL_UNSIGNED_BYTE, tex_bits); // out

    glTexImage2D(GL_TEXTURE_2D, 0, 3, tex_width, tex_height, 0, GL_RGB, GL_UNSIGNED_BYTE, tex_bits);
//  gluBuild2DMipmaps(GL_TEXTURE_2D, 3, tex_width, tex_height, GL_RGB, GL_UNSIGNED_BYTE, tex_bits);

    delete [] tex_bits;

    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
//  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
//  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
}

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