src/Gui/Inventor/SoFCBackgroundGradient.cpp

// SPDX-License-Identifier: LGPL-2.1-or-later

/***************************************************************************
 *   Copyright (c) 2005 Werner Mayer <wmayer[at]users.sourceforge.net>     *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library 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 Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/

#include <array>
#include <boost/math/constants/constants.hpp>
#include <cmath>
#include <numbers>

#include <FCConfig.h>

#ifdef FC_OS_WIN32
# include <windows.h>
#endif

#ifdef FC_OS_MACOSX
# include <OpenGL/gl.h>
#else
# include <GL/gl.h>
#endif

#include "SoFCBackgroundGradient.h"

static const std::array<GLfloat[2], 32> big_circle = [] {
    constexpr float pi = std::numbers::pi_v<float>;
    constexpr float sqrt2 = std::numbers::sqrt2_v<float>;
    std::array<GLfloat[2], 32> result;
    int c = 0;
    for (GLfloat i = 0; i < 2 * pi; i += 2 * pi / 32, c++) {
        result[c][0] = sqrt2 * cosf(i);
        result[c][1] = sqrt2 * sinf(i);
    }
    return result;
}();
static const std::array<GLfloat[2], 32> small_oval = [] {
    constexpr float pi = std::numbers::pi_v<float>;
    constexpr float sqrt2 = std::numbers::sqrt2_v<float>;
    static const float sqrt1_2 = std::sqrt(1 / 2.F);

    std::array<GLfloat[2], 32> result;
    int c = 0;
    for (GLfloat i = 0; i < 2 * pi; i += 2 * pi / 32, c++) {
        result[c][0] = 0.3 * sqrt2 * cosf(i);
        result[c][1] = sqrt1_2 * sinf(i);
    }
    return result;
}();

using namespace Gui;

SO_NODE_SOURCE(SoFCBackgroundGradient)

void SoFCBackgroundGradient::finish()
{
    atexit_cleanup();
}

/*!
  Constructor.
*/
SoFCBackgroundGradient::SoFCBackgroundGradient()
{
    SO_NODE_CONSTRUCTOR(SoFCBackgroundGradient);
    fCol.setValue(0.5f, 0.5f, 0.8f);
    tCol.setValue(0.7f, 0.7f, 0.9f);
    mCol.setValue(1.0f, 1.0f, 1.0f);
    gradient = Gradient::LINEAR;
}

/*!
  Destructor.
*/
SoFCBackgroundGradient::~SoFCBackgroundGradient() = default;

// doc from parent
void SoFCBackgroundGradient::initClass()
{
    SO_NODE_INIT_CLASS(SoFCBackgroundGradient, SoNode, "Node");
}

void SoFCBackgroundGradient::GLRender(SoGLRenderAction* /*action*/)
{
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
    glOrtho(-1, 1, -1, 1, -1, 1);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    glPushAttrib(GL_ENABLE_BIT);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_LIGHTING);
    glDisable(GL_TEXTURE_2D);

    if (gradient == Gradient::LINEAR) {
        glBegin(GL_TRIANGLE_STRIP);
        if (mCol[0] < 0) {
            glColor3f(fCol[0], fCol[1], fCol[2]);
            glVertex2f(-1, 1);
            glColor3f(tCol[0], tCol[1], tCol[2]);
            glVertex2f(-1, -1);
            glColor3f(fCol[0], fCol[1], fCol[2]);
            glVertex2f(1, 1);
            glColor3f(tCol[0], tCol[1], tCol[2]);
            glVertex2f(1, -1);
        }
        else {
            glColor3f(fCol[0], fCol[1], fCol[2]);
            glVertex2f(-1, 1);
            glColor3f(mCol[0], mCol[1], mCol[2]);
            glVertex2f(-1, 0);
            glColor3f(fCol[0], fCol[1], fCol[2]);
            glVertex2f(1, 1);
            glColor3f(mCol[0], mCol[1], mCol[2]);
            glVertex2f(1, 0);
            glEnd();
            glBegin(GL_TRIANGLE_STRIP);
            glColor3f(mCol[0], mCol[1], mCol[2]);
            glVertex2f(-1, 0);
            glColor3f(tCol[0], tCol[1], tCol[2]);
            glVertex2f(-1, -1);
            glColor3f(mCol[0], mCol[1], mCol[2]);
            glVertex2f(1, 0);
            glColor3f(tCol[0], tCol[1], tCol[2]);
            glVertex2f(1, -1);
        }
    }
    else {  // radial gradient
        glBegin(GL_TRIANGLE_FAN);
        glColor3f(fCol[0], fCol[1], fCol[2]);
        glVertex2f(0.0f, 0.0f);

        if (mCol[0] < 0) {  // simple radial gradient
            glColor3f(tCol[0], tCol[1], tCol[2]);
            for (const GLfloat* vertex : big_circle) {
                glVertex2fv(vertex);
            }
            glVertex2fv(big_circle.front());
        }
        else {
            glColor3f(mCol[0], mCol[1], mCol[2]);
            for (const GLfloat* vertex : small_oval) {
                glVertex2fv(vertex);
            }
            glVertex2fv(small_oval.front());
            glEnd();

            glBegin(GL_TRIANGLE_STRIP);
            for (std::size_t i = 0; i < small_oval.size(); i++) {
                glColor3f(mCol[0], mCol[1], mCol[2]);
                glVertex2fv(small_oval[i]);
                glColor3f(tCol[0], tCol[1], tCol[2]);
                glVertex2fv(big_circle[i]);
            }

            glColor3f(mCol[0], mCol[1], mCol[2]);
            glVertex2fv(small_oval.front());
            glColor3f(tCol[0], tCol[1], tCol[2]);
            glVertex2fv(big_circle.front());
        }
    }  // end of radial gradient
    glEnd();

    glPopAttrib();
    glPopMatrix();  // restore modelview
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glMatrixMode(GL_MODELVIEW);
}

void SoFCBackgroundGradient::setGradient(SoFCBackgroundGradient::Gradient grad)
{
    gradient = grad;
}

SoFCBackgroundGradient::Gradient SoFCBackgroundGradient::getGradient() const
{
    return gradient;
}

void SoFCBackgroundGradient::setColorGradient(const SbColor& fromColor, const SbColor& toColor)
{
    fCol = fromColor;
    tCol = toColor;
    mCol[0] = -1.0f;
}

void SoFCBackgroundGradient::setColorGradient(
    const SbColor& fromColor,
    const SbColor& toColor,
    const SbColor& midColor
)
{
    fCol = fromColor;
    tCol = toColor;
    mCol = midColor;
}