// 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

// Copyright 2007, Daniel Fontijne, University of Amsterdam -- fontijne@science.uva.nl

#ifdef WIN32
#include <windows.h>
#endif

#include <GL/gl.h>
#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>

#include <vector>

#include <libgasandbox/e3ga.h>
#include <libgasandbox/e3ga_draw.h>
#include <libgasandbox/e3ga_util.h>
#include <libgasandbox/gl_util.h>
#include <libgasandbox/glut_util.h>

using namespace e3ga;
using namespace mv_draw;

const char *WINDOW_TITLE = "Geometric Algebra, Chapter 3, Example 2: Implementing the Cross Product (SOLUTION)";

// GLUT state information
int g_viewportWidth = 800;
int g_viewportHeight = 600;
int g_GLUTmenu;

// mouse position on last call to MouseButton() / MouseMotion()
e3ga::vector g_prevMousePos;

// when true, MouseMotion() will rotate the model
bool g_rotateModel = false;
bool g_rotateModelOutOfPlane = false;

// rotation of the model
e3ga::rotor g_modelRotor(_rotor(1.0f));

// when dragging vectors: which one, and at what depth:
float g_dragDistance = -1.0f;
int g_dragObject = -1;

// the three vectors:
e3ga::vector g_vectors[3] = {
    _vector(e1 - e2 - 0.3f * e3),
    _vector(e1 + 0.3f * e2 - 0.1f * e3),
    e3ga::vector()
};


// SPOILER WARNING: solution to Chapter 3, exercise 2 right below

/// returns a x b
e3ga::vector crossProduct(const e3ga::vector &a, const e3ga::vector &b) {
    // exercise: compute the cross product, return it:
    return _vector(dual(a ^ b));
}

void display() {
    doIntelWarning(); // warn for possible problems with pciking on Intel graphics chipsets

    // compute the 3rd vector as g_vectors[0] X g_vectors[1]
    g_vectors[2] = crossProduct(g_vectors[0], g_vectors[1]);

    // setup projection & transform for the vectors:
    glViewport(0, 0, g_viewportWidth, g_viewportHeight);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    const float screenWidth = 1600.0f;
    glLoadIdentity();
    pickLoadMatrix();
    GLpick::g_frustumWidth = 2.0 *  (double)g_viewportWidth / screenWidth;
    GLpick::g_frustumHeight = 2.0 *  (double)g_viewportHeight / screenWidth;
    glFrustum(
        -GLpick::g_frustumWidth / 2.0, GLpick::g_frustumWidth / 2.0,
        -GLpick::g_frustumHeight / 2.0, GLpick::g_frustumHeight / 2.0,
        GLpick::g_frustumNear, GLpick::g_frustumFar);
    glMatrixMode(GL_MODELVIEW);
    glTranslatef(0.0f, 0.0f, -10.0f);


    glClearColor(0.3f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glEnable(GL_DEPTH_TEST);
    glPolygonMode(GL_FRONT, GL_FILL);
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);


    glMatrixMode(GL_MODELVIEW);

    glPushMatrix();
    rotorGLMult(g_modelRotor);

    glLineWidth(2.0);

    // draw vector 1
    if (GLpick::g_pickActive) glLoadName(1);
    glColor3fm(1.0f, 0.0f, 0.0f);
    draw(g_vectors[0]);

    // draw vector 2
    if (GLpick::g_pickActive) glLoadName(2);
    glColor3fm(0.0f, 1.0f, 0.0f);
    draw(g_vectors[1]);

    // draw (vector 1) ^ (vector 2)
    if (GLpick::g_pickActive) glLoadName((GLuint)-1);
    glColor3fm(1.0f, 1.0f, 1.0f);
    draw(g_vectors[0] ^ g_vectors[1]);


    // draw vector 3
    if (GLpick::g_pickActive) glLoadName(3);
    glColor3fm(0.0f, 0.0f, 1.0f);
    draw(g_vectors[2]);

    glPopMatrix();

    if (!GLpick::g_pickActive) {
        glViewport(0, 0, g_viewportWidth, g_viewportHeight);
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0, g_viewportWidth, 0, g_viewportHeight, -100.0, 100.0);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        glDisable(GL_LIGHTING);
        glColor3f(1,1,1);
        void *font = GLUT_BITMAP_HELVETICA_12;
        renderBitmapString(10, 40, font, "-use left mouse button to drag red/green vectors and to orbit scene");
        renderBitmapString(10, 20, font, "-the blue vector should always be orthogonal to the red and green vectors");
    }

    if (!GLpick::g_pickActive) {
        glutSwapBuffers();
    }
}

void reshape(GLint width, GLint height) {
    g_viewportWidth = width;
    g_viewportHeight = height;

    // redraw viewport
    glutPostRedisplay();
}


e3ga::vector vectorAtDepth(double depth, const e3ga::vector &v2d) {
    if ((GLpick::g_frustumWidth <= 0) || (GLpick::g_frustumHeight <= 0) ||
        (GLpick::g_frustumNear <= 0) || (GLpick::g_frustumFar <= 0)) {
        return e3ga::vector();
    }

    return _vector((depth * (double)v2d.e1() * GLpick::g_frustumWidth) / (g_viewportWidth * GLpick::g_frustumNear) * e1 +
        (depth * (double)v2d.e2() * GLpick::g_frustumHeight) / (g_viewportHeight * GLpick::g_frustumNear) * e2);
}


e3ga::vector mousePosToVector(int x, int y) {
    x -= g_viewportWidth / 2;
    y -= g_viewportHeight / 2;
    return e3ga::_vector((float)x * e3ga::e1 - (float)y * e3ga::e2);
}

void MouseButton(int button, int state, int x, int y) {
    g_rotateModel = false;

    g_prevMousePos = mousePosToVector(x, y);

    g_dragObject = pick(x, g_viewportHeight - y, display, &g_dragDistance);
    if (g_dragObject < 0) {
        e3ga::vector mousePos = mousePosToVector(x, y);
        g_rotateModel = true;
        if ((_Float(norm_e(mousePos)) / _Float(norm_e(g_viewportWidth * e1 + g_viewportHeight * e2))) < 0.2)
            g_rotateModelOutOfPlane = true;
        else g_rotateModelOutOfPlane = false;
    }
}

void MouseMotion(int x, int y) {
    // get mouse position, motion
    e3ga::vector mousePos = mousePosToVector(x, y);
    e3ga::vector motion = _vector(mousePos - g_prevMousePos);
    if (g_rotateModel) {
        // update rotor
        if (g_rotateModelOutOfPlane)
            g_modelRotor = _rotor(e3ga::exp(0.005f * (motion ^ e3ga::e3)) * g_modelRotor);
        else g_modelRotor = _rotor(e3ga::exp(0.00001f * (motion ^ mousePos)) * g_modelRotor);
    }
    else if ((g_dragObject >= 1) && (g_dragObject <= 2)) {
        // add motion to vector:
        e3ga::vector T = vectorAtDepth(g_dragDistance, motion);
        T = _vector(inverse(g_modelRotor) * T * g_modelRotor);
        g_vectors[g_dragObject-1] += T;
    }

    // remember mouse pos for next motion:
    g_prevMousePos = mousePos;

        // redraw viewport
        glutPostRedisplay();

}

void Keyboard(unsigned char key, int x, int y) {

}

int main(int argc, char*argv[]) {
    // profiling for Gaigen 2:
    e3ga::g2Profiling::init();

    // GLUT Window Initialization:
    glutInit (&argc, argv);
    glutInitWindowSize(g_viewportWidth, g_viewportHeight);
    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow(WINDOW_TITLE);

    // Register callbacks:
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutKeyboardFunc(Keyboard);
    glutMouseFunc(MouseButton);
    glutMotionFunc(MouseMotion);

    glutMainLoop();

    return 0;
}