/*

This program gives a basic introduction to "animation"

*/

# include <math.h>
# include <stdlib.h>
# include <windows.h>
# include <GL/glut.h>


void DrawBoxAt(float x, float y)
{
    const float size = 1.0f;
    const float x1 = x - size;
    const float x2 = x + size;
    const float y1 = y - size;
    const float y2 = y + size;

    glVertex2f(x1, y1);
    glVertex2f(x2, y1);

    glVertex2f(x2, y1);
    glVertex2f(x2, y2);

    glVertex2f(x2, y2);
    glVertex2f(x1, y2);

    glVertex2f(x1, y2);
    glVertex2f(x1, y1);
}


void UpdateLeftPalm(float *x)
{
    unsigned int time = GetTickCount();
    float theta = time * 0.01f;

    float x1 = -25.0f;
    float x2 = -15.0f;
    float w = 0.5f * sinf(theta) + 0.5f;

    *x = w*x1 + x2*(1.0f - w);

}


void Draw(void)
{
# define PARTS_COUNT 13
    float points[PARTS_COUNT][2] = 
                        {//     x       y
                               0.0f,  30.0f,  //head
                               0.0f,  20.0f,  //neck
                              -5.0f,  18.0f,  //left_shoulder
                               5.0f,  18.0f,  //right_shoulder
                             -18.0f,  15.0f,  //left_elbow
                              12.0f,   5.0f,  //right_elbow
                               0.0f,   0.0f,  //waist
                             -25.0f,  30.0f,  //left_palm
                              20.0f,  -5.0f,  //right_palm
                             -10.0f, -15.0f,  //left_knee
                              10.0f, -15.0f,  //right_knee  
                             -15.0f, -30.0f,  //left_foot
                              15.0f, -30.0f,  //right_foot
                        };

    const int head = 0;
    const int neck = 1;
    const int left_shoulder = 2;
    const int right_shoulder = 3;
    const int left_elbow = 4;
    const int right_elbow = 5;
    const int waist = 6;
    const int left_palm = 7;
    const int right_palm = 8;
    const int left_knee = 9;
    const int right_knee = 10;
    const int left_foot = 11;
    const int right_foot = 12;
    
    int adjacency[PARTS_COUNT][PARTS_COUNT];
    int loop1, loop2;
    
    for(loop1 = 0; loop1 < PARTS_COUNT; loop1++)
        for(loop2 = 0; loop2 < PARTS_COUNT; loop2++)
            adjacency[loop1][loop2] = 0;

# define Connect(a, b) adjacency[a][b] = adjacency[b][a] = 1

    Connect(head, neck);

    Connect(neck, left_shoulder);
    Connect(neck, right_shoulder);
    Connect(neck, waist);

    Connect(left_elbow, left_shoulder);
    Connect(left_elbow, left_palm);
    
    Connect(right_elbow, right_shoulder);
    Connect(right_elbow, right_palm);

    Connect(waist, left_knee);
    Connect(waist, right_knee);

    Connect(left_knee, left_foot);
    Connect(right_knee, right_foot);

    //            r    g    b    a
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT);

    UpdateLeftPalm(&points[left_palm][0]);

    glColor3f(1.0f, 1.0f, 1.0f);
    glBegin(GL_LINES);

    for(loop1 = 0; loop1 < PARTS_COUNT; loop1++)
    {
        DrawBoxAt(points[loop1][0], points[loop1][1]);

        for(loop2 = 0; loop2 < loop1; loop2++)
        {
            if(adjacency[loop1][loop2])
            {
                glVertex2f(points[loop1][0], points[loop1][1]);
                glVertex2f(points[loop2][0], points[loop2][1]);
            }
        }
    }

    glEnd();

    glutSwapBuffers();
}


void OnWindowResize(int width, int height)
{
    //See how the output changes if you change left and top
    int left = 0;
    int bottom = 0;

    glViewport(left, bottom, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluOrtho2D(-width/2.0, width/2.0, -height/2.0, height/2.0);
}


void OnKeyPress(unsigned char key, int x, int y)
{
# define ESC_Key 27

    switch (key)
    {
        case ESC_Key:
            exit(0);
        break;
    }

    //printf("\nThe mouse is @..(%d, %d)\n", x, y);
}


int main(int argc, char** argv)
{
    const int left = 0;
    const int top = 0;
    const int width = 256;
    const int height = 256;

    const char* windowTitle = "Hasta La Vista Baby!!!";

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(width, height); 
    glutInitWindowPosition(left, top);
    glutCreateWindow(windowTitle);
    
    glutDisplayFunc(Draw);
    glutReshapeFunc(OnWindowResize);
    glutKeyboardFunc(OnKeyPress);

    //NEW FUNCTION in this tutorial's main function
    glutIdleFunc(Draw);

    glutMainLoop();

    return 0;
}



/*
EXERCISE 1:
Restructure the code so that.....
the connections are not done again and again inside the Draw

HINT:
Make the points and adjacency matrix global...
so that they are calculated only once



EXERCISE 2:
Draw the head with a bigger box
and try to have more details like eyes and mouth
*/


//
//   MORAL of this tutorial
//  ~~~~~~~~~~~~~~~~~~~~~~~~
// All that waves is not friend.
//