/********************************************************************
  File: gradient.cc 
  Author:       Dana Vrajitoru
  Project:      Simple gradient program
  Last updated: January 9, 2017.

  Drawing several gradients using simple lines.

********************************************************************/

#include <GL/glut.h>
#include "gradient.h"

// display a vertical gradient going from the bg color on the left to
// the fg color on the right
void verticalGrad(float bg[], float fg[], 
                  float start[], float end[])
{
    glBegin(GL_POLYGON);
    glColor3f(bg[0], bg[1], bg[2]);
    glVertex2f(start[0], start[1]); // bottom left
    glColor3f(fg[0], fg[1], fg[2]);
    glVertex2f(end[0], start[1]);   // bottom right
    glVertex2f(end[0], end[1]);     // top right
    glColor3f(bg[0], bg[1], bg[2]);
    glVertex2f(start[0], end[1]);   // top left
    glEnd();
}

// display a vertical gradient made of horizontal lines of varying color
void verticalGrad1(float bg[], float fg[], 
                   float start[], float end[])
{
    int i;
    float y, color[3], alpha;
    for (y=start[1]; y<end[1]; y += 1) 
    {
        //draw a horizontal line from the bg color to the fg color
        glBegin(GL_LINES);
        glColor3f(bg[0], bg[1], bg[2]);
        glVertex2f(start[0], y);
        glColor3f(fg[0], fg[1], fg[2]);
        glVertex2f(end[0], y);
        glEnd();
    }
}


// display a horizontal gradient going from the bg color on the bottom to
// the fg color on the top
void horizontalGrad(float bg[], float fg[], 
                    float start[], float end[])
{
    // To be completed by the student.
}

// display a square gradient going from the bg color in the center to
// the fg color on the outside
void squareGrad(float bg[], float fg[], 
                float start[], float end[])
{
    // To be completed by the student.
}

// display a main diagonal gradient going from the bg color in the
// bottom left corner to the fg color in the top right corner
void diagonalGrad(float bg[], float fg[], 
                  float start[], float end[])
{
    // To be completed by the student.
}

// display a custom gradient
void customGrad(float bg[], float fg[], 
                 float start[], float end[])
{
    // To be implemented by the student.
}