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

typedef struct
{
    int x;
    int y;
    char color;
}Punto;    //definicion de estructura

//Variables globales
Punto puntos[50];
int num_puntos = 0;
int alto_ventana;
float size = 4.0f;
char cColor = 'a';
//Colores
float rojo[3] = {1.0f, 0.0f, 0.0f};
float azul[3] = {0.0f, 0.0f, 1.0f};
float verde[3] = {0.0f, 1.0f, 0.0f};
float amarillo[3] = {1.0f, 1.0f, 0.0f};
float gris[3] = {0.5f, 0.5f, 0.5f};
float negro[3] = {0.0f, 0.0f, 0.0f};

void redimensiona (int w, int h);
void dibuja (void);
void raton (int button, int state, int cx, int cy);
void teclado (unsigned char key, int x, int y);
void tecladoEspacial (int key, int x, int y);

int main (int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
    glutInitWindowSize(640, 480);
    glutInitWindowPosition(100, 150);
    glutCreateWindow("Dibujando puntos...");
    
    //Registro de funciones de callback
    glutDisplayFunc(dibuja);
    glutMouseFunc(raton);
    glutKeyboardFunc(teclado);
    glutReshapeFunc(redimensiona);
    glutSpecialFunc(tecladoEspacial);
    glutMainLoop();
    
    return 0;
}

//=================== Inicializa =========================

void redimensiona (int ancho, int alto) {
	glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
	glViewport(0, 0, (GLsizei) ancho, (GLsizei) alto);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0.0, (GLdouble) ancho, 0.0, (GLdouble) alto);
	alto_ventana = alto;
}

//=================== Dibujo =============================

void dibuja (void)
{
    int i;
    
    glClear(GL_COLOR_BUFFER_BIT);
    glPointSize(size);
    
    glBegin(GL_POINTS);
    for (i = 0; i < num_puntos; i++) {       
        switch(puntos[i].color) {
           
           case 'r':
           glColor3fv(rojo);
           break;
        
           case 'a':
           glColor3fv(azul);
           break;
           
           case 'v':
           glColor3fv(verde);
           break;
           
           case 'y':
           glColor3fv(amarillo);
           break;
           
           case 'g':
           glColor3fv(gris);
           break;
           
           case 'n':
           glColor3fv(negro);
           break;
           
           default: break; 
        }
           
        glVertex2i(puntos[i].x, puntos[i].y);
    }
    glEnd();
    
    glFlush();
}

//======================== Mouse ================

void raton (int button, int state, int cx, int cy)
{
    
    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
        puntos[num_puntos].x = cx;
        puntos[num_puntos].y = alto_ventana - cy;
        puntos[num_puntos].color = cColor;
        num_puntos++;
    }
    else if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
       exit(0);
    
    glutPostRedisplay();
}

//======================= Teclado ========================

void teclado (unsigned char key, int x, int y)
{
    switch (key) {
        case 'R':
        case 'r':
           cColor = 'r';
           break;
        
        case 'A':
        case 'a':
           cColor = 'a';
           break;
           
        case 'V':
        case 'v':
           cColor = 'v';
           break;
        
        case 'Y':
        case 'y':
           cColor = 'y';
           break;
           
        case 'N':
        case 'n':
           cColor = 'n';
           break;
           
        case 'G':
        case 'g':
           cColor = 'g';
           break;
           
        case 27:
           exit(0);
           break;
           
        default: break;
    }
}

void tecladoEspacial (int key, int x, int y)
{
    if (key == GLUT_KEY_PAGE_UP) {
    	size += 1.0f;
    }
    else if (key == GLUT_KEY_PAGE_DOWN) {
    	size -= 1.0f;
    }
    
    if (size < 1.0f) {
    	size = 1.0f;
    }
    
    glutPostRedisplay();
}