ball.c

/**
   Ball module source code
   @team 128
   @author Ambrose Ledbrook - 79172462
   @author Josh Jarvis - 28803714
   @date 13-oct-2018
   @brief This module provides the ball functionality to the game through the use
          of the provided api module boing. It includes methods to intialise,
          update, send, receive and check collisons for the ball.
*/


// Including modules used in this module
#include "boing.h"
#include "tinygl.h"
#include "comms.h"
#include "paddle.h"
#include "ball.h"
#include <stdlib.h>


// A boing_state_t variable which holds the postion and direction of the ball
static boing_state_t ball;


/**
   Generates a random value between 0 and 1 which corresponds to the directions
   North west and North east. This is used to make the ball seem more random.
   @return A random boing_dir_t which is either DIR_NW, DIR_SW
*/
boing_dir_t get_rand_dir(void) {
    // Generating number
    uint8_t index = rand() % NUM_START_DIRS;
    boing_dir_t dir = DIR_N;
    // Getting direction from index
    switch(index) {
        case 0 :
            dir = DIR_NW;
            break;
        case 1 :
            dir = DIR_SW;
            break;
    }
    return dir;
}


/**
   Intialising the state and postion of the ball
*/
void ball_init(void) {
    ball = boing_init(BOTTOM_COLUMN, CENTER_ROW, get_rand_dir());
}


/**
   Updating the postion of the ball through the use of the boing_update method
*/
void ball_update(void) {
    // Removing current ball from ledmat
    tinygl_draw_point(ball.pos, BALL_NOT_VISIBLE);
    // Updating ball postion
    ball = boing_update(ball);
    // showing ball in its new postion
    tinygl_draw_point(ball.pos, BALL_VISIBLE);
}


/**
   Swithcing the direction of the ball when it hits the paddle
*/
void bounce_ball (void) {
    switch(ball.dir) {
        case DIR_SE :
            ball.dir = DIR_SW;
            break;
        case DIR_NE :
            ball.dir = DIR_NW;
            break;
        default :
            break;
    }
}


/**
   Reversing the direction os the ball.
*/
void ball_reverse(void) {
    // Removing current ball from ledmat
    tinygl_draw_point(ball.pos, BALL_NOT_VISIBLE);
    // Updating ball postion
    ball = boing_reverse(ball);
    // showing ball in its new postion
    tinygl_draw_point(ball.pos, BALL_VISIBLE);
}


/**
   Used to check if the ball has hit the paddle. Also handling the ball
   bouncing off the paddle.
   @return 0 if ball is on back of screen 1 otherwise
*/
uint8_t check_paddle(void) {
    // Checking the ball is on the bottom layer of the ledmat
    if (ball.pos.x == BOTTOM_COLUMN) {
        // Checking if the ball is within the paddle
        if (check_ball(ball.pos)) {
            return 1;
        } else {
            // Ball is not within the paddle and the game is over
            return 0;
        }
    // Checking if the ball is one layer above the paddle
    } else if (ball.pos.x == ABOVE_PADDLE_COLUMN) {
        // Checking edge cases where the ball hits the side of the paddle
        if (((paddle.left.y + 1) == ball.pos.y) && ball.dir == DIR_SE) {
            ball_reverse();
        } else if (((paddle.right.y - 1) == ball.pos.y) && ball.dir == DIR_NE) {
            ball_reverse();
        }
        // Checking if ball is over the paddle
        if (check_ball(ball.pos)) {
            bounce_ball();
        }
    }
    return 1;
}


/**
   Sending the postion and direction of the ball to the other board over
   through the use of the comms module.
*/
void send_ball_pos(void) {
    // Sending the ball
    send_ball(ball);
    // Removing the ball from the ledmat
    tinygl_draw_point(ball.pos, BALL_NOT_VISIBLE);
}


/**
   Processing a ball that was received from the other board. Takes a y-coordinate
   and a direction and updates the ball to match.
   @param pos the y coordinate received for the ball
   @param dir the direction received for the ball
*/
void receive_ball(uint8_t pos, uint8_t dir) {
    // Setting x and y postions of the ball
    ball.pos.x = TOP_COLUMN;
    ball.pos.y = pos;
    // setting the direction of the ball
    switch (dir) {
        case NORTH_EAST :
            ball.dir = DIR_NE;
            break;
        case EAST :
            ball.dir = DIR_E;
            break;
        case SOUTH_EAST :
            ball.dir = DIR_SE;
            break;
    }
    // Showing the ball on the ledmat
    tinygl_draw_point(ball.pos, BALL_VISIBLE);
}


/**
   Checking if the ball needs to be sent to the other board. The ball will be
   sent to the other board if its x-coordinate is 0 which is the top row of the
   ledmat.
   @return 1 if the ball is to be sent 0 otherwise
*/
uint8_t check_send(void) {
    // Checking if send conditions are met
    if (ball.pos.x == TOP_COLUMN && (ball.dir == DIR_W || ball.dir == DIR_SW || ball.dir == DIR_NW)) {
        return 1;
    } else {
        return 0;
    }
}


/**
  Resetting the postion of the ball to default. Used when the game is restarted
*/
void reset_ball(void) {
    ball.pos.x = BOTTOM_COLUMN;
    // Getting center postion of the paddle
    ball.pos.y = get_paddle_center();
    // Getting random direction
    ball.dir = get_rand_dir();
}