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Field Guide

Fly Catch Eaten

Our last step shows how to check for the spider catching the fly.

using SplashKitSDK;
using static SplashKitSDK.SplashKit;


const string GAME_TIMER = "GameTimer";


const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;
const int SPIDER_RADIUS = 25;
const int SPIDER_SPEED = 3;


const int FLY_RADIUS = 10;


// Set the spider in the center of the screen
int spiderX = SCREEN_WIDTH / 2;
int spiderY = SCREEN_HEIGHT / 2;


// Create the fly
int flyX = Rnd(SCREEN_WIDTH), flyY = Rnd(SCREEN_HEIGHT);
bool flyAppeared = false;
long appearAtTime = 1000 + Rnd(2000);
long escapeAtTime = 0;


OpenWindow("Fly Catch", SCREEN_WIDTH, SCREEN_HEIGHT);


CreateTimer(GAME_TIMER);
StartTimer(GAME_TIMER);


// The event loop
while (!QuitRequested())
{
    // Handle Input
    if (KeyDown(KeyCode.RightKey) && spiderX + SPIDER_RADIUS < SCREEN_WIDTH)
    {
        spiderX += SPIDER_SPEED;
    }
    if (KeyDown(KeyCode.LeftKey) && spiderX - SPIDER_RADIUS > 0)
    {
        spiderX -= SPIDER_SPEED;
    }


    // Update the Game
    // Check if the fly should appear
    if (!flyAppeared && TimerTicks(GAME_TIMER) > appearAtTime)
    {
        // Make the fly appear
        flyAppeared = true;


        // Give it a new random position
        flyX = Rnd(SCREEN_WIDTH);
        flyY = Rnd(SCREEN_HEIGHT);


        // Set its escape time
        escapeAtTime = TimerTicks(GAME_TIMER) + 2000 + Rnd(5000);
    }
    else if (flyAppeared && TimerTicks(GAME_TIMER) > escapeAtTime)
    {
        flyAppeared = false;
        appearAtTime = TimerTicks(GAME_TIMER) + 1000 + Rnd(2000);
    }


    // Test if the spider and fly are touching
    if (CirclesIntersect(spiderX, spiderY, SPIDER_RADIUS, flyX, flyY, FLY_RADIUS))
    {
        flyAppeared = false;
        appearAtTime = TimerTicks(GAME_TIMER) + 1000 + Rnd(2000);
    }


    // Draw the game
    ClearScreen(ColorWhite());
    // Draw the spider
    FillCircle(ColorBlack(), spiderX, spiderY, SPIDER_RADIUS);


    if (flyAppeared)
    {
        // Draw the fly
        FillCircle(ColorDarkGreen(), flyX, flyY, FLY_RADIUS);
    }


    // Show it to  the user
    RefreshScreen(60);


    // Get any new user interactions
    ProcessEvents();
}