Flash game creation tutorial – part 4

Emanuele Feronato Flash

March 14th update: part 5.3 released.
March 3rd update: part 5.2 released.
February 9th update: part 5.1 released.
December 31st update: 5th part released.

Welcome to the 4th step of this flash game creation tutorial.

Read steps 1, 2 and 3 if you’re new to this tutorial, then follow this one.

The direction

Knowing the direction of the player may be very useful if we decide to add some special features to our game.
Always remember that it’s useless to make a simple clone of a game. If you decide to inspire yourself to an existing game, add some new features, or people will ignore your work.

I’ll explain you later in this tutorial how many pretty things you can do if you know the direction your player is moving.

Look at this actionscript

the formula at line 28 allows us to know the angle (direction) the player is moving, starting from its x and y speed.
Of course, you have to know the bare bones of trigonometry, but it’s very easy.
Lines 29-34 simply transofrm trigonometry angles into flash angles. This is due because of differences between flash axis system and trigonometry axis system.
Line 35 rotates a movieclip instanced as hero_dir of angles degrees minus the _rotation value, since the hero_dir movieclip is attached to the hero so it rotates with this one. So, if the hero has an rotation of 5 degrees and is moving in a direction of 85 degrees, the line of rotation should have a rotation angle of 85-5 = 80 degrees. Watch the movieclip to see how does it work.

Good. Now you can determine the direction your hero is moving in.
How can you use it?

One-direction walls

One-direction walls are walls that your player can pass through without crashing into them, for example, from left to right, while they still remain deadly if passed from right to left.

So I created a movieclip instanced as “oneway”. Look at the actionscript:

Line 42 Checks if the player hitted the oneway movieclip and if it has a direction angle from 90 to 270.
In this case, and only in this case, we know the hero is trying to pass the wall from right to left (remember that 0 degrees: right, 90 degrees: down, 180 degrees: left, 270 degrees, up), so the player dies.
The result of this actionscript is: if the wall can be passed from left to right, but it’s deadly from right to left.

You may say: there’s no need to play with trigonometry to do that: you can simply remember the old x position and verify that x position is increasing (moving to the right) or decreasing (moving to le left). That means I wasted a tutorial.

Or maybe not.

One-direction walls 2

Sometimes walls may not be just horizontal or vertical, and sometimes one-direction walls may allow to be passed only if the player has a given range of direction angle.

Now the oneway movieclip is rotated by 30° counter-clockwise

Line 43 now kills the player if it touchs the walls in a direction that is less of 300 degrees (or: in a range from 300 and 360 degrees). This means you have to pass the wall paying a lot of attention to your direction: the range of angles allowed are only 30 clockwise and 30 counter-clockwise, so the direction of the player must be very similar to the direction of the wall.

This can only easily be done if you know the direction of the player.

Later in this tutorial you will find another amazing way to have a special feature knowing player direction.

Now it’s time for player’s speed.

The speed

Sometimes it’s important to know the player speed.
Time to unveil the Pythagorean theorem:

In any right triangle, the area of the square whose side is the hypotenuse (the side of a right triangle opposite the right angle) is equal to the sum of areas of the squares whose sides are the two legs (i.e. the two sides other than the hypotenuse). (from Wikipedia)

Well, it’s rather obvious that the hypotenuse is the absolute speed and the two other sides are xspeed and yspeed values.

Line 27 applies the Pythagorean Theorem as explained above
Line 28 simply writes the speed in a text object.

How is the speed measured? It’s measured in pixels/frame

How can we use the speed?

Speed walls

Sometimes you may decide to place a wall the player can pass through only if he has a speed greater than… something.
The new movieclip instanced as speed_wall is our new obstacle

Line 44 makes the player die if he hits the wall with a speed slower than 5 pixels/frame.
Of course you can combine speed walls with one-way walls and normal walls… if you play well with those kind of walls you can create amazing mazes in minutes.

Time to introduce a new element now…

The dark

Since I hate the player (it’s obvious, isn’t it?) I want him to play in dark areas with only a spotlight around him.
The new movieclip I created is instanced as “dark” and consists in a big black rectangle with a hole in its center filled with a semi-transpared gradient.

Then with only two lines (line 27 and line 28) we move the dark in the same way we move the player.
The result is simple but very amazing. The player has to move carefully through dark areas trying to spot walls before he hits them.

The last feature for this tutorial is a combination of dark and direction

The directional light

It works basically as the example covered before, but this time the dark movieclip does not have a spotlight but a directional light, so it will rotate in the angle the player moves. I told you knowing the player angle is useful…

While lines 27 and 28 moves the dark movieclip according to player movements, line 37 provides the directional light rotation.

Well, that’s enough at the moment. This tutorial is over but the game is way to be completed. You will learn how to manage lives, energy, enemies, room exits, code-cleaning and some other useful things.

Meanwhile, download the source of the examples covered in this tutorial and give me feedback.
At this time, you should be able to code a little game like Collectabubble or something more complex.
If you make a game following one mf my tutorials, or want to draw some graphics for walls or backgrounds for the final game, please give me your works and I will put them on this site with a credit to you and a link to your website, if any.

Continue to part 5

Want to learn more? Learn by example!

Get the full commented source code of an actual commercial cross platform HTML5 game!!

Comments 80

  1. Pingback: Flash game creation tutorial - part 1 at Emanuele Feronato

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  4. dunno

    ur tuorials are rubbish i followed the 1st one and thats it i did a bit of the second one but nne of it worked and this u dont even tell me how to do some the stuff u jsut say do this and that

  5. Post
    Author
  6. Matt

    Emanuele, I want to congratulate you on an excellent tutorial and also for not rising up to the rudeness of aome of the people who have posted comments here. Comments such as ‘Your tutorials are rubbish’ only show up these individuals as the childish and immature individuals that they truely are – it’s no wonder they can’t grasp even the simplest bits of actionscript when the first thing they do when they don’t understand something is throw the dummy out of the pram and cry like a baby ;) You’ve given up your own time and expertise for free and I personally think that so far it has all been incredibly simple and clear. Looking forward to the next part :)

  7. Tony

    Could someone tell me how to advance a level?

    I put this in the “Actions” layer but it doesn’t work

    if (score==10) {
    gotoAndStop(2);
    }
    else {
    gotoAndPlay(1);
    }

    The tutorial is very good, thank you Em.

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    Author
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  10. bobby bean

    Hi
    I was learning flash and stumbled across your site. i found it really helpful and easy to fallow. it taught me a lot and showed me how to do a lot of things. thanks. i made a little game based on your tutorial.
    http://img128.imageshack.us/my.php?image=gameswl1.swf
    its nowhere near finished but our class is moving on to databases soon so I thing thats all it will get. If you want the source or how to do anything just email me at
    bobbybean@exemail.com.au
    once again thanks and bye :P
    P.S. big prize to anyone who can beat the LVL 5 big boss

  11. dooey100

    Im having problems with the direction. I am using MX 2004, what are you using? The source files wouldn’t open , and what happens is that the rotation kinda jumps back and forth. Help please?
    (Otherwise a very nice tutorial)

  12. confused pinguine

    Very good tutorial as said.
    but I really dont get it with the darkness, if someone could help me I would be very thankfull

  13. NoobInFlash

    i dunno if u already explained this but how would i put in a guy different other than the square. wat i mean is how can i create wats stuff looks like iin the game. for example could i put a gaint lizard , if i made on, into the game. and aslo how would i create one in the first place. plz get bak to me.

  14. wah wah wah

    the tutorials are great. Like someone already said, thanks for taking your time to do these. and for free too…you’re a great instructor. I hope the people that are complaining and saying rude stuff back up a step, relax, and keep trying. You’ll get it eventually and you will be happy you did. Quitting when it gets difficult and then blaming the guy who is giving a free tutorial is only going to get you into a bad habit that leads to a very unhappy life.

  15. a grateful user

    I just wanted to say that to put so much time into the tutorial is fantastic of you. The teaching is wonderful, every single step is explained in detail. I am surprised that so many people write to ask or comment on things that they need without first acknowledging the wonderful resource you have provided.

    I have no questions or complaints, I simply wanted to say thank you.

  16. Gilberto

    Hi Emanuele Feronato. Uhm, I have a problem with my game… You see, I’m making a game (in flash MX, it uses flash player 6.0) and I want it to look like a Crono Trigger… well my problem is that I want to include a lot of movie clips in the background and I’m using 2 kind of movement (in the center of the screen, the character changes its position x, y and when it hits the edge of the screen, then the background moves)… When I do so, the character and the bachground moves too slowly. I tried to change the vector images to GIF and PNG images but it’s just the same… I’d really appreciate if you answer to my mail dude. Well, thanks a lot. See you.

  17. Chance

    Please tell me the program to put ACTIONSCRIPT in. Emanuele, please, if i cant make a flash game, i will lead a sad, deppressed life.

  18. anon

    I had the same problem as ‘some1′, the dark symbol was moving with the hero but instead of the centre circle being over it, the top left corner is.

    I solved it by changing lines 27 and 28 to:

    _root.dark._x = _x – 780;
    _root.dark._y = _y – 700;

    Obviously the two numbers depend on the size of the symbol, but why have I had to do this?

  19. Izzy

    to anon:

    It is probably because the root of the symbol (marked by a sort of plus sign) is at the top-left corner of the lighter area… you can sort this by moving the lighening area so that the plus sign covers the centre of where your hero should be

    Hope this helps!

    Izzy

  20. Adam_ae

    Great guide, didn’t run into any problems with the tutorial other than a single missing “-” (my bad) which stumped me for quarter of an hour, preferred typing out the code rather than copy+paste, never goes well it seems.

    Thanks for putting up this tutorial, hopefully these tutorials will help me complete a decent game for once =P

  21. Connor

    I’m pretty confused about the angle… I put in the same ActionScript as you, but the line doesn’t go to the left. Could you please help me?

  22. Paul

    I have used a control system where the left and right keys just rotate the character, and the up and down keys control its movement in the direction it’s pointing at.
    I’m in a bind now however, as I want to fire an object from the character’s weapon. Using the direction equation on this tut, my bullet just goes in the same direction, but it starts from the weapon like I wanted.
    How would I get the bullet to travel in the direction that the weapon is facing whenever I press the trigger key? I’m totally stumped.
    P.S. I think I’ve used more trigonometry trying to figure this out than ever.

  23. andy 60

    yer this is possibly meant for intermediates as you need to know how to create movie clips and things? i understand it and think it is fantastic however.

  24. Umer

    THis is the best tutorial i have ever had ,I have advice instead of writting
    _y = _y + yspeed or yspeed = yspeed + gravity
    & every thing like that Can also be written as
    _y +=yspeed and yspeed+=gravity
    Need Help I am Trying to make the game like this one http://www.addictinggames.com/maxdirtbike.html
    But Problem Is this tutorial do not Explain Rotation And hittest do not work with curve objects So plsz Reply plzzzzzzzzzzzzzzzzz also i didn’t understand this one part 4

  25. trent

    Hey, i’m really new to actionscript and game design, so here’s my question:

    I’m trying to make a platform game where the character can jump and fall down. In the first part I learned how to apply gravity, but when he falls, he goes of the screen! How do I make it so that when he falls he hits the ground and stays there?

  26. Samuel Benson

    For the direction of the circle I found that I had to alter the script of the ball because it did not 100% work, for all those out there who find that the line does not show direction for yspeed >0 and xspeed >0 heres what to do:

    if (xspeed=0 && yspeed0 && yspeed>0) {
    angle -=90;
    }
    this.hero_dir._rotation = angle-_rotation;

    I don’t know why but it does work :)

  27. Matt 2

    This is a great website, Emanuele, I am a total beginner but I found the site easy to use and very user friendly, thanks.
    But I still have a couple of questions:
    1. Whenever I create a boundary to stop my ball(the hero) I use the code:

    “if(_root.wall.hitTest(_x,_y,true)){
    xspeed=0;
    yspeed=0;
    } ”

    but this, for some reason, only slows down the ball, and it does not (as I had hoped for) stop the ball completely. I would like some assistance here.

    2. As I have NOT made my ball rotate according to the x and y movements, I want to make the ball face the direction it is travelling in instead. So I modified the above code to:

    “angle=Math.atan(yspeed/xspeed)/(Math.PI/180);
    if (xspeed=0 && yspeed<0) {
    angle += 360;
    } ”

    I am quite sure there is something wrong there as nothing changed in the animation. But, as I said, I’m just a newbie!

    Any help would be greatly welcomed, thanks!

  28. NuclearDuckie

    Hey, do you know how I could make the character rotate to face the direction they’re moving in? I tried replacing the instance of the line with the instance of the hero, but that didn’t work…

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  31. NuclearDuckie

    Teh Newby:

    The program is called Adobe Flash, formerly Macromedia Flash, and you can find it on http://www.adobe.com/

    Also, I figured out the problem I was having before. I forgot to remove “this.” from line 35.

  32. renato

    I was doing something here and my scenario and text follow the ball. How can I make them fixed to the stage?

  33. PC Soft

    I like the tutorials. Main character her its a bit strange. But the help is quite good. I dont know if someone is reading online. Most people are downloading the files asap. :D

  34. x

    this sucks and its hard as hell! i DLed those files and there was shitload of unuseable dunnowhat extension file instead of swf!

  35. reluctant-to-comment

    I am still a noob at flash after realising that my school has it installed. I have done everything up to here, but i’m stumped on how to attach a movieclip to another movieclip, so i don’t have a hero.hit. Now this hadn’t botherd me because my scoreing is based on how many frames it has been since you died, and not how many items you have collected. It bothers me here because i want to know the direction of my player for *coughobviouscough* reasons and i can’t find a tutorial on the net explaining how to attach them.

    The installation of Flash is CS4, and i’m told that is very different.

  36. reluctant-to-comment

    Well i guess it’s back to random searching. I guess if i can find one i can do this tutorial and maby the AS3 vierson (if it exists).

  37. Nemo

    Hi Emanuele,

    I’ve learnt a lot from your tutorials. I was looking at your AS3 version of this tutorial, and I found that you hadn’t covered the dark/light part of this tutorial in the new version tutorials. I was wondering if you could explain to me how I should go about it?

    In my game I have a background, and then randomly generated coins on top that move from the top of the screen to the bottom. I wanted to have the light circle my hero and like you have above, the areas the light touches you can see the coins and background.
    The initial problem I came across was my darkened screen was under my generated fruit, but I (think I) fixed that by reshuffling my code around. However now I cannot get the light ring to follow my hero…

    Have you got any advice?
    Thanks

  38. I am.. Who am I ?? Vs. I am Who I am...

    Weehw!! A tutorial like this only gives a guideline on AS2 Game develoment for Novice Only!!

    It worked for me…
    You people should try giving instance name correctly and also should have decent experience on AS scripting to make anything work…

    Although I am refering this only for AS3 purpose!!… I know its AS2 .. but i can convert it to As3 …

  39. Aleks

    Awsome tutorials man! But what about if I want to make the wall not deadly, but just unpassable if my movement speed is not high enough? Im really lost here, will be great if u can help!

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  41. Christian

    hi!
    I really like your tuts,Im just loking at certan parts that i’d like to now how to do,I started with flash (I learned VB2010 first then I wanted to make some games) about a week ago and you have vary good tuts.
    I was wondering if any of your tuts will have stop on colision stuff?
    Thanks!

  42. Reed

    Thank you Emanuel,
    I’m brand new to Flash, looking at developing my own games to put on line and your tutorials have been invaluable! In combination with the shootorials over at http://www.kongregate.com I am beginning to think that flash game design isn’t as impossible as I once thought!

  43. andy

    Fantastic tutorial!
    More than 5 years ago and still going … !

    Well, it should be noted for once that some people would charge you a HELLUVA lot of money in their tutorial courses for this, you can bet your life on it!
    This guy does ’em on-line, and for free, spending heaps of his free time and even getting spit in the face by many! So I can only say: don’t let yourself discourage by some underage (?) morons that can’t even spell.

    Besides, that “flashlight effect” literally blew me away!!!
    Fun stuff. It also shows that you MUST NOT HATE MATH to write these kinds of games. People that shun math will never be good programmers. Read my lips.

  44. raco

    Man i realy dont get the direction thing. I thought i got it through an _root.attachMovie.hero_dir; ,but when i’m doing it in the second time, its not working. code is the sam in every letter as my old one (working) but this isn,t. And i realy dont have idea why and right now i wish that this cs5 program would be a human coz i wanna stab someone -.-

  45. Erebus9997

    For The Speed, I could not initially get the dynamic text to actually change. I fiddled around for half an hour and eventually solved the problem by changing the line ‘_root.speed.text = “speed: ” + speed;’ to ‘_root.speed = “speed: ” + speed;’. I don’t know what the ‘.text’ was supposed to be doing in there, but removing it solved all my problems. Hope this helps anyone else having the same trouble and thanks for the amazing tutorials!

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