bullet collision with object

[sammi]

What is it you are trying to achieve?
I am trying to make the bullet and the box disappear when the bullet hits the box


What is the problem you are having?
I dont know how to remove a value in an array to make the bullet disappear


Describe what you have tried to solve this problem
<tried making sure the program actually detected the collision but I dont know where to go from there>


Post any relevant code (You may choose to attach the file instead of posting the code if it is too long)
<Answer Here>

Turing:

View.Set ("offscreenonly") var keys : array char of boolean % Number of bullets currently on the screen var numBullets : int := 0 % used so holding space only % fires once var firing : boolean firing := false % x-location of bullets on screen var bulletX : array 1 .. 10 of int var bulletY : array 1 .. 10 of int %player location var playerX : int := 100 var playerY : int := 200 % box location var boxX : int := 350 var boxY : int := 200 loop     Input.KeyDown (keys) % update keyboard info     %%%%%%% MOVING %%%%%%%%%%%%     % Move Bullets     % 2) PUT CODE HERE TO MOVE BULLETS TO THE RIGHT     for i : 1 .. numBullets         bulletX (i) := bulletX (i) + 2     end for     if keys ('s') = true then         playerY := playerY - 2     end if     if keys ('w') = true then         playerY := playerY + 2     end if     if keys ('d') = true then         playerX := playerX + 2     end if     if keys ('a') = true then         playerX := playerX - 2     end if     %%%%%%% FIRE CHECK  %%%%%%%%%%     % Fire Pressed?     if keys (' ') = true and firing = false and numBullets < 10 then         numBullets := numBullets + 1         bulletX (numBullets) := playerX         bulletY (numBullets) := playerY         firing := true     end if     if keys (' ') = false then         firing := false     end if     %%%%%%% REMOVE CHECK  %%%%%%%%     % this check is only if the furthest bullet     % has reached the wall, will modify later     if numBullets > 0 then         if bulletX (1) > maxx then             % 3) PUT CODE HERE TO REMOVE BULLET IN SLOT 1         end if     end if     %%%%%%%% DRAWING  %%%%%%%%%%     cls ()         % clear screen     % Draw Character     Draw.FillOval (playerX, playerY, 10, 10, 7)     % Draw Bullets     for i : 1 .. numBullets         Draw.FillOval (bulletX (i), bulletY (i), 4, 4, 10)     end for     % Draw Boxes     Draw.FillBox (boxX, boxY, 300, 300, blue)     for i : 1 .. numBullets     if numBullets > 0 then         if bulletX (i) > boxX - 55 then             put "they have collided"         end if     end if     end for     delay (25)     View.Update end loop

Please specify what version of Turing you are using
<Answer Here>

[Aange10]

Hmm, I'll share some code with you that I made one day when I got bored ; Try to compare it to what you have, and see how my code works. Look at what I've made, and try to base yours off of it.



DO NOT copy and paste my code. That's counter productive. Use it as a guide.

Turing:

View.Set ("offscreenonly") var chars1 : array char of boolean % ________Bullet Data________ type BulletData :     record         xv, yv : real % Bullet Velocities         x, y, width, height, time_made, time_past : int % Positioning & Timer         used : boolean % If the bullet is in use (has been fired)     end record var bullets : array 1 .. 10 of BulletData % 10 bullets % ________Bullets on screen________ var bullet_reload, bullet_reload2 : int % Delay for shooting var bullets_on_screen : boolean % _______Define Bullet Values_______ for i : lower (bullets) .. upper (bullets)     bullets (i).xv := 8     bullets (i).yv := 4     bullets (i).x := 0     bullets (i).y := 0     bullets (i).width := 0     bullets (i).height := 0     bullets (i).used := false end for bullet_reload2 := Time.Elapsed () bullet_reload := Time.Elapsed () bullets_on_screen := false % ________________ Procedures ________________ % ________ Shooting _________ proc Shoot     if chars1 ('s') = true or chars1 ('s') = true then % If you hit s         bullets_on_screen := true % Bullets are on the screen         % Defining the Bullet Values         for i : lower (bullets) .. upper (bullets)             % if the bulelt isn't used, and 300 milisceonds has passed since the last shot             % Then it defines the bullet Vlaues             if bullets (i).used = false and bullet_reload > 300 then                 bullets (i).used := true                 bullets (i).x := 20                 bullets (i).y := 20                 bullets (i).width := 10                 bullets (i).height := 5                 bullets (i).time_made := Time.Elapsed ()                 bullets (i).time_past := Time.Elapsed ()                 bullet_reload2 := Time.Elapsed % Bullet was just shot                 exit             end if         end for     end if     % This is the reload timer. Bullet_reload2 is the time the last bullet was     % shot, and bullet_reload is the current time.     bullet_reload := Time.Elapsed ()     bullet_reload := bullet_reload - bullet_reload2 end Shoot % _________ Draw Bullets ________ proc DrawBullet     for i : lower (bullets) .. upper (bullets)         if bullets (i).used = true then % Only draw bullets that are shot/ in use             drawfilloval (bullets (i).x, bullets (i).y, bullets (i).width, bullets (i).height, 13)         end if     end for end DrawBullet % _________ Calculating _________ proc Calculate     for i : lower (bullets) .. upper (bullets)         % If the bullet is in use         if bullets (i).used = true then             % Move the bullet             bullets (i).x += round (bullets (i).xv)             % If you activate the following line, the bullets will fluctuate!             %bullets (i).height += 1                         % Updates the current time             bullets (i).time_past := Time.Elapsed ()             % Updates how long the bullet has been on the screen             bullets (i).time_past := bullets (i).time_past - bullets (i).time_made             % If the bullet has been on the screen for 5 seconds, then it             % defaults the bullet's values, and unactivates it.             % **TIP: Instead of 5 seconds, collision could be the time when a             % bullet is deactivated.             if bullets (i).time_past > 5000 then                 bullets (i).xv := 8                 bullets (i).yv := 4                 bullets (i).x := 0                 bullets (i).y := 0                 bullets (i).width := 0                 bullets (i).height := 0                 bullets (i).used := false % No longer in use             end if         end if     end for end Calculate % ________ Drawing the Screen ________ proc DrawScreen     drawfillbox (0, 0, maxx, maxy, grey)     drawfilloval (0, 40, 15, 15, black)     Draw.ThickLine (0, 39, 0, 0, 3, black)     Draw.ThickLine (0, 15, 20, 27, 2, black)     put " PRESS S "     DrawBullet end DrawScreen % ________Main Loop_________ loop     cls     Input.KeyDown (chars1)     Shoot     Calculate     DrawScreen     View.Update     delay (100) end loop

Also, for your collision:

Turing:

if bulletX (i) > boxX - 55 then

What are you saying here? You're telling the computer to look for the bullet to be to the right of boxX - 55. So, anytime it's to the right of the box, whether it's touching the box or not, it is true. That is why the collision message is off.

[sammi]

i cant follow your're code, its confusing me

[Aange10]

sammi @ 12/11/2011, 12:26 pm wrote:

i cant follow your're code, its confusing me

What parts?

[sammi]

i just need to know how to remove a bullet from the array so that it disappears when it hits the box.

[Aange10]

Aange10 @ 12/11/2011, 12:27 pm wrote:

sammi @ 12/11/2011, 12:26 pm wrote:

i cant follow your're code, its confusing me

What parts?

sammi wrote:

i just need to know how to remove a bullet from the array so that it disappears when it hits the box.

Right. What part of the coding I showed you are you confused about? I can help you understand it; hence solving your problem.

[Tony]

sammi @ Sat Nov 12, 2011 1:43 pm wrote:

how to remove a bullet from the array

you... don't. Because you can't. The type is array 1 .. 10 of int, so you'd always have a block of 10 integers. Someone will probably say something about resizing flexible arrays, but that's not necessary if we have a reasonable bound on the count of bullets.

You don't need to "remove" bullets, just to not draw them. In fact, you've already solved this problem elsewhere in your own code. When you fire first 3 shots, you still have an array block of 10, but you draw only 3 (and not all 10). What did you do to those other 7 slots?

[sammi]

Aange10 @ Sat Nov 12, 2011 1:44 pm wrote:

Aange10 @ 12/11/2011, 12:27 pm wrote:

sammi @ 12/11/2011, 12:26 pm wrote:

i cant follow your're code, its confusing me

What parts?

sammi wrote:

i just need to know how to remove a bullet from the array so that it disappears when it hits the box.

Right. What part of the coding I showed you are you confused about? I can help you understand it; hence solving your problem.

Your variables names are really hard to follow.........

[Aange10]

Bullet reload, x,y, xv, yv, width, height, used (boolean), time_made / time_past are all hard to follow?

Also they are comented, but here, I'll help you decipher it.

Turing:

bullet ().xv        % Bullet's x velocity bullet ().yv        % Bullet's y velocity bullet ().x         % Bullet's x cordinate bullet ().y         % Bullet's y cordinate bullet ().width     % Bullet's width bullet ().height    % Bullet's height bullet ().used      % If the bullet is fired bullet ().time_made % Time the bullet was fired bullet ().time_past % Time past since the bullet was fired bullet_reload       % Time the last bullet was shot bullet_reload       % Time past since the last bullet was shot bullets_on_screen   % If bullets are on the screen

[sammi]

Aange10 @ Sat Nov 12, 2011 5:32 pm wrote:

Bullet reload, x,y, xv, yv, width, height, used (boolean), time_made / time_past are all hard to follow?

Also they are comented, but here, I'll help you decipher it.

Turing:

bullet ().xv        % Bullet's x velocity bullet ().yv        % Bullet's y velocity bullet ().x         % Bullet's x cordinate bullet ().y         % Bullet's y cordinate bullet ().width     % Bullet's width bullet ().height    % Bullet's height bullet ().used      % If the bullet is fired bullet ().time_made % Time the bullet was fired bullet ().time_past % Time past since the bullet was fired bullet_reload       % Time the last bullet was shot bullet_reload       % Time past since the last bullet was shot bullets_on_screen   % If bullets are on the screen

alright so where the part where you make the stuff disappear off the screen once you hit it?

[Aange10]

If you can't read the comments, then you really aren't trying. I'm not getting paid to do this; I'm not going to do it for you.

[Zren]

Okay, full blown source code didn't work. Thinking by yourself didn't work. Theory Time! Huzzah!

Take a gander at this program:

Turing:

View.Set ("offscreenonly") var arr : array 1 .. 10 of boolean var currentIndex := lower (arr) % first index of the array arr (1) % Initialize for i : lower (arr) .. upper (arr)     arr (i) := false end for loop     % Logic     % Randomly (1 in 5 chance) turn off an index if it's on.     for i : lower (arr) .. upper (arr)         if arr (i) then             if Rand.Int (1, 5) = 1 then                 arr (i) := false             end if         end if     end for     % Input     % Check current index, if it's off, turn it on. Then increment current index to the next spot.     if not arr (currentIndex) then         arr (currentIndex) := true         currentIndex += 1         % Wrap around to begining         if currentIndex > upper (arr) then             currentIndex := lower (arr)         end if     end if     % Output     cls     for i : lower (arr) .. upper (arr)         color (white)         if arr (i) then             colorback (green)         else             colorback (red)         end if         put i, " " ..     end for     colorback (white)     color (black)     put "" % Finish line     put "Current Index: ", currentIndex     View.Update     delay (100) end loop

This is the basic logic for having a fixed amount of bullets.

Turing:

loop     % Logic     % Randomly (1 in 5 chance) turn off an index if it's on.     % -> Move all bullets, if it collides or goes off screen, turn it off (stop drawing)     % Input     % Check current index, if it's off, turn it on. Then increment current index to the next spot.     % -> If 'fire button' is pressed, 'spawn a new bullet'. This means reseting     %    the data at the current index. Then setting it up normally according to your player, etc.     %    You then turn the bullet 'on' or signal that you're now drawing this bullet.     % Output     % -> Cycle through the entire array of bullets, but only draw those that are 'on'. end loop

As you might of noticed before in the sample code, currentIndex would pause even though we we're trying to 'fire'. This is because the value at the currentIndex was already on. That would mean it's still on screen. You could deem to either:

1) Don't continue (like the sample code) and wait until it turns off (leaves the screen).
2) Continue and overwrite the data. This causes the effect of disappearing bullets when the limit is reached.
3) A combination of 1 and 2. Basically you look for an ready (off state) index. Set that as the currentIndex, and continue. Be warned, make sure to only run through the array once when checking or you might generate an infinite loop in the condition that all indexes are on.

*) In all cases, you can minimize the chance of catching up to the tail and hitting an 'on state' by increasing the size of the array. Be careful not to make it too big though. Counting (for looping) over large amounts, even when not doing anything else, can slow your program down. Don't believe me? Try this:

Turing:

for e : 0 .. 10     var limit := 10 ** e     var start := Time.Elapsed     for i : 0 .. limit     end for     var timeTaken := Time.Elapsed - start     put "0 .. ", limit, " took ", timeTaken, " ms" end for

[sammi]

ok sorry Aange10 i just had to read it over some more but i understand it now a little more

[Aange10]

sammi @ 13/11/2011, 11:03 am wrote:

ok sorry Aange10 i just had to read it over some more but i understand it now a little more

Oh you mean

Turing:

% If the bullet has been on the screen for 5 seconds, then it             % defaults the bullet's values, and unactivates it.             % **TIP: Instead of 5 seconds, collision could be the time when a             % bullet is deactivated.

Yeah, that must have been hard to decipher.

[sammi]

Aange10 @ Sun Nov 13, 2011 1:06 pm wrote:

sammi @ 13/11/2011, 11:03 am wrote:

ok sorry Aange10 i just had to read it over some more but i understand it now a little more

Oh you mean

Turing:

% If the bullet has been on the screen for 5 seconds, then it             % defaults the bullet's values, and unactivates it.             % **TIP: Instead of 5 seconds, collision could be the time when a             % bullet is deactivated.

Yeah, that must have been hard to decipher.

no lol i meant the entire code