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brycemk

Fri Nov 30, 2012 7:22 pm


I need help with collision detection!

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Help... any ideas?



Need help with collision detection



I cant seem to get make the collision detection with the falling wall



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




setscreen ("graphics:v16,nocursor,noecho")
randomize
var x1, x2, x3, x4, y1, y2, barspeed, score : int
var c : int
var guy : int := Pic.FileNew ("guy.bmp")
var width : int := Pic.Width (guy)
var height : int := Pic.Height (guy)
var chars : array char of boolean
var x_pos , y_pos : int

x_pos := 300
y_pos :=1
randint (x2, 101, maxx - 151)
colourback (0)
score := 0
x1 := 100
x3 := x2 + 50
x4 := maxx - 100
y1 := maxy
y2 := y1 - 30

barspeed := 7
c := 1


procedure everythingelse
    drawfillbox (0, 0, x1 - 1, maxy, 24)
    drawfillbox (x4 + 1, 0, maxx, maxy, 24)
    drawfillbox (x1, y1, x2, y2, 0)
    drawfillbox (x3, y1, x4, y2, 0)
    y1 -= barspeed
    y2 -= barspeed
    drawfillbox (x1, y1, x2, y2, 24) %left side of thing
    drawfillbox (x3, y1, x4, y2, 24) %right side of thing
    sound (c, 100)
    if y1 < 10 and barspeed < 15 then
        c -= 20
        sound (c, 100)
    elsif barspeed > 15 then
        c += 0
        sound (c, 100)
    else
        c += 1
        sound (c, 100)
    end if
    if y1 < 0 then
        y1 := maxy
        y2 := y1 - 30
        randint (x2, 101, maxx - 151)
        x3 := x2 + 50
        score += barspeed
        if barspeed > 20 then
            barspeed += 0
        else
            barspeed += 1
        end if
    end if
end everythingelse
delay (2000)

loop
Input.KeyDown (chars)
if chars (KEY_LEFT_ARROW) then 
   x_pos := max (x_pos - 10, 20)
   width := max (width - 10, 20)
end if
if chars (KEY_RIGHT_ARROW) then 
   x_pos := min (x_pos + 10, 600)
   width := min (width + 10, 600)
 end if
cls
 Pic.Draw (guy, x_pos, y_pos,picMerge)

 
delay (1)

if whatdotcolor (x_pos, y_pos) not=0 then

exit
end if
    everythingelse
    
   
end loop

cls
put "Your score is: ", score



Newest version



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Panphobia

Fri Nov 30, 2012 7:31 pm


RE:I need help with collision detection!

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(x1+x2)^2-(y1+y2)==0, for the edges etc, it checks if the two points you want to collide are occupying the same space


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Dreadnought

Fri Nov 30, 2012 8:08 pm


Re: I need help with collision detection!

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(x1+x2)^2-(y1+y2)==0, for the edges etc, it checks if the two points you want to collide are occupying the same space

You might want to double check your formula.

@brycemk Please fill in the form, it's there for a reason.

What are you trying to do? What exactly is giving you trouble? How have you tried approaching the problem thus far?


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Zren

Fri Nov 30, 2012 8:26 pm


Re: RE:I need help with collision detection!

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(x1+x2)^2-(y1+y2)==0, for the edges etc, it checks if the two points you want to collide are occupying the same space

Um. I'm thinking that you're mixing that formula up. I noticed you wrote it wrong in the other thread as well.

How To Get The Distance Between Two Points (2D)
Or How Math.Distance() Works.

Pythagoras Theorem (which is what circle collision detection is based off) is: a^2 + b^2 = c^2
Which is where we apply it onto the cartesian plane like so: x^2 + y^2 = d^2 d = sqrt(x^2 + y^2) f(x, y) = sqrt(x^2 + y^2)

We can use this to get the distance from point A -> point B by first centering all vectors/coordinates to be relative to point A as if it were the origin.
Take:
point_a = (x1, y1)
point_b = (x2, y2)

Which we then translate so that point_a is at origin.
point_a = (x1 - x1, y1 - y1)
point_b = (x2 - x1, y2 - y1)

Which ends up as:
point_a = (0, 0) 

Which we then use in our function:
f(x2 - x1, y2 - y1)
= sqrt((x2 - x1)^2 + (y2 - y1)^2)

~

Edit: So like, making it look pretty took way longer than I thought...


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Panphobia

Fri Nov 30, 2012 8:32 pm


RE:I need help with collision detection!

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yea ^


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Panphobia

Fri Nov 30, 2012 8:34 pm


RE:I need help with collision detection!

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sorry forgot square root haha :D, pythagorean theorum haha ;D


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Zren

Fri Nov 30, 2012 8:38 pm


Re: RE:I need help with collision detection!

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sorry forgot square root haha :D, pythagorean theorum haha ;D

You were also adding instead of subtracting.


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Panphobia

Fri Nov 30, 2012 8:43 pm


RE:I need help with collision detection!

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aha i mixed it all up haha, :P ((x1-x2)^2+(y1-y2)^2)^1/2


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Panphobia

Fri Nov 30, 2012 9:54 pm


RE:I need help with collision detection!

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technically speaking, the square root of 0 is still 0, so you do not need to calculate it :P, so he does not have to put the square root