Best way to make an object jump in a 3d program

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cheese pwner

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Posted: 9th Jul 2011 16:08

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Im working on a simple 3d program, where an object jumps when the spacebar is hit

My current code is :

+ Code Snippet

sync on
sync rate 25
autocam off
make matrix 1,2000,2000,20,20
make object sphere 1,5
make object collision Box 1,-2.5,-2.5,-2.5,2.5,2.5,2.5,0
position object 1,500,5,200
z2#=10
do
z2#=z2#+mousemovez()/100
if z2#<0 then z2#=0
if z2#>25 then z2#=25
print z2#   
print screen fps()
    If Leftkey()=1 then Yrotate object 1,Wrapvalue(AngleY#-2.5)
    If Rightkey()=1 then Yrotate object 1,Wrapvalue(AngleY#+2.5)
    If Upkey()=1
        XTest# = Newxvalue(X#,AngleY#,20)
        ZTest# = Newzvalue(Z#,AngleY#,20)
        If XTest#>0 and XTest#<10000 and ZTest#>0 and ZTest#<10000
        Move object 1,2
        Endif
        endif
    CameraZ# = Newzvalue(Z#,AngleY#-180,20)    
    CameraX# = Newxvalue(X#,AngleY#-180,20)
    CameraY# = 0
    Position camera CameraX#,CameraY#+0+z2#,CameraZ#
    Point camera X#,Y#,Z#
If Object collision(1,0)>0 then position object 1,X#,y#,Z#
     X# = Object position x(1)
    Z# = Object position z(1)
    y#=Object position y(1)
    AngleY# = object angle Y(1)

this is simple movement code, simple camera following code, the z2# is to change the angle at which you look at the object, then some basic collision detection (there are no other objects on the matrix yet, i removed them earlier on).

i still am unsure of how to make an object jump, then come back down in one fluid motion. Any help is appreciated thanks

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Bulsatar

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Posted: 9th Jul 2011 18:17 Edited at: 9th Jul 2011 18:18

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For your object, you could create a udt so that way it has a jump indicator and where the starting jump position is. Then you can have a pre-determined amount that the object will jump up before it comes back down. This is the simplest, if you want more realism you will have to get some simple physics involved.

easy example:

+ Code Snippet

Type MyChar
     DidJump As Integer
     JumpStart as Integer
     YPos as Integer
endtype
If spacebar() = 1 
     MyChar.DidJump = 1
     MyChar.JumpStart = YPos
endif
If MyChar.DidJump = 1 
     If MyChar.YPos <> MyChar.JumpStart + 100 Then inc MyChar.YPos Else MyChar.DidJump = 0
If MyChar.DidJump = 0
     ~Run your collision detection function here with a focus on dec-ing the ypos of your character.

All of this above is off the top of my head and I am uncertain of the syntax, but it should work. For more realism in the jump, you can give your characters and world gravity and mass and do some basic F=G*(M*m)/r^2 and then covert the force to an acceleration, but I am pretty sure that there is code out there all ready established to mimic that.

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Webber

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Posted: 18th Jul 2011 08:32

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Jumping

I love making stuff with jumping!

I used to have the same problem, now I'm an expert on jumping.

The trick is to add some more variables.

Here is a perfect example on how to make things jump.

sync on
sync rate 25
autocam off

make matrix 1,2000,2000,20,20
make object sphere 1,5
make object collision Box 1,-2.5,-2.5,-2.5,2.5,2.5,2.5,0
position object 1,500,5,200
z2#=10
do
z2#=z2#+mousemovez()/100
if z2#<0 then z2#=0
if z2#>25 then z2#=25
print z2#
print screen fps()
    If Leftkey()=1 then Yrotate object 1,Wrapvalue(AngleY#-2.5)
    If Rightkey()=1 then Yrotate object 1,Wrapvalue(AngleY#+2.5)
    If Upkey()=1
        XTest# = Newxvalue(X#,AngleY#,20)
        ZTest# = Newzvalue(Z#,AngleY#,20)
        If XTest#>0 and XTest#<10000 and ZTest#>0 and ZTest#<10000
        Move object 1,2
        Endif
        endif
    CameraZ# = Newzvalue(Z#,AngleY#-180,20)
    CameraX# = Newxvalue(X#,AngleY#-180,20)
    CameraY# = 0
    Position camera CameraX#,CameraY#+0+z2#,CameraZ#
    Point camera X#,Y#,Z#
If Object collision(1,0)>0 then position object 1,X#,Y#,Z#
    X# = Object position x(1)
    Z# = Object position z(1)
    Y# = Object position y(1)
    AngleY# = object angle Y(1)

Rem Jumps when the user press the space key
if Jump = 0 and spacekey() = 1 `The jump variable stops the player from being kirby
`Gravity turns negative, making the player jump
Gravity# = -2.0 `This number can be changed, to make the player jump higher or lower.
Jump = 1
endif

Rem adjusting the gravity
if Jump = 1 `If the player is in the air
Inc Gravity#,.1 `increases the strength of the gravity, allowing a smooth curve when the player falls
Move object down 1,Gravity# `This makes the player fall based on the Gravity# variable
`sometimes I put a maximum speed on the gravity for collision purposes.
endif

Rem Stop the sphere from falling through the floor
Rem You might want to change this if you want more complicated collision
if Y# < 2.5
Jump = 0 `Allows the player to jump again
position object 1,X#,2.5,Z# `repositions the sphere, so it doesn't stick in the floor
endif

sync
loop

+ Code Snippet

sync on
sync rate 25
autocam off

make matrix 1,2000,2000,20,20
make object sphere 1,5
make object collision Box 1,-2.5,-2.5,-2.5,2.5,2.5,2.5,0
position object 1,500,5,200
z2#=10
do
z2#=z2#+mousemovez()/100
if z2#<0 then z2#=0
if z2#>25 then z2#=25
print z2#
print screen fps()
    If Leftkey()=1 then Yrotate object 1,Wrapvalue(AngleY#-2.5)
    If Rightkey()=1 then Yrotate object 1,Wrapvalue(AngleY#+2.5)
    If Upkey()=1
        XTest# = Newxvalue(X#,AngleY#,20)
        ZTest# = Newzvalue(Z#,AngleY#,20)
        If XTest#>0 and XTest#<10000 and ZTest#>0 and ZTest#<10000
        Move object 1,2
        Endif
        endif
    CameraZ# = Newzvalue(Z#,AngleY#-180,20)
    CameraX# = Newxvalue(X#,AngleY#-180,20)
    CameraY# = 0
    Position camera CameraX#,CameraY#+0+z2#,CameraZ#
    Point camera X#,Y#,Z#
If Object collision(1,0)>0 then position object 1,X#,Y#,Z#
    X# = Object position x(1)
    Z# = Object position z(1)
    Y# = Object position y(1)
    AngleY# = object angle Y(1)


Rem Jumps when the user press the space key
if Jump = 0 and spacekey() = 1 `The jump variable stops the player from being kirby
`Gravity turns negative, making the player jump
Gravity# = -2.0 `This number can be changed, to make the player jump higher or lower.
Jump = 1
endif

Rem adjusting the gravity
if Jump = 1 `If the player is in the air
Inc Gravity#,.1 `increases the strength of the gravity, allowing a smooth curve when the player falls
Move object down 1,Gravity# `This makes the player fall based on the Gravity# variable
`sometimes I put a maximum speed on the gravity for collision purposes.
endif

Rem Stop the sphere from falling through the floor
Rem You might want to change this if you want more complicated collision
if Y# < 2.5
Jump = 0 `Allows the player to jump again
position object 1,X#,2.5,Z# `repositions the sphere, so it doesn't stick in the floor
endif

sync
loop

I like games, and stuff.

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TheComet

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Posted: 19th Jul 2011 18:39

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Good one Webber

Let me make you a master at jumping

It is possible to squeeze out one more variable:

+ Code Snippet

Rem Jumps when the user press the space key
if Gravity# = 0 and spacekey() = 1 `Only jump if gravity equals 0 (when the player is on the ground)

   `Gravity turns negative, making the player jump
   Gravity# = -2.0 `This number can be changed, to make the player jump higher or lower.
endif

Rem adjusting the gravity
Inc Gravity#,.1 `increases the strength of the gravity, allowing a smooth curve when the player falls
Move object down 1,Gravity# `This makes the player fall based on the Gravity# variable
`sometimes I put a maximum speed on the gravity for collision purposes.
endif

Rem Stop the sphere from falling through the floor
Rem You might want to change this if you want more complicated collision
if Y# < 2.5
Gravity# = 0 `Allows the player to jump again
position object 1,X#,2.5,Z# `repositions the sphere, so it doesn't stick in the floor
endif

TheComet

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Webber

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Posted: 25th Jul 2011 04:53

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I dono bout dat, its an important variable for collision purposes.

Its possible that it will make the player boble/shake on the ground without it. Kinda like an earth quake.
But there are ways of fixing the collision glitch.
Unfortunately other side effects usually occur, and depending on the numbers you use, the character will fly instead of fall.
And in some cases the character will forget to fall.

Because of the parabolic curve when the character jumps, at one point in time the gravity does equal 0.

So you need to detect the collision of the floor, not the speed of the gravity.
Also depending on the complexity of your collision, the gravity might still exist when on a slope.
Or if you want to get real fancy you might want to make your character do wall jumps.

And if you tested your code, you would have noticed that you forgot to get rid of an endif command.
Sometimes I make mistakes like that too.

It is possible to get rid of another variable, but depending on the game that you are making, it isn't the best thing to do.
One variable isn't going to change the speed of the game very much.
But if you're really concerned about the variable you can declare it as a boolean.
Not a bad idea.

After all it only ever equals 0 or 1.

+ Code Snippet

Jump as boolean

Looks like we're all masters of jumping now.

If only I was a master with object collision.
I have an awesome platform engine on the code base.
Its listed in 3D effects, its called "Boxes and More Boxes".
Its a great example of jumping, collision, and other cool stuff.
Very unique, I don't even think it uses any collision commands.
I should probably update it though.
To bad that I can't figure out how to make such nice collision with angles.

I like games, and stuff.

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TheComet

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Location: I`m under ur bridge eating ur goatz.

Posted: 25th Jul 2011 12:29

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Hah, yeah, I see your point

If you need help with collision, I have an example lying around that uses sparky's. You might be interested

Oh, and this:

Quote: "After all it only ever equals 0 or 1."

+ Code Snippet

rem setup screen
sync on
sync rate 60
backdrop on
color backdrop 0
hide mouse

rem global variables
global jump as boolean

rem do some magic...
jump=0
dec jump

rem main loop
ink 0xFFFFFFFF,0
do

   rem text for user
   text 0,0,"So, jump can really only equal 0 or 1?"
   text 0,20,"value of jump : "+str$(jump)

   rem refresh screen
   sync

rem end of main loop
loop

rem end
end

TheComet

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WLGfx

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Posted: 26th Jul 2011 05:19

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Just popped in and noticed you were talking about booleans.

Try this:

+ Code Snippet

b as boolean
b=0

dec b
print b

do
loop

It will give the result as 255.

A boolean isn't a proper boolean in DBPro. So be careful with it.

The only way around this is to use something like this:

+ Code Snippet

b = b && 1

Warning! May contain Nuts!

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Webber

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Posted: 10th Aug 2011 20:00

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That's really weird, I never noticed that. Is that a glitch?
Booleans have the same values as a byte.
Or is a byte not a proper byte in DBP?
If you look up the value of a boolean in DBP it clearly says that it's a value between 1 and 0.
Well just don't subtract a boolean with a value of 0 or add to a value of 1.

I like games, and stuff.

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