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"perfect collisions!! (Best collision for stopping an object when it collides with another) *updated!!*", by grim_1_2_3

The reason I say this is the best collision code for making an object stop next to the object being collidied with, Is simply because it works regardless of how many pixels at a time you are moving the object across the screen, And it STILL detects even 1 pixel!!! Anywayz, You will need to replace the 2 images in the code with you're own to see how it works. Change the variable for 'dspeed' to however fast(number of pixels) you want the object to move across the screen when you use the keys to move it.

Note: You can now use floats for the dspeed also :)

Code

; **************************
; *     By Grim_1_2_3      *
; **************************

; This is a very recent piece of code which I wrote because of a minor annoyance I had with the 
; normal collision code I had. I noticed that with the old method of collision detection, If you 
; wanted to change the amount of movement for the 'dude' that you move around the screen 
; - For example - say, moving the dude 10 pixels per key press instead of 1 pixel at a time, It would
; cause the dude to go past a wall before a collision was detected!(Unless the wall was bigger than
; the amount of movement) Obviously, This was no good. So,
; I decided I needed to come up with a better way -- One where it wouldn't matter how fast the dude 
; was moving across the screen, Or how big any walls were - And voila! Here it is :) Simply change 
; the dspeed(dude speed) To the amount of pixels you want the dude To move across the screen whenever
; you hit a key. This is the very BEST collision detection routine I have Right now, And I think it
; is another essential For anyone who is serious about writing a game.

; **PLEASE NOTE** : This isn't the fastest of my collision detection routines, It is however the most
; accurate by far.

Graphics 640,480,32

SetBuffer BackBuffer()

Global dude = LoadImage("guy.bmp")
Global maze = LoadImage("bigmz_7.bmp")
Global dx# = 163 ; Dude image's starting x position on the screen
Global dy# = 52 ; Dude image's starting y position on the screen
Global dspeed# = 1.3 ; change this to whatever number you want
Global dcount# = 0.0 ; do not change(controlled by program)
Global up_key = 0 ; do not change(controlled by program)
Global down_key = 0 ; do not change(controlled by program)
Global left_key = 0 ; do not change(controlled by program)
Global right_key = 0 ; do not change(controlled by program)

main_loop()

Function main_loop()
While Not KeyHit(1)
movement_and_collision()
Flip
Cls
Wend
End Function

Function movement_and_collision()
MaskImage maze,255,255,255
DrawImage maze,120,50
DrawImage dude,dx#,dy#
If up_key = 1 And down_key = 0 And left_key = 0 And right_key = 0 Then move_dude_up()
If down_key = 1 And up_key = 0 And left_key = 0 And right_key = 0 Then move_dude_down()
If left_key = 1 And up_key = 0 And down_key = 0 And right_key = 0 Then move_dude_left()
If right_key = 1 And up_key = 0 And down_key = 0 And left_key = 0 Then move_dude_right()
check_for_keyhit()
End Function

Function check_for_keyhit()
If KeyDown(200) Then
up_key = 1
Else
If Not KeyDown(200) Then
up_key = 0
EndIf
EndIf
If KeyDown(208) Then
down_key = 1
Else
If Not KeyDown(208) Then
down_key = 0
EndIf
EndIf
If KeyDown(203) Then
left_key = 1
Else
If Not KeyDown(203) Then
left_key = 0
EndIf
EndIf
If KeyDown(205) Then
right_key = 1
Else
If Not KeyDown(205) Then
right_key = 0
EndIf
EndIf
End Function

Function move_dude_up()
If dspeed# > .1 And dcount# < dspeed# Then
Repeat 
dy# = dy# - .1
dcount# = dcount# + .1
If ImagesCollide(dude,dx#,dy#,0,maze,120,50,0) Then
dy# = dy# + .1
EndIf
Until dcount# > dspeed# Or ImagesCollide(dude,dx#,dy#,0,maze,120,50,0)
dcount# = 0.0
Else 
dy# = dy# - .1
EndIf
End Function

Function move_dude_down()
If dspeed# > .1 And dcount# < dspeed# Then
Repeat 
dy# = dy# + .1
dcount# = dcount# + .1
If ImagesCollide(dude,dx#,dy#,0,maze,120,50,0) Then
dy# = dy# - .1
EndIf
Until dcount# > dspeed# Or ImagesCollide(dude,dx#,dy#,0,maze,120,50,0)
dcount# = 0.0
Else 
dy# = dy# + .1
EndIf
End Function

Function move_dude_left()
If dspeed# > .1 And dcount# < dspeed# Then
Repeat 
dx# = dx# - .1
dcount# = dcount# + .1
If ImagesCollide(dude,dx#,dy#,0,maze,120,50,0) Then
dx# = dx# + .1
EndIf
Until dcount# > dspeed# Or ImagesCollide(dude,dx#,dy#,0,maze,120,50,0)
dcount# = 0.0
Else 
dx# = dx# - .1
EndIf
End Function

Function move_dude_right()
If dspeed# > .1 And dcount# < dspeed# Then
Repeat 
dx# = dx# + .1
dcount# = dcount# + .1
If ImagesCollide(dude,dx#,dy#,0,maze,120,50,0) Then
dx# = dx# - .1
EndIf
Until dcount# > dspeed# Or ImagesCollide(dude,dx#,dy#,0,maze,120,50,0)
dcount# = 0.0
Else 
dx# = dx# + .1
EndIf
End Function

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