Shoot em up smooth player movement code?

Blitz3D Forums/Blitz3D Programming/Shoot em up smooth player movement code?

Boiled Sweets

(Posted 2007) [#1]

Hi has anyone got some code that moves a player left right in a kinda 'ramped' / smooth way with a little inertia?

GfK	(Posted 2007) [#2]

This should get you going the right direction. Typed straight into replybox, so, untested.

Const KEY_LEFT = 203
Const KEY_RIGHT = 205

Repeat
  cls
  If KeyDown(KEY_LEFT)
    xSpeed = xSpeed - 0.1
  EndIf
  If KeyDown(KEY_RIGHT)
    xSpeed = xSpeed + 0.1
  EndIf
  If not KeyDown(KEY_LEFT) and xSpeed < 0
    xSpeed = xSpeed + 0.1
  EndIf
  If not KeyDown(KEY_RIGHT) and xSpeed > 0
    xSpeed = xSpeed - 0.1
  EndIf
  if Abs(xSpeed) < 0.1
    xSpeed = 0
  endif
  If xSpeed < -5 then xSpeed = -5
  If xSpeed > 5 then xSpeed = 5
  x = x + xSpeed
  DrawImage ship,x,y
flip
Forever

Ross C

(Posted 2007) [#3]

You could look into using sin/cos to produce that deired effect. Build up the angle to 90 to full movement, then when no direction key/button is pressed slow decrease the angle parameter of sin to 0.

[code]

if keydown(LEFT) then
if angle < 90 then
angle = angle + 1
end if
else if keydown(RIGHT) then
If angle > -90 then
angle = angle - 1
end if
else
if angle > 0 then
angle = angle - 1
if angle < 0 then
angle = 0
end if
elseif angle < 0 then
angle = angle + 1
if angle > 0 then
angle = 0
end if
end if
end if

move ship sin(angle),0

[\code]

stick that in your loop. Some of that code isn't fully blitz, but you get the jist of it :o). The sin(angle) part is the movement part, with the effect you mentioned.

Sorry i'm in a rush, need to run!

Stevie G

(Posted 2007) [#4]

Maybe this?

Graphics 640,480,16,1
Const KEY_LEFT = 203
Const KEY_RIGHT = 205
Global Velocity#, x#=320, y#=450
Const Acceleration# = .25
Const Drag# = .95
;max speed = Acceleration / ( 1- Drag )

Global Ship = CreateImage( 32, 32 )
MidHandle Ship
SetBuffer ImageBuffer( Ship )
Color 255,255,255
Rect 8,0,16,32,1
Rect 0,16,32,16,1
SetBuffer BackBuffer()

Repeat
	Cls
	Thrust# = Acceleration * ( KeyDown( KEY_RIGHT ) - KeyDown( KEY_LEFT ) ) 
	Velocity = Velocity * Drag + Thrust
	x = x + Velocity
	DrawImage ship,x,y
	Flip
Until KeyDown(1)

Boiled Sweets

(Posted 2007) [#5]

Thanks people!

Stevie G, your one is perfect, ta. Can this go into the code archives?

Ross C

(Posted 2007) [#6]

Nice code stevie!