Need help with collision detection

[JavaMan]

Can someone help me with my collision detection in my game:

Turing:

View.Set ("graphics:550;650,nobuttonbar") const Gravity := 1 var x := 16 var y := 16 var y_velocity := 0 var keys : array char of boolean var timerunning : int var score := 0 loop     %---Time/Score Counters---%     clock (timerunning)     Draw.FillBox (0, 595, 550, 600, black)     Draw.FillBox (0, 0, 650, 5, black)     locate (1, 53)     put "Time: ", timerunning / 1200 : 0 : 1, " sec"     locate (2, 52)     put "Score: ", score     locate (3, 51)     put x, ", ", y     %---Movement---%     Input.KeyDown (keys)     if keys (KEY_UP_ARROW) and y <= 16 or keys ('w') and y <= 16 then         y_velocity := 25     end if     if keys (KEY_LEFT_ARROW) and x > 12 or keys ('a') and x > 12 then         x -= 5     end if     if keys (KEY_RIGHT_ARROW) and x < 536 or keys ('d') and x < 536 then         x += 5     end if     if keys (KEY_ESC) then         cls         exit     end if     y_velocity -= Gravity     y += y_velocity     if y < 16 then         y := 16         y_velocity := 0     end if     %---Collision Detection---%     if x < 400 and x > 300 and y > 165 then         y := 165         y_velocity := 0     end if     Draw.FillBox (300, 175, 400, 180, black)     %---Power Ups---%     Draw.FillOval (x, y, 10, 10, red)     View.Update     delay (25)     cls end loop

I cant figure out how to get collision detection for the blocker to work properly.

Mod Edit:

Pleas wrap you code in either of the following in order to preserve whitespace (indentation) and to highlight the syntax.

code:

[syntax="turing"] ... code ... [/syntax] [code] ... code ... [/code ]

[Zren]

When you punch a wall, your hand doesn't go through the wall, then magically be set outside of it. Instead, you don't even reach where your hand would be if it remained at the same velocity.

Right now, you're moving the (x,y) coordinates during your input stage. Instead hold off until reaching the logic stage. Due to which, you try to set the player outside of the object in a specific position.

Exhibit A: A general game engine loop.

code:

loop:     % Input     % Logic     % Draw

Basically you should only change the velocity during the input stage, then later check where the entity will end up first. If it will end up somewhere it doesn't collide with anything, you can move it there.

Example:

code:

entity.position.x = ... entity.position.y = ... entity.velocity.x = ... entity.velocity.y = ... loop:     % Input     if onKeyPress():         % Eg: Right arrow         playerControlledEntity.velocity.dx = +playerControlledEntity.speed         % Logic     for each entity:         % Create temporary variables to find out where the entity will end up.         p.x = entity.position.x + entity.velocity.x         p.y = entity.position.y + entity.velocity.y                 if entity being at p.x collised with something (collision detection):             % Don't move         else:             % Move             entity.position.x = p.x             entity.position.y = p.y             % Draw     ...

Note that this method is also flawed, but this should help get the ball rolling.