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talyboy

Fri Jun 06, 2008 10:44 pm


Please, need help with a driving simulation

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I have to create the illusion that my car is driving. To do this i'm moving the yellow bars down my screen. My variable "speed" goes down and up depending on whether the user clicks on the up or down arrow keys. My problem is moving the actual yellow bar. The bar moves down using increments of variable "speed". But for some reason, even though you can see the speed going up in the speedometer, the actually yellow rectangle does not move faster. How come? Can anyone help PLEASE!!!!!!!!!!

procedure userInput
    var speed : int := 0
    var horizontalLocation : int := 0
    var key : string (1)
    var delaySpeed : int
    delaySpeed := 90 - speed
    drawfillbox (0, 0, 704, 704, 26) %The road
    drawfillarc (100, 0, 75, 75, 0, 180, 2)     %Original speedometer
    locate (43, 13)
    put speed ..     %original drawing of speed

    loop
        loop
            %Gets keyboard input
            getch (key)

            %Measures speed (up and down arrows)
            if key = chr (200) and speed < 640 then %Up arrow key
                speed := speed + 1
                delay (0) %Acceleration speed. delay (0) means 0 - 80 km/h in 3 seconds.
            elsif key = chr (208) and speed > 0 then %Down arrow key
                speed := speed - 1
            end if
            drawfillarc (100, 0, 75, 75, 0, 180, 2) %Drawing the speedometer
            locate (43, 13)
            put speed .. %Changing speed

            %Measures horizontal placement on screen (left and right arrows)
            if key = chr (205) and horizontalLocation < 200 then %Right arrow key
                horizontalLocation := horizontalLocation + 10
            elsif key = chr (203) and horizontalLocation > 0 then %left arrow key
                horizontalLocation := horizontalLocation - 10
            end if
                drawfillbox (300, 700-1*speed, 325, 640-1*speed , 26)
                drawfillbox (300, 699-1*speed, 325, 639-1*speed, 14)
                delay (60 - speed)
        end loop
    end loop
end userInput
userInput



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DemonWasp

Thu Jun 12, 2008 8:31 pm


RE:Please, need help with a driving simulation

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This is a logic problem. You appear to be drawing the yellow line with one of these calls:


drawfillbox (300, 700-1*speed, 325, 640-1*speed , 26)
drawfillbox (300, 699-1*speed, 325, 639-1*speed, 14) 


This is your problem. Instead of always starting from the base coordinates of 700 to 640 (or 699 to 639, whichever), you need to keep track of where each line is (use a variable).

Essentially, the reason it doesn't move any faster is because "speed" isn't being used as a speed - it's being used as an offset.

What you want is more along these lines (pseudocode...don't copy-paste and expect it to work):


var lineY : int := 700
var lineLength : int := 60
...

loop
  % Other drawing stuff
  % Yellow Median drawing stuff
  lineY = lineY - speed
 drawfillbox (300, lineY, 325, lineY-lineLength , 26)
end loop


Of course, you'll have to figure out what happens when that line gets to the bottom of the screen, and also what happens when it should go behind the dashboard and so on. But that's a start.