My ongoing newbie questions

[eliasaif]

Here is my solution of moving left and right with my avatar:

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    //Moving left
    vx, vy = playerbody:getVelocity()

    if love.keyboard.isDown(love.key_left) then
        //This gives an acceleration to the avatar body
        newX, newY = 0.5*math.cos(3) + vx, 0.5*math.sin(3) + vy
        
        //Here, I set a maximum speed of the avatar body
        if newX < -13 then
            newX = -13
        end

        //When the new velocity is calculated, it's set to the avatar body
        playerbody:setVelocity(newX, newY)

     //Moving right
    elseif love.keyboard.isDown(love.key_right) then

        newX, newY = -0.5*math.cos(-3) + vx, -0.5*math.sin(-3) + vy

        if newX > 13 then
            newX = 13
        end

        playerbody:setVelocity(newX, newY)
    end

You put this code in the update function. Don't forget to rename "playerbody" with your avatar's body name.

[essell]

Great - thanks. Will try it tonight

[Jake]

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newX, newY = -0.5*math.cos(-3) + vx, -0.5*math.sin(-3) + vy

What's this all about?

[Person]

I'm sorry if you don't like me posting my own questions, I just thought this was the most appropriate place for them because of what you said on the first page...

I figured instead of starting threads for each of them, I'd post them all here

I'm attempting to set up a basic menu for my tetris clone (well, it's really an inventory tetris clone ). I want to show an image for each "button" of the menu that when clicked will change the game_state variable to a different value, which tells draw() what part of the game to draw. The problem is that some of these images will be PNG files that include transparent, non-uniform edges (read: not square buttons). Is there anyway for LOVE to tell if the mouse is over a non-transparent pixel? Should I abandon my hopes for a homebrew menu and use an existing library (will this make the buttons easier to code)? Or maybe I should hide the mouse and let users interface with the keyboard only!

I read the documentation and it said that images aren't stored in memory and per-pixel calculations were unavailable, so maybe that puts my homebrew version out of the question. I learned basic programming in C++ and the switch to Lua was hard, so I'm hoping the GUI library is out because they're so complex. The keyboard control method seems to be a code intensive way out and seems limiting to the player (or at least that is my experience).

Q: Which of the three methods (Homebrew, GUI library, and Keyboard Control) would be easiest to code and most usable?

[bartbes]

Homebrew and non-square buttons is a pain in the ass, I wouldn't recommend it. GUI libs are of good quality, that might be a way to go, and keyboard-only is another good option as well, so, it's a case of what you prefer, and how much time you have. (building GUIs tends to be a lengthy process)

[eliasaif]

Jake: This code will make the object accelerate smoothley.

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newX, newY = -0.5*math.cos(-3) + vx, -0.5*math.sin(-3) + vy

Ofcourse you can do something like this if you don't want any acceleration:

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//Move left
newX, newY = vx -5, vy

//Move right
newX, newY = vx + 5, vy

But when you do that, the velocity in X-axis will always be a constant velocity. So when you press the button, the object will instantly get the chosen velocity.

So the weird code is for a smooth acceleration. I hope i didn't explain it too messy..

[Robin]

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newX, newY = -0.5*math.cos(-3) + vx, -0.5*math.sin(-3) + vy

So the weird code is for a smooth acceleration. I hope i didn't explain it too messy..

But why didn't you put the calculated sine and cosine values in variables? They're constant, so there is no point in calculating them every time again.

[eliasaif]

Good point!

[Jake]

Jake: This code will make the object accelerate smoothley.

Code: Select all

newX, newY = -0.5*math.cos(-3) + vx, -0.5*math.sin(-3) + vy

Ofcourse you can do something like this if you don't want any acceleration:

Code: Select all

//Move left
newX, newY = vx -5, vy

//Move right
newX, newY = vx + 5, vy

But when you do that, the velocity in X-axis will always be a constant velocity. So when you press the button, the object will instantly get the chosen velocity.

So the weird code is for a smooth acceleration. I hope i didn't explain it too messy..

But cos of -3 is 0.998629535, then you multiply by -0.5 to get -0.4993.., so really you're only decreasing by about 0.5 each time and you may aswell remove the sines and cosines thus getting what you gave in the second code box.

[essell]

For about a week I'd not gotten round to working on my game at all, but just last night i started getting back to work on it, and now have most of what I did working with everything as physics objects instead of just moving pictures

To get the ball rolling on those questions again...

Q. How do I limit the top speed of a physics object moving in a certain direction (i.e. the speed at which the player moves retreats to the left in a side scrolling shooter)?