Weird Alpha, Layers, Sound and Rotate image to mouse pos

[WolfosoBastardo]

Alright so(I started using LÖVE a few days ago, I've been scripting Lua on Garry's Mod for 2-3 years), there are three little problems I'm having:
1°Weird Alpha

As you can see

Even though I'm setting color with this

Code: Select all

love.graphics.setColor( 226, 65, 65, 255 )

, alpha still doesn't appear to be 255. What am I doing wrong?

2° Layers.

Same image as above, you can see, the tank's barrel is above its base, which isn't suppose to happen. I tried to put the piece of code where I both load and draw the image above or below the base load / draw code, but nothing happened.

3° love.audio.play()

Whenever the tank shoots, it is supposed to play a sound, but it only works sometimes...

4° How do I rotate an image so that it always follows the mouse position? My brother suggested using sine and cosine but I couldn't seem to find the right operation on the wiki.

Thanks for anything helpful you are going to post!

[Robin]

I'm not sure what exactly is going on here, but here are a few things I noticed:

1. You uploaded a .zip with a .love in it. It is preferred to upload the .love directly to the forums.
2. The color problems you have might be due to the colormode or the blendmode, I'm not sure. Try experimenting with them.
3. Please don't put code that is not directly related to drawing things in love.draw. That's where love.update is for.
4. To point something to something else, you need math.atan2. Specifically:

   Code: Select all

   rotation = math.atan2(drawy - mousey, mousex - drawx)

   Replace "rotation", "drawx", "drawy", "mousex" and "mousey" with the appropriate variables.

[vrld]

1. You set the blend mode to additive.
2. Additive blending...
3. It's a bug in love.audio. Until this get's fixed, use .ogg files.
4. You can get the angle you need the image to rotate to point to the mouse using math.atan2:

   Code: Select all

   -- anchorx and anchor y are the points you want rotate the sprite around
   local mx, my = love.mouse.getPosition()
   local angle = math.atan2(mx - anchorx, my - anchory)
   

As for your code:

• You do a lot of stuff in love.draw() that should be done in love.update(dt) instead. Things like fullscreen toggling and position updates have nothing to do with drawing.
• Because of that, your code is depends on the framerate. That's not a good thing (use dt).
• Events that should get triggered only once when a key (fullscreen toggling) or mouse button (shooting) is pressed are better moved to love.keypressed and love.mousepressed.

[WolfosoBastardo]

1. You uploaded a .zip with a .love in it. It is preferred to upload the .love directly to the forums.
2. The color problems you have might be due to the colormode or the blendmode, I'm not sure. Try experimenting with them.
3. Please don't put code that is not directly related to drawing things in love.draw. That's where love.update is for.
4. To point something to something else, you need math.atan2. Specifically:

   Code: Select all

   rotation = math.atan2(drawy - mousey, mousex - drawx)

Alright I will do that next time.

Also thanks! I'll try that now.

1. You set the blend mode to additive.
2. Additive blending...
3. It's a bug in love.audio. Until this get's fixed, use .ogg files.
4. You can get the angle you need the image to rotate to point to the mouse using math.atan2:

   Code: Select all

   -- anchorx and anchor y are the points you want rotate the sprite around
   local mx, my = love.mouse.getPosition()
   local angle = math.atan2(mx - anchorx, my - anchory)
   

Alright I'll use .ogg file, thanks!

As for your code:

• You do a lot of stuff in love.draw() that should be done in love.update(dt) instead. Things like fullscreen toggling and position updates have nothing to do with drawing.
• Because of that, your code is depends on the framerate. That's not a good thing (use dt).
• Events that should get triggered only once when a key (fullscreen toggling) or mouse button (shooting) is pressed are better moved to love.keypressed and love.mousepressed.

Interesting, thanks, I'm going to do it now.

[Boolsheet]

1. It's a bug in love.audio. Until this get's fixed, use .ogg files.

I don't think you can call it a bug.

An already playing source does not rewind itself if you pass it to love.audio.play(). You either have to stop the source first or create a few sources and play them in sequence so they overlap. There was talk about changing the behavior of play.
(The love.audio.rewind function seems broken. Is that just me? Edit: Ah, not broken. There is something strange going on though)

The wave decoder that LÖVE uses pads wav files to 5 seconds for some reason. This is probably not a bug, but a design decision by the developer of the library. So yeah, avoid wav for now.

[WolfosoBastardo]

Alright just did everything suggested and everything works fine, except for love.keyboardpressed that of course only works when a key is pressed, not down; so in which function can I put the love.keyboard.isDown()?

[Robin]

Alright just did everything suggested and everything works fine, except for love.keyboardpressed that of course only works when a key is pressed, not down; so in which function can I put the love.keyboard.isDown()?

That goes into love.update. But I don't think you'll want to use that for toggling fullscreen, because holding the "f" key gets really annoying then.

[WolfosoBastardo]

Alright just did everything suggested and everything works fine, except for love.keypressed that of course only works when a key is pressed, not down; so in which function can I put the love.keyboard.isDown()?

That goes into love.update. But I don't think you'll want to use that for toggling fullscreen, because holding the "f" key gets really annoying then.

I did use love.keypressed for fullscreen toggling and put everything else (that requires key down) in love.update of course
(just mis-typed keypressed into keyboardpressed but I did use keypressed)

[vrld]

It's love.keypressed, not love.keyboardpressed.