Transparent vs. Nonexistant

[Threeleggedyoyo]

Forgive me if this has been asked before, but I couldn't even begin to think what to call it or what to search for.

So I have a character who carries a big gun. Basically, he is in the shape of a capital T with a long cross line at the top.

As it stands, no collisions occur inside his "space," (the areas under the armpits of the T) which is transparent in the sprite. This is great for things that are shooting at him to decide if he gets hit or not.

However, it creates an uneven surface that gets caught on things - for example, he can hang on ledges, feet dangling, by his gun (which might be cool some other time but not today. :p).

So here's what I'm wondering:

1) Is there a way to make the sprite a complete square without making him have a sold-colored square background that follows him everywhere?

2) Is there a way to make his gun functionally transparent while still being part of his sprite?

3) Is there a way to make some objects detect the space for collisions and not others?

Thanks

[Jacob]

For #1 you can use an alpha channel that is just above black so you don't see it but it will still register collisions with it.

[Threeleggedyoyo]

I was wondering what the alpha channel was for... I was just playing with that.

What do you mean by just above black, and what exactly IS the alpha channel? Thanks.

[Jacob]

The alpha channel is a feature that allows variable per-pixel transparency. The closer to black it is, the more transparent and the closer to white the more opaque. If you use an alpha channel, and select black, double click on the foreground color box to bring up the advanced color selector. Then select something just a few shades lighter than black and use that for areas you eant to have collisions.

[Threeleggedyoyo]

Wonderful. Thank you.

Edit: Hrrm... I can see his square shadow...

[RayMarble]

There's a very neat DavidN's tutorial (links on the right) that could maybe help deal with collisions? It's called Fastloop tutorial or something similar.

[DaveC]

i think an easier way would be to go into the character objects properties and tick 'collision with box'

this makes the transparent area solid for collisions. thats what you wanted right?

[DavidN]

That's what I was going to suggest, too - backdrop and active objects have a property "Collision with box" (or "Use fine detection") that you can tick to make collisions count when objects are anywhere within the square boundaries of the sprite.

RayMarble mentioned my tutorial above - in that, I mention using two separate objects to represent your player, a "collider" that remains invisible and a "sprite" that's shown to the player. Collisions are handled using the collider object that always has a constant shape and size, rather than the animated player character.

[Threeleggedyoyo]

Yeah, that's what I needed! Thanks everyone. Between each of you that answers all my questions.

I got a lot done on my game last night. Even without knowing some of these things, I seem to have found some new ways to make some of the platforming issues work out. It seems to be a different way to program an engine than the tutorial I read, which was too mathy for me just getting ready to start something simple.

I even inadvertently found solutions to some of these questions, which surprised me. I am by no means an expert but I think I will share my work for examination when I get a bit further along. I'd be interested in knowing how it compares to some of the more schooled methods.