Problems with collisions and sdl_rects

SDL Development
#1

source here: http://www.mediafire.com/download/8d0osuuabogodb9/NickTest_6-2-2013_1741.zip

I am having a problem with collisions. Now I know the problem, I just cant find anywhere on a way to better optimize it. In player.cpp, you will see the code

Code:
void player::move()
{
//Move the player left or right
box.x += xVel;

//If the player went too far to the left or right or has collided with the wall
for( i = 0; i<= 0; i++)
{
	if( ( box.x < 0 ) || ( box.x + player_w > screenx ) || ( check_collision( box, wall[i] ) ) )
	{
		//Move back
		box.x -= xVel;
	}
}

//Move the player up or down
box.y += yVel;

//Falling
for( i = 0; i<= 0; i++)
{
	if( ( box.y < 0 ) || ( box.y + player_h > screeny ) || ( check_collision( box, wall[i] ) ) )
	{
		box.y -= yVel;
		grounded = true;
		//printf("player is on the ground\n");
	} 
	else //if there is nothing underneath the player
	{
		box.y += yVel;
		grounded = false;
		//printf("player is in air\n");
	}
}

}

I know that it is checking to collide with every instance of wall (ill rename is block later on). Wall[0] is a rectangle that represents the floor, Wall[1] is a rectangle that represents the wall; in the future, I want to make every wall a 16x16 or 32x32 block, and that will mean having a zillion different wall[i]'s.

Is my system on the right track or will it cause problems later? Can any of you show me with my code how to improve this? I have been stuck on this for three days because of this. Thanks------------------------
I am making an awesome SDL platformer

#2

Message-ID: <1370496621.m2f.37366 at forums.libsdl.org>
Content-Type: text/plain; charset=“iso-8859-1”

source here:
http://www.mediafire.com/download/8d0osuuabogodb9/NickTest_6-2-2013_1741.zip

I am having a problem with collisions. Now I know the problem, I just cant
find anywhere on a way to better optimize it. In player.cpp, you will see
the code

I know that it is checking to collide with every instance of wall (ill
rename is block later on). Wall[0] is a rectangle that represents the floor,
Wall[1] is a rectangle that represents the wall; in the future, I want to
make every wall a 16x16 or 32x32 block, and that will mean having a zillion
different wall[i]'s.

Is my system on the right track or will it cause problems later? Can any of
you show me with my code how to improve this? I have been stuck on this for
three days because of this. Thanks

I am making an awesome SDL platformer

Do you have a working demo form of the program? If so, then build a
large level, and attempt to play it in the game. If it’s too slow or
takes too much CPU then you’ll want to do an optimization, otherwise
you can leave it as-is.

Now, as far as optimizations go, what you want is a scene graph. A
scene graph basically just divides an environment into pieces, so that
you can deal with only the parts you’re close to, instead of dealing
with all of it.

You’re building a platformer, right? If it’s an old-school
side-scroller then you’ll probably be able to get away with dividing
the levels up into “screens”, and only check the “screen” that you’re
currently on, and the two beside it. If it has any meaningful height
then you might want to add some “screens” in that direction as well,
and if it’s a full 3d platformer then you’ll want “depth” screens in
addition, but those are just extensions to the basic concept.> Date: Wed, 05 Jun 2013 22:30:21 -0700

From: “DrNicholas”
To: sdl at lists.libsdl.org
Subject: [SDL] problems with collisions and sdl_rects

#3

Given he wants to make every block the same size, why not just go with
tiles? As a bonus, you will literally only ever check with the blocks
that would get in the way of the player, and never any other. The only
downside is that 1) it’s a 2D array (even old games used to do this
though, so not much of an issue!) and 2) all blocks have to be aligned
to a grid (that may look better anyway).

…just make sure to make the type of array with the map data the
smallest you can (ideally byte-sized, that gives you room for 255
unique blocks besides empty).

2013/6/8, Jared Maddox :>> Date: Wed, 05 Jun 2013 22:30:21 -0700

From: “DrNicholas”
To: sdl at lists.libsdl.org
Subject: [SDL] problems with collisions and sdl_rects
Message-ID: <1370496621.m2f.37366 at forums.libsdl.org>
Content-Type: text/plain; charset=“iso-8859-1”

source here:
http://www.mediafire.com/download/8d0osuuabogodb9/NickTest_6-2-2013_1741.zip

I am having a problem with collisions. Now I know the problem, I just
cant
find anywhere on a way to better optimize it. In player.cpp, you will see
the code

I know that it is checking to collide with every instance of wall (ill
rename is block later on). Wall[0] is a rectangle that represents the
floor,
Wall[1] is a rectangle that represents the wall; in the future, I want to
make every wall a 16x16 or 32x32 block, and that will mean having a
zillion
different wall[i]'s.

Is my system on the right track or will it cause problems later? Can any
of
you show me with my code how to improve this? I have been stuck on this
for
three days because of this. Thanks

I am making an awesome SDL platformer

Do you have a working demo form of the program? If so, then build a
large level, and attempt to play it in the game. If it’s too slow or
takes too much CPU then you’ll want to do an optimization, otherwise
you can leave it as-is.

Now, as far as optimizations go, what you want is a scene graph. A
scene graph basically just divides an environment into pieces, so that
you can deal with only the parts you’re close to, instead of dealing
with all of it.

You’re building a platformer, right? If it’s an old-school
side-scroller then you’ll probably be able to get away with dividing
the levels up into “screens”, and only check the “screen” that you’re
currently on, and the two beside it. If it has any meaningful height
then you might want to add some “screens” in that direction as well,
and if it’s a full 3d platformer then you’ll want “depth” screens in
addition, but those are just extensions to the basic concept.

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org