I'm making a game in cocos2d with box2d and I'm running into some issues.
I have the program iterate through a tilemap's (.tmx) rows and columns , searching for tiles with a "collidable" property set to "true". If one is found, a square static box2d body (with fixtures and all) is set at that tile's position. So essentially, I should end up with a bunch of square bodies set up where I need them (depending on the tilemap) after the iteration is complete. I also have a square dynamic body that is controlled by gesture (up gesture slides it upward, down gesture downward, etc.), and it is supposed to only move in one of four directions: up, down, left, right. The restitution of the body is 0.0f so that it stops on impact with no rebound, and the friction is 0.0f as well because it's not needed (gravity of the world is 0.0f, 0.0f too). Since the iteration through the tilemap can only place bodies that are square, the "walls" in the game are composed of several of these squares lined up adjacent to each other, end to end, which creates a flush edge for the dynamic body to collide with.
The problem arises when the dynamic body collides with the wall of squares. I control movement of the body by setting the velocity of the body according to the gesture. An example of movement to the right would be:
#define bodyVel 100
...
if (gestureRight)
{
body->SetLinearVelocity( b2Vec2(bodyVel / PTM_RATIO, 0) );
}
I have the body set as a bullet so that when it collides with the wall it will not become embedded, but I have encountered some weird results. An example would be this:
I move the body rightwards into a wall and it stops. Good. Next, I want to move it up, so I gesture upwards. Good. But then, at times, as it is sliding up the wall, the body seems to "catch" on to something and it spins out of control and in multiple directions. Bad.
The only explanation I can come up with is that the dynamic body is in fact becoming imbedded in the wall upon the first head on contact, and as it slides up the wall upon the next given gesture for movement, it gets caught on the one of edges of the squares that make up the wall and becomes jarred from a straight path. I confirmed this strange activity by setting the body to have a fixed rotation (not rotate at all), and consequently, instead of the body spinning out of control, it would simply stop. This was expected given my hypothesis. So the dynamic body is becoming embedded is what I'm trying to say.
I don't understand why this is happening because I have the body set to behave like a bullet to avoid problems exactly like this. All I want the object to do is be able to move along a straight path - either up, down, left, or right -, stop upon contact with a wall, and move along the wall without interference from the bodies that make up the wall.
I feel like unless I have a misunderstanding of how bullet bodies work, the embedding that is occurring should not be an issue.
I also used to DebugDraw to see if the square static bodies created a flush wall and they did.
