Collision questions

[EDN Admin]

I need some help with precise collision in my game. I already got code working, but somehow it glitches up when I land on the ground. First, here is the collision code:bool check_collision( std::vector<SDL_Rect> &A, std::vector<SDL_Rect> &B )
{
//The sides of the rectangles
int leftA, leftB;
int rightA, rightB;
int topA, topB;
int bottomA, bottomB;

//Go through the A boxes
for( int Abox = 0; Abox < A.size(); Abox++ )
{
//Calculate the sides of rect A
leftA = A[ Abox ].x;
rightA = A[ Abox ].x + A[ Abox ].w;
topA = A[ Abox ].y;
bottomA = A[ Abox ].y + A[ Abox ].h;

//Go through the B boxes
for( int Bbox = 0; Bbox < B.size(); Bbox++ )
{
//Calculate the sides of rect B
leftB = B[ Bbox ].x;
rightB = B[ Bbox ].x + B[ Bbox ].w;
topB = B[ Bbox ].y;
bottomB = B[ Bbox ].y + B[ Bbox ].h;

//If no sides from A are outside of B
if( ( ( bottomA <= topB ) || ( topA >= bottomB ) || ( rightA <= leftB ) || ( leftA >= rightB ) ) == false )
{
//cout << "Touching" << endl;
//A collision is detected
return true;
}
}
}
//If neither set of collision boxes touched
return false;
}
Here is the movement code of my player:void player::move( std::vector<SDL_Rect> &rects )
{
//Move the player left or right
x += xVel;

//Move the collision boxes
shift_boxes();

//If the player went too far to the left or right or has collided
if( check_collision( box, rects ) )
{
//Move back
x -= xVel;
shift_boxes();
}

yNew = y + yVel;

while ( y != yNew && yVel != 0 )
{
if (yVel >= 0)
{
y ++;
cout << "y++;" << endl;
} else {
y --;
cout << "y--;" << endl;
}

shift_boxes();

// Check collisions at pixel level
if( check_collision( box, rects ) )
{
if( falling == true && ( on_ground && jumping ) == false )
{
cout << "collision with ground" << endl;
on_ground = true;
falling = false;
}
if( jumping == true && ( on_ground && falling ) == false )
{
cout << "collision with ceiling" << endl;
yVel = 0;
air_time = air_climax;
}
if( on_ground == true && ( jumping && falling ) == false )
{
cout << "still on the ground" << endl;
y -= yVel;
}
shift_boxes();
} else {
if ( jumping == false )
{
cout << "nothing below you so falling" << endl;
falling = true;
on_ground = false;
}
}
}
}Here is the air code of my player (which decides when to fall, after jumping):
void player::air()
{
if( jumping == true && ( on_ground && falling ) == false )
{
//if( yVel > 0 ){ yVel = 0; }
//if( yVel > -yspeed ){ yVel--; }
yVel = -yspeed;
if( air_time < air_climax )
{
air_time++;
} else { //when air_time is greater than or equal to air_climax
yVel = 0;
falling = true;
jumping = false;
}
}

if( jumping == false ){ air_time = 0; }

if( falling == true && ( on_ground && jumping ) == false )
{
//if( yVel < yspeed ){ yVel++; }
yVel = yspeed;
}
}You will see I have commented out code in the player::air code, that is because I want to make this easier for you and for me right now. With my current code in player::movement, the part with the yNew variable and all that, I see that it collides spot on with the cieling (in some older code I had, which had y+=yVel instead of yNew = y + yVel and didnt have the "while ( y != yNew && yVel != 0 )" as well as the "if (yVel >= 0)" code in it, the player jumped at a contant rate and his head would stick into the cieling a little bit before the falling occured) and then falls. While it is jumping, it will print the "y--;" message to console, while it is falling it will do "y++;". When you are falling and land on the ground, the game freezes and prints about 6 or 7 "y++;" at an alarming rate to every "collision with ground" and once in awhile "nothing below you so falling" pops up.

I have no idea what needs to be fixed, but that is where the code I need help with is. If you think you need anything else to help me, just ask. Thanks

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