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# Lee Walker

Member Since 08 Feb 2011
Offline Last Active Jul 30 2014 04:44 AM

### Basic 2D square collision

17 April 2012 - 05:03 PM

I've developed my game to a point where I'm now starting to notice that my current approach to box collisions is wrong.

The code is as follows:

//if the block's origin is within 32px of the actor
if(collision[r][c]->GetPosition().x >= (a.x + av.x) - 32 &&
collision[r][c]->GetPosition().x <= (a.x + av.x) + 32 &&
collision[r][c]->GetPosition().y >= (a.y + av.y) - 32 &&
collision[r][c]->GetPosition().y <= (a.y + av.y) + 32)
{

MyRect b = collision[r][c]->GetPosition();

//Actor collision left
if(a.left() + av.x < b.right() &&
a.right() > b.left() &&
(a.top() < b.bottom() &&
a.bottom() > b.top()) &&
av.x < 0)
{
MyRect newVel = av;
newVel.x = 0;
act->SetVelocity(&newVel);
MyRect newPos = a;
newPos.x = (b.x + b.w);
act->Move(&newPos);
}
//Actor collision right
if(a.right() + av.x > b.left() &&
a.left() < b.right() &&
(a.top() < b.bottom() &&
a.bottom() > b.top()) &&
av.x > 0)
{
MyRect newVel = av;
newVel.x = av.x - av.x;
act->SetVelocity(&newVel);
MyRect newPos = a;
newPos.x = (b.x - a.w);
act->Move(&newPos);
}
//Actor collision Top
if(a.top() + av.y < b.bottom() &&
a.bottom() > b.top() &&
a.left() < b.right() &&
a.right() > b.left() &&
av.y < 0)
{
act->jumping = false;
MyRect newVel = av;
newVel.y = 1;//-(av.y < 0 ? av.y/2 : -1);
act->SetVelocity(&newVel);
MyRect newPos = a;
newPos.y = (b.y + b.h);
act->Move(&newPos);
}
//Actor collision Bottom
if(a.bottom() + av.y > b.top() &&
a.top() + av.y < b.bottom() &&
a.left() < b.right() &&
a.right() > b.left() &&
av.y > 0)
{
MyRect newVel = av;
newVel.y = 0;
act->SetVelocity(&newVel);
MyRect newPos = a;
newPos.y = (b.y - a.h);
act->Move(&newPos);
groundCollided = true;
act->jumping = false;
}
}

if(!groundCollided)
{
act->isOnGround = false;
}
else {
act->isOnGround = true;
}

Where a = the actor's current rectangle
Where av = the actor's velocity
Where b = the collision tile's rectangle

What happens currently is that the actors warp inside walls when moving into corners, which causes them to accelerate very fast until the character is out of the wall. Which often leads to the character is off the screen and then killed.

I've tried several different things but I'm not entirely sure how to fix it, any help would be greatly appreciated!

A video of the problem can be found here

### Level management

16 April 2012 - 02:33 PM

Over the last few days, I've picked up my games programming project once again.

Where I was up to was to implement trigger zones and manage level changes.

I've now done the triggers, however the problem area now lies within the way I thought about implementing the level changes. This is as follows:
- Level class
- Overall level object which holds the current level instance
- The level class has a "nextmap" filename

Once the "End" trigger is reached, the current level will unload it's self and create a new instance which gets assigned to the overall level object. This then will load the new level - one problem here is that there will be no loading screen as a result of this, however I feel like I know a method of implementing that.

I feel like there is a problem in doing this however I'm not entirely sure what it is.

### Unit Spawning (RTS)

08 February 2011 - 02:45 PM

Hi guys,

I'm currently working on an RTS game using DarkGDK (C++) and was wondering how I would create individual objects for units.

I've made a reference object and cloned it, but I don't think that's the best way to do it. Along with that, I'm not entirely sure how I would go about creating a new object per click of the mouse.

I have currently got the following:

if ( mouseclicked )
{
MouseY = dbGetTerrainGroundHeight( 1, dbMouseX(), dbMouseY() ) + 10; // Gets the Y co-ordinate which is just above ground height

dbCloneObject( unit, 10 ); // Clone the reference object and create another one with id of "unit" which is 100 to start

dbPositionObject( unit, dbMouseX(), MouseY, dbMouseY() ); // This is currently spawning it at the 2D co-ordinates of the mouse, I'm sure I'll be able to sort that though

unit++;

}

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