Adding Barriers with cBarrier

Even though the barrier class marks areas on the map using geometric shapes in
exactly the same way as the trigger class does, the barrier class also positions meshes.
Looking again at the cBarrier class declaration, notice that each of the add barrier
functions — add_sphere, add_box, add_cylinder, and add_triangle—have a set of coordinates
that position and rotate the barrier’s mesh before being rendered.

To determine where the mesh is positioned, set the x_pos, y_pos, and z_pos arguments
of the add barrier functions to where you want the mesh rendered. You also need
to set the x_rot, y_rot, and z_rot arguments to the rotational values to draw the mesh.

For example, say that you want to add a spherical barrier that already has a mesh
assigned. The barrier is positioned at coordinates 10,20,30 (with a radius of 40),
while the mesh is positioned at 10,0,30 using no rotational values. To add the barrier,
you call the add_sphere function as follows:

cBarrier::add_sphere(1, TRUE,
                     10.0f, 0.0f, 30.0f, 0.0f, 0.0f, 0.0f,
                     10.0f, 20.0f, 30.0f, 40.0f);

You get a better understanding of adding and using barriers in the next section.

Using the Barrier Class

Using the barrier class is not difficult; it’s much like using the trigger class. The
biggest difference is that you have to add object placement data to the barrier data
files and assign the appropriate meshes and animations.

Creating the Barrier Data File

The barrier data files are arranged just like trigger data files, except that you start
each barrier definition with the identification number, type, enabled flag, placement
coordinates (X, Y, Z), and rotations (X-rotation, Y-rotation, and Z-rotation) to
place the barrier graphics object. Finish each definition with the respective barrier
type’s data.

The following defines two barriers to use (contained in a file called test.bar). Note
that the coordinates and rotational values of the barrier are shown in bold:

1 1 1 -900 0 0 0 0 0 -1154 0 10 -645 100 -10
2 1 0 0 0 -900 0 1.57 0 -10 0 -1154 10 100 -645

Here are two barriers, both using a box shape. The first barrier’s graphics object is
placed at -900,0,0 and has rotational values of 0,0,0. The first box covers the area
from -1154,0,10 to -645,100, -10.

The second barrier has a graphics object placed at 0,0, -900 and has rotational values
of 0,1.57,0. The second barrier covers the area from -10,0,-1154 to 10,100,-645.

Loading the Barrier Data

In order to load and use a barrier data file, instance the cBarrier class, load the data
file and appropriate meshes, and assign the meshes:

cBarrier Barrier;

// Load a barrier data file
Barrier.Load(“test.bar”);

// Load a mesh and animation to use
cMesh Mesh;
cAnimation Anim;
Mesh.Load(“barrier.x”);
Anim.Load(“barrier.x”, &Mesh);

// Assign mesh and animation to both barriers loaded
Barrier.SetMesh(1, &Mesh);
Barrier.SetMesh(2, &Mesh);
Barrier.SetAnim(1, &Anim, “AnimationName”, 0);
Barrier.SetAnim(2, &Anim, “AnimationName”, 0);

Checking Barrier Collisions

To see whether an area on the map is blocked, call get_barrier with the character
coordinates. If a value of TRUE is returned, passage is blocked, and you should take
appropriate actions. Take the following example that checks a character’s coordinates
against all barriers loaded from the barrier list.

You use a trio of values that represents the direction the character is moving in
each axis to determine beforehand whether the movement is blocked by a barrier.
Say that a character is moving 10 units in the position Z-axis, meaning that the
upcoming ZMove variable will be set to 10. That ZMove variable is added to the character’s
current position, and if intersecting with a barrier, that ZMove variable is cleared
out, thus not allowing such a movement along the axis, as shown here:

// XPos, YPos, ZPos = character coordinates
// XMove, YMove, ZMove = character movement values
if(Barrier.get_barrier(XPos+XMove,YPos+YMove,ZPos+ZMove)) {
  // Passage not allowed, clear movement variables
  XMove = YMove = ZMove = 0.0f;
}

Rendering Barriers

Last, you only need to call cBarrier::Render to draw all barrier objects within view:

// Frustum = pre-initialize cFrustum object
Barrier.render(timeGetTime(), &Frustum);