SetBordersAtZ

Introduction

As explained in this tutorial the Camera's X and Y position are the center of the screen (unless the Camera is rotated). Therefore, to keep the Camera from viewing outside of a specific area, the visible width and height must be calculated. In other words, if the Camera should not be able to see anything to the left of X = 0, then the width of the Camera needs to be calculated, and the actual minimum X becomes

0 + cameraWidthAtSomeZ/2.0f;

The SetBordersAtZ simplifies this process by doing the calculation of cameraWidthAtSomeZ automatically, and even updating mins and maxes if the Camera moves along the Z axis. The SetBordersAtZ sets the following Camera properties:

• MinimumX

• MinimumY

• MaximumX

• MaximumY

The SetBordersAtZ calculates what the minimum and maximum values need to be set at to keep the first four argument values as the visible borders at the Z value passed (fifth argument).

Code Example

The following code prevents the user from viewing behind +/- 40 on the X and Y axes. Note that bounds will be exceeded if the field of view or aspect ratio is too large for the argument values. The Keyboard moves the Camera so the bounds can be tested. Add the following using statements:

using FlatRedBall.Input;

Add the following to Initialize after initializing FlatRedBall:

float minimumX = -40;
float minimumY = -40;
float maximumX = 40;
float maximumY = 40;
float zToSetAt = 0;

SpriteManager.Camera.SetBordersAtZ(minimumX, minimumY, maximumX, maximumY, zToSetAt);

// Add a Sprite so the bounds can be visibly tested
Sprite sprite = SpriteManager.AddSprite("redball.bmp");
sprite.ScaleX = 40;
sprite.ScaleY = 40;

Add the following to Update:

// Use the arrow keys to move the Camera
InputManager.Keyboard.ControlPositionedObject(SpriteManager.Camera);

CameraBounds.png