LastCollisionPoint

FlatRedBall.Math.Geometry.Line

Introduction

The LastCollisionPoint is a property which can tell you the last location where collision occurred. This can be used if you would like to play effects or perform custom physics where collision has occurred.

Code Example

The following example creates two Lines and calls CollideAgainst between them. It then uses the LastCollisionPoint (if it is valid) to position a circle. One of the lines (Line1) can be controlled with the keyboard, resulting in a changing LastColliisionPoint.

This example is structured for Glue, but can be duplicated in a code-only FlatRedBall project:

Add the following to class scope in a Screen:

Circle circle;
Line line1;
Line line2;

Add the following to CustomInitialize in a Screen:

void CustomInitialize()
{
    circle = ShapeManager.AddCircle();
    circle.Radius = 10;

    line1 = ShapeManager.AddLine();

    line2 = ShapeManager.AddLine();
    line2.RelativePoint2 = new Point3D(100, 100);
}

Add the following to CustomActivity in a Screen:

void CustomActivity(bool firstTimeCalled)
{
    InputManager.Keyboard.ControlPositionedObject(line1, 100);

    line1.CollideAgainst(line2);

    // If no collision occurred, then LastCollisionPoint's X and Y values will be NaN:
    if (!double.IsNaN(line1.LastCollisionPoint.X) &&
        !double.IsNaN(line1.LastCollisionPoint.Y))
    {
        circle.X = (float)line1.LastCollisionPoint.X;
        circle.Y = (float)line1.LastCollisionPoint.Y;
    }
}

LineLastCollisionPoint.PNG