BoundingFrustum test

boundingFrustumTest.cs

static void testFunction ()
{
Vector3 camPos,camDir;

	// test camera looking into X direction
	camPos=new Vector3 (0,0,0);
	camDir=new Vector3 (1,0,0);
	doFrustumTest (camPos,camDir);

	// test camera looking into Z direction
	camPos=new Vector3 (0,0,0);
	camDir=new Vector3 (0,0,1);
	doFrustumTest (camPos,camDir);

	// test camera looking into Z direction, slightly looking into the sky
	camPos=new Vector3 (0,0,0);
	camDir=Vector3.Normalize (new Vector3 (0,0.1f,1));
	doFrustumTest (camPos,camDir);								// FAILS !! Says box behind camera intersects

}



static void doFrustumTest (Vector3 cameraPos,Vector3 cameraDir)
{
	// I use up, but the crossproducts inside CreateLookAt should correct it to the real up (as long as cameraDir is not too steep)
	var view = Matrix.CreateLookAt (cameraPos,cameraDir, Vector3.Up);
	var projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver4, 1, 1, 100);
	var frustum = new BoundingFrustum(view * projection);

	// use a very tall box 
	Vector3 boxSize=new Vector3 (4,1000,4);

	// create a box IN FRONT OF the camera, inside the viewing frustum. It should intersect it because the box is very tall
	Vector3 boxPos1=cameraPos + cameraDir*10;
	var bbox1 = new BoundingBox (boxPos1-boxSize/2,boxPos1+boxSize/2);
	Debug.Assert (frustum.Contains (bbox1) == ContainmentType.Intersects);

	// create a box BEHIND the camera. It should be disjoint, because it's behind.
	Vector3 boxPos2=cameraPos - cameraDir*10;
	var bbox2 = new BoundingBox (boxPos2-boxSize/2,boxPos2+boxSize/2);
	Debug.Assert (frustum.Contains (bbox2) == ContainmentType.Disjoint);

}