# Create a frustum transformation matrix
	#
	# `left, right, bottom, top, near, far` defines the world clip planes.
	new frustum(left, right, bottom, top, near, far: Float)
	do
		var dx = right - left
		var dy = top - bottom
		var dz = far - near

		assert near > 0.0
		assert far > 0.0
		assert dx > 0.0
		assert dy > 0.0
		assert dz > 0.0

		var mat = new Matrix(4, 4)

		mat[0, 0] = 2.0 * near / dx
		mat[0, 1] = 0.0
		mat[0, 2] = 0.0
		mat[0, 3] = 0.0

		mat[1, 0] = 0.0
		mat[1, 1] = 2.0 * near / dy
		mat[1, 2] = 0.0
		mat[1, 3] = 0.0

		mat[2, 0] = (right + left) / dx
		mat[2, 1] = (top + bottom) / dy
		mat[2, 2] = -(near + far) / dz
		mat[2, 3] = -1.0

		mat[3, 0] = 0.0
		mat[3, 1] = 0.0
		mat[3, 2] = -2.0 * near * far / dz
		mat[3, 3] = 0.0

		return mat
	end