Axiom.Core.Frustum.UpdateVertexData C# (CSharp) Method

		protected virtual void UpdateVertexData()
		{
			if ( _recalculateVertexData )
			{
				// Note: Even though we could be dealing with general a projection matrix here,
				//       it is incompatible with the infinite far plane, thus, we need to work
				//		 with projection parameters.

				// Calc near plane corners
				Real nearLeft, nearRight, nearBottom, nearTop;
				CalculateProjectionParameters( out nearLeft, out nearRight, out nearBottom, out nearTop );

				// Treat infinite fardist as some arbitrary far value
				Real farDist = ( _farDistance == 0 ) ? 100000 : _farDistance;

				// Calc far palne corners
				Real ratio = _projectionType == Projection.Perspective ? _farDistance / _nearDistance : 1;
				Real farLeft = nearLeft * ratio;
				Real farRight = nearRight * ratio;
				Real farBottom = nearBottom * ratio;
				Real farTop = nearTop * ratio;

				// Calculate vertex positions
				// 0 is the origin
				// 1, 2, 3, 4 are the points on the near plane, top left first, clockwise
				// 5, 6, 7, 8 are the points on the far plane, top left first, clockwise
				HardwareVertexBuffer buffer = _vertexData.vertexBufferBinding.GetBuffer( 0 );

				IntPtr posPtr = buffer.Lock( BufferLocking.Discard );

				unsafe
				{
					float* pPos = (float*)posPtr.ToPointer();

					// near plane (remember frustum is going in -Z direction)
					*pPos++ = nearLeft;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;
					*pPos++ = nearRight;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;

					*pPos++ = nearRight;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;
					*pPos++ = nearRight;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;

					*pPos++ = nearRight;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;
					*pPos++ = nearLeft;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;

					*pPos++ = nearLeft;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;
					*pPos++ = nearLeft;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;

					// far plane (remember frustum is going in -Z direction)
					*pPos++ = farLeft;
					*pPos++ = farTop;
					*pPos++ = -farDist;
					*pPos++ = farRight;
					*pPos++ = farTop;
					*pPos++ = -farDist;

					*pPos++ = farRight;
					*pPos++ = farTop;
					*pPos++ = -farDist;
					*pPos++ = farRight;
					*pPos++ = farBottom;
					*pPos++ = -farDist;

					*pPos++ = farRight;
					*pPos++ = farBottom;
					*pPos++ = -farDist;
					*pPos++ = farLeft;
					*pPos++ = farBottom;
					*pPos++ = -farDist;

					*pPos++ = farLeft;
					*pPos++ = farBottom;
					*pPos++ = -farDist;
					*pPos++ = farLeft;
					*pPos++ = farTop;
					*pPos++ = -farDist;

					// Sides of the pyramid
					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = nearLeft;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;

					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = nearRight;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;

					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = nearRight;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;

					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = 0.0f;
					*pPos++ = nearLeft;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;

					// Sides of the box
					*pPos++ = nearLeft;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;
					*pPos++ = farLeft;
					*pPos++ = farTop;
					*pPos++ = -farDist;

					*pPos++ = nearRight;
					*pPos++ = nearTop;
					*pPos++ = -_nearDistance;
					*pPos++ = farRight;
					*pPos++ = farTop;
					*pPos++ = -farDist;

					*pPos++ = nearRight;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;
					*pPos++ = farRight;
					*pPos++ = farBottom;
					*pPos++ = -farDist;

					*pPos++ = nearLeft;
					*pPos++ = nearBottom;
					*pPos++ = -_nearDistance;
					*pPos++ = farLeft;
					*pPos++ = farBottom;
					*pPos++ = -farDist;
				}

				// don't forget to unlock!
				buffer.Unlock();

				_recalculateVertexData = false;
			}
		}