# Andy's blog

## Interactive Earth Cross Section

This is a slightly improve Earth Cross Section model of the previous one, with added animation and some interaction. Previously, the focus was on using VRMath2 Editor to construct the model. This time, the focus is on the learning about the Earth's geo structure. This is one of the main purpose of VRMath2 as a learning community for all to create, share, discuss and learn.

## Earth Cross Section

In the X3DOM mailing list, there was a discussion about constructing solid geometry. One application of solid geometry is to model the cross section of Earth. Unfortunately, solid geometry is not supported in X3DOM. However, the cross section can be achieved by using other geometry available in X3DOM. Here is an example.

## Waves at sea

Following my previous blog about 3D function graphing, I did another experiment to animate the 3D graphs. In this blog, I used the same 3D function f(x,z) = x*z^3-z*x^3 to generate two sets of heights. Then a VECTORINTERPOLATOR (or VECINT) was used to animate this 3D graph. It looks to me like a wave on the sea surface. What do you think?

## 3D function with ElevationGrid

I have been thinking about 3D graphing using ElevationGrid for a while and finally got time to demonstrate here. Previously, I have blogged about 3D plotting and ElevationGrid, This blog is simply taking the same maths function f(x,z) = x*z^3-z*x^3 in the 3D plotting blog and apply to the ElevationGrid object.

## Analog clock

The TIMESENSOR of X3D is quite a complicated time mechanism to understand. As I have created some commands for easy animation, I thought that it would be interesting to test the TIMESENSOR with an analog clock.