# Algorithm What is the mathematical explanation behind this implementation of simulating eyeballs roll in eyes?

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caymanbruce    209
Posted (edited)

I want to simulate eyeballs roll in eyes and I have found and forked this implementation in codepen.io. This is exactly what I need.

Smart way but I don't understand why it needs to work like this way. Why is it using ratioX and ratioY which are calculated from dividing mouseX and mouseY with their sum?  Is there a simpler or even cleverer way to do similar simulation?

Edited by caymanbruce

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missionctrl    206
Posted (edited)

I think they are using the x/y ratio as a cheap way to do fake trigonometry. If the mouse is far away from the eyes, they should rotate slower. If the mouse is close to the eyes, it will rotate faster. That would happen naturally with sin/cos. So I think what they have is already pretty simple and clever.

Edited by missionctrl

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Finally, we have constrained multi-material marching squares, which is much like other constrained triangulation problems. In addition to the multi-material grid, we now have pre-defined boundary edges in some of the grid cells, and the multi-material marching squares must respect those pre-defined edges as if they accurately represent the boundary between two materials. I'm finding it hard to wrap my head around this problem. It seems that a look-up table will be of no use because the pre-defined edges create too many possibilities, even if those edges are restricted to the kinds of edges that marching square would naturally produce, but doing this without a look-up table also seems daunting.
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