[Radiance-general] RE: Water any news ???

[Thomas Bleicher]

Hello Sotiris.

2009/8/13 Σωτήρης Παπαντωνίου <sotos.enveng at gmail.com>:
> Hello again with a new question,
>
> the pool I am trying to simulate has a bottom that it's depth varies. This
> means that i can not use the poolcoords.cal formula as it is and i need to
> make some necessary changes.

I don't think you need to change anything in this formula. It returns
the bin number for a point (Px,Py) based on the x and y resolution.
The "depth" of the plane is not taken into account. If you would add
another component you would split the 2-d array into a 3-d array.
I don't think that's what you want to do.

> The part of formula i don't understand, but i
> think can not work as it is, is the following:
>
> "floor_bin = floor(FloorXres*(Px - FloorOrigX)/FloorWidth) +
> floor(FloorYres*(1 - (Py - FloorOrigY)/FloorLength))*FloorXres;"

This formula returns the number of the bin for the particular
"tile" in the Xres (columns) * Yres (rows) grid.

floor_bin = column position + ( row position * columns)

floor() is the math formula to return the next smaller integer number.

It's easy to understand if you replace all the variables with
actual values. Example:

FloorXres = 13
FloorYres = 17
FloorOrigX = 0
FloorOrigY = 0
FloorWidth = 26
FloorLength = 34

Px = 5.67
Py = 12.34

floor_bin = floor( 13 * ( 5.67 - 0 ) / 26 ) + floor( 17 * ( 1 - ( 12.34 - 0
) / 34 ) ) * 13

floor_bin = floor( 13 * rel X position ) + floor ( 17 * ( 1 - rel Y postion)
) * 13

> In this formula 3 more parameters must be added in my opinion: FloorOrigZ,
> FloorZres, FloorDepth.

Z is not taken into account here.

> The role of the this formula is to calculate how many points (bins) should
> be used for calculating how much energy falls on them,

Not "how many" bins but "which" bin. The "how many" is set by Xres and Yres.

> If someone can explain how the specific formula works [ floor(...) , Px,
Py
> ], or give me directly a new one with the parameters of depth in it, I
> whould be grateful.

I hope you can go on with the explanation above. If your floor slopes down
you might have adjust the area of the floor relative to a horizontal plane.
But that should be all.


Thomas
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