At Fri, 20 Feb 2009 12:44:23 -0800, Joshua Gargus wrote:

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[1.2 <text/html; ISO-8859-1 (7bit)>] Yoshiki Ohshima wrote:

At Fri, 20 Feb 2009 03:11:20 -0800 (PST),
Ang Beepeng wrote:

    I'm facing problem to pass a float array over to C, to create a plugin. 

    Previously, I use variableWordSubclass: to create a class to store floats,
    in an array. It works fine, as floats are stored as words.
    Now that I need to have an instance variable, I use variableSubclass: to
    store floats. It seems like floats are being stored as object in the array
    this time. The VM crashes when I try to use to same method to access to the
    float array.

  To get a Float object and use the value in C, use #floatValueOf:.
Look at the senders of the method for examples.

I'm not sure that this is the right thing, since each Float represents a double-precision floating point number, and the contents of FloatArray are single-precision.

I would look at the primitives in CroquetPlugin, which you can find in an OpenCroquet or Cobalt image. For example, # primitiveTransformVector3 transforms a 3-element vector by a 4x4 matrix. Matrix4x4 and Vector3 are both subclasses of FloatArray.

Yes, I may be just misunderstanding what he wants. Though, he did have a variant of MatrixPlugins that manipulates FloatArrays already, and now going to have some additional data involved in the computation. So I thought he want to have a way to get that additional data that is stored as Squeak's Float.

This might still not be answering your question directly (since you are talking about adding inst-vars to a 'variable-word' class). My suggestion would be add another inst-var to hold a separate FloatArray object which contains your floating point data.

Yes, that would do, too.

-- Yoshiki