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Re: [Public WebGL] Size of GL_FLOAT



On Jan 12, 2010, at 3:20 PM, Kenneth Russell wrote:

> On Tue, Jan 12, 2010 at 3:12 PM, Chris Marrin <cmarrin@apple.com> wrote:
> 
> On Jan 12, 2010, at 3:08 PM, Kenneth Russell wrote:
> 
> > ...We already specify the size of each type in the WebGLArray. That constrains what the vertex arrays can contain, which constrains the underlying OpenGL (or other) implementation. If a WebGLFloatArray contains 32 bit floats in every implementation and the VBO is sent in and defined as a buffer of FLOAT type, then WebGL constrains the type of FLOAT to be 32 bits.
> >
> > This is one way of looking at it: that the WebGL spec implies constraints on the OpenGL implementation underneath, for example that it supports 32-bit floats as input data. Another way of looking at it is that WebGL conforms to the typedefs of the OpenGL implementation on the platform.
> >
> > So wouldn't it be best to remove sizeInBytes() and replace it with constants for each supported WebGLArray type? This might be best done with a constant in each WebGLArray subtype (WebGLFloatArray.SIZE, WebGLUnsignedByteArray.SIZE, etc.).
> >
> > Realistically I think that every OpenGL implementation out there will support the primitive data types currently in the WebGL spec, so it's OK with me if we make this change. I would suggest a name like WebGLFloatArray.ELEMENT_SIZE to be more clear about the meaning.
> 
> ELEMENT_SIZE makes me thing of elements in an array, not bytes. Maybe we should just go with SIZE_IN_BYTES (as wordy as that is), or BYTE_SIZE? :-)
> 
> I don't like SIZE_IN_BYTES or BYTE_SIZE because we already have a method called byteLength(). We should have an indication that we're talking about the size of one element in the array.

Speaking of which, I'd feel better if this were lengthInBytes or something. Right now it sounds like its describing the length of a byte!

> 
> What about ELEMENT_SIZE_IN_BYTES? ELEMENT_BYTE_SIZE?

BYTES_PER_ELEMENT?

-----
~Chris
cmarrin@apple.com




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