[Openmcl-devel] Multi-dimensional foreign memory array

Gary Byers gb at clozure.com
Tue Mar 8 21:56:13 UTC 2005



On Tue, 8 Mar 2005, nrms wrote:

> Hi Gary!
> It got me started, but I guess I will need some more enlightment which
> maybe a result of the fact that I am not a Lisp veteran. I tried to
> start quite easy with programm that paints a white quadrat on a black
> background. This something I have done in a small C-program before. As
> a starting point I used opengl-ffi.lisp
> and tried to adapt it. Unfortunately I don't get a white quadrat, I get
> only the black background.
> Furthermore I have two rather naive (or stupit) questions, although I
> think the answers won't solve my problem
> Does  ":element-type '(unsigned-byte 8)" mean the element get 8 bits in
> memory, i.e. 1 byte?
> In (%stack-block ((p size)) p is a pointer and size is size of the
> memory block, but in which unit? Bytes?
> By the way chapter 9.3 refers to 9.1 for a description of rlet, but
> there is none there.
>
> So what I coded myself is the following segment (or run the attachement
> if interested).

> 				    (for (i 1 100)
> 					 (#_glRasterPos2i i (* i i))

Hmm.  This will cause the raster position to vary from (1, 1) to
(100, 10000).

What coordinate system have you set up ?  Where is the point (1, 1) ?
(Hint: where is the point (0, 0) ?  Where is (-1,-1) ?)





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