World: r3wp

You need a lot performance?

I'm using this feature in the OpenGL API, I'm working at. Maybe I 
could do a late reduce, when accessing the inner blocks.

Volker, yes I need all the performance, I can get for this.

Is there a time when one doesn't want inner blocks to be reduced?

 I don't wanna have REDUCE inside the block.

 Is that only inconveniert, or would it really make problems? Maybe 
 some kind of automatic rewriting could help?

James,  parse-rules inside a block?

Yep. You're right.

I was just thinking how this particular behavior has caused me some 
trouble in the past but I see why they did it that way.

You would think  there would be a "complete" reduce parameter though 
that just works the way one would think it would.

Would rebcode be an option? Or a dll for some datastructures?

Volker, a rebcode version will probably make sense later, but I'm 
under OSX right now, where the rebcode is an old version.

I doubt  i find a good idea, so if i am boring just say stop.

Would it work to flatten the datastructure? /skip instead of nested 
blocks? Tehn 'reduce would work.

Well, that could work. But the situation is, that the datastructure 
is made by the user, so it should be as straight-forward as possible. 
Example of a structure:

vdata: [	
	[- X 0.0 Z] [X 0.0 Z] [- X 0.0 - Z] [X 0.0 - Z]	
	[0.0 Z X] [0.0 Z - X] [0.0 - Z X] [0.0 - Z - X]	
	[Z X 0.0] [- Z X 0.0] [Z - X 0.0] [- Z - X 0.0]
]


I think, I'll do a late REDUCE of the inner blocks, when I access 
them. But thanks for your ideas! :-)

You could also "compile" the users data into something else one time, 
and have a better format in the loops?

But if it works for now go on with the funnier stuff :)

You see, the C version of that structure is this:

static GLfloat vdata[12][3] = {	
   {-X, 0.0, Z}, {X, 0.0, Z}, {-X, 0.0, -Z}, {X, 0.0, -Z},	
   {0.0, Z, X}, {0.0, Z, -X}, {0.0, -Z, X}, {0.0, -Z, -X},	
   {Z, X, 0.0}, {-Z, X, 0.0}, {Z, -X, 0.0}, {-Z, -X, 0.0} 
};

And I want something similar, so users don't confused too much.

Makessense.

Are the users going to enter such an array as above?

I already have some OpenGL examples from the red book of OpenGL running 
in REBOL syntax. It's funny to see those examples in REBOL with the 
minor syntax. :-) I have no real idea of performance yet, I need 
heavier examples for that.

james, no C syntax. I'm making a REBOL version of the OpenGL API 
with REBOL syntax. Users will be able to use normal REBOL and call 
OpenGL functions (with REBOL syntax).

Thanks. And right now, it's the variables (x,y,z) reduction that 
is the problem?

yes

To give you an idea.
Instead of doing this in C:

	glClear (GL_COLOR_BUFFER_BIT);

	glColor3f (1.0, 1.0, 1.0);
	glBegin (GL_POLYGON);
		glVertex3f (0.25, 0.25, 0.0);
		glVertex3f (0.75, 0.25, 0.0);
		glVertex3f (0.75, 0.75, 0.0);
		glVertex3f (0.25, 0.75, 0.0);
	glEnd ();

	glFlush ();

You can do this in REBOL:

	glClear GL_COLOR_BUFFER_BIT

	glColor3f 1.0 1.0 1.0
	glBegin GL_POLYGON
		glVertex3f 0.25 0.25 0.0
		glVertex3f 0.75 0.25 0.0
		glVertex3f 0.75 0.75 0.0
		glVertex3f 0.25 0.75 0.0
	glEnd

	glFlush

Those are functions, so you can mix it with other REBOL words, like 
loops or whatever.

so something like glBegin GL_POLYGON
		glVertex3f 0.25 0.25 0.0
		glVertex3f 0.75 0.25 0.0
		glVertex3f 0.75 0.75 0.0
		glVertex3f 0.25 0.75 0.0
	glEnd

Gets turned into
vdata: [	
	[- X 0.0 Z] [X 0.0 Z] [- X 0.0 - Z] [X 0.0 - Z]	
	[0.0 Z X] [0.0 Z - X] [0.0 - Z X] [0.0 - Z - X]	
	[Z X 0.0] [- Z X 0.0] [Z - X 0.0] [- Z - X 0.0]
]

Without the vars of course.

John, Is your opengl api rendering in a rebol window or face?

The commands are sent to a C program (task), that'll execute the 
OpenGL code. So the C program owns the window, not REBOL.

Jaime, the answer to your question is: no.

james, no. It's from 2 different programs. The datastructure is just 
used in one example. Some OpenGL commands take pointers to datastructures 
as a parameter.

You can see the full example here: http://home.tiscali.dk/john.niclasen/OpenGL/GLClient.html

First you have the C source, and below that the REBOL source, that'll 
do the same thing. I first thought about putting a REDUCE in, where 
vdata is defined, but I've changed my mind. The glVertex3fv function 
has to reduce it's argument.

And that of course doesn't work. The datastructure has to be like 
this in REBOL:

vdata: [	
	[- X 0.0 Z] [X 0.0 Z] [- X 0.0 (- Z)] [X 0.0 (- Z)]	
	[0.0 Z X] [0.0 Z (- X)] [0.0 (- Z) X] [0.0 (- Z) (- X)]	
	[Z X 0.0] [(- Z) X 0.0] [Z (- X) 0.0] [(- Z) (- X) 0.0]
]


Maybe it's time to make a new group about this. I'm not home the 
rest of the day (beer festival going on), but I should have something 
for others to try out tomorrow (those who's interested).

enblock (reduce deblock data) 3

Some meazzines i use sometimes. But they are meazzines, if speed 
reeally is  an issue..

I could use NEGATE in stead of unary minus though. hmm

Volker, I've solved the reduce problem, and it makes sense now. The 
C function glVertex3fv takes a pointer to it's data as a parameter. 
I do the same thing in REBOL (using a block), and I then reduce it 
inside the REBOL function glVertex3fv itself.

Good idea. Also lazy, if you have lots of unused data its only reduced 
if needed.

That way the block can hold variables, that'll change, and only when 
the function is called, the block is reduced to values.

But make sure the datadoes not change in the meantime. The 'x etc.

Well, if the programmer wants it to change, that'll work too. :-)

Or that way around :)

heh, it works now. I get a icosahedron drawn. :-)

Congrats :)

Is there a way to mix it with the 3d-engine from the contests? So 
plain rebol could be used as 3d-editor?

YOu would get  a robot for free :)

Thanks! Actually I map from the pointer function glVertex3fv to glVertex3f, 
which takes it parameters as values, but that should be no problem. 
(I can't send a pointer to another task over tcp.)

What contests? What 3d-engine? :)

with /viewtop: rebol/contest/i-rebot.r

(I suddenly have name-blackouts) That great tutotial-writer has a 
little demo how to use the  engine IIRC.

http://musiclessonz.com/rebol_tutorial.html#section-21.9

Yes, it should be possible to call my OpenGL functions from an engine 
like that. That's the sort of things, I'm going to use this for. 
Only thing is, that the OpenGL window is inside a C execute, so you 
can't put REBOL controls (view stuff) in there. But you can then 
just have 2 windows.