Path: chuka.playstation.co.uk!news
From: "Mario Wynands" <mario@sidhe.co.nz>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: Pls help a 3dimensional newbie...
Date: Wed, 10 Nov 1999 18:40:36 +1300
Organization: PlayStation Net Yaroze (SCEE)
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<john.j@netway.at> wrote in message news:38289F81.EAB12E24@netway.at...
> Andrew Murray schrieb:
> >
> > I'm not 100% sure how to put this into code but I'd imagine that is you
> > make a "handler" of the object then make this handler in some way always
> > point towards this point, I advise taking a look at the camera viewpoint
> > settings as this can be done similar to what you are looking for.
>
> Hmmm...
> - First of all: thanx a lot for your answer! (I thought noone would read
it)  :D
>
> I'll tell you the whole story:
> I have an airplane, and (of course) I want a "fireblast" (dunno the
word...)
> at the end. Making an object (many polys - difficult in changing textures)
> seemed to be not the best solution, so I had a (little) look at
> "g-police2", and I thought: "it seems, this guys just use a SINGLE poly
> and turn it always toward the camera..."

Ahhh, billboarding.  Here is some code to turn an object towards the camera
for rendering

------------

MATRIX world_matrix, screen_matrix;

GsGetLwsdobj->coord2, &world_matrix, &screen_matrix);

if (billboard)
{
     screen_matrix.m[0][0] = GsIDMATRIX2.m[0][0];
     screen_matrix.m[0][1] = GsIDMATRIX2.m[0][1];
     screen_matrix.m[0][2] = GsIDMATRIX2.m[0][2];
     screen_matrix.m[1][0] = GsIDMATRIX2.m[1][0];
     screen_matrix.m[1][1] = GsIDMATRIX2.m[1][1];
     screen_matrix.m[1][2] = GsIDMATRIX2.m[1][2];
     screen_matrix.m[2][0] = GsIDMATRIX2.m[2][0];
     screen_matrix.m[2][1] = GsIDMATRIX2.m[2][1];
     screen_matrix.m[2][2] = GsIDMATRIX2.m[2][2];
}

GsSetLsMatrix(&screen_matrix);
GsSortObject4(dobj, ot, 14 - ot->length, (u_long *)getScratchAddr(0));

------------


Let me know if you need more help.


Regards

Mario

mario@sidhe.co.nz
www.sidhe.co.nz