Path: chuka.playstation.co.uk!news
From: byron@snsys.com (Byron)
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: Re: 3d sprites solved!
Date: Tue, 01 Dec 1998 11:38:43 GMT
Organization: PlayStation Net Yaroze (SCEE)
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On Sun, 29 Nov 1998 19:09:54 +0000, "Harvey.C" <hc054@mdx.ac.uk>
wrote:

>Woohoo!
>
>I'd like to say a big thankyou to James Russell. I've managed to
>turn 2d sprites into 3d objects for my game. Here is a little function
>I made based on the code given to me by James:
>
>
>void draw_3dsprite (GsSPRITE *sprite,long x,long y,long z,short
>precision)
>{
>	VECTOR spritePosition,transformedPosition;
>
>	// This is the position of your sprite in 3d space
>	spritePosition.vx=x;
>	spritePosition.vy=y;
>	spritePosition.vz=z;
>
>	ApplyMatrixLV(&GsWSMATRIX,&spritePosition,&transformedPosition);
>	transformedPosition.vx+=GsWSMATRIX.t[0];
>	transformedPosition.vy+=GsWSMATRIX.t[1];
>	transformedPosition.vz+=GsWSMATRIX.t[2];
>
>	// Only draw tree sprite if its in front of the camera
>	if (transformedPosition.vz>0)
>	{
>		// Scales the tree - 16777216=4096<<12 is a constant (works for me)
>		sprite->scalex=sprite->scaley=16777216/transformedPosition.vz;
>	        sprite->x=transformedPosition.vx*250/transformedPosition.vz;
>	        sprite->y=transformedPosition.vy*250/transformedPosition.vz;
>	
>GsSortSprite(&sprite,&OTable_Header[CurrentBuffer],transformedPosition.vz>>precision)
>	}
>}
>
>
>I guess this must be trivial to most of you, but its all new to me.
>And before you scorn and reject using 2d sprites as 3d objects, I must
>say they are extremely effective and best of all - extremely fast!
>
>Many thanks.
>-- 
>Regards  |  E-mail: hc054@mdx.ac.uk
>Harvey   |  ICQ: 4269478

Hi,

Another slant on this....

For years I have always wanted to write a Space Harrier type game. I
have been toying with the idea of using 3D Sprites for a while and the
above code reduces a considerable amount of work that I have to do
(thank god!) so cheers!

Any ideas on using the above code to work out a relative scaling
factor - i.e. when a sprite is in the distance it will be small and
get larger as it approaches you?

Byron. 

Byron@SNSYS.COM