Path: chuka.playstation.co.uk!news
From: "Harvey.C" <hc054@mdx.ac.uk>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: 3d sprites solved!
Date: Sun, 29 Nov 1998 19:09:54 +0000
Organization: PlayStation Net Yaroze (SCEE)
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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