ref: ed82668431413cf8d5389a631cad56a6c4d2d6da
dir: /ref/r_part.c/
/*
Copyright (C) 1997-2001 Id Software, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <u.h>
#include <libc.h>
#include <stdio.h>
#include "../q_shared.h"
vec3_t r_pright, r_pup, r_ppn;
#define PARTICLE_33 0
#define PARTICLE_66 1
#define PARTICLE_OPAQUE 2
typedef struct
{
particle_t *particle;
int level;
int color;
} partparms_t;
static partparms_t partparms;
static byte BlendParticle33( int pcolor, int dstcolor )
{
return vid.alphamap[pcolor + dstcolor*256];
}
static byte BlendParticle66( int pcolor, int dstcolor )
{
return vid.alphamap[pcolor*256+dstcolor];
}
static byte BlendParticle100( int pcolor, int /*dstcolor*/ )
{
return pcolor;
}
/*
** R_DrawParticle
**
** Yes, this is amazingly slow, but it's the C reference
** implementation and should be both robust and vaguely
** understandable. The only time this path should be
** executed is if we're debugging on x86 or if we're
** recompiling and deploying on a non-x86 platform.
**
** To minimize error and improve readability I went the
** function pointer route. This exacts some overhead, but
** it pays off in clean and easy to understand code.
*/
void R_DrawParticle( void )
{
particle_t *pparticle = partparms.particle;
int level = partparms.level;
vec3_t local, transformed;
float zi;
byte *pdest;
short *pz;
int color = pparticle->color;
int i, izi, pix, count, u, v;
/*
** transform the particle
*/
VectorSubtract (pparticle->origin, r_origin, local);
transformed[0] = DotProduct(local, r_pright);
transformed[1] = DotProduct(local, r_pup);
transformed[2] = DotProduct(local, r_ppn);
if (transformed[2] < PARTICLE_Z_CLIP)
return;
/*
** bind the blend function pointer to the appropriate blender
*/
/*
byte (*blendparticle)( int, int );
if ( level == PARTICLE_33 )
blendparticle = BlendParticle33;
else if ( level == PARTICLE_66 )
blendparticle = BlendParticle66;
else
blendparticle = BlendParticle100;
*/
/*
** project the point
*/
// FIXME: preadjust xcenter and ycenter
zi = 1.0 / transformed[2];
u = (int)(xcenter + zi * transformed[0] + 0.5);
v = (int)(ycenter - zi * transformed[1] + 0.5);
if ((v > d_vrectbottom_particle) ||
(u > d_vrectright_particle) ||
(v < d_vrecty) ||
(u < d_vrectx))
{
return;
}
/*
** compute addresses of zbuffer, framebuffer, and
** compute the Z-buffer reference value.
*/
pz = d_pzbuffer + (d_zwidth * v) + u;
pdest = d_viewbuffer + d_scantable[v] + u;
izi = (int)(zi * 0x8000);
/*
** determine the screen area covered by the particle,
** which also means clamping to a min and max
*/
pix = izi >> d_pix_shift;
if (pix < d_pix_min)
pix = d_pix_min;
else if (pix > d_pix_max)
pix = d_pix_max;
/*
** render the appropriate pixels
*/
count = pix;
switch (level) {
case PARTICLE_33 :
for ( ; count ; count--, pz += d_zwidth, pdest += r_screenwidth)
{
//FIXME--do it in blocks of 8?
for (i=0 ; i<pix ; i++)
{
if (pz[i] <= izi)
{
pz[i] = izi;
pdest[i] = vid.alphamap[color + ((int)pdest[i]<<8)];
}
}
}
break;
case PARTICLE_66 :
for ( ; count ; count--, pz += d_zwidth, pdest += r_screenwidth)
{
for (i=0 ; i<pix ; i++)
{
if (pz[i] <= izi)
{
pz[i] = izi;
pdest[i] = vid.alphamap[(color<<8) + (int)pdest[i]];
}
}
}
break;
default: //100
for ( ; count ; count--, pz += d_zwidth, pdest += r_screenwidth)
{
for (i=0 ; i<pix ; i++)
{
if (pz[i] <= izi)
{
pz[i] = izi;
pdest[i] = color;
}
}
}
break;
}
}
/*
** R_DrawParticles
**
** Responsible for drawing all of the particles in the particle list
** throughout the world. Doesn't care if we're using the C path or
** if we're using the asm path, it simply assigns a function pointer
** and goes.
*/
void R_DrawParticles (void)
{
particle_t *p;
int i;
extern unsigned long fpu_sp24_cw, fpu_chop_cw;
VectorScale( vright, xscaleshrink, r_pright );
VectorScale( vup, yscaleshrink, r_pup );
VectorCopy( vpn, r_ppn );
for (p=r_newrefdef.particles, i=0 ; i<r_newrefdef.num_particles ; i++,p++)
{
if ( p->alpha > 0.66 )
partparms.level = PARTICLE_OPAQUE;
else if ( p->alpha > 0.33 )
partparms.level = PARTICLE_66;
else
partparms.level = PARTICLE_33;
partparms.particle = p;
partparms.color = p->color;
R_DrawParticle();
}
}