// d_part.c: software driver module for drawing particles

#include "quakedef.h"
#include "d_local.h"


/*
==============
D_EndParticles
==============
*/
void D_EndParticles(void)
{
// not used by software driver
}


/*
==============
D_StartParticles
==============
*/
void D_StartParticles(void)
{
// not used by software driver
}


/*
==============
D_DrawParticle
==============
*/
void D_DrawParticle(particle_t * pparticle)
{
    vec3_t local, transformed;
    float zi;
    byte *pdest;
    short *pz;
    int i, izi, pix, count, u, v;

// transform point
    VectorSubtract(pparticle->org, 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;

// 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;
    }

    pz = d_pzbuffer + (d_zwidth * v) + u;
    pdest = d_viewbuffer + d_scantable[v] + u;
    izi = (int) (zi * 0x8000);

    pix = izi >> d_pix_shift;

    if (pix < d_pix_min)
	pix = d_pix_min;
    else if (pix > d_pix_max)
	pix = d_pix_max;

    switch (pix) {
    case 1:
	count = 1 << d_y_aspect_shift;

	for (; count; count--, pz += d_zwidth, pdest += screenwidth) {
	    if (pz[0] <= izi) {
		pz[0] = izi;
		pdest[0] = pparticle->color;
	    }
	}
	break;

    case 2:
	count = 2 << d_y_aspect_shift;

	for (; count; count--, pz += d_zwidth, pdest += screenwidth) {
	    if (pz[0] <= izi) {
		pz[0] = izi;
		pdest[0] = pparticle->color;
	    }

	    if (pz[1] <= izi) {
		pz[1] = izi;
		pdest[1] = pparticle->color;
	    }
	}
	break;

    case 3:
	count = 3 << d_y_aspect_shift;

	for (; count; count--, pz += d_zwidth, pdest += screenwidth) {
	    if (pz[0] <= izi) {
		pz[0] = izi;
		pdest[0] = pparticle->color;
	    }

	    if (pz[1] <= izi) {
		pz[1] = izi;
		pdest[1] = pparticle->color;
	    }

	    if (pz[2] <= izi) {
		pz[2] = izi;
		pdest[2] = pparticle->color;
	    }
	}
	break;

    case 4:
	count = 4 << d_y_aspect_shift;

	for (; count; count--, pz += d_zwidth, pdest += screenwidth) {
	    if (pz[0] <= izi) {
		pz[0] = izi;
		pdest[0] = pparticle->color;
	    }

	    if (pz[1] <= izi) {
		pz[1] = izi;
		pdest[1] = pparticle->color;
	    }

	    if (pz[2] <= izi) {
		pz[2] = izi;
		pdest[2] = pparticle->color;
	    }

	    if (pz[3] <= izi) {
		pz[3] = izi;
		pdest[3] = pparticle->color;
	    }
	}
	break;

    default:
	count = pix << d_y_aspect_shift;

	for (; count; count--, pz += d_zwidth, pdest += screenwidth) {
	    for (i = 0; i < pix; i++) {
		if (pz[i] <= izi) {
		    pz[i] = izi;
		    pdest[i] = pparticle->color;
		}
	    }
	}
	break;
    }
}
