strand.c

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/*
 * $Id: strand.c 37667 2011-06-20 15:17:02Z campbellbarton $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: none of this file.
 *
 * Contributors: Brecht Van Lommel.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <math.h>
#include <string.h>
#include <stdlib.h>

#include "MEM_guardedalloc.h"

#include "DNA_key_types.h"
#include "DNA_material_types.h"
#include "DNA_meshdata_types.h"

#include "BLI_math.h"
#include "BLI_blenlib.h"
#include "BLI_utildefines.h"
#include "BLI_ghash.h"
#include "BLI_memarena.h"
#include "BLI_rand.h"

#include "BKE_DerivedMesh.h"
#include "BKE_key.h"


#include "render_types.h"
#include "initrender.h"
#include "rendercore.h"
#include "renderdatabase.h"
#include "renderpipeline.h"
#include "pixelblending.h"
#include "shading.h"
#include "strand.h"
#include "zbuf.h"

/* to be removed */
void hoco_to_zco(ZSpan *zspan, float *zco, float *hoco);
void zspan_scanconvert_strand(ZSpan *zspan, void *handle, float *v1, float *v2, float *v3, void (*func)(void *, int, int, float, float, float) );
void zbufsinglewire(ZSpan *zspan, int obi, int zvlnr, float *ho1, float *ho2);

/* *************** */

static float strand_eval_width(Material *ma, float strandco)
{
        float fac;

        strandco= 0.5f*(strandco + 1.0f);

        if(ma->strand_ease!=0.0f) {
                if(ma->strand_ease<0.0f)
                        fac= pow(strandco, 1.0+ma->strand_ease);
                else
                        fac= pow(strandco, 1.0/(1.0f-ma->strand_ease));
        }
        else fac= strandco;
        
        return ((1.0f-fac)*ma->strand_sta + (fac)*ma->strand_end);
}

void strand_eval_point(StrandSegment *sseg, StrandPoint *spoint)
{
        Material *ma;
        StrandBuffer *strandbuf;
        float *simplify;
        float p[4][3], data[4], cross[3], crosslen, w, dx, dy, t;
        int type;

        strandbuf= sseg->buffer;
        ma= sseg->buffer->ma;
        t= spoint->t;
        type= (strandbuf->flag & R_STRAND_BSPLINE)? KEY_BSPLINE: KEY_CARDINAL;

        VECCOPY(p[0], sseg->v[0]->co);
        VECCOPY(p[1], sseg->v[1]->co);
        VECCOPY(p[2], sseg->v[2]->co);
        VECCOPY(p[3], sseg->v[3]->co);

        if(sseg->obi->flag & R_TRANSFORMED) {
                mul_m4_v3(sseg->obi->mat, p[0]);
                mul_m4_v3(sseg->obi->mat, p[1]);
                mul_m4_v3(sseg->obi->mat, p[2]);
                mul_m4_v3(sseg->obi->mat, p[3]);
        }

        if(t == 0.0f) {
                VECCOPY(spoint->co, p[1]);
                spoint->strandco= sseg->v[1]->strandco;

                spoint->dtstrandco= (sseg->v[2]->strandco - sseg->v[0]->strandco);
                if(sseg->v[0] != sseg->v[1])
                        spoint->dtstrandco *= 0.5f;
        }
        else if(t == 1.0f) {
                VECCOPY(spoint->co, p[2]);
                spoint->strandco= sseg->v[2]->strandco;

                spoint->dtstrandco= (sseg->v[3]->strandco - sseg->v[1]->strandco);
                if(sseg->v[3] != sseg->v[2])
                        spoint->dtstrandco *= 0.5f;
        }
        else {
                key_curve_position_weights(t, data, type);
                spoint->co[0]= data[0]*p[0][0] + data[1]*p[1][0] + data[2]*p[2][0] + data[3]*p[3][0];
                spoint->co[1]= data[0]*p[0][1] + data[1]*p[1][1] + data[2]*p[2][1] + data[3]*p[3][1];
                spoint->co[2]= data[0]*p[0][2] + data[1]*p[1][2] + data[2]*p[2][2] + data[3]*p[3][2];
                spoint->strandco= (1.0f-t)*sseg->v[1]->strandco + t*sseg->v[2]->strandco;
        }

        key_curve_tangent_weights(t, data, type);
        spoint->dtco[0]= data[0]*p[0][0] + data[1]*p[1][0] + data[2]*p[2][0] + data[3]*p[3][0];
        spoint->dtco[1]= data[0]*p[0][1] + data[1]*p[1][1] + data[2]*p[2][1] + data[3]*p[3][1];
        spoint->dtco[2]= data[0]*p[0][2] + data[1]*p[1][2] + data[2]*p[2][2] + data[3]*p[3][2];

        VECCOPY(spoint->tan, spoint->dtco);
        normalize_v3(spoint->tan);

        VECCOPY(spoint->nor, spoint->co);
        VECMUL(spoint->nor, -1.0f);
        normalize_v3(spoint->nor);

        spoint->width= strand_eval_width(ma, spoint->strandco);
        
        /* simplification */
        simplify= RE_strandren_get_simplify(strandbuf->obr, sseg->strand, 0);
        spoint->alpha= (simplify)? simplify[1]: 1.0f;

        /* outer points */
        cross_v3_v3v3(cross, spoint->co, spoint->tan);

        w= spoint->co[2]*strandbuf->winmat[2][3] + strandbuf->winmat[3][3];
        dx= strandbuf->winx*cross[0]*strandbuf->winmat[0][0]/w;
        dy= strandbuf->winy*cross[1]*strandbuf->winmat[1][1]/w;
        w= sqrt(dx*dx + dy*dy);

        if(w > 0.0f) {
                if(strandbuf->flag & R_STRAND_B_UNITS) {
                        crosslen= len_v3(cross);
                        w= 2.0f*crosslen*strandbuf->minwidth/w;

                        if(spoint->width < w) {
                                spoint->alpha= spoint->width/w;
                                spoint->width= w;
                        }

                        if(simplify)
                                /* squared because we only change width, not length */
                                spoint->width *= simplify[0]*simplify[0];

                        mul_v3_fl(cross, spoint->width*0.5f/crosslen);
                }
                else
                        mul_v3_fl(cross, spoint->width/w);
        }

        sub_v3_v3v3(spoint->co1, spoint->co, cross);
        add_v3_v3v3(spoint->co2, spoint->co, cross);

        VECCOPY(spoint->dsco, cross);
}

/* *************** */

static void interpolate_vec1(float *v1, float *v2, float t, float negt, float *v)
{
        v[0]= negt*v1[0] + t*v2[0];
}

static void interpolate_vec3(float *v1, float *v2, float t, float negt, float *v)
{
        v[0]= negt*v1[0] + t*v2[0];
        v[1]= negt*v1[1] + t*v2[1];
        v[2]= negt*v1[2] + t*v2[2];
}

static void interpolate_vec4(float *v1, float *v2, float t, float negt, float *v)
{
        v[0]= negt*v1[0] + t*v2[0];
        v[1]= negt*v1[1] + t*v2[1];
        v[2]= negt*v1[2] + t*v2[2];
        v[3]= negt*v1[3] + t*v2[3];
}

static void interpolate_shade_result(ShadeResult *shr1, ShadeResult *shr2, float t, ShadeResult *shr, int addpassflag)
{
        float negt= 1.0f - t;

        interpolate_vec4(shr1->combined, shr2->combined, t, negt, shr->combined);

        if(addpassflag & SCE_PASS_VECTOR) {
                interpolate_vec4(shr1->winspeed, shr2->winspeed, t, negt, shr->winspeed);
        }
        /* optim... */
        if(addpassflag & ~(SCE_PASS_VECTOR)) {
                if(addpassflag & SCE_PASS_Z)
                        interpolate_vec1(&shr1->z, &shr2->z, t, negt, &shr->z);
                if(addpassflag & SCE_PASS_RGBA)
                        interpolate_vec4(shr1->col, shr2->col, t, negt, shr->col);
                if(addpassflag & SCE_PASS_NORMAL) {
                        interpolate_vec3(shr1->nor, shr2->nor, t, negt, shr->nor);
                        normalize_v3(shr->nor);
                }
                if(addpassflag & SCE_PASS_EMIT)
                        interpolate_vec3(shr1->emit, shr2->emit, t, negt, shr->emit);
                if(addpassflag & SCE_PASS_DIFFUSE)
                        interpolate_vec3(shr1->diff, shr2->diff, t, negt, shr->diff);
                if(addpassflag & SCE_PASS_SPEC)
                        interpolate_vec3(shr1->spec, shr2->spec, t, negt, shr->spec);
                if(addpassflag & SCE_PASS_SHADOW)
                        interpolate_vec3(shr1->shad, shr2->shad, t, negt, shr->shad);
                if(addpassflag & SCE_PASS_AO)
                        interpolate_vec3(shr1->ao, shr2->ao, t, negt, shr->ao);
                if(addpassflag & SCE_PASS_ENVIRONMENT)
                        interpolate_vec3(shr1->env, shr2->env, t, negt, shr->env);
                if(addpassflag & SCE_PASS_INDIRECT)
                        interpolate_vec3(shr1->indirect, shr2->indirect, t, negt, shr->indirect);
                if(addpassflag & SCE_PASS_REFLECT)
                        interpolate_vec3(shr1->refl, shr2->refl, t, negt, shr->refl);
                if(addpassflag & SCE_PASS_REFRACT)
                        interpolate_vec3(shr1->refr, shr2->refr, t, negt, shr->refr);
                if(addpassflag & SCE_PASS_MIST)
                        interpolate_vec1(&shr1->mist, &shr2->mist, t, negt, &shr->mist);
        }
}

static void strand_apply_shaderesult_alpha(ShadeResult *shr, float alpha)
{
        if(alpha < 1.0f) {
                shr->combined[0] *= alpha;
                shr->combined[1] *= alpha;
                shr->combined[2] *= alpha;
                shr->combined[3] *= alpha;

                shr->col[0] *= alpha;
                shr->col[1] *= alpha;
                shr->col[2] *= alpha;
                shr->col[3] *= alpha;

                shr->alpha *= alpha;
        }
}

static void strand_shade_point(Render *re, ShadeSample *ssamp, StrandSegment *sseg, StrandVert *svert, StrandPoint *spoint)
{
        ShadeInput *shi= ssamp->shi;
        ShadeResult *shr= ssamp->shr;
        VlakRen vlr;
        int seed;

        memset(&vlr, 0, sizeof(vlr));
        vlr.flag= R_SMOOTH;
        if(sseg->buffer->ma->mode & MA_TANGENT_STR)
                vlr.flag |= R_TANGENT;

        shi->vlr= &vlr;
        shi->v1= NULL;
        shi->v2= NULL;
        shi->v3= NULL;
        shi->strand= sseg->strand;
        shi->obi= sseg->obi;
        shi->obr= sseg->obi->obr;

        /* cache for shadow */
        shi->samplenr= re->shadowsamplenr[shi->thread]++;

        /* all samples */
        shi->mask= 0xFFFF;

        /* seed RNG for consistent results across tiles */
        seed = shi->strand->index + (svert - shi->strand->vert);
        BLI_thread_srandom(shi->thread, seed);

        shade_input_set_strand(shi, sseg->strand, spoint);
        shade_input_set_strand_texco(shi, sseg->strand, sseg->v[1], spoint);
        
        /* init material vars */
        shade_input_init_material(shi);
        
        /* shade */
        shade_samples_do_AO(ssamp);
        shade_input_do_shade(shi, shr);

        /* apply simplification */
        strand_apply_shaderesult_alpha(shr, spoint->alpha);

        /* include lamphalos for strand, since halo layer was added already */
        if(re->flag & R_LAMPHALO)
                if(shi->layflag & SCE_LAY_HALO)
                        renderspothalo(shi, shr->combined, shr->combined[3]);
        
        shi->strand= NULL;
}

/* *************** */

struct StrandShadeCache {
        GHash *resulthash;
        GHash *refcounthash;
        MemArena *memarena;
};

StrandShadeCache *strand_shade_cache_create(void)
{
        StrandShadeCache *cache;

        cache= MEM_callocN(sizeof(StrandShadeCache), "StrandShadeCache");
        cache->resulthash= BLI_ghash_new(BLI_ghashutil_ptrhash, BLI_ghashutil_ptrcmp, "strand_shade_cache_create1 gh");
        cache->refcounthash= BLI_ghash_new(BLI_ghashutil_ptrhash, BLI_ghashutil_ptrcmp, "strand_shade_cache_create2 gh");
        cache->memarena= BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "strand shade cache arena");
        
        return cache;
}

void strand_shade_cache_free(StrandShadeCache *cache)
{
        BLI_ghash_free(cache->refcounthash, NULL, NULL);
        BLI_ghash_free(cache->resulthash, NULL, (GHashValFreeFP)MEM_freeN);
        BLI_memarena_free(cache->memarena);
        MEM_freeN(cache);
}

static void strand_shade_get(Render *re, StrandShadeCache *cache, ShadeSample *ssamp, StrandSegment *sseg, StrandVert *svert)
{
        ShadeResult *hashshr;
        StrandPoint p;
        int *refcount;

        hashshr= BLI_ghash_lookup(cache->resulthash, svert);
        refcount= BLI_ghash_lookup(cache->refcounthash, svert);

        if(!hashshr) {
                /* not shaded yet, shade and insert into hash */
                p.t= (sseg->v[1] == svert)? 0.0f: 1.0f;
                strand_eval_point(sseg, &p);
                strand_shade_point(re, ssamp, sseg, svert, &p);

                hashshr= MEM_callocN(sizeof(ShadeResult), "HashShadeResult");
                *hashshr= ssamp->shr[0];
                BLI_ghash_insert(cache->resulthash, svert, hashshr);
        }
        else
                /* already shaded, just copy previous result from hash */
                ssamp->shr[0]= *hashshr;
        
        /* lower reference count and remove if not needed anymore by any samples */
        (*refcount)--;
        if(*refcount == 0) {
                BLI_ghash_remove(cache->resulthash, svert, NULL, (GHashValFreeFP)MEM_freeN);
                BLI_ghash_remove(cache->refcounthash, svert, NULL, NULL);
        }
}

void strand_shade_segment(Render *re, StrandShadeCache *cache, StrandSegment *sseg, ShadeSample *ssamp, float t, float s, int addpassflag)
{
        ShadeResult shr1, shr2;

        /* get shading for two endpoints and interpolate */
        strand_shade_get(re, cache, ssamp, sseg, sseg->v[1]);
        shr1= ssamp->shr[0];
        strand_shade_get(re, cache, ssamp, sseg, sseg->v[2]);
        shr2= ssamp->shr[0];

        interpolate_shade_result(&shr1, &shr2, t, ssamp->shr, addpassflag);

        /* apply alpha along width */
        if(sseg->buffer->widthfade != 0.0f) {
                s = 1.0f - pow(fabs(s), sseg->buffer->widthfade);

                strand_apply_shaderesult_alpha(ssamp->shr, s);
        }
}

void strand_shade_unref(StrandShadeCache *cache, StrandVert *svert)
{
        int *refcount;

        /* lower reference count and remove if not needed anymore by any samples */
        refcount= BLI_ghash_lookup(cache->refcounthash, svert);

        (*refcount)--;
        if(*refcount == 0) {
                BLI_ghash_remove(cache->resulthash, svert, NULL, (GHashValFreeFP)MEM_freeN);
                BLI_ghash_remove(cache->refcounthash, svert, NULL, NULL);
        }
}

static void strand_shade_refcount(StrandShadeCache *cache, StrandVert *svert)
{
        int *refcount= BLI_ghash_lookup(cache->refcounthash, svert);

        if(!refcount) {
                refcount= BLI_memarena_alloc(cache->memarena, sizeof(int));
                *refcount= 1;
                BLI_ghash_insert(cache->refcounthash, svert, refcount);
        }
        else
                (*refcount)++;
}

/* *************** */

typedef struct StrandPart {
        Render *re;
        ZSpan *zspan;

        APixstrand *apixbuf;
        int *totapixbuf;
        int *rectz;
        int *rectmask;
        intptr_t *rectdaps;
        int rectx, recty;
        int sample;
        int shadow;
        float (*jit)[2];

        StrandSegment *segment;
        float t[3], s[3];

        StrandShadeCache *cache;
} StrandPart;

typedef struct StrandSortSegment {
        struct StrandSortSegment *next;
        int obi, strand, segment;
        float z;
} StrandSortSegment;

static int compare_strand_segment(const void *poin1, const void *poin2)
{
        const StrandSortSegment *seg1= (const StrandSortSegment*)poin1;
        const StrandSortSegment *seg2= (const StrandSortSegment*)poin2;

        if(seg1->z < seg2->z)
                return -1;
        else if(seg1->z == seg2->z)
                return 0;
        else
                return 1;
}

static void do_strand_point_project(float winmat[][4], ZSpan *zspan, float *co, float *hoco, float *zco)
{
        projectvert(co, winmat, hoco);
        hoco_to_zco(zspan, zco, hoco);
}

static void strand_project_point(float winmat[][4], float winx, float winy, StrandPoint *spoint)
{
        float div;

        projectvert(spoint->co, winmat, spoint->hoco);

        div= 1.0f/spoint->hoco[3];
        spoint->x= spoint->hoco[0]*div*winx*0.5f;
        spoint->y= spoint->hoco[1]*div*winy*0.5f;
}

static APixstrand *addpsmainAstrand(ListBase *lb)
{
        APixstrMain *psm;

        psm= MEM_mallocN(sizeof(APixstrMain), "addpsmainA");
        BLI_addtail(lb, psm);
        psm->ps= MEM_callocN(4096*sizeof(APixstrand),"pixstr");

        return psm->ps;
}

static APixstrand *addpsAstrand(ZSpan *zspan)
{
        /* make new PS */
        if(zspan->apstrandmcounter==0) {
                zspan->curpstrand= addpsmainAstrand(zspan->apsmbase);
                zspan->apstrandmcounter= 4095;
        }
        else {
                zspan->curpstrand++;
                zspan->apstrandmcounter--;
        }
        return zspan->curpstrand;
}

#define MAX_ZROW        2000

static void do_strand_fillac(void *handle, int x, int y, float u, float v, float z)
{
        StrandPart *spart= (StrandPart*)handle;
        StrandShadeCache *cache= spart->cache;
        StrandSegment *sseg= spart->segment;
        APixstrand *apn, *apnew;
        float t, s;
        int offset, mask, obi, strnr, seg, zverg, bufferz, maskz=0;

        offset = y*spart->rectx + x;
        obi= sseg->obi - spart->re->objectinstance;
        strnr= sseg->strand->index + 1;
        seg= sseg->v[1] - sseg->strand->vert;
        mask= (1<<spart->sample);

        /* check against solid z-buffer */
        zverg= (int)z;

        if(spart->rectdaps) {
                /* find the z of the sample */
                PixStr *ps;
                intptr_t *rd= spart->rectdaps + offset;
                
                bufferz= 0x7FFFFFFF;
                if(spart->rectmask) maskz= 0x7FFFFFFF;
                
                if(*rd) {       
                        for(ps= (PixStr *)(*rd); ps; ps= ps->next) {
                                if(mask & ps->mask) {
                                        bufferz= ps->z;
                                        if(spart->rectmask)
                                                maskz= ps->maskz;
                                        break;
                                }
                        }
                }
        }
        else {
                bufferz= (spart->rectz)? spart->rectz[offset]: 0x7FFFFFFF;
                if(spart->rectmask)
                        maskz= spart->rectmask[offset];
        }

#define CHECK_ADD(n) \
        if(apn->p[n]==strnr && apn->obi[n]==obi && apn->seg[n]==seg) \
        { if(!(apn->mask[n] & mask)) { apn->mask[n] |= mask; apn->v[n] += t; apn->u[n] += s; } break; }
#define CHECK_ASSIGN(n) \
        if(apn->p[n]==0) \
        {apn->obi[n]= obi; apn->p[n]= strnr; apn->z[n]= zverg; apn->mask[n]= mask; apn->v[n]= t; apn->u[n]= s; apn->seg[n]= seg; break; }

        /* add to pixel list */
        if(zverg < bufferz && (spart->totapixbuf[offset] < MAX_ZROW)) {
                if(!spart->rectmask || zverg > maskz) {
                        t = u*spart->t[0] + v*spart->t[1] + (1.0f-u-v)*spart->t[2];
                        s = fabs(u*spart->s[0] + v*spart->s[1] + (1.0f-u-v)*spart->s[2]);

                        apn= spart->apixbuf + offset;
                        while(apn) {
                                CHECK_ADD(0);
                                CHECK_ADD(1);
                                CHECK_ADD(2);
                                CHECK_ADD(3);
                                CHECK_ASSIGN(0);
                                CHECK_ASSIGN(1);
                                CHECK_ASSIGN(2);
                                CHECK_ASSIGN(3);

                                apnew= addpsAstrand(spart->zspan);
                                SWAP(APixstrand, *apnew, *apn);
                                apn->next= apnew;
                                CHECK_ASSIGN(0);
                        }

                        if(cache) {
                                strand_shade_refcount(cache, sseg->v[1]);
                                strand_shade_refcount(cache, sseg->v[2]);
                        }
                        spart->totapixbuf[offset]++;
                }
        }
}

/* width is calculated in hoco space, to ensure strands are visible */
static int strand_test_clip(float winmat[][4], ZSpan *UNUSED(zspan), float *bounds, float *co, float *zcomp, float widthx, float widthy)
{
        float hoco[4];
        int clipflag= 0;

        projectvert(co, winmat, hoco);

        /* we compare z without perspective division for segment sorting */
        *zcomp= hoco[2];

        if(hoco[0]+widthx < bounds[0]*hoco[3]) clipflag |= 1;
        else if(hoco[0]-widthx > bounds[1]*hoco[3]) clipflag |= 2;
        
        if(hoco[1]-widthy > bounds[3]*hoco[3]) clipflag |= 4;
        else if(hoco[1]+widthy < bounds[2]*hoco[3]) clipflag |= 8;

        clipflag |= testclip(hoco);

        return clipflag;
}

static void do_scanconvert_strand(Render *UNUSED(re), StrandPart *spart, ZSpan *zspan, float t, float dt, float *co1, float *co2, float *co3, float *co4, int sample)
{
        float jco1[3], jco2[3], jco3[3], jco4[3], jx, jy;

        VECCOPY(jco1, co1);
        VECCOPY(jco2, co2);
        VECCOPY(jco3, co3);
        VECCOPY(jco4, co4);

        if(spart->jit) {
                jx= -spart->jit[sample][0];
                jy= -spart->jit[sample][1];

                jco1[0] += jx; jco1[1] += jy;
                jco2[0] += jx; jco2[1] += jy;
                jco3[0] += jx; jco3[1] += jy;
                jco4[0] += jx; jco4[1] += jy;

                /* XXX mblur? */
        }

        spart->sample= sample;

        spart->t[0]= t-dt;
        spart->s[0]= -1.0f;
        spart->t[1]= t-dt;
        spart->s[1]= 1.0f;
        spart->t[2]= t;
        spart->s[2]= 1.0f;
        zspan_scanconvert_strand(zspan, spart, jco1, jco2, jco3, do_strand_fillac);
        spart->t[0]= t-dt;
        spart->s[0]= -1.0f;
        spart->t[1]= t;
        spart->s[1]= 1.0f;
        spart->t[2]= t;
        spart->s[2]= -1.0f;
        zspan_scanconvert_strand(zspan, spart, jco1, jco3, jco4, do_strand_fillac);
}

static void strand_render(Render *re, StrandSegment *sseg, float winmat[][4], StrandPart *spart, ZSpan *zspan, int totzspan, StrandPoint *p1, StrandPoint *p2)
{
        if(spart) {
                float t= p2->t;
                float dt= p2->t - p1->t;
                int a;

                if(re->osa) {
                        for(a=0; a<re->osa; a++)
                                do_scanconvert_strand(re, spart, zspan, t, dt, p1->zco2, p1->zco1, p2->zco1, p2->zco2, a);
                }
                else
                        do_scanconvert_strand(re, spart, zspan, t, dt, p1->zco2, p1->zco1, p2->zco1, p2->zco2, 0);
        }
        else {
                float hoco1[4], hoco2[4];
                int a, obi, index;
  
                obi= sseg->obi - re->objectinstance;
                index= sseg->strand->index;

                projectvert(p1->co, winmat, hoco1);
                projectvert(p2->co, winmat, hoco2);

  
                for(a=0; a<totzspan; a++) {
#if 0
                        /* render both strand and single pixel wire to counter aliasing */
                        zbufclip4(re, &zspan[a], obi, index, p1->hoco2, p1->hoco1, p2->hoco1, p2->hoco2, p1->clip2, p1->clip1, p2->clip1, p2->clip2);
#endif
                        /* only render a line for now, which makes the shadow map more
                           similiar across frames, and so reduces flicker */
                        zbufsinglewire(&zspan[a], obi, index, hoco1, hoco2);
                }
        }
}

static int strand_segment_recursive(Render *re, float winmat[][4], StrandPart *spart, ZSpan *zspan, int totzspan, StrandSegment *sseg, StrandPoint *p1, StrandPoint *p2, int depth)
{
        StrandPoint p;
        StrandBuffer *buffer= sseg->buffer;
        float dot, d1[2], d2[2], len1, len2;

        if(depth == buffer->maxdepth)
                return 0;

        p.t= (p1->t + p2->t)*0.5f;
        strand_eval_point(sseg, &p);
        strand_project_point(buffer->winmat, buffer->winx, buffer->winy, &p);

        d1[0]= (p.x - p1->x);
        d1[1]= (p.y - p1->y);
        len1= d1[0]*d1[0] + d1[1]*d1[1];

        d2[0]= (p2->x - p.x);
        d2[1]= (p2->y - p.y);
        len2= d2[0]*d2[0] + d2[1]*d2[1];

        if(len1 == 0.0f || len2 == 0.0f)
                return 0;
        
        dot= d1[0]*d2[0] + d1[1]*d2[1];
        if(dot*dot > sseg->sqadaptcos*len1*len2)
                return 0;

        if(spart) {
                do_strand_point_project(winmat, zspan, p.co1, p.hoco1, p.zco1);
                do_strand_point_project(winmat, zspan, p.co2, p.hoco2, p.zco2);
        }
        else {
#if 0
                projectvert(p.co1, winmat, p.hoco1);
                projectvert(p.co2, winmat, p.hoco2);
                p.clip1= testclip(p.hoco1);
                p.clip2= testclip(p.hoco2);
#endif
        }

        if(!strand_segment_recursive(re, winmat, spart, zspan, totzspan, sseg, p1, &p, depth+1))
                strand_render(re, sseg, winmat, spart, zspan, totzspan, p1, &p);
        if(!strand_segment_recursive(re, winmat, spart, zspan, totzspan, sseg, &p, p2, depth+1))
                strand_render(re, sseg, winmat, spart, zspan, totzspan, &p, p2);
        
        return 1;
}

void render_strand_segment(Render *re, float winmat[][4], StrandPart *spart, ZSpan *zspan, int totzspan, StrandSegment *sseg)
{
        StrandBuffer *buffer= sseg->buffer;
        StrandPoint *p1= &sseg->point1;
        StrandPoint *p2= &sseg->point2;

        p1->t= 0.0f;
        p2->t= 1.0f;

        strand_eval_point(sseg, p1);
        strand_project_point(buffer->winmat, buffer->winx, buffer->winy, p1);
        strand_eval_point(sseg, p2);
        strand_project_point(buffer->winmat, buffer->winx, buffer->winy, p2);

        if(spart) {
                do_strand_point_project(winmat, zspan, p1->co1, p1->hoco1, p1->zco1);
                do_strand_point_project(winmat, zspan, p1->co2, p1->hoco2, p1->zco2);
                do_strand_point_project(winmat, zspan, p2->co1, p2->hoco1, p2->zco1);
                do_strand_point_project(winmat, zspan, p2->co2, p2->hoco2, p2->zco2);
        }
        else {
#if 0
                projectvert(p1->co1, winmat, p1->hoco1);
                projectvert(p1->co2, winmat, p1->hoco2);
                projectvert(p2->co1, winmat, p2->hoco1);
                projectvert(p2->co2, winmat, p2->hoco2);
                p1->clip1= testclip(p1->hoco1);
                p1->clip2= testclip(p1->hoco2);
                p2->clip1= testclip(p2->hoco1);
                p2->clip2= testclip(p2->hoco2);
#endif
        }

        if(!strand_segment_recursive(re, winmat, spart, zspan, totzspan, sseg, p1, p2, 0))
                strand_render(re, sseg, winmat, spart, zspan, totzspan, p1, p2);
}

/* render call to fill in strands */
int zbuffer_strands_abuf(Render *re, RenderPart *pa, APixstrand *apixbuf, ListBase *apsmbase, unsigned int lay, int UNUSED(negzmask), float winmat[][4], int winx, int winy, int UNUSED(sample), float (*jit)[2], float clipcrop, int shadow, StrandShadeCache *cache)
{
        ObjectRen *obr;
        ObjectInstanceRen *obi;
        ZSpan zspan;
        StrandRen *strand=0;
        StrandVert *svert;
        StrandBound *sbound;
        StrandPart spart;
        StrandSegment sseg;
        StrandSortSegment *sortsegments = NULL, *sortseg, *firstseg;
        MemArena *memarena;
        float z[4], bounds[4], obwinmat[4][4];
        int a, b, c, i, totsegment, clip[4];

        if(re->test_break(re->tbh))
                return 0;
        if(re->totstrand == 0)
                return 0;

        /* setup StrandPart */
        memset(&spart, 0, sizeof(spart));

        spart.re= re;
        spart.rectx= pa->rectx;
        spart.recty= pa->recty;
        spart.apixbuf= apixbuf;
        spart.zspan= &zspan;
        spart.rectdaps= pa->rectdaps;
        spart.rectz= pa->rectz;
        spart.rectmask= pa->rectmask;
        spart.cache= cache;
        spart.shadow= shadow;
        spart.jit= jit;

        zbuf_alloc_span(&zspan, pa->rectx, pa->recty, clipcrop);

        /* needed for transform from hoco to zbuffer co */
        zspan.zmulx= ((float)winx)/2.0;
        zspan.zmuly= ((float)winy)/2.0;
        
        zspan.zofsx= -pa->disprect.xmin;
        zspan.zofsy= -pa->disprect.ymin;

        /* to center the sample position */
        if(!shadow) {
                zspan.zofsx -= 0.5f;
                zspan.zofsy -= 0.5f;
        }

        zspan.apsmbase= apsmbase;

        /* clipping setup */
        bounds[0]= (2*pa->disprect.xmin - winx-1)/(float)winx;
        bounds[1]= (2*pa->disprect.xmax - winx+1)/(float)winx;
        bounds[2]= (2*pa->disprect.ymin - winy-1)/(float)winy;
        bounds[3]= (2*pa->disprect.ymax - winy+1)/(float)winy;

        memarena= BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "strand sort arena");
        firstseg= NULL;
        sortseg= sortsegments;
        totsegment= 0;

        /* for all object instances */
        for(obi=re->instancetable.first, i=0; obi; obi=obi->next, i++) {
                Material *ma;
                float widthx, widthy;

                obr= obi->obr;

                if(!obr->strandbuf || !(obr->strandbuf->lay & lay))
                        continue;

                /* compute matrix and try clipping whole object */
                if(obi->flag & R_TRANSFORMED)
                        mul_m4_m4m4(obwinmat, obi->mat, winmat);
                else
                        copy_m4_m4(obwinmat, winmat);

                /* test if we should skip it */
                ma = obr->strandbuf->ma;

                if(shadow && !(ma->mode & MA_SHADBUF))
                        continue;
                else if(!shadow && (ma->mode & MA_ONLYCAST))
                        continue;

                if(clip_render_object(obi->obr->boundbox, bounds, obwinmat))
                        continue;
                
                widthx= obr->strandbuf->maxwidth*obwinmat[0][0];
                widthy= obr->strandbuf->maxwidth*obwinmat[1][1];

                /* for each bounding box containing a number of strands */
                sbound= obr->strandbuf->bound;
                for(c=0; c<obr->strandbuf->totbound; c++, sbound++) {
                        if(clip_render_object(sbound->boundbox, bounds, obwinmat))
                                continue;

                        /* for each strand in this bounding box */
                        for(a=sbound->start; a<sbound->end; a++) {
                                strand= RE_findOrAddStrand(obr, a);
                                svert= strand->vert;

                                /* keep clipping and z depth for 4 control points */
                                clip[1]= strand_test_clip(obwinmat, &zspan, bounds, svert->co, &z[1], widthx, widthy);
                                clip[2]= strand_test_clip(obwinmat, &zspan, bounds, (svert+1)->co, &z[2], widthx, widthy);
                                clip[0]= clip[1]; z[0]= z[1];

                                for(b=0; b<strand->totvert-1; b++, svert++) {
                                        /* compute 4th point clipping and z depth */
                                        if(b < strand->totvert-2) {
                                                clip[3]= strand_test_clip(obwinmat, &zspan, bounds, (svert+2)->co, &z[3], widthx, widthy);
                                        }
                                        else {
                                                clip[3]= clip[2]; z[3]= z[2];
                                        }

                                        /* check clipping and add to sortsegments buffer */
                                        if(!(clip[0] & clip[1] & clip[2] & clip[3])) {
                                                sortseg= BLI_memarena_alloc(memarena, sizeof(StrandSortSegment));
                                                sortseg->obi= i;
                                                sortseg->strand= strand->index;
                                                sortseg->segment= b;

                                                sortseg->z= 0.5f*(z[1] + z[2]);

                                                sortseg->next= firstseg;
                                                firstseg= sortseg;
                                                totsegment++;
                                        }

                                        /* shift clipping and z depth */
                                        clip[0]= clip[1]; z[0]= z[1];
                                        clip[1]= clip[2]; z[1]= z[2];
                                        clip[2]= clip[3]; z[2]= z[3];
                                }
                        }
                }
        }

        if(!re->test_break(re->tbh)) {
                /* convert list to array and sort */
                sortsegments= MEM_mallocN(sizeof(StrandSortSegment)*totsegment, "StrandSortSegment");
                for(a=0, sortseg=firstseg; a<totsegment; a++, sortseg=sortseg->next)
                        sortsegments[a]= *sortseg;
                qsort(sortsegments, totsegment, sizeof(StrandSortSegment), compare_strand_segment);
        }

        BLI_memarena_free(memarena);

        spart.totapixbuf= MEM_callocN(sizeof(int)*pa->rectx*pa->recty, "totapixbuf");

        if(!re->test_break(re->tbh)) {
                /* render segments in sorted order */
                sortseg= sortsegments;
                for(a=0; a<totsegment; a++, sortseg++) {
                        if(re->test_break(re->tbh))
                                break;

                        obi= &re->objectinstance[sortseg->obi];
                        obr= obi->obr;

                        sseg.obi= obi;
                        sseg.strand= RE_findOrAddStrand(obr, sortseg->strand);
                        sseg.buffer= sseg.strand->buffer;
                        sseg.sqadaptcos= sseg.buffer->adaptcos;
                        sseg.sqadaptcos *= sseg.sqadaptcos;

                        svert= sseg.strand->vert + sortseg->segment;
                        sseg.v[0]= (sortseg->segment > 0)? (svert-1): svert;
                        sseg.v[1]= svert;
                        sseg.v[2]= svert+1;
                        sseg.v[3]= (sortseg->segment < sseg.strand->totvert-2)? svert+2: svert+1;
                        sseg.shaded= 0;

                        spart.segment= &sseg;

                        render_strand_segment(re, winmat, &spart, &zspan, 1, &sseg);
                }
        }

        if(sortsegments)
                MEM_freeN(sortsegments);
        MEM_freeN(spart.totapixbuf);
        
        zbuf_free_span(&zspan);

        return totsegment;
}

/* *************** */

StrandSurface *cache_strand_surface(Render *re, ObjectRen *obr, DerivedMesh *dm, float mat[][4], int timeoffset)
{
        StrandSurface *mesh;
        MFace *mface;
        MVert *mvert;
        float (*co)[3];
        int a, totvert, totface;

        totvert= dm->getNumVerts(dm);
        totface= dm->getNumFaces(dm);

        for(mesh=re->strandsurface.first; mesh; mesh=mesh->next)
                if(mesh->obr.ob == obr->ob && mesh->obr.par == obr->par
                        && mesh->obr.index == obr->index && mesh->totvert==totvert && mesh->totface==totface)
                        break;

        if(!mesh) {
                mesh= MEM_callocN(sizeof(StrandSurface), "StrandSurface");
                mesh->obr= *obr;
                mesh->totvert= totvert;
                mesh->totface= totface;
                mesh->face= MEM_callocN(sizeof(int)*4*mesh->totface, "StrandSurfFaces");
                mesh->ao= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfAO");
                mesh->env= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfEnv");
                mesh->indirect= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfIndirect");
                BLI_addtail(&re->strandsurface, mesh);
        }

        if(timeoffset == -1 && !mesh->prevco)
                mesh->prevco= co= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfCo");
        else if(timeoffset == 0 && !mesh->co)
                mesh->co= co= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfCo");
        else if(timeoffset == 1 && !mesh->nextco)
                mesh->nextco= co= MEM_callocN(sizeof(float)*3*mesh->totvert, "StrandSurfCo");
        else
                return mesh;

        mvert= dm->getVertArray(dm);
        for(a=0; a<mesh->totvert; a++, mvert++) {
                VECCOPY(co[a], mvert->co);
                mul_m4_v3(mat, co[a]);
        }

        mface= dm->getFaceArray(dm);
        for(a=0; a<mesh->totface; a++, mface++) {
                mesh->face[a][0]= mface->v1;
                mesh->face[a][1]= mface->v2;
                mesh->face[a][2]= mface->v3;
                mesh->face[a][3]= mface->v4;
        }

        return mesh;
}

void free_strand_surface(Render *re)
{
        StrandSurface *mesh;

        for(mesh=re->strandsurface.first; mesh; mesh=mesh->next) {
                if(mesh->co) MEM_freeN(mesh->co);
                if(mesh->prevco) MEM_freeN(mesh->prevco);
                if(mesh->nextco) MEM_freeN(mesh->nextco);
                if(mesh->ao) MEM_freeN(mesh->ao);
                if(mesh->env) MEM_freeN(mesh->env);
                if(mesh->indirect) MEM_freeN(mesh->indirect);
                if(mesh->face) MEM_freeN(mesh->face);
        }

        BLI_freelistN(&re->strandsurface);
}

void strand_minmax(StrandRen *strand, float *min, float *max, float width)
{
        StrandVert *svert;
        float vec[3], width2= 2.0f*width;
        int a;

        for(a=0, svert=strand->vert; a<strand->totvert; a++, svert++) {
                VECCOPY(vec, svert->co);
                DO_MINMAX(vec, min, max);
                
                if(width!=0.0f) {
                        vec[0]+= width; vec[1]+= width; vec[2]+= width;
                        DO_MINMAX(vec, min, max);
                        vec[0]-= width2; vec[1]-= width2; vec[2]-= width2;
                        DO_MINMAX(vec, min, max);
                }
        }
}