git-svn-id: http://bladebattles.com/kurok/SVN@11 20cd92bb-ff49-0410-b73e-96a06e42c3b9

[kurok.git] / r_edge.c

/*
Copyright (C) 1996-1997 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.

*/
// r_edge.c

#include "quakedef.h"
#include "r_local.h"

#if 0
// FIXME
the complex cases add new polys on most lines, so dont optimize for keeping them the same
have multiple free span lists to try to get better coherence?
low depth complexity -- 1 to 3 or so

this breaks spans at every edge, even hidden ones (bad)

have a sentinal at both ends?
#endif


edge_t  *auxedges;
edge_t  *r_edges, *edge_p, *edge_max;

surf_t  *surfaces, *surface_p, *surf_max;

// surfaces are generated in back to front order by the bsp, so if a surf
// pointer is greater than another one, it should be drawn in front
// surfaces[1] is the background, and is used as the active surface stack

edge_t  *newedges[MAXHEIGHT];
edge_t  *removeedges[MAXHEIGHT];

espan_t *span_p, *max_span_p;

int             r_currentkey;

extern  int     screenwidth;

int     current_iv;

int     edge_head_u_shift20, edge_tail_u_shift20;

static void (*pdrawfunc)(void);

edge_t  edge_head;
edge_t  edge_tail;
edge_t  edge_aftertail;
edge_t  edge_sentinel;

float   fv;

void R_GenerateSpans (void);
void R_GenerateSpansBackward (void);

void R_LeadingEdge (edge_t *edge);
void R_LeadingEdgeBackwards (edge_t *edge);
void R_TrailingEdge (surf_t *surf, edge_t *edge);


//=============================================================================


/*
==============
R_DrawCulledPolys
==============
*/
void R_DrawCulledPolys (void)
{
        surf_t                  *s;
        msurface_t              *pface;

        currententity = &cl_entities[0];

        if (r_worldpolysbacktofront)
        {
                for (s=surface_p-1 ; s>&surfaces[1] ; s--)
                {
                        if (!s->spans)
                                continue;

                        if (!(s->flags & SURF_DRAWBACKGROUND))
                        {
                                pface = (msurface_t *)s->data;
                                R_RenderPoly (pface, 15);
                        }
                }
        }
        else
        {
                for (s = &surfaces[1] ; s<surface_p ; s++)
                {
                        if (!s->spans)
                                continue;

                        if (!(s->flags & SURF_DRAWBACKGROUND))
                        {
                                pface = (msurface_t *)s->data;
                                R_RenderPoly (pface, 15);
                        }
                }
        }
}


/*
==============
R_BeginEdgeFrame
==============
*/
void R_BeginEdgeFrame (void)
{
        int             v;

        edge_p = r_edges;
        edge_max = &r_edges[r_numallocatededges];

        surface_p = &surfaces[2];       // background is surface 1,
                                                                //  surface 0 is a dummy
        surfaces[1].spans = NULL;       // no background spans yet
        surfaces[1].flags = SURF_DRAWBACKGROUND;

// put the background behind everything in the world
        if (r_draworder.value)
        {
                pdrawfunc = R_GenerateSpansBackward;
                surfaces[1].key = 0;
                r_currentkey = 1;
        }
        else
        {
                pdrawfunc = R_GenerateSpans;
                surfaces[1].key = 0x7FFFFFFF;
                r_currentkey = 0;
        }

// FIXME: set with memset
        for (v=r_refdef.vrect.y ; v<r_refdef.vrectbottom ; v++)
        {
                newedges[v] = removeedges[v] = NULL;
        }
}


#if     !id386

/*
==============
R_InsertNewEdges

Adds the edges in the linked list edgestoadd, adding them to the edges in the
linked list edgelist.  edgestoadd is assumed to be sorted on u, and non-empty (this is actually newedges[v]).  edgelist is assumed to be sorted on u, with a
sentinel at the end (actually, this is the active edge table starting at
edge_head.next).
==============
*/
void R_InsertNewEdges (edge_t *edgestoadd, edge_t *edgelist)
{
        edge_t  *next_edge;

        do
        {
                next_edge = edgestoadd->next;
edgesearch:
                if (edgelist->u >= edgestoadd->u)
                        goto addedge;
                edgelist=edgelist->next;
                if (edgelist->u >= edgestoadd->u)
                        goto addedge;
                edgelist=edgelist->next;
                if (edgelist->u >= edgestoadd->u)
                        goto addedge;
                edgelist=edgelist->next;
                if (edgelist->u >= edgestoadd->u)
                        goto addedge;
                edgelist=edgelist->next;
                goto edgesearch;

        // insert edgestoadd before edgelist
addedge:
                edgestoadd->next = edgelist;
                edgestoadd->prev = edgelist->prev;
                edgelist->prev->next = edgestoadd;
                edgelist->prev = edgestoadd;
        } while ((edgestoadd = next_edge) != NULL);
}

#endif  // !id386
        

#if     !id386

/*
==============
R_RemoveEdges
==============
*/
void R_RemoveEdges (edge_t *pedge)
{

        do
        {
                pedge->next->prev = pedge->prev;
                pedge->prev->next = pedge->next;
        } while ((pedge = pedge->nextremove) != NULL);
}

#endif  // !id386


#if     !id386

/*
==============
R_StepActiveU
==============
*/
void R_StepActiveU (edge_t *pedge)
{
        edge_t          *pnext_edge, *pwedge;

        while (1)
        {
nextedge:
                pedge->u += pedge->u_step;
                if (pedge->u < pedge->prev->u)
                        goto pushback;
                pedge = pedge->next;
                        
                pedge->u += pedge->u_step;
                if (pedge->u < pedge->prev->u)
                        goto pushback;
                pedge = pedge->next;
                        
                pedge->u += pedge->u_step;
                if (pedge->u < pedge->prev->u)
                        goto pushback;
                pedge = pedge->next;
                        
                pedge->u += pedge->u_step;
                if (pedge->u < pedge->prev->u)
                        goto pushback;
                pedge = pedge->next;
                        
                goto nextedge;          
                
pushback:
                if (pedge == &edge_aftertail)
                        return;
                        
        // push it back to keep it sorted               
                pnext_edge = pedge->next;

        // pull the edge out of the edge list
                pedge->next->prev = pedge->prev;
                pedge->prev->next = pedge->next;

        // find out where the edge goes in the edge list
                pwedge = pedge->prev->prev;

                while (pwedge->u > pedge->u)
                {
                        pwedge = pwedge->prev;
                }

        // put the edge back into the edge list
                pedge->next = pwedge->next;
                pedge->prev = pwedge;
                pedge->next->prev = pedge;
                pwedge->next = pedge;

                pedge = pnext_edge;
                if (pedge == &edge_tail)
                        return;
        }
}

#endif  // !id386


/*
==============
R_CleanupSpan
==============
*/
void R_CleanupSpan ()
{
        surf_t  *surf;
        int             iu;
        espan_t *span;

// now that we've reached the right edge of the screen, we're done with any
// unfinished surfaces, so emit a span for whatever's on top
        surf = surfaces[1].next;
        iu = edge_tail_u_shift20;
        if (iu > surf->last_u)
        {
                span = span_p++;
                span->u = surf->last_u;
                span->count = iu - span->u;
                span->v = current_iv;
                span->pnext = surf->spans;
                surf->spans = span;
        }

// reset spanstate for all surfaces in the surface stack
        do
        {
                surf->spanstate = 0;
                surf = surf->next;
        } while (surf != &surfaces[1]);
}


/*
==============
R_LeadingEdgeBackwards
==============
*/
void R_LeadingEdgeBackwards (edge_t *edge)
{
        espan_t                 *span;
        surf_t                  *surf, *surf2;
        int                             iu;

// it's adding a new surface in, so find the correct place
        surf = &surfaces[edge->surfs[1]];

// don't start a span if this is an inverted span, with the end
// edge preceding the start edge (that is, we've already seen the
// end edge)
        if (++surf->spanstate == 1)
        {
                surf2 = surfaces[1].next;

                if (surf->key > surf2->key)
                        goto newtop;

        // if it's two surfaces on the same plane, the one that's already
        // active is in front, so keep going unless it's a bmodel
                if (surf->insubmodel && (surf->key == surf2->key))
                {
                // must be two bmodels in the same leaf; don't care, because they'll
                // never be farthest anyway
                        goto newtop;
                }

continue_search:

                do
                {
                        surf2 = surf2->next;
                } while (surf->key < surf2->key);

                if (surf->key == surf2->key)
                {
                // if it's two surfaces on the same plane, the one that's already
                // active is in front, so keep going unless it's a bmodel
                        if (!surf->insubmodel)
                                goto continue_search;

                // must be two bmodels in the same leaf; don't care which is really
                // in front, because they'll never be farthest anyway
                }

                goto gotposition;

newtop:
        // emit a span (obscures current top)
                iu = edge->u >> 20;

                if (iu > surf2->last_u)
                {
                        span = span_p++;
                        span->u = surf2->last_u;
                        span->count = iu - span->u;
                        span->v = current_iv;
                        span->pnext = surf2->spans;
                        surf2->spans = span;
                }

                // set last_u on the new span
                surf->last_u = iu;
                                
gotposition:
        // insert before surf2
                surf->next = surf2;
                surf->prev = surf2->prev;
                surf2->prev->next = surf;
                surf2->prev = surf;
        }
}


/*
==============
R_TrailingEdge
==============
*/
void R_TrailingEdge (surf_t *surf, edge_t *edge)
{
        espan_t                 *span;
        int                             iu;

// don't generate a span if this is an inverted span, with the end
// edge preceding the start edge (that is, we haven't seen the
// start edge yet)
        if (--surf->spanstate == 0)
        {
                if (surf->insubmodel)
                        r_bmodelactive--;

                if (surf == surfaces[1].next)
                {
                // emit a span (current top going away)
                        iu = edge->u >> 20;
                        if (iu > surf->last_u)
                        {
                                span = span_p++;
                                span->u = surf->last_u;
                                span->count = iu - span->u;
                                span->v = current_iv;
                                span->pnext = surf->spans;
                                surf->spans = span;
                        }

                // set last_u on the surface below
                        surf->next->last_u = iu;
                }

                surf->prev->next = surf->next;
                surf->next->prev = surf->prev;
        }
}


#if     !id386

/*
==============
R_LeadingEdge
==============
*/
void R_LeadingEdge (edge_t *edge)
{
        espan_t                 *span;
        surf_t                  *surf, *surf2;
        int                             iu;
        float                   fu, newzi, testzi, newzitop, newzibottom;

        if (edge->surfs[1])
        {
        // it's adding a new surface in, so find the correct place
                surf = &surfaces[edge->surfs[1]];

        // don't start a span if this is an inverted span, with the end
        // edge preceding the start edge (that is, we've already seen the
        // end edge)
                if (++surf->spanstate == 1)
                {
                        if (surf->insubmodel)
                                r_bmodelactive++;

                        surf2 = surfaces[1].next;

                        if (surf->key < surf2->key)
                                goto newtop;

                // if it's two surfaces on the same plane, the one that's already
                // active is in front, so keep going unless it's a bmodel
                        if (surf->insubmodel && (surf->key == surf2->key))
                        {
                        // must be two bmodels in the same leaf; sort on 1/z
                                fu = (float)(edge->u - 0xFFFFF) * (1.0 / 0x100000);
                                newzi = surf->d_ziorigin + fv*surf->d_zistepv +
                                                fu*surf->d_zistepu;
                                newzibottom = newzi * 0.99;

                                testzi = surf2->d_ziorigin + fv*surf2->d_zistepv +
                                                fu*surf2->d_zistepu;

                                if (newzibottom >= testzi)
                                {
                                        goto newtop;
                                }

                                newzitop = newzi * 1.01;
                                if (newzitop >= testzi)
                                {
                                        if (surf->d_zistepu >= surf2->d_zistepu)
                                        {
                                                goto newtop;
                                        }
                                }
                        }

continue_search:

                        do
                        {
                                surf2 = surf2->next;
                        } while (surf->key > surf2->key);

                        if (surf->key == surf2->key)
                        {
                        // if it's two surfaces on the same plane, the one that's already
                        // active is in front, so keep going unless it's a bmodel
                                if (!surf->insubmodel)
                                        goto continue_search;

                        // must be two bmodels in the same leaf; sort on 1/z
                                fu = (float)(edge->u - 0xFFFFF) * (1.0 / 0x100000);
                                newzi = surf->d_ziorigin + fv*surf->d_zistepv +
                                                fu*surf->d_zistepu;
                                newzibottom = newzi * 0.99;

                                testzi = surf2->d_ziorigin + fv*surf2->d_zistepv +
                                                fu*surf2->d_zistepu;

                                if (newzibottom >= testzi)
                                {
                                        goto gotposition;
                                }

                                newzitop = newzi * 1.01;
                                if (newzitop >= testzi)
                                {
                                        if (surf->d_zistepu >= surf2->d_zistepu)
                                        {
                                                goto gotposition;
                                        }
                                }

                                goto continue_search;
                        }

                        goto gotposition;

newtop:
                // emit a span (obscures current top)
                        iu = edge->u >> 20;

                        if (iu > surf2->last_u)
                        {
                                span = span_p++;
                                span->u = surf2->last_u;
                                span->count = iu - span->u;
                                span->v = current_iv;
                                span->pnext = surf2->spans;
                                surf2->spans = span;
                        }

                        // set last_u on the new span
                        surf->last_u = iu;
                                
gotposition:
                // insert before surf2
                        surf->next = surf2;
                        surf->prev = surf2->prev;
                        surf2->prev->next = surf;
                        surf2->prev = surf;
                }
        }
}


/*
==============
R_GenerateSpans
==============
*/
void R_GenerateSpans (void)
{
        edge_t                  *edge;
        surf_t                  *surf;

        r_bmodelactive = 0;

// clear active surfaces to just the background surface
        surfaces[1].next = surfaces[1].prev = &surfaces[1];
        surfaces[1].last_u = edge_head_u_shift20;

// generate spans
        for (edge=edge_head.next ; edge != &edge_tail; edge=edge->next)
        {                       
                if (edge->surfs[0])
                {
                // it has a left surface, so a surface is going away for this span
                        surf = &surfaces[edge->surfs[0]];

                        R_TrailingEdge (surf, edge);

                        if (!edge->surfs[1])
                                continue;
                }

                R_LeadingEdge (edge);
        }

        R_CleanupSpan ();
}

#endif  // !id386


/*
==============
R_GenerateSpansBackward
==============
*/
void R_GenerateSpansBackward (void)
{
        edge_t                  *edge;

        r_bmodelactive = 0;

// clear active surfaces to just the background surface
        surfaces[1].next = surfaces[1].prev = &surfaces[1];
        surfaces[1].last_u = edge_head_u_shift20;

// generate spans
        for (edge=edge_head.next ; edge != &edge_tail; edge=edge->next)
        {                       
                if (edge->surfs[0])
                        R_TrailingEdge (&surfaces[edge->surfs[0]], edge);

                if (edge->surfs[1])
                        R_LeadingEdgeBackwards (edge);
        }

        R_CleanupSpan ();
}


/*
==============
R_ScanEdges

Input: 
newedges[] array
        this has links to edges, which have links to surfaces

Output:
Each surface has a linked list of its visible spans
==============
*/
void R_ScanEdges (void)
{
        int             iv, bottom;
        byte    basespans[MAXSPANS*sizeof(espan_t)+CACHE_SIZE];
        espan_t *basespan_p;
        surf_t  *s;

        basespan_p = (espan_t *)
                        ((long)(basespans + CACHE_SIZE - 1) & ~(CACHE_SIZE - 1));
        max_span_p = &basespan_p[MAXSPANS - r_refdef.vrect.width];

        span_p = basespan_p;

// clear active edges to just the background edges around the whole screen
// FIXME: most of this only needs to be set up once
        edge_head.u = r_refdef.vrect.x << 20;
        edge_head_u_shift20 = edge_head.u >> 20;
        edge_head.u_step = 0;
        edge_head.prev = NULL;
        edge_head.next = &edge_tail;
        edge_head.surfs[0] = 0;
        edge_head.surfs[1] = 1;
        
        edge_tail.u = (r_refdef.vrectright << 20) + 0xFFFFF;
        edge_tail_u_shift20 = edge_tail.u >> 20;
        edge_tail.u_step = 0;
        edge_tail.prev = &edge_head;
        edge_tail.next = &edge_aftertail;
        edge_tail.surfs[0] = 1;
        edge_tail.surfs[1] = 0;
        
        edge_aftertail.u = -1;          // force a move
        edge_aftertail.u_step = 0;
        edge_aftertail.next = &edge_sentinel;
        edge_aftertail.prev = &edge_tail;

// FIXME: do we need this now that we clamp x in r_draw.c?
        edge_sentinel.u = 2000 << 24;           // make sure nothing sorts past this
        edge_sentinel.prev = &edge_aftertail;

//      
// process all scan lines
//
        bottom = r_refdef.vrectbottom - 1;

        for (iv=r_refdef.vrect.y ; iv<bottom ; iv++)
        {
                current_iv = iv;
                fv = (float)iv;

        // mark that the head (background start) span is pre-included
                surfaces[1].spanstate = 1;

                if (newedges[iv])
                {
                        R_InsertNewEdges (newedges[iv], edge_head.next);
                }

                (*pdrawfunc) ();

        // flush the span list if we can't be sure we have enough spans left for
        // the next scan
                if (span_p >= max_span_p)
                {
                        VID_UnlockBuffer ();
                        S_ExtraUpdate ();       // don't let sound get messed up if going slow
                        VID_LockBuffer ();
                
                        if (r_drawculledpolys)
                        {
                                R_DrawCulledPolys ();
                        }
                        else
                        {
                                D_DrawSurfaces ();
                        }

                // clear the surface span pointers
                        for (s = &surfaces[1] ; s<surface_p ; s++)
                                s->spans = NULL;

                        span_p = basespan_p;
                }

                if (removeedges[iv])
                        R_RemoveEdges (removeedges[iv]);

                if (edge_head.next != &edge_tail)
                        R_StepActiveU (edge_head.next);
        }

// do the last scan (no need to step or sort or remove on the last scan)

        current_iv = iv;
        fv = (float)iv;

// mark that the head (background start) span is pre-included
        surfaces[1].spanstate = 1;

        if (newedges[iv])
                R_InsertNewEdges (newedges[iv], edge_head.next);

        (*pdrawfunc) ();

// draw whatever's left in the span list
        if (r_drawculledpolys)
                R_DrawCulledPolys ();
        else
                D_DrawSurfaces ();
}