ref: 18c2fe5605dfe16142b6dd4eb7356038989d5801
dir: /r_edge.c/
#include "quakedef.h"
/* 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?
*/
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];
static espan_t *span_p, *max_span_p;
int r_currentkey;
extern int screenwidth;
static int current_iv, edge_head_u_shift20, edge_tail_u_shift20;
static edge_t edge_head, edge_tail, edge_aftertail, edge_sentinel;
static float fv;
static void (*pdrawfunc)(void);
void R_GenerateSpans (void);
void R_LeadingEdge (edge_t *edge);
void R_TrailingEdge (surf_t *surf, edge_t *edge);
//=============================================================================
/*
==============
R_BeginEdgeFrame
==============
*/
void R_BeginEdgeFrame (void)
{
r_edges = Arr_AllocExtra(r_edges, &r_numallocatededges, r_outofedges);
edge_p = r_edges;
edge_max = &r_edges[r_numallocatededges];
r_outofedges = 0;
surfaces = Arr_AllocExtra(surfaces, &r_cnumsurfs, r_outofsurfaces);
surf_max = &surfaces[r_cnumsurfs];
r_outofsurfaces = 0;
surface_p = &surfaces[2]; // background is surface 1,
// surface 0 is a dummy
surfaces[1].spans = nil; // no background spans yet
surfaces[1].flags = SURF_DRAWBACKGROUND;
// put the background behind everything in the world
pdrawfunc = R_GenerateSpans;
surfaces[1].key = 0x7FFFFFFF;
r_currentkey = 0;
memset(newedges, 0, sizeof(newedges));
memset(removeedges, 0, sizeof(removeedges));
}
/*
==============
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) != nil);
}
/*
==============
R_RemoveEdges
==============
*/
void R_RemoveEdges (edge_t *pedge)
{
do
{
pedge->next->prev = pedge->prev;
pedge->prev->next = pedge->next;
} while ((pedge = pedge->nextremove) != nil);
}
/*
==============
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;
}
}
/*
==============
R_CleanupSpan
==============
*/
void R_CleanupSpan (void)
{
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_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 == 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;
}
}
/*
==============
R_LeadingEdge
==============
*/
void R_LeadingEdge (edge_t *edge)
{
espan_t *span;
surf_t *surf, *surf2;
int iu;
double 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)
{
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;
// 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 ();
}
/*
==============
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;
espan_t *basespan_p;
surf_t *s;
r_basespans = Arr_AllocExtra(r_basespans, &r_numallocatedbasespans, r_outofspans);
basespan_p = (espan_t *)r_basespans;
assert(r_numallocatedbasespans > r_refdef.vrect.width);
max_span_p = &basespan_p[r_numallocatedbasespans - r_refdef.vrect.width];
span_p = basespan_p;
r_outofspans = 0;
// 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 = nil;
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 = 0x7d << 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)
{
r_outofspans++;
D_DrawSurfaces ();
// clear the surface span pointers
for (s = &surfaces[1] ; s<surface_p ; s++)
s->spans = nil;
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
D_DrawSurfaces ();
}