
// r_draw.c

#include "quakedef.h"
#include "r_local.h"
#include "d_local.h"		// FIXME: shouldn't need to include this

#define MAXLEFTCLIPEDGES		100

#define FULLY_CLIPPED_CACHED	0x80000000
#define FRAMECOUNT_MASK			0x7FFFFFFF

unsigned int cacheoffset;

int c_faceclip;			// number of faces clipped

zpointdesc_t r_zpointdesc;

polydesc_t r_polydesc;



clipplane_t *entity_clipplanes;
clipplane_t view_clipplanes[4];
clipplane_t world_clipplanes[16];

medge_t *r_pedge;

qboolean r_leftclipped, r_rightclipped;
static qboolean makeleftedge, makerightedge;
qboolean r_nearzionly;

int sintable[1280];
int intsintable[1280];

mvertex_t r_leftenter, r_leftexit;
mvertex_t r_rightenter, r_rightexit;

typedef struct {
    float u, v;
    int ceilv;
} evert_t;

int r_emitted;
float r_nearzi;
float r_u1, r_v1, r_lzi1;
int r_ceilv1;

qboolean r_lastvertvalid;


/*
================
R_EmitEdge
================
*/
void R_EmitEdge(mvertex_t * pv0, mvertex_t * pv1)
{
    edge_t *edge, *pcheck;
    int u_check;
    float u, u_step;
    vec3_t local, transformed;
    float *world;
    int v, v2, ceilv0;
    float scale, lzi0, u0, v0;
    int side;

    if (r_lastvertvalid) {
	u0 = r_u1;
	v0 = r_v1;
	lzi0 = r_lzi1;
	ceilv0 = r_ceilv1;
    } else {
	world = &pv0->position[0];

	// transform and project
	VectorSubtract(world, modelorg, local);
	TransformVector(local, transformed);

	if (transformed[2] < NEAR_CLIP)
	    transformed[2] = NEAR_CLIP;

	lzi0 = 1.0 / transformed[2];

	// FIXME: build x/yscale into transform?
	scale = xscale * lzi0;
	u0 = (xcenter + scale * transformed[0]);
	if (u0 < r_refdef.fvrectx_adj)
	    u0 = r_refdef.fvrectx_adj;
	if (u0 > r_refdef.fvrectright_adj)
	    u0 = r_refdef.fvrectright_adj;

	scale = yscale * lzi0;
	v0 = (ycenter - scale * transformed[1]);
	if (v0 < r_refdef.fvrecty_adj)
	    v0 = r_refdef.fvrecty_adj;
	if (v0 > r_refdef.fvrectbottom_adj)
	    v0 = r_refdef.fvrectbottom_adj;

	ceilv0 = (int) ceil(v0);
    }

    world = &pv1->position[0];

// transform and project
    VectorSubtract(world, modelorg, local);
    TransformVector(local, transformed);

    if (transformed[2] < NEAR_CLIP)
	transformed[2] = NEAR_CLIP;

    r_lzi1 = 1.0 / transformed[2];

    scale = xscale * r_lzi1;
    r_u1 = (xcenter + scale * transformed[0]);
    if (r_u1 < r_refdef.fvrectx_adj)
	r_u1 = r_refdef.fvrectx_adj;
    if (r_u1 > r_refdef.fvrectright_adj)
	r_u1 = r_refdef.fvrectright_adj;

    scale = yscale * r_lzi1;
    r_v1 = (ycenter - scale * transformed[1]);
    if (r_v1 < r_refdef.fvrecty_adj)
	r_v1 = r_refdef.fvrecty_adj;
    if (r_v1 > r_refdef.fvrectbottom_adj)
	r_v1 = r_refdef.fvrectbottom_adj;

    if (r_lzi1 > lzi0)
	lzi0 = r_lzi1;

    if (lzi0 > r_nearzi)	// for mipmap finding
	r_nearzi = lzi0;

// for right edges, all we want is the effect on 1/z
    if (r_nearzionly)
	return;

    r_emitted = 1;

    r_ceilv1 = (int) ceil(r_v1);


// create the edge
    if (ceilv0 == r_ceilv1) {
	// we cache unclipped horizontal edges as fully clipped
	if (cacheoffset != 0x7FFFFFFF) {
	    cacheoffset = FULLY_CLIPPED_CACHED |
		(r_framecount & FRAMECOUNT_MASK);
	}

	return;			// horizontal edge
    }

    side = ceilv0 > r_ceilv1;

    edge = edge_p++;

    edge->owner = r_pedge;

    edge->nearzi = lzi0;

    if (side == 0) {
	// trailing edge (go from p1 to p2)
	v = ceilv0;
	v2 = r_ceilv1 - 1;

	edge->surfs[0] = surface_p - surfaces;
	edge->surfs[1] = 0;

	u_step = ((r_u1 - u0) / (r_v1 - v0));
	u = u0 + ((float) v - v0) * u_step;
    } else {
	// leading edge (go from p2 to p1)
	v2 = ceilv0 - 1;
	v = r_ceilv1;

	edge->surfs[0] = 0;
	edge->surfs[1] = surface_p - surfaces;

	u_step = ((u0 - r_u1) / (v0 - r_v1));
	u = r_u1 + ((float) v - r_v1) * u_step;
    }

    edge->u_step = u_step * 0x100000;
    edge->u = u * 0x100000 + 0xFFFFF;

// we need to do this to avoid stepping off the edges if a very nearly
// horizontal edge is less than epsilon above a scan, and numeric error causes
// it to incorrectly extend to the scan, and the extension of the line goes off
// the edge of the screen
// FIXME: is this actually needed?
    if (edge->u < r_refdef.vrect_x_adj_shift20)
	edge->u = r_refdef.vrect_x_adj_shift20;
    if (edge->u > r_refdef.vrectright_adj_shift20)
	edge->u = r_refdef.vrectright_adj_shift20;

//
// sort the edge in normally
//
    u_check = edge->u;
    if (edge->surfs[0])
	u_check++;		// sort trailers after leaders

    if (!newedges[v] || newedges[v]->u >= u_check) {
	edge->next = newedges[v];
	newedges[v] = edge;
    } else {
	pcheck = newedges[v];
	while (pcheck->next && pcheck->next->u < u_check)
	    pcheck = pcheck->next;
	edge->next = pcheck->next;
	pcheck->next = edge;
    }

    edge->nextremove = removeedges[v2];
    removeedges[v2] = edge;
}

/*
================
R_ClipEdge
================
*/
void R_ClipEdge(mvertex_t * pv0, mvertex_t * pv1, clipplane_t * clip)
{
    float d0, d1, f;
    mvertex_t clipvert;

    if (clip) {
	do {
	    d0 = DotProduct(pv0->position, clip->normal) - clip->dist;
	    d1 = DotProduct(pv1->position, clip->normal) - clip->dist;

	    if (d0 >= 0) {
		// point 0 is unclipped
		if (d1 >= 0) {
		    // both points are unclipped
		    continue;
		}
		// only point 1 is clipped

		// we don't cache clipped edges
		cacheoffset = 0x7FFFFFFF;

		f = d0 / (d0 - d1);
		clipvert.position[0] = pv0->position[0] +
		    f * (pv1->position[0] - pv0->position[0]);
		clipvert.position[1] = pv0->position[1] +
		    f * (pv1->position[1] - pv0->position[1]);
		clipvert.position[2] = pv0->position[2] +
		    f * (pv1->position[2] - pv0->position[2]);

		if (clip->leftedge) {
		    r_leftclipped = true;
		    r_leftexit = clipvert;
		} else if (clip->rightedge) {
		    r_rightclipped = true;
		    r_rightexit = clipvert;
		}

		R_ClipEdge(pv0, &clipvert, clip->next);
		return;
	    } else {
		// point 0 is clipped
		if (d1 < 0) {
		    // both points are clipped
		    // we do cache fully clipped edges
		    if (!r_leftclipped)
			cacheoffset = FULLY_CLIPPED_CACHED |
			    (r_framecount & FRAMECOUNT_MASK);
		    return;
		}
		// only point 0 is clipped
		r_lastvertvalid = false;

		// we don't cache partially clipped edges
		cacheoffset = 0x7FFFFFFF;

		f = d0 / (d0 - d1);
		clipvert.position[0] = pv0->position[0] +
		    f * (pv1->position[0] - pv0->position[0]);
		clipvert.position[1] = pv0->position[1] +
		    f * (pv1->position[1] - pv0->position[1]);
		clipvert.position[2] = pv0->position[2] +
		    f * (pv1->position[2] - pv0->position[2]);

		if (clip->leftedge) {
		    r_leftclipped = true;
		    r_leftenter = clipvert;
		} else if (clip->rightedge) {
		    r_rightclipped = true;
		    r_rightenter = clipvert;
		}

		R_ClipEdge(&clipvert, pv1, clip->next);
		return;
	    }
	} while ((clip = clip->next) != NULL);
    }
// add the edge
    R_EmitEdge(pv0, pv1);
}

/*
================
R_EmitCachedEdge
================
*/
void R_EmitCachedEdge(void)
{
    edge_t *pedge_t;

    pedge_t =
	(edge_t *) ((unsigned long) r_edges + r_pedge->cachededgeoffset);

    if (!pedge_t->surfs[0])
	pedge_t->surfs[0] = surface_p - surfaces;
    else
	pedge_t->surfs[1] = surface_p - surfaces;

    if (pedge_t->nearzi > r_nearzi)	// for mipmap finding
	r_nearzi = pedge_t->nearzi;

    r_emitted = 1;
}


/*
================
R_RenderFace
================
*/
void R_RenderFace(msurface_t * fa, int clipflags)
{
    int i, lindex;
    unsigned mask;
    mplane_t *pplane;
    float distinv;
    vec3_t p_normal;
    medge_t *pedges, tedge;
    clipplane_t *pclip;

// skip out if no more surfs
    if ((surface_p) >= surf_max) {
	r_outofsurfaces++;
	return;
    }
// ditto if not enough edges left, or switch to auxedges if possible
    if ((edge_p + fa->numedges + 4) >= edge_max) {
	r_outofedges += fa->numedges;
	return;
    }

    c_faceclip++;

// set up clip planes
    pclip = NULL;

    for (i = 3, mask = 0x08; i >= 0; i--, mask >>= 1) {
	if (clipflags & mask) {
	    view_clipplanes[i].next = pclip;
	    pclip = &view_clipplanes[i];
	}
    }

// push the edges through
    r_emitted = 0;
    r_nearzi = 0;
    r_nearzionly = false;
    makeleftedge = makerightedge = false;
    pedges = currententity->model->edges;
    r_lastvertvalid = false;

    for (i = 0; i < fa->numedges; i++) {
	lindex = currententity->model->surfedges[fa->firstedge + i];

	if (lindex > 0) {
	    r_pedge = &pedges[lindex];

	    // if the edge is cached, we can just reuse the edge
	    if (!insubmodel) {
		if (r_pedge->cachededgeoffset & FULLY_CLIPPED_CACHED) {
		    if ((r_pedge->cachededgeoffset & FRAMECOUNT_MASK) ==
			r_framecount) {
			r_lastvertvalid = false;
			continue;
		    }
		} else {
		    if ((((unsigned long) edge_p -
			  (unsigned long) r_edges) >
			 r_pedge->cachededgeoffset)
			&&
			(((edge_t *) ((unsigned long) r_edges +
				      r_pedge->cachededgeoffset))->owner ==
			 r_pedge)) {
			R_EmitCachedEdge();
			r_lastvertvalid = false;
			continue;
		    }
		}
	    }
	    // assume it's cacheable
	    cacheoffset = (byte *) edge_p - (byte *) r_edges;
	    r_leftclipped = r_rightclipped = false;
	    R_ClipEdge(&r_pcurrentvertbase[r_pedge->v[0]],
		       &r_pcurrentvertbase[r_pedge->v[1]], pclip);
	    r_pedge->cachededgeoffset = cacheoffset;

	    if (r_leftclipped)
		makeleftedge = true;
	    if (r_rightclipped)
		makerightedge = true;
	    r_lastvertvalid = true;
	} else {
	    lindex = -lindex;
	    r_pedge = &pedges[lindex];
	    // if the edge is cached, we can just reuse the edge
	    if (!insubmodel) {
		if (r_pedge->cachededgeoffset & FULLY_CLIPPED_CACHED) {
		    if ((r_pedge->cachededgeoffset & FRAMECOUNT_MASK) ==
			r_framecount) {
			r_lastvertvalid = false;
			continue;
		    }
		} else {
		    // it's cached if the cached edge is valid and is owned
		    // by this medge_t
		    if ((((unsigned long) edge_p -
			  (unsigned long) r_edges) >
			 r_pedge->cachededgeoffset)
			&&
			(((edge_t *) ((unsigned long) r_edges +
				      r_pedge->cachededgeoffset))->owner ==
			 r_pedge)) {
			R_EmitCachedEdge();
			r_lastvertvalid = false;
			continue;
		    }
		}
	    }
	    // assume it's cacheable
	    cacheoffset = (byte *) edge_p - (byte *) r_edges;
	    r_leftclipped = r_rightclipped = false;
	    R_ClipEdge(&r_pcurrentvertbase[r_pedge->v[1]],
		       &r_pcurrentvertbase[r_pedge->v[0]], pclip);
	    r_pedge->cachededgeoffset = cacheoffset;

	    if (r_leftclipped)
		makeleftedge = true;
	    if (r_rightclipped)
		makerightedge = true;
	    r_lastvertvalid = true;
	}
    }

// if there was a clip off the left edge, add that edge too
// FIXME: faster to do in screen space?
// FIXME: share clipped edges?
    if (makeleftedge) {
	r_pedge = &tedge;
	r_lastvertvalid = false;
	R_ClipEdge(&r_leftexit, &r_leftenter, pclip->next);
    }
// if there was a clip off the right edge, get the right r_nearzi
    if (makerightedge) {
	r_pedge = &tedge;
	r_lastvertvalid = false;
	r_nearzionly = true;
	R_ClipEdge(&r_rightexit, &r_rightenter, view_clipplanes[1].next);
    }
// if no edges made it out, return without posting the surface
    if (!r_emitted)
	return;

    r_polycount++;

    surface_p->data = (void *) fa;
    surface_p->nearzi = r_nearzi;
    surface_p->flags = fa->flags;
    surface_p->insubmodel = insubmodel;
    surface_p->spanstate = 0;
    surface_p->entity = currententity;
    surface_p->key = r_currentkey++;
    surface_p->spans = NULL;

    pplane = fa->plane;
// FIXME: cache this?
    TransformVector(pplane->normal, p_normal);
// FIXME: cache this?
    distinv = 1.0 / (pplane->dist - DotProduct(modelorg, pplane->normal));

    surface_p->d_zistepu = p_normal[0] * xscaleinv * distinv;
    surface_p->d_zistepv = -p_normal[1] * yscaleinv * distinv;
    surface_p->d_ziorigin = p_normal[2] * distinv -
	xcenter * surface_p->d_zistepu - ycenter * surface_p->d_zistepv;

//JDC   VectorCopy (r_worldmodelorg, surface_p->modelorg);
    surface_p++;
}


/*
================
R_RenderBmodelFace
================
*/
void R_RenderBmodelFace(bedge_t * pedges, msurface_t * psurf)
{
    int i;
    unsigned mask;
    mplane_t *pplane;
    float distinv;
    vec3_t p_normal;
    medge_t tedge;
    clipplane_t *pclip;

// skip out if no more surfs
    if (surface_p >= surf_max) {
	r_outofsurfaces++;
	return;
    }
// ditto if not enough edges left, or switch to auxedges if possible
    if ((edge_p + psurf->numedges + 4) >= edge_max) {
	r_outofedges += psurf->numedges;
	return;
    }

    c_faceclip++;

// this is a dummy to give the caching mechanism someplace to write to
    r_pedge = &tedge;

// set up clip planes
    pclip = NULL;

    for (i = 3, mask = 0x08; i >= 0; i--, mask >>= 1) {
	if (r_clipflags & mask) {
	    view_clipplanes[i].next = pclip;
	    pclip = &view_clipplanes[i];
	}
    }

// push the edges through
    r_emitted = 0;
    r_nearzi = 0;
    r_nearzionly = false;
    makeleftedge = makerightedge = false;
// FIXME: keep clipped bmodel edges in clockwise order so last vertex caching
// can be used?
    r_lastvertvalid = false;

    for (; pedges; pedges = pedges->pnext) {
	r_leftclipped = r_rightclipped = false;
	R_ClipEdge(pedges->v[0], pedges->v[1], pclip);

	if (r_leftclipped)
	    makeleftedge = true;
	if (r_rightclipped)
	    makerightedge = true;
    }

// if there was a clip off the left edge, add that edge too
// FIXME: faster to do in screen space?
// FIXME: share clipped edges?
    if (makeleftedge) {
	r_pedge = &tedge;
	R_ClipEdge(&r_leftexit, &r_leftenter, pclip->next);
    }
// if there was a clip off the right edge, get the right r_nearzi
    if (makerightedge) {
	r_pedge = &tedge;
	r_nearzionly = true;
	R_ClipEdge(&r_rightexit, &r_rightenter, view_clipplanes[1].next);
    }
// if no edges made it out, return without posting the surface
    if (!r_emitted)
	return;

    r_polycount++;

    surface_p->data = (void *) psurf;
    surface_p->nearzi = r_nearzi;
    surface_p->flags = psurf->flags;
    surface_p->insubmodel = true;
    surface_p->spanstate = 0;
    surface_p->entity = currententity;
    surface_p->key = r_currentbkey;
    surface_p->spans = NULL;

    pplane = psurf->plane;
// FIXME: cache this?
    TransformVector(pplane->normal, p_normal);
// FIXME: cache this?
    distinv = 1.0 / (pplane->dist - DotProduct(modelorg, pplane->normal));

    surface_p->d_zistepu = p_normal[0] * xscaleinv * distinv;
    surface_p->d_zistepv = -p_normal[1] * yscaleinv * distinv;
    surface_p->d_ziorigin = p_normal[2] * distinv -
	xcenter * surface_p->d_zistepu - ycenter * surface_p->d_zistepv;

//JDC   VectorCopy (r_worldmodelorg, surface_p->modelorg);
    surface_p++;
}


/*
================
R_RenderPoly
================
*/
void R_RenderPoly(msurface_t * fa, int clipflags)
{
    int i, lindex, lnumverts, s_axis, t_axis;
    float dist, lastdist, lzi, scale, u, v, frac;
    unsigned mask;
    vec3_t local, transformed;
    clipplane_t *pclip;
    medge_t *pedges;
    mplane_t *pplane;
    mvertex_t verts[2][100];	//FIXME: do real number
    polyvert_t pverts[100];	//FIXME: do real number, safely
    int vertpage, newverts, newpage, lastvert;
    qboolean visible;

// FIXME: clean this up and make it faster
// FIXME: guard against running out of vertices

    s_axis = t_axis = 0;	// keep compiler happy

// set up clip planes
    pclip = NULL;

    for (i = 3, mask = 0x08; i >= 0; i--, mask >>= 1) {
	if (clipflags & mask) {
	    view_clipplanes[i].next = pclip;
	    pclip = &view_clipplanes[i];
	}
    }

// reconstruct the polygon
// FIXME: these should be precalculated and loaded off disk
    pedges = currententity->model->edges;
    lnumverts = fa->numedges;
    vertpage = 0;

    for (i = 0; i < lnumverts; i++) {
	lindex = currententity->model->surfedges[fa->firstedge + i];

	if (lindex > 0) {
	    r_pedge = &pedges[lindex];
	    verts[0][i] = r_pcurrentvertbase[r_pedge->v[0]];
	} else {
	    r_pedge = &pedges[-lindex];
	    verts[0][i] = r_pcurrentvertbase[r_pedge->v[1]];
	}
    }

// clip the polygon, done if not visible
    while (pclip) {
	lastvert = lnumverts - 1;
	lastdist = DotProduct(verts[vertpage][lastvert].position,
			      pclip->normal) - pclip->dist;

	visible = false;
	newverts = 0;
	newpage = vertpage ^ 1;

	for (i = 0; i < lnumverts; i++) {
	    dist = DotProduct(verts[vertpage][i].position, pclip->normal) -
		pclip->dist;

	    if ((lastdist > 0) != (dist > 0)) {
		frac = dist / (dist - lastdist);
		verts[newpage][newverts].position[0] =
		    verts[vertpage][i].position[0] +
		    ((verts[vertpage][lastvert].position[0] -
		      verts[vertpage][i].position[0]) * frac);
		verts[newpage][newverts].position[1] =
		    verts[vertpage][i].position[1] +
		    ((verts[vertpage][lastvert].position[1] -
		      verts[vertpage][i].position[1]) * frac);
		verts[newpage][newverts].position[2] =
		    verts[vertpage][i].position[2] +
		    ((verts[vertpage][lastvert].position[2] -
		      verts[vertpage][i].position[2]) * frac);
		newverts++;
	    }

	    if (dist >= 0) {
		verts[newpage][newverts] = verts[vertpage][i];
		newverts++;
		visible = true;
	    }

	    lastvert = i;
	    lastdist = dist;
	}

	if (!visible || (newverts < 3))
	    return;

	lnumverts = newverts;
	vertpage ^= 1;
	pclip = pclip->next;
    }

// transform and project, remembering the z values at the vertices and
// r_nearzi, and extract the s and t coordinates at the vertices
    pplane = fa->plane;
    switch (pplane->type) {
    case PLANE_X:
    case PLANE_ANYX:
	s_axis = 1;
	t_axis = 2;
	break;
    case PLANE_Y:
    case PLANE_ANYY:
	s_axis = 0;
	t_axis = 2;
	break;
    case PLANE_Z:
    case PLANE_ANYZ:
	s_axis = 0;
	t_axis = 1;
	break;
    }

    r_nearzi = 0;

    for (i = 0; i < lnumverts; i++) {
	// transform and project
	VectorSubtract(verts[vertpage][i].position, modelorg, local);
	TransformVector(local, transformed);

	if (transformed[2] < NEAR_CLIP)
	    transformed[2] = NEAR_CLIP;

	lzi = 1.0 / transformed[2];

	if (lzi > r_nearzi)	// for mipmap finding
	    r_nearzi = lzi;

	// FIXME: build x/yscale into transform?
	scale = xscale * lzi;
	u = (xcenter + scale * transformed[0]);
	if (u < r_refdef.fvrectx_adj)
	    u = r_refdef.fvrectx_adj;
	if (u > r_refdef.fvrectright_adj)
	    u = r_refdef.fvrectright_adj;

	scale = yscale * lzi;
	v = (ycenter - scale * transformed[1]);
	if (v < r_refdef.fvrecty_adj)
	    v = r_refdef.fvrecty_adj;
	if (v > r_refdef.fvrectbottom_adj)
	    v = r_refdef.fvrectbottom_adj;

	pverts[i].u = u;
	pverts[i].v = v;
	pverts[i].zi = lzi;
	pverts[i].s = verts[vertpage][i].position[s_axis];
	pverts[i].t = verts[vertpage][i].position[t_axis];
    }

// build the polygon descriptor, including fa, r_nearzi, and u, v, s, t, and z
// for each vertex
    r_polydesc.numverts = lnumverts;
    r_polydesc.nearzi = r_nearzi;
    r_polydesc.pcurrentface = fa;
    r_polydesc.pverts = pverts;

// draw the polygon
    D_DrawPoly();
}


/*
================
R_ZDrawSubmodelPolys
================
*/
void R_ZDrawSubmodelPolys(model_t * pmodel)
{
    int i, numsurfaces;
    msurface_t *psurf;
    float dot;
    mplane_t *pplane;

    psurf = &pmodel->surfaces[pmodel->firstmodelsurface];
    numsurfaces = pmodel->nummodelsurfaces;

    for (i = 0; i < numsurfaces; i++, psurf++) {
	// find which side of the node we are on
	pplane = psurf->plane;

	dot = DotProduct(modelorg, pplane->normal) - pplane->dist;

	// draw the polygon
	if (((psurf->flags & SURF_PLANEBACK) && (dot < -BACKFACE_EPSILON))
	    || (!(psurf->flags & SURF_PLANEBACK)
		&& (dot > BACKFACE_EPSILON))) {
	    // FIXME: use bounding-box-based frustum clipping info?
	    R_RenderPoly(psurf, 15);
	}
    }
}
