/*
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.

*/
// d_edge.c

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

static int	miplevel;

float		scale_for_mip;
int			ubasestep, errorterm, erroradjustup, erroradjustdown;
int			vstartscan;

vec3_t		transformed_modelorg;

// FIXME: should go away
extern void		R_RotateBmodel (void);
extern void		R_TransformFrustum (void);

int D_MipLevelForScale (float scale)
{
	int lmiplevel;

	if (scale >= d_scalemip[0] )
		lmiplevel = 0;
	else if (scale >= d_scalemip[1] )
		lmiplevel = 1;
	else if (scale >= d_scalemip[2] )
		lmiplevel = 2;
	else
		lmiplevel = 3;

	if (lmiplevel < d_minmip)
		lmiplevel = d_minmip;

	return lmiplevel;
}

// FIXME: clean this up
void D_DrawSolidSurface (struct surf *surf, int color)
{
	espan_t *span;
	byte *pdest;
	int u, u2, pix;

	pix = (color << 24) | (color << 16) | (color << 8) | color;
	for (span = surf->spans; span; span=span->pnext)
	{
		pdest = (byte *)d_viewbuffer + screenwidth*span->v;
		u = span->u;
		u2 = span->u + span->count - 1;
		((byte *)pdest)[u] = pix;

		if (u2 - u < 8)
		{
			for (u++; u <= u2; u++)
				((byte *)pdest)[u] = pix;
		}
		else
		{
			for (u++ ; u & 3; u++)
				((byte *)pdest)[u] = pix;

			u2 -= 4;
			for ( ; u <= u2; u+=4)
				*(int *)((byte *)pdest + u) = pix;
			u2 += 4;
			for ( ; u <= u2; u++)
				((byte *)pdest)[u] = pix;
		}
	}
}

void D_CalcGradients (msurface_t *pface)
{
	float mipscale, t;
	vec3_t p_temp1, p_saxis, p_taxis;

	mipscale = 1.0 / (float)(1 << miplevel);

	TransformVector (pface->texinfo->vecs[0], p_saxis);
	TransformVector (pface->texinfo->vecs[1], p_taxis);

	t = xscaleinv * mipscale;
	d_sdivzstepu = p_saxis[0] * t;
	d_tdivzstepu = p_taxis[0] * t;

	t = yscaleinv * mipscale;
	d_sdivzstepv = -p_saxis[1] * t;
	d_tdivzstepv = -p_taxis[1] * t;

	d_sdivzorigin = p_saxis[2] * mipscale - xcenter * d_sdivzstepu -
			ycenter * d_sdivzstepv;
	d_tdivzorigin = p_taxis[2] * mipscale - xcenter * d_tdivzstepu -
			ycenter * d_tdivzstepv;

	VectorScale (transformed_modelorg, mipscale, p_temp1);

	t = 0x10000*mipscale;
	sadjust = ((fixed16_t)(DotProduct (p_temp1, p_saxis) * 0x10000 + 0.5)) -
			((pface->texturemins[0] << 16) >> miplevel)
			+ pface->texinfo->vecs[0][3]*t;
	tadjust = ((fixed16_t)(DotProduct (p_temp1, p_taxis) * 0x10000 + 0.5)) -
			((pface->texturemins[1] << 16) >> miplevel)
			+ pface->texinfo->vecs[1][3]*t;

	// -1 (-epsilon) so we never wander off the edge of the texture
	bbextents = ((pface->extents[0] << 16) >> miplevel) - 1;
	bbextentt = ((pface->extents[1] << 16) >> miplevel) - 1;
}

void D_DrawSurfaces (void)
{
	struct surf *s;
	msurface_t *pface;
	surfcache_t *pcurrentcache;
	vec3_t world_transformed_modelorg, local_modelorg;
	unsigned int i;

	currententity = &r_worldentity;
	TransformVector (modelorg, transformed_modelorg);
	VectorCopy (transformed_modelorg, world_transformed_modelorg);

	// TODO: could preset a lot of this at mode set time
	for(i=1,s=surfaces+1;i<surf_cur;i++,s++)
	{
		if (!s->spans)
			continue;

		r_drawnpolycount++;

		d_zistepu = s->d_zistepu;
		d_zistepv = s->d_zistepv;
		d_ziorigin = s->d_ziorigin;

		if (s->flags & SURF_DRAWSKY)
		{
			extern cvar_t r_fastsky;
			extern cvar_t r_skycolor;

			if (r_fastsky.value || cl.worldmodel->bspversion == HL_BSPVERSION)
				D_DrawSolidSurface (s, (int)r_skycolor.value & 0xFF);
			else
			{
				if (!r_skymade)
					R_MakeSky ();
				D_DrawSkyScans8 (s->spans);
			}
			D_DrawZSpans (s->spans);
		}
		else if (s->flags & SURF_DRAWBACKGROUND)
		{
			// set up a gradient for the background surface that places it
			// effectively at infinity distance from the viewpoint
			d_zistepu = 0;
			d_zistepv = 0;
			d_ziorigin = -0.9;

			D_DrawSolidSurface (s, (int)r_clearcolor.value & 0xFF);
			D_DrawZSpans (s->spans);
		}
		else if (s->flags & SURF_DRAWTURB)
		{
			extern cvar_t r_fastturb;
			if (r_fastturb.value)
			{
				texture_t *tx;

				pface = s->data;
				tx = pface->texinfo->texture;
				D_DrawSolidSurface (s, *((byte*) tx + tx->offsets[0] + ((tx->width * tx->height) >> 1)));
				D_DrawZSpans(s->spans);
				continue;
			}
			pface = s->data;
			miplevel = 0;
			cacheblock = (pixel_t *) ((byte *) pface->texinfo->texture + pface->texinfo->texture->offsets[0]);
			cachewidth = 64;

			if (s->insubmodel)
			{
				// FIXME: we don't want to do all this for every polygon!
				// TODO: store once at start of frame
				currententity = s->entity;	//FIXME: make this passed in to
				// R_RotateBmodel ()
				VectorSubtract (r_origin, currententity->origin, local_modelorg);
				TransformVector (local_modelorg, transformed_modelorg);
				R_RotateBmodel ();	// FIXME: don't mess with the frustum,
				// make entity passed in
			}

			D_CalcGradients (pface);

			Turbulent8 (s->spans);
			D_DrawZSpans (s->spans);

			if (s->insubmodel)
			{
				// restore the old drawing state
				// FIXME: we don't want to do this every time!
				// TODO: speed up
				currententity = &r_worldentity;
				VectorCopy (world_transformed_modelorg, transformed_modelorg);
				VectorCopy (base_vpn, vpn);
				VectorCopy (base_vup, vup);
				VectorCopy (base_vright, vright);
				VectorCopy (base_modelorg, modelorg);
				R_TransformFrustum ();
			}
		}
		else
		{
			if (s->insubmodel)
			{
				// FIXME: we don't want to do all this for every polygon!
				// TODO: store once at start of frame
				currententity = s->entity;	//FIXME: make this passed in to
				// R_RotateBmodel ()
				VectorSubtract (r_origin, currententity->origin, local_modelorg);
				TransformVector (local_modelorg, transformed_modelorg);

				R_RotateBmodel ();	// FIXME: don't mess with the frustum,
				// make entity passed in
			}

			pface = s->data;
			miplevel = D_MipLevelForScale (s->nearzi * scale_for_mip * pface->texinfo->mipadjust);

			// FIXME: make this passed in to D_CacheSurface
			pcurrentcache = D_CacheSurface (pface, miplevel);

			cacheblock = (pixel_t *)pcurrentcache->data;
			cachewidth = pcurrentcache->width;

			D_CalcGradients (pface);

			(*d_drawspans) (s->spans);

			D_DrawZSpans (s->spans);

			if (s->insubmodel)
			{
				// restore the old drawing state
				// FIXME: we don't want to do this every time!
				// TODO: speed up
				VectorCopy (world_transformed_modelorg, transformed_modelorg);
				VectorCopy (base_vpn, vpn);
				VectorCopy (base_vup, vup);
				VectorCopy (base_vright, vright);
				VectorCopy (base_modelorg, modelorg);
				R_TransformFrustum ();
				currententity = &r_worldentity;
			}
		}
	}
}

