/*
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_sprite.c

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

static int				clip_current;
static vec5_t			clip_verts[2][MAXWORKINGVERTS];
static int				sprite_width, sprite_height;

spritedesc_t			r_spritedesc;


/*
================
R_RotateSprite
================
*/
void R_RotateSprite(float beamlength)
{
    vec3_t	vec;

    if (beamlength == 0.0) {
        return;
    }

    VectorScale(r_spritedesc.vpn, -beamlength, vec);
    VectorAdd(r_entorigin, vec, r_entorigin);
    VectorSubtract(modelorg, vec, modelorg);
}


/*
=============
R_ClipSpriteFace

Clips the winding at clip_verts[clip_current] and changes clip_current
Throws out the back side
==============
*/
int R_ClipSpriteFace(int nump, clipplane_t *pclipplane)
{
    int		i, outcount;
    float	dists[MAXWORKINGVERTS+1];
    float	frac, clipdist, *pclipnormal;
    float	*in, *instep, *outstep, *vert2;

    clipdist = pclipplane->dist;
    pclipnormal = pclipplane->normal;

// calc dists
    if (clip_current) {
        in = clip_verts[1][0];
        outstep = clip_verts[0][0];
        clip_current = 0;
    } else {
        in = clip_verts[0][0];
        outstep = clip_verts[1][0];
        clip_current = 1;
    }

    instep = in;
    for (i=0 ; i<nump ; i++, instep += sizeof(vec5_t) / sizeof(float)) {
        dists[i] = DotProduct(instep, pclipnormal) - clipdist;
    }

// handle wraparound case
    dists[nump] = dists[0];
    Q_memcpy(instep, in, sizeof(vec5_t));


// clip the winding
    instep = in;
    outcount = 0;

    for (i=0 ; i<nump ; i++, instep += sizeof(vec5_t) / sizeof(float)) {
        if (dists[i] >= 0) {
            Q_memcpy(outstep, instep, sizeof(vec5_t));
            outstep += sizeof(vec5_t) / sizeof(float);
            outcount++;
        }

        if (dists[i] == 0 || dists[i+1] == 0) {
            continue;
        }

        if ((dists[i] > 0) == (dists[i+1] > 0)) {
            continue;
        }

        // split it into a new vertex
        frac = dists[i] / (dists[i] - dists[i+1]);

        vert2 = instep + sizeof(vec5_t) / sizeof(float);

        outstep[0] = instep[0] + frac*(vert2[0] - instep[0]);
        outstep[1] = instep[1] + frac*(vert2[1] - instep[1]);
        outstep[2] = instep[2] + frac*(vert2[2] - instep[2]);
        outstep[3] = instep[3] + frac*(vert2[3] - instep[3]);
        outstep[4] = instep[4] + frac*(vert2[4] - instep[4]);

        outstep += sizeof(vec5_t) / sizeof(float);
        outcount++;
    }

    return outcount;
}


/*
================
R_SetupAndDrawSprite
================
*/
void R_SetupAndDrawSprite()
{
    int			i, nump;
    float		dot, scale, *pv;
    vec5_t		*pverts;
    vec3_t		left, up, right, down, transformed, local;
    emitpoint_t	outverts[MAXWORKINGVERTS+1], *pout;

    dot = DotProduct(r_spritedesc.vpn, modelorg);

// backface cull
    if (dot >= 0) {
        return;
    }

// build the sprite poster in worldspace
    // QC Scale - edited - begin
    VectorScale(r_spritedesc.vright,	r_spritedesc.pspriteframe->right*currententity->scale2*currententity->scalev[0], right);
    VectorScale(r_spritedesc.vright,	r_spritedesc.pspriteframe->left	*currententity->scale2*currententity->scalev[0], left);

    VectorScale(r_spritedesc.vup,		r_spritedesc.pspriteframe->up	*currententity->scale2*currententity->scalev[1], up);
    VectorScale(r_spritedesc.vup,		r_spritedesc.pspriteframe->down	*currententity->scale2*currententity->scalev[1], down);
    // QC Scale - edited - end

    pverts = clip_verts[0];

    pverts[0][0] = r_entorigin[0] + up[0] + left[0];
    pverts[0][1] = r_entorigin[1] + up[1] + left[1];
    pverts[0][2] = r_entorigin[2] + up[2] + left[2];
    pverts[0][3] = 0;
    pverts[0][4] = 0;

    pverts[1][0] = r_entorigin[0] + up[0] + right[0];
    pverts[1][1] = r_entorigin[1] + up[1] + right[1];
    pverts[1][2] = r_entorigin[2] + up[2] + right[2];
    pverts[1][3] = sprite_width;
    pverts[1][4] = 0;

    pverts[2][0] = r_entorigin[0] + down[0] + right[0];
    pverts[2][1] = r_entorigin[1] + down[1] + right[1];
    pverts[2][2] = r_entorigin[2] + down[2] + right[2];
    pverts[2][3] = sprite_width;
    pverts[2][4] = sprite_height;

    pverts[3][0] = r_entorigin[0] + down[0] + left[0];
    pverts[3][1] = r_entorigin[1] + down[1] + left[1];
    pverts[3][2] = r_entorigin[2] + down[2] + left[2];
    pverts[3][3] = 0;
    pverts[3][4] = sprite_height;

// clip to the frustum in worldspace
    nump = 4;
    clip_current = 0;

    for (i=0 ; i<4 ; i++) {
        nump = R_ClipSpriteFace(nump, &view_clipplanes[i]);
        if (nump < 3) {
            return;
        }
        if (nump >= MAXWORKINGVERTS) {
            Sys_Error("R_SetupAndDrawSprite: too many points");
        }
    }

// transform vertices into viewspace and project
    pv = &clip_verts[clip_current][0][0];
    r_spritedesc.nearzi = -999999;

    for (i=0 ; i<nump ; i++) {
        VectorSubtract(pv, r_origin, local);
        TransformVector(local, transformed);

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

        pout = &outverts[i];
        pout->zi = 1.0 / transformed[2];
        if (pout->zi > r_spritedesc.nearzi) {
            r_spritedesc.nearzi = pout->zi;
        }

        pout->s = pv[3];
        pout->t = pv[4];

        scale = xscale * pout->zi;
        pout->u = (xcenter + scale * transformed[0]);

        scale = yscale * pout->zi;
        pout->v = (ycenter - scale * transformed[1]);

        pv += sizeof(vec5_t) / sizeof(*pv);
    }

// draw it
    r_spritedesc.nump = nump;
    r_spritedesc.pverts = outverts;
    D_DrawSprite();
}


/*
================
R_GetSpriteframe
================
*/
mspriteframe_t *R_GetSpriteframe(msprite_t *psprite)
{
    mspritegroup_t	*pspritegroup;
    mspriteframe_t	*pspriteframe;
    int				i, numframes, frame;
    float			*pintervals, fullinterval, targettime, time;

    frame = currententity->frame;

    if ((frame >= psprite->numframes) || (frame < 0)) {
        Con_Printf("R_DrawSprite: no such frame %d\n", frame);
        frame = 0;
    }

    if (psprite->frames[frame].type == SPR_SINGLE) {
        pspriteframe = psprite->frames[frame].frameptr;
    } else {
        pspritegroup = (mspritegroup_t *)psprite->frames[frame].frameptr;
        pintervals = pspritegroup->intervals;
        numframes = pspritegroup->numframes;
        fullinterval = pintervals[numframes-1];

        time = cl.time + currententity->syncbase;

        // when loading in Mod_LoadSpriteGroup, we guaranteed all interval values
        // are positive, so we don't have to worry about division by 0
        targettime = time - ((int)(time / fullinterval)) * fullinterval;

        for (i=0 ; i<(numframes-1) ; i++) {
            if (pintervals[i] > targettime) {
                break;
            }
        }

        pspriteframe = pspritegroup->frames[i];
    }

    return pspriteframe;
}


/*
================
R_DrawSprite
================
*/
void R_DrawSprite(void)
{
    int				i;
    msprite_t		*psprite;
    vec3_t			tvec;
    float			dot, angle, sr, cr;

    psprite = currententity->model->cache.data;

    r_spritedesc.pspriteframe = R_GetSpriteframe(psprite);

    sprite_width = r_spritedesc.pspriteframe->width;
    sprite_height = r_spritedesc.pspriteframe->height;

// TODO: make this caller-selectable
    if (psprite->type == SPR_FACING_UPRIGHT) {
        // generate the sprite's axes, with vup straight up in worldspace, and
        // r_spritedesc.vright perpendicular to modelorg.
        // This will not work if the view direction is very close to straight up or
        // down, because the cross product will be between two nearly parallel
        // vectors and starts to approach an undefined state, so we don't draw if
        // the two vectors are less than 1 degree apart
        tvec[0] = -modelorg[0];
        tvec[1] = -modelorg[1];
        tvec[2] = -modelorg[2];
        VectorNormalize(tvec);
        dot = tvec[2];	// same as DotProduct (tvec, r_spritedesc.vup) because
        //  r_spritedesc.vup is 0, 0, 1
        if ((dot > 0.999848) || (dot < -0.999848)) {	// cos(1 degree) = 0.999848
            return;
        }
        r_spritedesc.vup[0] = 0;
        r_spritedesc.vup[1] = 0;
        r_spritedesc.vup[2] = 1;
        r_spritedesc.vright[0] = tvec[1];
        // CrossProduct(r_spritedesc.vup, -modelorg,
        r_spritedesc.vright[1] = -tvec[0];
        //              r_spritedesc.vright)
        r_spritedesc.vright[2] = 0;
        VectorNormalize(r_spritedesc.vright);
        r_spritedesc.vpn[0] = -r_spritedesc.vright[1];
        r_spritedesc.vpn[1] = r_spritedesc.vright[0];
        r_spritedesc.vpn[2] = 0;
        // CrossProduct (r_spritedesc.vright, r_spritedesc.vup,
        //  r_spritedesc.vpn)
    } else if (psprite->type == SPR_VP_PARALLEL) {
        // generate the sprite's axes, completely parallel to the viewplane. There
        // are no problem situations, because the sprite is always in the same
        // position relative to the viewer
        for (i=0 ; i<3 ; i++) {
            r_spritedesc.vup[i] = vup[i];
            r_spritedesc.vright[i] = vright[i];
            r_spritedesc.vpn[i] = vpn[i];
        }
    } else if (psprite->type == SPR_VP_PARALLEL_UPRIGHT) {
        // generate the sprite's axes, with vup straight up in worldspace, and
        // r_spritedesc.vright parallel to the viewplane.
        // This will not work if the view direction is very close to straight up or
        // down, because the cross product will be between two nearly parallel
        // vectors and starts to approach an undefined state, so we don't draw if
        // the two vectors are less than 1 degree apart
        dot = vpn[2];	// same as DotProduct (vpn, r_spritedesc.vup) because
        //  r_spritedesc.vup is 0, 0, 1
        if ((dot > 0.999848) || (dot < -0.999848)) {	// cos(1 degree) = 0.999848
            return;
        }
        r_spritedesc.vup[0] = 0;
        r_spritedesc.vup[1] = 0;
        r_spritedesc.vup[2] = 1;
        r_spritedesc.vright[0] = vpn[1];
        // CrossProduct (r_spritedesc.vup, vpn,
        r_spritedesc.vright[1] = -vpn[0];	//  r_spritedesc.vright)
        r_spritedesc.vright[2] = 0;
        VectorNormalize(r_spritedesc.vright);
        r_spritedesc.vpn[0] = -r_spritedesc.vright[1];
        r_spritedesc.vpn[1] = r_spritedesc.vright[0];
        r_spritedesc.vpn[2] = 0;
        // CrossProduct (r_spritedesc.vright, r_spritedesc.vup,
        //  r_spritedesc.vpn)
    } else if (psprite->type == SPR_ORIENTED) {
        // generate the sprite's axes, according to the sprite's world orientation
        AngleVectors(currententity->angles, r_spritedesc.vpn,
                     r_spritedesc.vright, r_spritedesc.vup);
    } else if (psprite->type == SPR_VP_PARALLEL_ORIENTED) {
        // generate the sprite's axes, parallel to the viewplane, but rotated in
        // that plane around the center according to the sprite entity's roll
        // angle. So vpn stays the same, but vright and vup rotate
        angle = currententity->angles[ROLL] * (M_PI*2 / 360);
        sr = sin(angle);
        cr = cos(angle);

        for (i=0 ; i<3 ; i++) {
            r_spritedesc.vpn[i] = vpn[i];
            r_spritedesc.vright[i] = vright[i] * cr + vup[i] * sr;
            r_spritedesc.vup[i] = vright[i] * -sr + vup[i] * cr;
        }
    } else {
        Sys_Error("R_DrawSprite: Bad sprite type %d", psprite->type);
    }

    R_RotateSprite(psprite->beamlength);

    R_SetupAndDrawSprite();
}

