/*
Copyright (C) 1996-2001 Id Software, Inc.
Copyright (C) 2002-2009 John Fitzgibbons and others
Copyright (C) 2007-2008 Kristian Duske
Copyright (C) 2010-2014 QuakeSpasm developers

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 -- sprite model rendering

#include "q_defs.h"

/*
================
R_GetSpriteFrame
================
*/
mspriteframe_t *R_GetSpriteFrame(entity_t *currentent)
{
	msprite_t               *psprite;
	mspritegroup_t  *pspritegroup;
	mspriteframe_t  *pspriteframe;
	int32_t                         i, numframes, frame;
	float                   *pintervals, fullinterval, targettime, time;

	psprite = (msprite_t *) currentent->model->cache.data;
	frame = currentent->frame;

	if((frame >= psprite->numframes) || (frame < 0))
	{
		Con_DPrintf("R_DrawSprite: no such frame %" PRIi32 " for '%s'\n", frame, currentent->model->name);
		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 + currentent->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 - ((int32_t)(time / fullinterval)) * fullinterval;

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

		pspriteframe = pspritegroup->frames[i];
	}

	return pspriteframe;
}

/*
=================
R_DrawSpriteModel -- johnfitz -- rewritten: now supports all orientations
=================
*/
void R_DrawSpriteModel(entity_t *e)
{
	vec3_t                  point, v_forward, v_right, v_up;
	msprite_t               *psprite;
	mspriteframe_t  *frame;
	float                   *s_up, *s_right;
	float                   angle, sr, cr;

	//TODO: frustum cull it?

	frame = R_GetSpriteFrame(e);
	psprite = (msprite_t *) currententity->model->cache.data;

	switch(psprite->type)
	{
	case SPR_VP_PARALLEL_UPRIGHT: //faces view plane, up is towards the heavens
		v_up[0] = 0;
		v_up[1] = 0;
		v_up[2] = 1;
		s_up = v_up;
		s_right = vright;
		break;
	case SPR_FACING_UPRIGHT: //faces camera origin, up is towards the heavens
		VectorSubtract(currententity->origin, r_origin, v_forward);
		v_forward[2] = 0;
		VectorNormalizeFast(v_forward);
		v_right[0] = v_forward[1];
		v_right[1] = -v_forward[0];
		v_right[2] = 0;
		v_up[0] = 0;
		v_up[1] = 0;
		v_up[2] = 1;
		s_up = v_up;
		s_right = v_right;
		break;
	case SPR_VP_PARALLEL: //faces view plane, up is towards the top of the screen
		s_up = vup;
		s_right = vright;
		break;
	case SPR_ORIENTED: //pitch yaw roll are independent of camera
		AngleVectors(currententity->angles, v_forward, v_right, v_up);
		s_up = v_up;
		s_right = v_right;
		break;
	case SPR_VP_PARALLEL_ORIENTED: //faces view plane, but obeys roll value
		angle = currententity->angles[ROLL] * PI_DIV_180;
		sr = sin(angle);
		cr = cos(angle);
		v_right[0] = vright[0] * cr + vup[0] * sr;
		v_right[1] = vright[1] * cr + vup[1] * sr;
		v_right[2] = vright[2] * cr + vup[2] * sr;
		v_up[0] = vright[0] * -sr + vup[0] * cr;
		v_up[1] = vright[1] * -sr + vup[1] * cr;
		v_up[2] = vright[2] * -sr + vup[2] * cr;
		s_up = v_up;
		s_right = v_right;
		break;
	default:
		return;
	}

	//johnfitz: offset decals
	if(psprite->type == SPR_ORIENTED)
		GL_PolygonOffset(OFFSET_DECAL);

	glColor3f(1, 1, 1);

	GL_DisableMultitexture();

	GL_Bind(frame->gltexture);

	glEnable(GL_ALPHA_TEST);
	glBegin(GL_TRIANGLE_FAN);  //was GL_QUADS, but changed to support r_showtris

	glTexCoord2f(0, frame->tmax);
	VectorMA(e->origin, frame->down, s_up, point);
	VectorMA(point, frame->left, s_right, point);
	glVertex3fv(point);

	glTexCoord2f(0, 0);
	VectorMA(e->origin, frame->up, s_up, point);
	VectorMA(point, frame->left, s_right, point);
	glVertex3fv(point);

	glTexCoord2f(frame->smax, 0);
	VectorMA(e->origin, frame->up, s_up, point);
	VectorMA(point, frame->right, s_right, point);
	glVertex3fv(point);

	glTexCoord2f(frame->smax, frame->tmax);
	VectorMA(e->origin, frame->down, s_up, point);
	VectorMA(point, frame->right, s_right, point);
	glVertex3fv(point);

	glEnd();
	glDisable(GL_ALPHA_TEST);

	//johnfitz: offset decals
	if(psprite->type == SPR_ORIENTED)
		GL_PolygonOffset(OFFSET_NONE);
}