quakeforge/libs/video/renderer/r_billboard.c
Bill Currie 1df3c2eea0 [renderer] Make R_BillboarFrame's comments true
While they weren't entirely false, they were overly verbose and thus
clouded the point.
2021-12-24 06:45:13 +09:00

120 lines
3.4 KiB
C

/*
r_billboard.c
Billboard frame setup
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:
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <string.h>
#endif
#include <math.h>
#include "QF/render.h"
#include "QF/sys.h"
#include "QF/scene/entity.h"
#include "r_internal.h"
int
R_BillboardFrame (entity_t *ent, int orientation, const vec3_t cameravec,
vec3_t bbup, vec3_t bbright, vec3_t bbpn)
{
vec3_t tvec;
float dot;
switch (orientation) {
case SPR_FACING_UPRIGHT:
// the billboard has its up vector parallel with world up, and
// its right vector perpendicular to cameravec.
// Undefined if the camera is too close to the entity.
VectorNegate (cameravec, tvec);
VectorNormalize (tvec);
dot = tvec[2]; // DotProduct (tvec, world up)
if ((dot > 0.999848) || (dot < -0.999848)) // cos(1 degree)
return 0;
VectorSet (0, 0, 1, bbup);
//CrossProduct(bbup, -cameravec, bbright)
VectorSet (tvec[1], -tvec[0], 0, bbright);
VectorNormalize (bbright);
//CrossProduct (bbright, bbup, bbpn)
VectorSet (-bbright[1], bbright[0], 0, bbpn);
break;
case SPR_VP_PARALLEL:
// the billboard always has the same orientation as the camera
VectorCopy (vup, bbup);
VectorCopy (vright, bbright);
VectorCopy (vpn, bbpn);
break;
case SPR_VP_PARALLEL_UPRIGHT:
// the billboar has its up vector parallel with world up, and
// its right vector parallel with the view plane.
// Undefined if the camera is looking straight up or down.
dot = vpn[2]; // DotProduct (vpn, world up)
if ((dot > 0.999848) || (dot < -0.999848)) // cos(1 degree)
return 0;
VectorSet (0, 0, 1, bbup);
//CrossProduct(bbup, vpn, bbright)
VectorSet (vpn[1], -vpn[0], 0, bbright);
VectorNormalize (bbright);
//CrossProduct (bbright, bbup, bbpn)
VectorSet (-bbright[1], bbright[0], 0, bbpn);
break;
case SPR_ORIENTED:
{
// The billboard's orientation is fully specified by the
// entity's orientation.
mat4f_t mat;
Transform_GetWorldMatrix (ent->transform, mat);
VectorCopy (mat[0], bbpn);
VectorNegate (mat[1], bbright);
VectorCopy (mat[2], bbup);
}
break;
case SPR_VP_PARALLEL_ORIENTED:
{
// The billboard is rotated relative to the camera using
// the entity's local rotation.
vec4f_t rot = Transform_GetLocalRotation (ent->transform);
// FIXME needs proper testing (need to find, make, or fake a
// parallel oriented sprite)
rot = qmulf (r_refdef.viewrotation, rot);
QuatMultVec (&rot[0], vpn, bbpn);
QuatMultVec (&rot[0], vright, bbright);
QuatMultVec (&rot[0], vup, bbup);
}
break;
default:
Sys_Error ("R_BillboardFrame: Bad orientation %d", orientation);
}
return 1;
}