Quake-III-Arena/q3map/brush_primit.c

/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

Quake III Arena source code 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.

Quake III Arena source code 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 Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
#include "qbsp.h"


// global flag
int	g_bBrushPrimit;

// NOTE : ComputeAxisBase here and in editor code must always BE THE SAME !
// WARNING : special case behaviour of atan2(y,x) <-> atan(y/x) might not be the same everywhere when x == 0
// rotation by (0,RotY,RotZ) assigns X to normal
void ComputeAxisBase(vec3_t normal,vec3_t texX,vec3_t texY)
{
	vec_t RotY,RotZ;
	// do some cleaning
	if (fabs(normal[0])<1e-6)
		normal[0]=0.0f;
	if (fabs(normal[1])<1e-6)
		normal[1]=0.0f;
	if (fabs(normal[2])<1e-6)
		normal[2]=0.0f;
	// compute the two rotations around Y and Z to rotate X to normal
	RotY=-atan2(normal[2],sqrt(normal[1]*normal[1]+normal[0]*normal[0]));
	RotZ=atan2(normal[1],normal[0]);
	// rotate (0,1,0) and (0,0,1) to compute texX and texY
	texX[0]=-sin(RotZ);
	texX[1]=cos(RotZ);
	texX[2]=0;
	// the texY vector is along -Z ( T texture coorinates axis )
	texY[0]=-sin(RotY)*cos(RotZ);
	texY[1]=-sin(RotY)*sin(RotZ);
	texY[2]=-cos(RotY);
}