// gutamatics projection data caching and other functions from SWWM GZ

Struct dt_ProjectionData
{
	dt_GM_Matrix wtc;
	int viewx, viewy, vieww, viewh;
}

Class dt_Utility
{
	// gutamatics caching
	static clearscope void PrepareProjData( out dt_ProjectionData d, Vector3 viewpos, double angle, double pitch, double roll, double fov )
	{
		double aspect = Screen.GetAspectRatio();
		// vertical fov
		double fovratio = (aspect>=1.3)?1.333333:aspect;
		double fovy = 2.*atan(tan(clamp(fov,5,170)/2.)/fovratio);
		// world→clip matrix
		dt_GM_Matrix view = dt_GM_Matrix.view(viewpos,angle,pitch,roll);
		dt_GM_Matrix perp = dt_GM_Matrix.perspective(fovy,aspect,5,65535);
		d.wtc = perp.multiplyMatrix(view);
		// screen coord data
		int sblocks = CVar.FindCVar('screenblocks').GetInt();
		int viewx, viewy, vieww, viewh;
		[viewx, viewy, vieww, viewh] = Screen.GetViewWindow();
		int sh = Screen.GetHeight();
		int h = sh;
		if ( sblocks < 10 ) h = (sblocks*sh/10)&~7;
		int bottom = sh-(h+viewy-((h-viewh)/2));
		d.viewx = viewx;
		d.viewy = sh-bottom-h;
		d.vieww = vieww;
		d.viewh = h;
	}

	static clearscope Vector3 ProjectPoint( dt_ProjectionData d, Vector3 worldpos )
	{
		return d.wtc.multiplyVector3(worldpos).asVector3();
	}

	static clearscope Vector2 NDCToViewport( dt_ProjectionData d, Vector3 ndc )
	{
		return (d.viewx,d.viewy)+(((ndc.x+1)*d.vieww)/2,((-ndc.y+1)*d.viewh)/2);
	}

	// checks if a point is inside the viewport
	static clearscope bool TestScreenBounds( dt_ProjectionData d, Vector2 vpos )
	{
		return ((vpos.x == clamp(vpos.x,d.viewx,d.viewx+d.vieww))
			&& (vpos.y == clamp(vpos.y,d.viewy,d.viewy+d.viewh)));
	}

	static clearscope Vector3 Vec3FromAngle( double angle, double pitch )
	{
		return (cos(angle)*cos(pitch),sin(angle)*cos(pitch),-sin(pitch));
	}

	static clearscope Vector3 CircleOffset( Vector3 y, Vector3 z, double angle, double radius )
	{
		return (y*cos(angle)*radius+z*sin(angle)*radius);
	}

	static clearscope Vector3 ConeSpread( Vector3 x, Vector3 y, Vector3 z, double angle, double spread )
	{
		return (x+y*cos(angle)*spread+z*sin(angle)*spread).unit();
	}

	static clearscope Vector3, Vector3, Vector3 GetAxes( double angle, double pitch, double roll )
	{
		Vector3 x = (1,0,0), y = (0,-1,0), z = (0,0,1);
		Quat r = Quat.FromAngles(angle,pitch,roll);
		return r*x, r*y, r*z;
	}

	// included here until Gutamatics updates to use native quaternions
	static double, double, double ToAngles( Quat q )
	{
		double angle = 0., pitch = 0., roll = 0.;
		double stest = q.z*q.x-q.w*q.y;
		double angY = 2.*(q.w*q.z+q.x*q.y);
		double angX = 1.-2.*(q.y*q.y+q.z*q.z);
		if ( stest < -.4999995 )
		{
			angle = atan2(angY,angX);
			pitch = 90.;
			roll = dt_GM_GlobalMaths.Normalize180(angle+(2.*atan2(q.x,q.w)));
		}
		else if ( stest > .4999995 )
		{
			angle = atan2(angY,angX);
			pitch = -90.;
			roll = dt_GM_GlobalMaths.Normalize180(angle+(2.*atan2(q.x,q.w)));
		}
		else
		{
			angle = atan2(angY,angX);
			pitch = -asin(2.*stest);
			roll = atan2(2.*(q.w*q.x+q.y*q.z),1.-2.*(q.x*q.x+q.y*q.y));
		}
		return angle, pitch, roll;
	}

	// for aiming and shooting
	static Vector3 GetPlayerViewDir( Actor player )
	{
		Quat r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		return r*(1,0,0);
	}
	static play Vector3 GetPlayerAimDir( Actor player )
	{
		FTranslatedLineTarget t;
		double pitch = player.BulletSlope(t);
		Quat r;
		if ( !t.linetarget ) r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		else r = Quat.FromAngles(player.angle,pitch,player.roll);
		return r*(1,0,0);
	}
	static Vector3, Vector3, Vector3 GetPlayerAxes( Actor player )
	{
		Quat r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		return r*(1,0,0), r*(0,-1,0), r*(0,0,1);
	}
	static play Vector3, Vector3, Vector3 GetPlayerAxesAutoAimed( Actor player )
	{
		FTranslatedLineTarget t;
		double pitch = player.BulletSlope(t);
		Quat r;
		if ( !t.linetarget ) r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		else r = Quat.FromAngles(player.angle,pitch,player.roll);
		return r*(1,0,0), r*(0,-1,0), r*(0,0,1);
	}
	static Vector3 GetPlayerEye( Actor player )
	{
		if ( !player.viewpos )
			return player.Vec2OffsetZ(0,0,player.player.viewz);
		if ( player.viewpos.flags&VPSF_ABSOLUTEPOS )
			return player.viewpos.offset;
		Vector3 origin = player.Vec2OffsetZ(0,0,player.player.viewz);
		if ( player.viewpos.flags&VPSF_ABSOLUTEOFFSET )
			return level.Vec3Offset(origin,player.viewpos.offset);
		Quat r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		return level.Vec3Offset(origin,r*player.viewpos.offset);
	}
	static Vector3 GetFireOffset( Actor player, double x, double y, double z )
	{
		Vector3 origin = GetPlayerEye(player);
		Quat r = Quat.FromAngles(player.angle,player.pitch,player.roll);
		return level.Vec3Offset(origin,r*(x,-y,z));
	}

}