liberscribble/src/scbutil.c File Reference

#include "scbutil.h"
#include <math.h>
#include <glib.h>
#include <scblog.h>

Go to the source code of this file.

Functions
int	CCW (const ScbPointPtr p0, const ScbPointPtr p1, const ScbPointPtr p2)
gboolean	Intersect (const ScbPointPtr p1, const ScbPointPtr p2, const ScbPointPtr p3, const ScbPointPtr p4)
gboolean	scb_is_rect_intersect (const ScbRectPtr r1, const ScbRectPtr r2)
gboolean	scb_is_lines_intersect (const ScbPointPtr p1, const ScbPointPtr p2, const ScbPointPtr p3, const ScbPointPtr p4)

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Function Documentation

int CCW	(	const ScbPointPtr	p0,
		const ScbPointPtr	p1,
		const ScbPointPtr	p2
	)

Copyright (C) 2005-2008 iRex Technologies B.V. All rights reserved.

Definition at line 42 of file scbutil.c.

{
    long dx1, dx2 ;
    long dy1, dy2 ;

    dx1 = p1->x - p0->x ; dx2 = p2->x - p0->x ;
    dy1 = p1->y - p0->y ; dy2 = p2->y - p0->y ;

    /* This is basically a slope comparison: we don't do divisions because

    * of divide by zero possibilities with pure horizontal and pure
    * vertical lines.
    */ 
    return ((dx1 * dy2 > dy1 * dx2) ? 1 : -1) ;
}

gboolean Intersect	(	const ScbPointPtr	p1,
		const ScbPointPtr	p2,
		const ScbPointPtr	p3,
		const ScbPointPtr	p4
	)

Definition at line 68 of file scbutil.c.

{
    return ((( CCW(p1, p2, p3) * CCW(p1, p2, p4)) <= 0)
        && (( CCW(p3, p4, p1) * CCW(p3, p4, p2)  <= 0) )) ;
}

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gboolean scb_is_lines_intersect	(	const ScbPointPtr	p1,
		const ScbPointPtr	p2,
		const ScbPointPtr	p3,
		const ScbPointPtr	p4
	)

Definition at line 89 of file scbutil.c.

{
    gboolean bRet = ((( CCW(p1, p2, p3) * CCW(p1, p2, p4)) <= 0)
        && (( CCW(p3, p4, p1) * CCW(p3, p4, p2)  <= 0) )) ;

   
    return bRet;
}

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gboolean scb_is_rect_intersect	(	const ScbRectPtr	rect1,
		const ScbRectPtr	rect2
	)

Copyright (C) 2005-2008 iRex Technologies B.V. All rights reserved.

Definition at line 78 of file scbutil.c.

{
    return ! ( r2->left > r1->right 
        || r2->right < r1->left 
        || r2->top > r1->bottom 
        || r2->bottom < r1->top 
        );
}