ReactOS
0.4.15-dev-326-g1c504f4
polyUtil.cc
Go to the documentation of this file.
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/*
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** License Applicability. Except to the extent portions of this file are
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** made subject to an alternative license as permitted in the SGI Free
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** Software License B, Version 1.1 (the "License"), the contents of this
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** file are subject only to the provisions of the License. You may not use
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** this file except in compliance with the License. You may obtain a copy
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** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
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** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
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**
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** http://oss.sgi.com/projects/FreeB
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**
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** Note that, as provided in the License, the Software is distributed on an
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** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
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** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
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** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
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** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
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**
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** Original Code. The Original Code is: OpenGL Sample Implementation,
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** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
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** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
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** Copyright in any portions created by third parties is as indicated
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** elsewhere herein. All Rights Reserved.
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**
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** Additional Notice Provisions: The application programming interfaces
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** established by SGI in conjunction with the Original Code are The
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** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
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** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
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** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
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** Window System(R) (Version 1.3), released October 19, 1998. This software
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** was created using the OpenGL(R) version 1.2.1 Sample Implementation
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** published by SGI, but has not been independently verified as being
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** compliant with the OpenGL(R) version 1.2.1 Specification.
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**
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*/
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/*
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*/
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//#include <stdlib.h>
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//#include <stdio.h>
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#include "
polyUtil.h
"
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Real
area
(
Real
A
[2],
Real
B
[2],
Real
C
[2])
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{
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Real
Bx, By, Cx, Cy;
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Bx =
B
[0] -
A
[0];
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By =
B
[1] -
A
[1];
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Cx =
C
[0] -
A
[0];
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Cy =
C
[1] -
A
[1];
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return
Bx*Cy - Cx*By;
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/* return (B[0]-A[0])*(C[1]-A[1]) - (C[0]-A[0])*(B[1]-A[1]);*/
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}
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/*given a directed line A->B, and a point P,
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*determine whether P is to the left of AB.
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*the line A->B (imagine it has beedn extended both
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*end to the infinity) divides the plan into two
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*half planes. When we walk from A to B, one
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*half is to the left and the other half is to the right.
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*return 1 if P is to the left.
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*if P is on AB, 0 is returned.
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*/
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Int
pointLeftLine
(
Real
A
[2],
Real
B
[2],
Real
P
[2])
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{
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if
(
area
(
A
,
B
,
P
) >0)
return
1;
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else
return
0;
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}
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/*given two directed line: A -> B -> C, and another point P.
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*determine whether P is to the left hand side of A->B->C.
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*Think of BA and BC extended as two rays. So that the plane is
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* divided into two parts. One part is to the left we walk from A
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*to B and to C, the other part is to the right.
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* In order for P to be the left, P must be either to the left
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*of
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*/
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Int
pointLeft2Lines
(
Real
A
[2],
Real
B
[2],
Real
C
[2],
Real
P
[2])
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{
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Int
C_left_AB = (
area
(
A
,
B
,
C
)>0);
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Int
P_left_AB = (
area
(
A
,
B
,
P
)>0);
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Int
P_left_BC = (
area
(
B
,
C
,
P
)>0);
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if
(C_left_AB)
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{
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return
(P_left_AB && P_left_BC);
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}
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else
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return
(P_left_AB || P_left_BC);
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}
pointLeftLine
Int pointLeftLine(Real A[2], Real B[2], Real P[2])
Definition:
polyUtil.cc:64
polyUtil.h
A
Definition:
ttei1.cpp:12
P
#define P(row, col)
pointLeft2Lines
Int pointLeft2Lines(Real A[2], Real B[2], Real C[2], Real P[2])
Definition:
polyUtil.cc:78
C
Definition:
ttei6.cpp:27
B
#define B(row, col)
Real
float Real
Definition:
definitions.h:36
area
Real area(Real A[2], Real B[2], Real C[2])
Definition:
polyUtil.cc:43
Int
int Int
Definition:
definitions.h:37
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polyUtil.cc
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