Question

我试图理解为什么我的代码用于确定给定的点是否在（包括边框）内还是没有矩形。目前我收到的是0，无论该点是否存在或者是否存在，并且我发现难以诊断这一点。我在哪里打个嗝？

#include <stdio.h> 

int InRectangle( float pt[2], float rect[4] )
{
    float x=pt[0];
    float y=pt[1];
    float box_x=rect[0];
    float box_y=rect[1];
    float box_x_opp=rect[2];
    float box_y_opp=rect[3];
    float x_diff=0;
    float y_diff=0;

    x_diff = box_x_opp - box_x ;
    y_diff = box_y_opp - box_y;

    //if x_diff is + and y diff is + 
    if (x_diff>=0  && y_diff>=0)
    {
        if ((x >= box_x) && (x <= box_x_opp) && (y>=box_y) && (y<=box_y_opp))
            {return 1;} 
    }
    //if x_diff is - and y diff is -

    if (x_diff<0  && y_diff<0)
    {
        if ((x <= box_x) && (x >= box_x_opp) && (y>=box_y) && (y<=box_y_opp))
            {return 1;} 
    }
    //if x_diff is + and y diff is -

    if (x_diff>=0  && y_diff<0)
    {
        if ((x >= box_x) && (x <= box_x_opp) && (y<=box_y) && (y>=box_y_opp))
            {return 1;} 
    }
    //if x_diff is - and y diff is +
    if (x_diff<0  && y_diff>=0)
    {
        if ((x <= box_x) && (x >= box_x_opp) && (y>=box_y) && (y<=box_y_opp))
            {return 1;} 
    }
    else 
        {return 0;}
}

Answer 1

似乎大规模过于复杂，这就是为什么很难找到错误！

您需要的只是：

return x > rect_minx_x && x < rect_max_x && y > rect_min_y && y < rect_max_y;

当然，您需要弄清楚所有这些值，但这很简单。

Answer 2

另外：如果是这样的话，你忘了在第二点翻转y点检查：

//if x_diff is - and y diff is -

if (x_diff<0  && y_diff<0)
{
    if ((x <= box_x) && (x >= box_x_opp) && (y>=box_y) && (y<=box_y_opp))
        {return 1;} 
}

应该是：

//if x_diff is - and y diff is -

if (x_diff<0  && y_diff<0)
{
    if ((x <= box_x) && (x >= box_x_opp) && (y <= box_y) && (y >= box_y_opp))
        {return 1;} 
}

因为在这种情况下box_x大于或等于box_x_opp且box_y大于或等于box_y_opp

让您的代码更具可读性，例如

float xMin, xMax, yMin, yMax;

if (rect[0] >= rect[2]) {
    xMin = rect[2];
    xMax = rect[0];
} else {
    xMin = rect[0];
    xMax = rect[2];
}

if (rect[1] >= rect[3]) {
    yMin = rect[3];
    yMax = rect[1];
} else {
    yMin = rect[1];
    yMax = rect[3];
}

然后你可以将它与solution by John3136结合起来解决：

return x >= xMin && x <= xMax && y >= yMin && y <= yMax;

确定给定点是否在定义的矩形内

2 个答案: