[英]What's wrong with my C++ code?
我试图创建一个输出到控制台的等边三角形,但是我的代码似乎在点0,0输出该三角形。
我怎样才能解决这个问题?
这就是我所拥有的:
头文件:
#include "shape.h"
#include "vertex.h"
#include <list>
// An equilateral triangle
class Triangle : public Shape
{
// the radius provides the length of a side
// and enables a vertex to be plotted from
// which the other two vertices can be derived
// via rotation
int radius;
public:
// constructor
Triangle(Vertex point, int radius = 10);
// calculates and returns a triangle's area
int area();
// calculates and returns a triangle's perimeter
int perimeter();
};
和cpp文件
#include "triangle.h"
#include "vertex.h"
#include <list>
Triangle::Triangle(Vertex point, int radius) : Shape(point)
{
this->radius = radius;
this->centroid = Vertex(0,0);
vertices.push_back(Vertex(centroid.getY() + radius));
vertices.push_back(Vertex(centroid.getY() + (radius*2)));
vertices.push_back(Vertex(centroid.getX() * cos(120) - centroid.getY() * sin(120),centroid.getY() * cos(120) + centroid.getX() * sin(120)));
vertices.push_back(Vertex(centroid.getX() * cos(240) - centroid.getY() * sin(240),centroid.getY() * cos(240) + centroid.getX() * sin(240)));
this->centroid = point;
}
// returns the area of an equilateral triangle
int Triangle::area()
{
return radius*radius*(sqrt(3)/4);
}
// returns the perimeter of an equilateral triangle
int Triangle::perimeter()
{
return radius *3;
}
我不确定这是怎么回事。 我尝试了许多不同的方法来修复它,但是这样做并没有运气。 有人可以帮忙吗?
sin
, cos
等使用弧度而不是度。
同样,您将质心设置为硬编码0,0
。
正如在另一个答案中指出的那样, sin
和cos
用弧度而不是度来表示他们的论点。
此外,您的构造函数似乎很奇怪。 请记住,我没有代码的所有详细信息( Vertex
, Shape
,...),但是假设vertices
需要包含三角形的三个顶点,并且Vertex
的构造函数采用了三个坐标,我会尝试这样的事情:
Triangle::Triangle(Vertex point, int radius) : Shape(point)
{
this->radius = radius;
// in any case, you want the traingle to be centered around the point given as input
this->centroid = point;
// we can just avoid calling trigonometric functions at runtime
// also, the values for these particular angles are well-known, so we don't need to call any actual trigonometric functions
static const float COS_60 = 0.5f;
static const float COS_30 = 0.5f * sqrt(3.f);
// compute the length of the side of the triangle based on its radius
// for instance, using any of the six right triangles between the center, a vertice and the projection of the center against one of the sides
const float side = radius * 2.f * COS_30;
// more basic geometry
const float bottomHeight = point.getY() - COS_60 * radius;
// first vertice is right above the center
this->vertices.push_back(Vertex(point.getX(), point.getY() + radius));
// second vertice is at the bottom height, and its X position is offset by half the side
this->vertices.push_back(Vertex(point.getX() + COS_60 * side, bottomHeight));
// same, but in the other direction
this->vertices.push_back(Vertex(point.getX() - COS_60 * side, bottomHeight));
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.