geometry.cpp

   1 #include "geometry.h"
   2 #include "math.h"
   3 #include <vector>
   4
   5 Linha::Linha(double x1,double y1,double x2, double y2) {
   6         vertices[0].x = x1;
   7         vertices[0].y = y1;
   8         vertices[1].x = x2;
   9         vertices[1].y = y2;
  10 }
  11
  12 Rect::Rect(double x1,double y1,double x2, double y2) {
  13         vertices[0].x = x1;
  14         vertices[0].y = y1;
  15         vertices[1].x = x2;
  16         vertices[1].y = y2;
  17         normaliza();
  18 }
  19
  20 void Rect::normaliza() {
  21         double xmin,xmax,ymin,ymax;
  22         xmin = std::min(vertices[0].x,vertices[1].x);
  23         xmax = std::max(vertices[0].x,vertices[1].x);
  24         ymin = std::min(vertices[0].y,vertices[1].y);
  25         ymax = std::max(vertices[0].y,vertices[1].y);
  26         vertices[0].x = xmin;
  27         vertices[1].x = xmax;
  28         vertices[0].y = ymin;
  29         vertices[1].y = ymax;
  30 }
  31
  32 void Linha::desenha() {
  33         glColor3f(0,0,0);
  34         glBegin(GL_LINES);
  35                 glVertex3f(vertices[0].x, vertices[0].y, 0.0f); // origin of the line
  36                 glVertex3f(vertices[1].x, vertices[1].y, 0.0f); // origin of the line
  37         glEnd( );
  38 }
  39
  40 void Polygon::desenha() {
  41         int n = linhas.size();
  42         for (int i = 0; i < n; i++) {
  43                 linhas[i].desenha();
  44         }
  45 }
  46
  47 double operator*(const Ponto &a, const Ponto &b) {
  48         return a.x * b.y - b.x * a.y;
  49 }
  50
  51 Ponto operator-(const Ponto &a, const Ponto &b) {
  52         Ponto ret;
  53         ret.x = a.x - b.x;
  54         ret.y = a.y - b.y;
  55         return ret;
  56 }
  57
  58 Ponto operator+(const Ponto &a, const Ponto &b) {
  59         Ponto ret;
  60         ret.x = a.x + b.x;
  61         ret.y = a.y + b.y;
  62         return ret;
  63 }
  64
  65 double distance(const Ponto &a,const Ponto &b) {
  66         return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
  67 }
  68
  69 void drawCircle(double radius, int lines)
  70 {
  71         double i2rad = PI/(lines/2.0);
  72         glBegin(GL_LINE_LOOP);
  73         for (int i=0; i < lines; i++) {
  74                 double degInRad = i*i2rad;
  75                 glVertex2f(cos(degInRad)*radius,sin(degInRad)*radius);
  76         }
  77
  78         glEnd();
  79 }
  80
  81 //calcula se a direcao dos segmentos p0p1 p1p2 é horaria, antihoraria ou se sao colineares
  82 double direction(const Ponto &p0,const Ponto &p1,const Ponto &p2) {
  83         return (p2 - p0) * (p1 - p0);
  84 }
  85
  86 bool onsegment(const Ponto &pi,const Ponto &pj,const Ponto &pk) {
  87         if ((std::min(pi.x, pj.x) <= pk.x && pk.x <= std::max(pi.x, pj.x)) &&
  88             (std::min(pi.y, pj.y) <= pk.y && pk.y <= std::max(pi.y, pj.y)))
  89                 return true;
  90         else
  91                 return false;
  92 }
  93
  94 bool linesIntersect(const Linha a,const Linha b) {
  95         Ponto p1 = a.vertices[0];
  96         Ponto p2 = a.vertices[1];
  97         Ponto p3 = b.vertices[0];
  98         Ponto p4 = b.vertices[1];
  99         double d1 = direction(p3, p4, p1);
 100         double d2 = direction(p3, p4, p2);
 101         double d3 = direction(p1, p2, p3);
 102         double d4 = direction(p1, p2, p4);
 103         if (((d1 > 0 && d2 < 0) || (d1 < 0 && d2 > 0)) &&
 104            ((d3 > 0 && d4 < 0) || (d3 < 0 && d4 > 0)))
 105                 return true;
 106         else if (d1 == 0.0 && onsegment(p3, p4, p1))
 107                 return true;
 108         else if (d2 == 0.0 && onsegment(p3, p4, p2))
 109                 return true;
 110         else if (d3 == 0.0 && onsegment(p1, p2, p3))
 111                 return true;
 112         else if (d4 == 0.0 && onsegment(p1, p2, p4))
 113                 return true;
 114         else
 115                 return false;
 116 }