Assignment 4: Triangles and Line Clipping

Assignment 4 involves:
1. Creating an applet that creates a cubic Bezier curve based on points created when the user clicks on the applet
2. Creating a function that takes 3 sets of coordinates and draws a triangle
3. Adding to the triangle function to create 5 triangles with random coordinates on a 720 x 480 image
4. To be continued....

1. Bezier curve using user input:

**Still working on embedding the applet here.

  int count=0;

  int x1=0;

  int x2=0;

  int x3=0;

  int x4=0;

  int y1=0;

  int y2=0;

  int y3=0;

  int y4=0;

  

  void setup(){

  size(200,200);

  background(0);

  stroke(255);

}

void draw(){}

  void mousePressed(){

  

  if (count==0){

    x1=mouseX;

    y1=mouseY;

    point(x1,y1);

    count++;

  }

  else if (count==1){

    x2=mouseX;

    y2=mouseY;

    point(x2,y2);

    count++;

  }

  else if (count==2){

    x3=mouseX;

    y3=mouseY;

    point(x3,y3);

    count++;

    

  }

  else if (count==3){

    background(0);

    x4=mouseX;

    y4=mouseY;

    cubBesCurve(x1,y1,x2,y2,x3,y3,x4,y4);

    count++;

  }

  else if (count==4){

     background(0);

     count=0;    

  }

}



void parLine(int x1, int y1, int x2, int y2){

  for (float t=0;t<1;t=t+.001){

    point(x1+t*(x2-x1),y1+t*(y2-21));

  }

}

void quadBesCurve(int x1, int y1, int x2, int y2, int x3, int y3){

for (float t=0;t<1;t=t+.001){

  point((sq(1-t)*x1+2*(1-t)*t*x2+sq(t)*x3),(sq(1-t)*y1+2*(1-t)*t*y2+sq(t)*y3));

}

}

void cubBesCurve(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4){

  for (float t=0;t<1;t=t+.001){

    point ((pow((1-t),3)*x1+3*sq(1-t)*t*x2+3*(1-t)*sq(t)*x3+pow(t,3)*x4),

          (pow((1-t),3)*y1+3*sq(1-t)*t*y2+3*(1-t)*sq(t)*y3+pow(t,3)*y4)); 

  }

}

2. Drawing Triangles:

The first step to this part was to create a function to draw 1 triangle, then I created another function to draw 5 triangles in random positions



Here is a shot after implementing a line clipping algorithm:

Source Code:

int XMAX=540;

int XMIN=180;

int YMAX=360;

int YMIN=120;



void setup(){

  size(720,480);

  stroke(255);

  background(0);

  fill(50);

  

  rect(XMIN,YMIN,360,240);

 

  myRandomTriangles(5);

  

}

void draw(){

  

}

void myRandomTriangles(int numTriangles){

  

  for (int i=0;i    int r=(int)random(255);

    int g=(int)random(255);

    int b=(int)random(255);

    int x1=(int)random(720);

    int x2=(int)random(720);

    int x3=(int)random(720);

    int y1=(int)random(480);

    int y2=(int)random(480);

    int y3=(int)random(480);

    stroke(r,g,b);

    myTriangle(x1,y1,x2,y2,x3,y3);

  }

}

void drawLine(int x1,int y1,int x2,int y2){

  int code1=getLocationCode(x1,y1);

  int code2=getLocationCode(x2,y2);

  if ((code2==0)&&(code1==0)){

     line(x1,y1,x2,y2);

  }

  else if ((code1&code2)!=0){

  }

  else {

     clipLine(x1,y1,x2,y2);

  }

}

void myTriangle(int x11,int y11,int x12, int y12, int x13, int y13){

  int x1=x11;

  int x2=x12;

  int x3=x13;

  int y1=y11;

  int y2=y12;

  int y3=y13;

  

  drawLine(x1,y1, x2,y2);

  drawLine(x2,y2, x3,y3);

  drawLine(x1,y1,x3,y3);

  

}

void clipLine(int x1, int y1,int x2, int y2){

  int code1=getLocationCode(x1, y1);

  int code2=getLocationCode(x2,y2);

  double m=((double)(y2-y1)/(x2-x1));

  double b=y2-m*x2;

      if( (code1&1)!=0){

        

        x1 = (int)((YMIN-b)/m);

        y1 = YMIN;

        code1=getLocationCode(x1,y1);

      }

      else if ((code1 & 2)!= 0){

        

        x1= (int)((YMAX-b)/m);

        y1 = YMAX;

        code1=getLocationCode(x1,y1);

      }

      if((code1 & 4)!= 0){

        

        y1 =(int)(m*XMAX+b);

        x1 = XMAX;

        code1=getLocationCode(x1,y1);

      }

      else if((code1 & 8)!=0){

        

        y1 = (int)(m*XMIN+b);

        x1 = XMIN;

        code1=getLocationCode(x1,y1);

      }

      if( (code2&1)!=0){

        

        x2 = (int)((YMIN-b)/m);

        y2 = YMIN;

        code2=getLocationCode(x2,y2);

      }

      else if ((code2 & 2)!= 0){

        

        x2= (int)((YMAX-b)/m);

        y2 = YMAX;

        code2=getLocationCode(x2,y2);

      }

      if((code2 & 4)!= 0){

        

        y2 =(int)(m*XMAX+b);

        x2 = XMAX;

        code2=getLocationCode(x2,y2);

      }

      else if((code2 & 8)!=0){

        

        y2 = (int)(m*XMIN+b);

        x2 = XMIN;

        code2=getLocationCode(x2,y2);

      }

    

  line(x1,y1,x2,y2);

}

int getLocationCode(int x, int y){

  int code=0;

  if (x>XMAX)

    code=code+4;

  if (x    code=code+8;

  if (y    code=code+1;

  if (y>YMAX)

    code=code+2;

  return code;

}