Question

CS 334 Final Exam Prof. Danyang Thang Read the following function and draw the corresponding geometric shape according 6. to the function call afterwards (draw it pixel-by-pixel, i.e., plot each pixel) (25 points) void draw (int xo, int yo, int xEnd, int yEnd) int dx = fabs (xEnd- :0), dy fabs(yEnd-yo); int p = 2 * dy-dx; int twoDy 2dy, twoDyMinusDx 2(dy dx) int x, y: if (xo> xEnd) f y yEnd; xEnd = x0; else f x=x0; setPixel (х, y); // plot point (x, y) while (x < xEnd) xtt; if (p < 0) else t ytt; p ttwoDyMinusDx; setPixel (x, y): //plot point (x, y) draw (18, 11, 10, 5):

Answer 1

CODE:

#include <Windows.h>
#include <GL\glew.h>
#include <GL\freeglut.h>
#include <iostream>
using namespace std;
int x, y;
void changeView(int w, int h)
{
   glViewport(0, 0, w, h);
}
void myinit(void)
{
   glClearColor(0, 0, 0, 1.0);
   glMatrixMode(GL_PROJECTION);
   gluOrtho2D(0.0, 100.0, 0.0, 100.0);
}
void setPixel(GLint x, GLint y){
   glPointSize(2);
   glBegin(GL_POINTS);
   glColor3f(1, 0, 0);
   glVertex2i(x, y);
   glEnd();
   glFlush();
}

void draw(){
   //int x0, int y0, int xEnd, int yEnd
   int x0 = 18, y0 = 11, xEnd = 10, yEnd = 5;
   int dx = fabs(static_cast<float>(xEnd - x0)), dy = fabs(static_cast<float>(yEnd - y0));
   int p = 2 * dy - dx;
   int twoDy = 2 * dy, twoDyMinusDx = 2 * (dy - dx);

   int x, y;

   if (x0 > xEnd){
       x = xEnd;
       y = yEnd;
       xEnd = x0;
   }
   else{
       x = x0;
       y = y0;
   }

   setPixel(x, y);
   while (x < xEnd){
      
       x++;
       if (p < 0){
           p += twoDy;
       }
       else{
           y++;
           p += twoDyMinusDx;
       }
       setPixel(x, y);
   }

   glutSwapBuffers();

}

void display(){
   glClear(GL_COLOR_BUFFER_BIT);

   draw(); //18, 11, 10, 5
   glFlush();
}
int main(int argc, char* argv[]){

   glutInit(&argc, argv); // Initialize glut

   //create memory buffers to display

   glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);

   glutInitWindowSize(800, 600); // window size

   glutCreateWindow(" "); // create window

   glutReshapeFunc(changeView);

   //glutDisplayFunc(render);

   glutDisplayFunc(display);//links the display event with the display event handler(display)
   myinit();
   glutIdleFunc(draw);

   GLenum error = glewInit();

   if (GLEW_OK != error){
       fprintf(stderr, "Glew error");
       return 1;
   }

   glutMainLoop();
   return 0;
}

OUTPUT: