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OpenGl Assg

The document contains OpenGL code to draw the first three letters of a name ('SYE') using Bresenham's and DDA line drawing algorithms. It also includes code to create the Olympic logo using a mid-point circle drawing algorithm and a classroom scene featuring a teacher and students. Each section provides detailed implementations for rendering graphics using OpenGL functions.

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20 views12 pages

OpenGl Assg

The document contains OpenGL code to draw the first three letters of a name ('SYE') using Bresenham's and DDA line drawing algorithms. It also includes code to create the Olympic logo using a mid-point circle drawing algorithm and a classroom scene featuring a teacher and students. Each section provides detailed implementations for rendering graphics using OpenGL functions.

Uploaded by

thug9104
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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2022115103

Draw first three letters of your name using OPgl. Use both DDA
and Bresenhams algorithm wherever needed
Output:

Code:

#include <GLUT/glut.h>

#include <iostream>
#include <cmath>

using namespace std;

void drawLineBresenham(int x1, int y1, int x2, int y2)


{
int dx = abs(x2 - x1);
int dy = abs(y2 - y1);
int sx = (x1 < x2) ? 1 : -1;
int sy = (y1 < y2) ? 1 : -1;
int err = dx - dy;

while (true)
{
glBegin(GL_POINTS);
glVertex2i(x1, y1);
glEnd();

if (x1 == x2 && y1 == y2)


break;

int e2 = 2 * err;
if (e2 > -dy)
{
err -= dy;
x1 += sx;
}
if (e2 < dx)
{
err += dx;
y1 += sy;
}
}
}

// Function to implement DDA Line Drawing Algorithm


void drawLineDDA(int x1, int y1, int x2, int y2)
{
int dx = x2 - x1;
int dy = y2 - y1;
int steps = abs(dx) > abs(dy) ? abs(dx) : abs(dy);
float xInc = dx / (float)steps;
float yInc = dy / (float)steps;
float x = x1;
float y = y1;

for (int i = 0; i <= steps; i++)


{
glBegin(GL_POINTS);
glVertex2i(round(x), round(y));
glEnd();
x += xInc;
y += yInc;
}
}

// Function to draw "SYE"


void drawSYE()
{
glColor3f(1.0, 1.0, 1.0); // White color

// Drawing 'S' using Bresenham


drawLineBresenham(50, 150, 100, 150);
drawLineBresenham(50, 150, 50, 100);
drawLineBresenham(50, 100, 100, 100);
drawLineBresenham(100, 100, 100, 50);
drawLineBresenham(100, 50, 50, 50);

// Drawing 'Y' using DDA


drawLineDDA(120, 150, 140, 120);
drawLineDDA(140, 120, 160, 150);
drawLineDDA(140, 120, 140, 50);

// Drawing 'E' using Bresenham


drawLineBresenham(180, 150, 230, 150);
drawLineBresenham(180, 150, 180, 50);
drawLineBresenham(180, 100, 220, 100);
drawLineBresenham(180, 50, 230, 50);
}

// OpenGL display function


void display()
{
glClear(GL_COLOR_BUFFER_BIT);
drawSYE();
glFlush();
}

void init()
{
glClearColor(0, 0, 0, 1);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, 300, 0, 200);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(600, 400);
glutCreateWindow("Draw first three letter of my name 'SYE' using OpenGL");
init();
glutDisplayFunc(display);
glutMainLoop();
return 0;
}

Draw the Olympics Logo using Mid-point circle drawing


algorithm and fill it with different pattern attributes.
Output:
Code:

#include <GLUT/glut.h>
#include <cmath>

void drawCircle(int xc, int yc, int r)


{
int x = 0, y = r, d = 1 - r;
while (x <= y)
{
glBegin(GL_POINTS);
glVertex2i(xc + x, yc + y);
glVertex2i(xc - x, yc + y);
glVertex2i(xc + x, yc - y);
glVertex2i(xc - x, yc - y);
glVertex2i(xc + y, yc + x);
glVertex2i(xc - y, yc + x);
glVertex2i(xc + y, yc - x);
glVertex2i(xc - y, yc - x);
glEnd();
x++;
if (d < 0)
d += 2 * x + 1;
else
{
y--;
d += 2 * (x - y) + 1;
}
}
}

void drawOlympicRings()
{

int r = 50;
int x1 = 100, y1 = 200;
int x2 = x1 + 60, y2 = y1;
int x3 = x2 + 60, y3 = y1;
int x4 = x1 + 30, y4 = y1 - 60;
int x5 = x2 + 30, y5 = y4;

glColor3f(0, 0, 1);
drawCircle(x1, y1, r);
glColor3f(1, 1, 0);
drawCircle(x2, y2, r);
glColor3f(0, 0, 0);
drawCircle(x3, y3, r);
glColor3f(0, 1, 0);
drawCircle(x4, y4, r);
glColor3f(1, 0, 0);
drawCircle(x5, y5, r);
}

void display()
{
glClear(GL_COLOR_BUFFER_BIT);
drawOlympicRings();
glFlush();
}

void init()
{
glClearColor(1, 1, 1, 1);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, 500, 0, 400);
}

int main(int argc, char **argv)


{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(500, 400);
glutCreateWindow("Olympic Rings");
init();
glutDisplayFunc(display);
glutMainLoop();
return 0;
}

3. Create a class room scene using the algorithms that you have
learnt.
Output:

Code:

#include <GLUT/glut.h>

void drawCircle(int xc, int yc, int r)


{
int x = 0, y = r, d = 1 - r;
while (x <= y)
{
glBegin(GL_POINTS);
glVertex2i(xc + x, yc + y);
glVertex2i(xc - x, yc + y);
glVertex2i(xc + x, yc - y);
glVertex2i(xc - x, yc - y);
glVertex2i(xc + y, yc + x);
glVertex2i(xc - y, yc + x);
glVertex2i(xc + y, yc - x);
glVertex2i(xc - y, yc - x);
glEnd();
x++;
if (d < 0)
d += 2 * x + 1;
else
{
y--;
d += 2 * (x - y) + 1;
}
}
}

void drawTeacher()
{
// Teacher's body (Rectangle)
glColor3f(0.4f, 0.2f, 0.0f); // Brown color
glBegin(GL_QUADS);
glVertex2i(230, 230);
glVertex2i(270, 230);
glVertex2i(270, 300);
glVertex2i(230, 300);
glEnd();

// Teacher's head (Circle)


glColor3f(1.0f, 0.8f, 0.6f); // Skin color
drawCircle(250, 320, 20);

// Teacher's arms (Lines)


glColor3f(0.4f, 0.2f, 0.0f); // Brown color
glBegin(GL_LINES);
glVertex2i(230, 270); // Left arm
glVertex2i(180, 230);
glVertex2i(270, 270); // Right arm
glVertex2i(320, 230);
glEnd();
}

void drawStudent(int x, int y)


{
// Student's body (Rectangle)
glColor3f(0.4f, 0.2f, 0.0f); // Brown color
glBegin(GL_QUADS);
glVertex2i(x, y);
glVertex2i(x + 40, y);
glVertex2i(x + 40, y + 50);
glVertex2i(x, y + 50);
glEnd();

// Student's head (Circle)


glColor3f(1.0f, 0.8f, 0.6f); // Skin color
drawCircle(x + 20, y + 60, 15);
}

void drawClassroom()
{
// Draw walls
glColor3f(0.8f, 0.8f, 0.8f); // Light grey walls
glBegin(GL_QUADS);
glVertex2i(50, 50); // Bottom-left corner
glVertex2i(450, 50); // Bottom-right corner
glVertex2i(450, 350); // Top-right corner
glVertex2i(50, 350); // Top-left corner
glEnd();
// Draw floor
glColor3f(0.6f, 0.4f, 0.2f); // Brown floor
glBegin(GL_QUADS);
glVertex2i(50, 50);
glVertex2i(450, 50);
glVertex2i(450, 100);
glVertex2i(50, 100);
glEnd();

// Draw blackboard
glColor3f(0.0f, 0.0f, 0.0f); // Black color
glBegin(GL_QUADS);
glVertex2i(100, 300);
glVertex2i(400, 300);
glVertex2i(400, 350);
glVertex2i(100, 350);
glEnd();

// Draw teacher
drawTeacher();

// Draw students
drawStudent(60, 150); // First student
drawStudent(120, 150); // Second student
drawStudent(180, 150); // Third student
drawStudent(240, 150); // Fourth student
drawStudent(300, 150); // Fifth student

// Draw benches (for students)


glColor3f(0.4f, 0.2f, 0.0f); // Brown color for benches
glBegin(GL_QUADS);
glVertex2i(60, 120); // First bench
glVertex2i(100, 120);
glVertex2i(100, 150);
glVertex2i(60, 150);
glEnd();
glBegin(GL_QUADS);
glVertex2i(120, 120); // Second bench
glVertex2i(160, 120);
glVertex2i(160, 150);
glVertex2i(120, 150);
glEnd();
glBegin(GL_QUADS);
glVertex2i(180, 120); // Third bench
glVertex2i(220, 120);
glVertex2i(220, 150);
glVertex2i(180, 150);
glEnd();
glBegin(GL_QUADS);
glVertex2i(240, 120); // Fourth bench
glVertex2i(280, 120);
glVertex2i(280, 150);
glVertex2i(240, 150);
glEnd();
glBegin(GL_QUADS);
glVertex2i(300, 120); // Fifth bench
glVertex2i(340, 120);
glVertex2i(340, 150);
glVertex2i(300, 150);
glEnd();
}

void display()
{
glClear(GL_COLOR_BUFFER_BIT);
drawClassroom();
glFlush();
}

void init()
{
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(0, 500, 0, 400);
}

int main(int argc, char **argv)


{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(500, 400);
glutCreateWindow("Classroom Scene with Teacher and Students");
init();
glutDisplayFunc(display);
glutMainLoop();
return 0;
}

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