Computer Graphics Basic (With Code)

 A pixel is one of the many tiny dots that make up the representation of a picture in a computer's memory.

Computer graphics can be created as either raster or vector images

1.      Raster Image - Pixel Based

2.      Vector Image - Mathematical Based

Raster image drawbacks –

·        Dpi(dots per inch)

·        Larger than vector in size

·        Less economical

Raster image advantages – User end friendly

Raster image formats – Tiff, Jpeg, Gif, Pcx, Bmp

Vector image drawbacks- Not suitable for complex graphic displays. Rasterization required for display.

Vector image advantages-

·        More malleable

·        More versatile

·        No upper or lower limit for sizing

Vector image formats- Ai, Eps, Cgm, Wmf, Pict(macOS)

Color Models- RGB and CMYK

Code	Color
W	White
R	Red
G	Green
B	Blue
C	Cyan
M	Magenta
Y	Yellow
K	Black

RGB – Additive Color

CMYK – Subtractive Color

C=G+B=W-R

M=R+B=W-G

Y=R+G=W-B

3 bit RGB = (2¹)³ = 8 ; [1 bit each color]

6 bit RGB = (2²)³ = 64 ; [2 bit each color]

Color Code	RGB
B	001
G	010
R	110
C	011

*RGB intensity value 0 to 255

                          

Color Palette: Color palette is a finite set of colors. CMYK range is 0 to 100%.

Example:

Color	RGB	CMYK
White	255,255,255	0,0,0,0

 

(Code for understanding and comment for describe what are the works of fucntion)

#include<GL/gl.h>

#include<GL/glut.h>

void display(void)

{

    glClear (GL_COLOR_BUFFER_BIT); //clear the pixels of previous code

    glColor3f(1.0,1.0,1.0);

    glBegin(GL_TRIANGLES); //Beginning of drawing triangle

    //2d Shape

    glVertex3f(0.5f,0.7f,0.0f);

    glVertex3f(0.9f,0.75f,0.0f);

    glVertex3f(0.54f,0.73f,0.0f);

    glEnd(); //End of drawing triangle

    glFlush(); //force execution of GL commands in finite time

}

void init (void) //new function

{

    glClearColor(0.0,0.0,0.0,0.0); //Select clearing (Background) Color

    glMatrixMode(GL_PROJECTION); //The value we use, it will be initialized through this function

    glLoadIdentity(); //replaces the current matrix with the identity matrix

    glOrtho(0.0,1.0,0.0,1.0,-10.0,10.0); //size of x-y-z axis like graph paper

}

int main(int argc, char** argv) //argc stands for argument count and argv stands for argument values. These are variables passed to the main function when it starts executing

{

    glutInit(&argc, argv); //is used to initialize the GLUT library

    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //display modes: Single and RGB

    glutInitWindowSize(600,600); //windows size

    glutCreateWindow("Hello"); //title of windows

    init(); //call and commit the function

    glutDisplayFunc(display); //call the display function

    glutMainLoop(); //use for change shape by keyboard

    return 0;

}