RGBA

Component	Name	Meaning	Range
R	Red	Red component	0 to 1
G	Green	Green component	0 to 1
B	Blue	Blue component	0 to 1
A	Alpha*	Transparency	0 (complete) to 1 (none)

*More on Alpha later

#include "stdafx.h"

#include <GL/glut.h>

void mydisplay()

{

glClear(GL_COLOR_BUFFER_BIT); //clear the canvas

glColor3f(1.0, 1.0, 0.0); //set the color

glBegin(GL_TRIANGLES); //draw 1st triangle at default origin

glVertex2f(-0.5, -0.5);

glVertex2f(-0.5, 0.5);

glVertex2f(0.5, 0.5);

glEnd();

glTranslatef(0.5f, 0.5f, 0.0f); //shift the origin

glColor3f(1.0, 0.0, 0.0); //set new color

glBegin(GL_TRIANGLES); //draw 2nd triangle at translated origin

glVertex2f(-0.5, -0.5);

glVertex2f(-0.5, 0.5);

glVertex2f(0.5, 0.5);

glEnd();

glFlush();

}

int main(int argc, char** argv)

{

glutCreateWindow("A Triangle");

glutDisplayFunc(mydisplay);

glutMainLoop();

}

#include "stdafx.h" // Microsoft's precompiled header - required for Visual C++

#include <gl/glut.h> // also includes gl.h, glu.h

// Initialize OpenGL Graphics

void initGL()

{

// Set clearing color to black (for filling the background)

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

}

// Handler for window-paint event. Call back whenever window needs to be re-painted.

void display()

{

glClear(GL_COLOR_BUFFER_BIT); // Clear the color buffer with current clearing color

// Define shapes enclosed with a pair of glBegin and glEnd

glBegin(GL_QUADS); // Each set of 4 vertices form a quad

glColor3f(1.0f, 0.0f, 0.0f); // Red

glVertex2f(-0.8f, 0.1f); // Define vertices in counter-clockwise

glVertex2f(-0.2f, 0.1f);

glVertex2f(-0.2f, 0.7f);

glVertex2f(-0.8f, 0.7f);

glColor3f(0.0f, 0.0f, 1.0f); // Blue

glVertex2f(-0.7f, -0.6f);

glVertex2f(-0.1f, -0.6f);

glVertex2f(-0.1f, 0.0f);

glVertex2f(-0.7f, 0.0f);

glColor3f(1.0f, 1.0f, 1.0f); // White

glVertex2f(-0.9f, -0.7f);

glVertex2f(-0.5f, -0.7f);

glVertex2f(-0.5f, -0.3f);

glVertex2f(-0.9f, -0.3f);

glEnd();

glBegin(GL_TRIANGLES); // Each set of 3 vertices form a triangle

glColor3f(1.0f, 0.0f, 1.0f); // Magenta

glVertex2f(0.1f, -0.6f);

glVertex2f(0.7f, -0.6f);

glVertex2f(0.4f, -0.1f);

glColor3f(1.0f, 1.0f, 0.0f); // Yellow

glVertex2f(0.3f, -0.4f);

glVertex2f(0.9f, -0.4f);

glVertex2f(0.6f, -0.9f);

glEnd();

glBegin(GL_POLYGON); // The vertices form one closed polygon

glColor3f(0.0f, 1.0f, 1.0f); // Cyan

glVertex2f(0.4f, 0.2f);

glVertex2f(0.6f, 0.2f);

glVertex2f(0.7f, 0.4f);

glVertex2f(0.6f, 0.6f);

glVertex2f(0.4f, 0.6f);

glVertex2f(0.3f, 0.4f);

glEnd();

glFlush(); // Render now

}

// Main function: GLUT runs as a Console Application

int main(int argc, char** argv)

{

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

glutInitWindowSize(320, 320); // Set the initial Window's width and height

glutInitWindowPosition(50, 50); // Position the initial Window's top-left corner

glutCreateWindow("2D Shapes"); // Create window with the given title

glutDisplayFunc(display); // Register callback handler for window re-paint event

glutMainLoop(); // Enter infinitely event-processing loop

return 0;

}