OpenGL

OpenGL (Open Graphics Library) is a cross-platform, open-standard API (Application Programming Interface) for rendering 2D and 3D vector graphics. It is widely used in computer graphics, video games, CAD (Computer-Aided Design), virtual reality, and scientific visualization.

OpenGL provides a set of functions that allow developers to create and manipulate graphics objects and images. It abstracts the underlying hardware, enabling developers to write graphics programs without needing to understand the specific details of the hardware.

Example: Here’s a simple example of an OpenGL program written in C++ that initializes a window and draws a triangle:

#include <GL/glut.h>  // GLUT, include glu.h and gl.h

// Initialize OpenGL Graphics
void initGL() {
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set background color to black and opaque
    glClearDepth(1.0f);                   // Set background depth to farthest
    glEnable(GL_DEPTH_TEST);   // Enable depth testing for z-culling
    glDepthFunc(GL_LEQUAL);    // Set the type of depth-test
    glShadeModel(GL_SMOOTH);   // Enable smooth shading
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  // Nice perspective corrections
}

// Function to draw a triangle
void display() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear color and depth buffers
    glLoadIdentity();                 // Reset the model-view matrix

    glBegin(GL_TRIANGLES);            // Begin drawing the triangle
        glVertex3f(0.0f, 1.0f, 0.0f); // Top
        glVertex3f(-1.0f, -1.0f, 0.0f); // Bottom left
        glVertex3f(1.0f, -1.0f, 0.0f); // Bottom right
    glEnd();   // End of drawing the triangle

    glutSwapBuffers();  // Swap the front and back frame buffers (double buffering)
}

int main(int argc, char** argv) {
    glutInit(&argc, argv);            // Initialize GLUT
    glutInitDisplayMode(GLUT_DOUBLE); // Enable double buffered mode
    glutInitWindowSize(640, 480);     // Set the window's initial width & height
    glutInitWindowPosition(50, 50);   // Position the window's initial top-left corner
    glutCreateWindow("OpenGL Setup Test"); // Create window with the given title
    glutDisplayFunc(display);         // Register callback handler for window re-paint event
    initGL();                         // Our own OpenGL initialization
    glutMainLoop();                   // Enter the infinite event-processing loop
    return 0;
}