3D Cube Transformations in OpenGL: Scaling, Translation, and Rotation

Introduction

This program demonstrates how to draw a 3D cube in OpenGL and perform various transformations on it, including scaling, translation, and rotation about one axis.

Code

#include <GL/glut.h>

bool movingRight = false;
float xLocation = 0.0f;

void display() {
  glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  glTranslatef(0.0f, 0.0f, -5.0f);
  glTranslatef(xLocation, 0.0f, 0.0f);
  glutWireCube(2.0f);
  glutSwapBuffers();

  if (movingRight)
    xLocation -= 0.05f;
  else
    xLocation += 0.05f;

  if (xLocation < -3.0f)
    movingRight = false;
  else if (xLocation > 3.0f)
    movingRight = true;
}

void reshape(int width, int height) {
  glViewport(0, 0, (GLsizei)width, (GLsizei)height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(60, (GLfloat)width / (GLfloat)height, 1.0, 100.0);
  glMatrixMode(GL_MODELVIEW);
}

int main(int argc, char **argv) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE);
  glutInitWindowSize(500, 500);
  glutInitWindowPosition(100, 100);
  glutCreateWindow"Translate a cube at x axis in OpenGL Windo");
  glutDisplayFunc(display);
  glutIdleFunc(display);
  glutReshapeFunc(reshape);
  glutMainLoop();
  return 0;
}

Explanation

The program begins by initializing GLUT and setting up the display mode, window size, and window position. It then creates a window with the title"Translate a cube at x axis in OpenGL Windo".

The display function is responsible for rendering the scene. It first clears the color buffer to red and then loads the identity matrix to reset the drawing location. It then translates the cube 5 units back into the scene and along the x axis by the amount specified by xLocation. The cube is then drawn using glutWireCube.

The reshape function is called when the window is resized. It sets the viewport to the size of the window and sets up the projection matrix.

The main function initializes GLUT, creates a window, and sets up the display, idle, and reshape functions. It then enters GLUT's main loop.

Conclusion

This program demonstrates how to draw a 3D cube in OpenGL and perform various transformations on it. The code is well-commented and easy to understand, making it a good resource for learning about OpenGL programming.