OpenGL Adventures - Endless Runner in OpenGL

Project Overview

Simple endless runner game made with C++ with openGL API and freeglut library. The absolute pain of working with C++ and decade-old freeglut library was worth it. I learned a lot about OpenGL and C++ in the process. I wish I could make it look more good… but we tried our best not to use any external library.

Challenges

The most challenging part of this project was to make the Synthwave-ish background. I had to use a lot of math and trigonometry to make it work. I also had to use a lot of math to make the player jump and fall in a realistic way. The discussed game is a 2D endless runner game. Due to this, the background scenery must scroll in a direction to give the impression that the player is moving forward. In addition, it must also scroll infinitely until the game comes to an end. The major challenge faced when implementing a scrolling background is ensuring the loop is seamless. It is important to hide the fact that one single image is being used to portray the background scenery. In this case, a seamless loop is essential to create an illusion that the background is scrolling infinitely. If it is the contrary, where the loop is not seamless and the player can spot the obvious joints, it would ruin the illusion and make apparent that the same image is being scrolled in a loop. To seamlessly animate the stars, the field, and the road, the game updates the value of the X-axis (distance of the object from the left edge of the screen) of each individual object when rendering each frame, instead of creating new objects. This makes the game performance-friendly and reduces the stress on the CPU (instantiating new objects). The X-axis coordinate value resets when the object reaches the furthest left side of the image. To emulate depth perception or the parallax effect, these three things must move at different speeds. It generates the illusion that the road is closer to the player than the field, and finally, the stars are the most distant. The sun is intentionally kept still since large celestial objects in the sky don’t seem to move in the real world when viewing while moving. The lines in the field are generated with a loop. For the horizontal lines, the distance between them decreases gradually. These types of lines are not animated. For the vertical lines, they are initially backward leaning when on the right portion of the screen. When moving from right to left, the lines smoothly get straight in the middle and finally forward-leaning when on the left side. This is done by X coordinates of the top-end of the line differently than the bottom-end of a line. With the combination of the vertical and the horizontal lines, it gives the impression of a 3-dimensional open space, which is in fact, drawn with 2D shapes on a 2D plane.

Please check out the full report for more details.