Everyone uses them!

In this tutorial, we’ll focus on the concept of a Coordinate System which is used as our very foundation for positioning every object that we need to draw. Whether we’re rendering a menu system, our player avatar, explosion sprites or
even our high score list, we’re taking advantage of the coordinate system to ensure everything’s in the right place.

While there’s some slight variance between the two implementations, both OpenGL and Direct3D use the same coordinate system, known as the Cartesian Coordinate System. It may ring some bells, because it’s the same coordinate system that you were taught in grade…5 or 6(?).

With the origin of our world always at (0,0,0), the positive Y-axis points straight up and the positive X-axis points to the right. The positive Z-axis either points away from you (into the screen) or towards you (out of the screen). This Z-axis difference depends upon if you are using the Left-Handed or Right-Handed system.

Left-Handed vs. Right-Handed

The only difference between the coordinate system implementation of OpenGL vs. the coordinate system implementation of Direct3D is the direction of the positive Z-axis. The Left-Handed coordinate system is used by Direct3D so as you travel further into your scene, you are increasing the Z-coordinate. Contrast that with the Right-Handed coordinate system employed by OpenGL in which as you travel further into your scene, you are decreasing the Z-coordinate.

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