OpenGL ES: Going 3D

Abstract

Super Jumper worked out rather well with the 2D OpenGL ES rendering engine. Now it’s time to go full 3D. We actually already worked in a 3D space when we defined our view frustum and the vertices of our sprites. In the latter case, the z coordinate of each vertex was simply set to 0 by default. The difference from 2D rendering really isn’t all that big:

• Vertices have not only x and y coordinates, but also a z coordinate.

• I nstead of an orthographic projection, a perspective projection is used. Objects further away from the camera appear smaller.

• Transformations, such as rotations, translations, and scales, have more degrees of freedom in 3D. Instead of just moving the vertices in the x–y plane, we can now move them around freely on all three axes.

• We can define a camera with an arbitrary position and orientation in 3D space.

• The order in which we render the triangles of our objects is now important. Objects further away from the camera must be overlapped by objects that are closer to the camera.