Optimizing Cython code by writing less Python and more C

In this recipe, we will consider a more complicated Cython example. Starting from a slow implementation in pure Python, we will use different Cython features to speed it up progressively.

We will implement a very simple ray tracing engine. Ray tracing consists of rendering a scene by simulating the physical properties of light propagation. This rendering method leads to photorealistic scenes, but it is computationally intensive.

Here, we will render a single sphere with diffuse and specular lighting. First we'll give the example's code in pure Python. Then, we will accelerate it incrementally with Cython.

Note

The code is long and contains many functions. We will first give the full code of the pure Python version. Then, we will just describe the changes required to accelerate the code with Cython. The entire scripts are available on the book's website.

How to do it…

1. First, let's implement the pure Python version:

   In [1]: import numpy as...