@ -39,10 +39,10 @@ GLSL stands for openGL Shading Language, which is the specific standard of shade
## Why are Shaders famously painful?
As Uncle Ben said “with great power comes great responsibility,” and parallel computation follows this rule; the powerful architectural design of the GPU comes with its own constrains and restrictions.
As Uncle Ben said “with great power comes great responsibility,” and parallel computation follows this rule; the powerful architectural design of the GPU comes with its own constraints and restrictions.
In order to run in parallel every pipe, or thread, has to be independent from every other thread. We say the threads are *blind* to what the rest of the threads are doing. This restriction implies that all data must flow in the same direction. So it’s impossible to check the result of another thread, modify the input data, or pass the outcome of a thread into another thread. Allowing thread-to-thread communications puts the integrity of the data at risk.
Also the GPU keeps the parallel micro-processor (the pipes) constantly busy; as soon as they get free they receive new information to processes. It's impossible for a thread to know what it was doing in the previous moment. It could be drawing a button from the UI of the operating system, then rendering a portion of sky in a game, then displaying the text of an email. Each thread is not just **blind** but also **memoryless**. Besides the abstraction require to code a general function that changes the result pixel by pixel depending on its position, the blind and memoryless constraints make shaders not very popular among beginning programmers.
Also the GPU keeps the parallel micro-processor (the pipes) constantly busy; as soon as they get free they receive new information to process. It's impossible for a thread to know what it was doing in the previous moment. It could be drawing a button from the UI of the operating system, then rendering a portion of sky in a game, then displaying the text of an email. Each thread is not just **blind** but also **memoryless**. Besides the abstraction required to code a general function that changes the result pixel by pixel depending on its position, the blind and memoryless constraints make shaders not very popular among beginning programmers.
Don't worry! In the following chapters, we will learn step-by-step how to go from simple to advanced shading computations. If you are reading this with a modern browser, you will appreciate playing with the interactive examples. So let's not delay the fun any longer and press *Next >>* to jump into the code!
Patricio Gonzalez Vivo
10 years ago