Adding postprocessing effects to Synthesia

[Chompy]

I'm not really talking about the Video Creator, but gameplay-wise, adding postprocessing effects (shaders) to the gameplay could be a very fun way to spice things up.

Each shader would need to be on either Vulkan (if not on Apple Silicon) or Metal (if on Apple Silicon), as GLSL is old and is being phased out.

Here are some of the possible shaders that could be applied from the Settings menu:

- Gameboy (A green colour palette resembling the original Gameboy screen from 1989, without any backlight)

- 8-Bit: Reduces the colours of Synthesia to just 8 colours. A fun throwback to the good old 90s videogame console days.

- 16-Bit: Reduces the colour count of Synthesia to just 16 colours. Another fun throwback to the old videogame console days.

- Old Movie: Does what it says. Makes Synthesia look like an old movie with all colours replaced by sepia.

- Negative: Reverses the colours of Synthesia (some hardcoded colours cannot be reversed)

- Black and White: Removes the colours of Synthesia, causing it to be black and white.

- Glow: Makes bright colours (like particles) glow. Also known as bloom.

- Frosted: Make Synthesia look like you were playing it through an old glass window! To make this less of a frustration, a slider will be implemented to tone this up or down. This shader's intensity is reduced by 50% as a default value.

- Custom: Make your own shaders for Synthesia and apply them.

Shaders can also be combined to create fun effects, etc. Extending them to the Video Creator would be fun too, but may require some work.

As a side note, any shader should be able to have it's parameters and settings adjusted in the Shaders part of the Settings menu. This is where you'd also apply the shader, preview it, etc. If a shader were to produce an error, Synthesia would display an error message and either stop using the shader or not use the shader at all.

This idea would also be extremely fun for children of all ages and for everyone of any age.