Use of shaders

[MiguelMJ]

The lights with the fade flag on currently use a custom texture (at least in RadialLight). This should be replaced by the usage of a shader, also because of the customiaztion it would allow through setUniform (for example to change fade linearity). Also, this can lead for better effects of light in the future (blur the edges of the light for softer lights).

Potentially useful resources:

• https://www.sfml-dev.org/tutorials/2.5/graphics-shader.php
• https://www.sfml-dev.org/documentation/2.5.1/classsf_1_1Shader.php
• https://learnopengl.com/Getting-started/Shaders
• https://github.com/DaiMysha/LightSystem/blob/dev/shaders/lightAttenuation.frag
• https://glusoft.com/tutorials/sfml/shader-example
• https://oprypin.github.io/crsfml/tutorials/graphics/shader.html