===== Differences between the CPU and GPU light model =====




1. Interpretation of specular and shininess reflection

{{ :tutorials:light-spec_vs_shiny2.png?direct&600 |}}

=====  =====

2. Interpretation of transparency of image textures

3. Implementation of the //GrinClonerNode// behaviour
    * CPU (Twilight) implementation: repeats objects only into first quadrant
    * GPU (Flux) implementation: repeats objects into all four quadrants

{{ :tutorials:light-gridcloner.png?direct&600 |}}

4. Only in the Twilight light light model the additional function of //getReceivedPower//, //getReflectedPower//, //getTransmittedPower//, //getAbsorbedPower//, and //getHitCount// are implemented. See: [[:02_user_tutorials:20_light:01_first_steps:15_more_light_functions| More light model functions... beyond getAbsorbedPower ]]

5. The twighlight model only handles skies with sky-shaders as light sources. Hence, the cloud texture does not act as a light source. GPUFlux handles any sky as light source, independent of the shader it uses. This allows the user to create its own sky light source. As a consequence, the cloud texture also acts as a light source, resulting in the dominantly blue lighting on some scenes. This was a deliberate choice to make the sky objects more flexible.