Add Aurora Night Effect

Release 0.14.3

STPAurora

To improve realism of night time, we also add a procedurally generated and rendered aurora and enable its rendering in SuperDemo+. Aurora renderer can be found in STPAurora.

General fixes and improvement

• Disambiguate conversion of some types in STPTerrainParaLoader.
• Add a new function to clear texture image for STPTexture.
• Formalise and clarify copyright notices for several 3rd-party licenses.

STPScenePipeline

• Improve robustness of light capacity checking when add a new light.
• For performance consideration, the first environment object is not forced to be drawn even when visibility is zero.
  • Instead, the environment area is cleared to black before drawing, or user-defiend clear colour if no environment object is available.
  • Post process buffer colour attachment is no longer cleared every frame because this already guarantees to draw over the whole screen every frame, even when there is no environment object.
  • Aerial perspective now works even when there is no environment object.
  • Environment clear colour is set to black when there is at least one environment object presented in the scene pipeline, or user-defined value if none.
• Refactor some function calls.
• Fix a bug that the ambient occlusion output framebuffer does not have stencil attachment causing computation to be done to the whole screen.
• Remove inline definitions for add() function in STPScenePipeline.
  • Now, if you are going to add a shadow opaque object, you need to call the add() function with the same opaque object twice, each time it will be cast to non-shadow opaque object and shadow opaque object implicitly.

STPSun

• Add a new setting to allow specifying the start of the year.
• Change the timing specification from the discrete tick to continuous second.
• Simplify sun orbiting calculation.