Ambient Occlusion

Release 0.11.8

Screen-space ambient occlusion

The focus in this release is the newly added STPAmbientOcclusion for performing SSAO which allows us to see the details on the terrain even when it is in shadow. The shader implementation can be found in STPScreenSpaceAmbientOcclusion.glsl. As always, the effect is configurable and the settings are located in STPOcclusionKernelSetting.

Also we introduced STPGaussianFilter which is a separable Gaussian blur kernel. It features a configurable Gaussian function. This class is currently used by the ambient occlusion calculator for blurring the final output.

Improve off-screen rendering

We refactor STPScreen into two sub-classes, STPScreenVertexShader and STPScreenVertexBuffer. This allows sharing vertex shader during initialisation among all off-screen renderers and vertex buffer during rendering to safe memory and reduce number of binding operations.

Additionally each STPScreen base instance contains a STPProgramManager with some helper functions to simplify the process for setting up off-screen rendering. Please keep in mind that drawScreen() function no longer binds vertex buffer automatically, binding and program usage needs to be done by the user externally.

Also add STPSimpleScreenFrameBuffer under STPScreen as a refactor class for single color attachment off-screen rendering.

General fixes and improvement

• Add a texture barrier call in the main rendering loop before deferred light pass to ensure data safety since there might still be a potential feedback loop problem.
• Add extra static_assert for camera buffer struct to ensure the alignment is consistent with OpenGL std430 alignment rule.
• For loading INI into the program, all setting names are made inlined to make it more readable. Add INI loader function for ambinent occlusion settings.
• Simplify spectrum generation shader. Remove explicit uniform for spectrum size since it can be queried by calling imageSize.
• Change memory barrier function post spectrum generation from image access barrier to texture fetch barrier.
• Fix a bug in STPSunSpectrum for forgetting to assign a sampler binding to the shader. This did not lead to error as OpenGL assigns sampler binding 0 by default.
• STPPostProcess now holds its own memory rather than taking it from the scene pipeline.
• Add new function in STPFrameBuffer to allow detaching a target.
• All color buffers are explicitly cleared instead of relying on the fact that they are all overdrawn to avoid running into bugs in the future.