Multi Sub-Pass & Multi Render-Target Shading In Vulkan : Performance Based Comparison In Real-time

Background. Games today are becoming more complex in computational andgraphical areas. Companies today want to develop games with state of the artgraphics while also having complicated and complex game logic. The vast majorityof users rarely meet the computer requirements. This creates an issue which lim-its the target demographic that a company wants to meet. This thesis will focuson two different methods that achieves deferred shading in Vulkan and how the en-vironment is affecting both methods as-well as the number of lights and attachments. Objectives. In Vulkan there are two ways of implementing deferred shading, one isthe traditional way of doing it which is by conducting multiple render-targets. Thesecond way is by utilizing a feature unique to Vulkan known as sub-passes. Our aimis to conduct experiments with these two ways of implementing deferred shading todetermine which one is the most optimal for a given situation. These situations willvary depending on the number of visible objects and number of lights in the scene. Methods. The experiments are conducted by a rendering system that have beenimplemented by us. By implementing both suggested deviations of the renderingtechnique ’deferred shading’ the data collected will suffer less from unexpected andunknown variables than it would if the implementations were taken from a separatesource. The experiments that will be conducted intend to measure performance met-rics in the form of average frames per second as well as average render frame time(inseconds). To measure the time performance metric, the system shall utilize Vulkan’ssupport for gpu-timestamping[7]. To provide reliable measurements without any un-warranted errors each rendering deviation will utilize pre-recorded command buffers. Conclusions. This thesis has shown that using multiple sub-passes within a singlerender-target performs faster write operations to the attached render attachments.This result in less memory bandwidth which leads to a faster geometry pass. Theperformance gain from a faster geometry pass can be used somewhere else to en-hance different aspects of the game or graphical application. Having less memorybandwidth would result in a longer battery life on mobile phones and laptops