GDSC KIIT Huddle Session 4 - "Graphics Pipelining"
- 1. 27th August, 2023 Session 4: Graphics Pipelining
- 2. Introduction
- 7. Layers •
- 8. Wallpaper layer Your phone has multiple layers / planes where components of your display reside: Recents layer Icon and widget layer Notification-shade layer Application layer
- 9. Recap… • Scenesarejustacombinationofmultiplelayers. • Layersareessentiallypartsofadesktopcomprisingascenethathousea particularelementsuchasapplications/wallpaper/icons.Simplyputthey containvarioustextures. • Compositionistheprocessofcreationofscenes.Acompositorperforms composition.
- 12. OpenGL
- 13. WhatisOpenGL? OpenGL is an interface to talk to the GPU with the aforementioned GLSL language. We can tell the GPU exactly what to draw and where, it will do exactly that and nothing more. Eg: Fill the entire display with black pixels and draw 1 red pixel at the coordinate (10,10) .(10,10)
- 14. Buffers
- 16. TypesofBuffers: ● A special type of buffer which is only used for dumping pixel data and is not actually drawn to the screen. Renderbuffer: 01 ● The buffer where applications cannot write their pixel data to, but can be presented to the screen. DisplayBuffer: 02
- 19. • Imagineyourcomputermonitororscreenasawindowthrough whichyouseethedigitalworld.Therefreshrateislikethespeed atwhichthiswindowupdatestheimagesitdisplays.It'smeasured inHertz(Hz),whichrepresentsthenumberoftimespersecond thescreenrefreshesorupdates. • Soessentiallyspeaking,weneedtoupdatethescreen60times everysecondtokeepthesceneup-todatewiththebuffer content. • Whileahigherrefreshrateisgreatforgamingorwatchingaction- packedvideos,fortaskslikereadingdocumentsorcoding,a lowerrefreshratemightworkjustfinewithoutaffectingyour experience.
- 21. VariableRefreshRate What if your GPU's rate of creating scenes doesn't match the refresh rate of your montior? EG: Your GPU is producing 100 frames per second, however your monitor is a 60 Hz monitor. Outcome: You won't be able to view any new frames unless the previous ones have been flushed out of the buffer. Another possible outcome is stuttering all over your screen. This is where VRR comes in: Variable Refresh Rate (VRR) is like a real-time communication between your monitor and graphics card. It adjusts the screen's refresh rate based on how fast your graphics card is working, preventing issues like screen tearing and stuttering during tasks like gaming. This technology, found in NVIDIA G-Sync and AMD FreeSync, ensures smoother and more synchronized visuals, enhancing your overall experience.
- 22. DamageTracking Now, what do you think happens when none of the buffers that make up a scene change between any of the frames in 1 render cycle ( 60 times per second / 60 hz). Answer: None of the scene components change however we're still drawing the scene 60 times per second which is very wasteful of resources and computing time! Eg: If you want to change 1 part of your drawing, would you rather trash it all or just redraw the required area? This is where damage tracking comes in: Damage tracking in rendering involves keeping track on which parts of a scene need to be redrawn. When objects change or move, only those portions are recalculated and redrawn, saving computational resources. It's like updating only the altered parts of a painting instead of redoing the entire artwork. This efficient process helps in faster image generation and is crucial for real-time graphics, as it optimizes rendering workload for better performance.
- 24. This is known as "tearing" and it is the compositors task to fix. Lets try to understand the problem by breaking it down into digestible chunks.
- 26. • Toavoidtheabovediscussedproblemwemakesurenew scenesaredumpedintoa"renderbuffer"whichis specificallyusedfordrawing.Afterdrawingiscomplete,it isswappedwithanotherbufferknownasthe"display buffer". • Asyoucansee,thissolvedthepreviousrace.Oncethe applicationisdonewritingtotherenderbuffer,theold displaybufferbecomesthenewrenderbuffer.Whilethe currentrenderbufferbecomesthenewdisplaybufferand getsdrawntothescreen. • Hencenewupdatestotheapplicationwillnotstartwriting tothebufferwhichisbeingusedtopresent,thereby solvingtearing.
- 30. • Writerenderes/contributetocomplexgraphicssoftwaresuchasblender Sowhereexactly isthisknowledgeused? • Compositors. • Scientificemulationsandvisualizations • VirtualReality(VR)andAugmentedReality(AR)
- 32. click to see visual effects
- 34. • ThankYou!