GFX Part 2 - Introduction to GPU Programming
This document discusses the C, F, F APIs in GPU programming, specifically clear, flush, and finish. It explains that clear clears the target view area to the specified color. Flush ensures pending operations are kicked off but does not wait for completion, while finish ensures operations are kicked off and waits for completion. It also discusses how clear can help the GPU avoid unnecessary memory reads by discarding previous content. Deferred rendering is described as the GPU applying intelligence to determine what draw calls or portions of draw calls need to be executed. The role of viewport in determining the draw area is also mentioned. WebGL handles initial platform configuration through the browser, while native code requires handling display, surface, and context creation directly through APIs like
GFX Part 2 - Introduction to GPU Programming
- 2. 2014THE C,F,F (CLEAR, FLUSH, FINISH) APIS Clear Clears the current target view area (entire screen – FBO or Fb) Is that it ? Sequence 1 Draw something <frame1> Draw something <frame2> Sequence 2 Draw something <frame1> Clear Draw something <frame2> The role of the GPU internal cache / fast memory Engine by default reads back from fb By specifying “Clear” – the engine can eliminate reads Further extensions allow discard as well Viewport determines the draw area
- 3. 2014FLUSH, AND FINISH Several types of rendering methods adopted by GPUs Immediate rendering Deferred rendering Immediate rendering – everyone is happy Except the memory bus! Deferred – the GPU applies its “intelligence” to do/not do certain draw calls/ portions of draw calls Used most commonly in embedded GPUs No concept of “bit exactness” in Graphics rendering Hence, some API calls may not finish intended operations Flush() – The call ensures pending operations are kicked off, returns Finish() – The call ensures pending operations are kicked off, “waits for completion”, returns
- 4. 2014A NOTE ON WEBGL – VS NATIVE CODE In native code, need to handle creation of a Display, Surface, Context For example, refer to this native code (sgxperf) eglGetDisplay eglInitialize – for this display eglBindAPI – bind to GLES/ VG context eglChooseConfig – configure surface type, GLES1/2/VG, Depth/Stencil buffer size eglCreateWindowSurface / eglCreatePixmapSurface eglCreateContext eglMakeCurrent eglSwapBuffers But Platform initialisation in WebGL is handled by browser Only configurations are – stencil, depth, AA, Alpha, preserve No EGL calls in JS application code No multi-threading issues (not yet, but “workers” are coming) The hands on labs will focus on GL (rendering), not EGL (platform) Lab framework
- 5. 2014 FUNCTIONS/API CALLS TO BE MODIFIED IN THE FRAMEWORK Provided in the workshop notes 5 Lab
- 6. PROGRAMMING ClearColor Clear – clears with color specified earlier Flush/ Finish First Lab Exercise
- 7. 2014LAB L1 – CLEAR COLOUR, VIEWPORT 7 (Clone Lab) (Edit Render code) (Launch Personal Lab) (Relaunch after Edit) (Launch Lab)