edit to add: The very helpful author of RenderDoc told me on Twitter that the command line capture utility is meant as an internal thing, and not for general use. So don’t complain if this breaks in the future. Also, he said that my “
--opt-ref-all-resources” is probably superfluous in most cases and will generally bloat the capture for no benefit.
One of the things I really like about Vulkan vs. OpenGL is that Vulkan is “offscreen by default” while OpenGL depends on the windowing system. With Vulkan, you can just allocate some space for an image, and draw/compute to that image. You can pick which specific device you are using, or do it once for every device. If you want to display the image, blit it to the swapchain. With OpenGL, you tend to need to open a Window with certain options, initialize OpenGL and create a Context using that Window handle, and use one of several extensions for offscreen rendering. (Probably FBO, maybe PBO. It’s an archaeological expedition through revisions of the spec and outdated documentation to be sure exactly what to do.)
Consequently, it is muuuuuch easier to make a “little” Vulkan application (that admittedly depends on a not-so-little engine/library with a bunch of boiler plate and convenience code) that does one thing off screen and exits without needing to pop up anything in the GUI as a part of the process.
This naturally raises the question… How are you sure that little utility actually does what you told it to?Continue reading