Coloring Window by Pixel

[cfpbiggs]

I saw a discussion post from 2022 about copying pixels to a window surface, but the question revolved more around a bug that user encountered than the process of writing/copying the pixels itself.

My question is this: what is the recommended workflow/set of functions for writing the colors of individual pixels to a window? For context: I am trying to write my own rendering engine (no intention of it being a good one, just that it works), and I have a series of compute shaders that will raytrace an object and return the rgba values for a given pixel. Unfortunately, I'm a bit lost in regards to actually updating the window with those pixel colors once I have them in-hand. Any help would be greatly appreciated!

[SludgePhD]

In order to render anything to a window, you need to acquire a Surface first (typically from a RawWindowHandle you get from the winit crate). You have to call Surface::configure to set its size to that of the window (or it can be a fixed size for convenience), and then Surface::get_current_texture to obtain a Texture you can render to.

The Texture this gives you is only guaranteed to support RENDER_TARGET usage, but you can request others during surface configuration if you want (which may not work on other systems). You can then either use a fragment shader to render to this surface texture, or use a compute shader (which sounds like it might be easier in your application to get started).

After you've submitted some work that writes to the surface texture you then have to call .present() on the surface to display it in the window.

(I'm not aware of a simpler way of doing this with just wgpu, but there might be other libraries that make this easier)

[SludgePhD]

You can probably use the hello_triangle example as a starting point, it shouldn't be too difficult to integrate your compute shader into it: https://github.com/gfx-rs/wgpu/blob/b34219ca214caea2af86dbb64a2a2b613ea5198c/examples/src/hello_triangle/mod.rs