Wgpu-rs: Question about `encoder.copy_texture_to_texture` with SwapChainTexture as the destination

[Neo-Zhixing]

I'm trying to draw a 2d texture directly onto the screen without vertices and shaders. Based on this Stackoverflow question it seems like all I have to do is copying the texture to the swap chain texture.

CommandEncoder::copy_texture_to_texture accepts a TextureCopyView as the destination

fn copy_texture_to_texture(
        &mut self,
        source: TextureCopyView,
        destination: TextureCopyView,
        copy_size: Extent3d,
    )

pub struct TextureCopyView<T> {
    pub texture: T,
    pub mip_level: u32,
    pub origin: Origin3d,
}

where T has type &'a Texture.

However, by calling SwapChain::get_current_frame() I get this:

pub struct SwapChainTexture {
    pub view: TextureView,
    detail: <C as Context>::SwapChainOutputDetail,
}

which only has a TextureView available to me.

I saw that for wgpu 0.3.0 there used to be a texture field in SwapChainOutput, which presumably can be used to construct my TextureCopyView. This was deleted in 0.4.0. So what would be the correct way to copy a texture to a SwapChainTexture?

Thank you for answering my question!

[cwfitzgerald]

Unfortunately due to compatibility, the only way to write data to the swapchain image is by rendering to it. In your case you should render a fullscreen triangle and copy from your framebuffer. This may end up being faster as there are a couple of optimizations drivers can do but only when they render.