What's the proper way to go about render_to_texture in 2D?

[Teajey]

I'm in over my head trying to mimic the 3d/render_to_texture.rs example in 2D so that I can render my game in a fixed-size image inside the window. I'm getting this error:

thread 'main' panicked at 'wgpu error: Validation Error

Caused by:
    In a RenderPass
      note: encoder = `<CommandBuffer-(0, 1, Vulkan)>`
    In a pass parameter
      note: command buffer = `<CommandBuffer-(0, 1, Vulkan)>`
    Attempted to use a texture (9, 1, Vulkan) mips 0..1 layers 0..1 with conflicting usages. Current usage RESOURCE and new usage COLOR_TARGET. COLOR_TARGET is an exclusive usage and cannot be used with any otherusages within the usage scope (renderpass or compute dispatch).

Does anyone have any immediate insight into what this means? I've basically just initialized an Image in the exact same way as in 3d/render_to_texture.rs, but set it as the render target of a Camera2dBundle rather than a Camera3dBundle. Perhaps Image requires a different configuration for 2D? I wouldn't know where to start

[grace125]

I got the same error because I didn't add the RenderLayers component to the 2d camera that rendered to texture. This seems to also happen whenever this camera's RenderLayers component contains layer 0. Here's some docs if it's at all helpful.

[Teajey]

I'm using let second_pass_layer = RenderLayers::layer(1); which I've inserted on the Image, and the Camera2dBundle with priority: 1 that renders that Image.

It's flipped from the example 3d/render_to_texture.rs which instead attaches the extra render layer to the first pass. But I think what I'm doing is right because I want to render everything to the Image by default, and then render the Image to the window in the second pass.

[Teajey]

I've found my mistake was attaching my render target to an ImageBundle rather than a SpriteBundle. That's about the extent of my understanding.

Now I'm dealing with a problem where my UI is rendering to both cameras, but that's another story 🙂🙂

It would be really nice to see an example of how to properly render to texture in 2D; would probably make for a simpler example too!

[fossegutten]

Do you have example code? I am struggling with some similar errors

[Teajey]

What does your error look like?

[rumbogs]

Hey @Teajey , I have the exact same requirement, can you share an example of how you fixed it?

Not sure I understand what ImageBundle you are referring to.

In my case I'm attaching the RenderTarget to the Camera:

                    commands.spawn_bundle(Camera2dBundle {
                        camera: Camera {
                            target: RenderTarget::Image(image_handle.clone()),
                            // renders after the main camera which has default value: 0
                            priority: 1,
                            ..default()
                        },
                        ..default()
                    })

[Teajey]

I'm referring to ImageBundle and SpriteBundle. Are you seeing the exact same wgpu error: Validation Error as me?

In my case I fixed this error by rendering the image to a SpriteBundle instead of an ImageBundle:

    commands
--      .spawn_bundle(ImageBundle {
--          image: UiImage::from(image_handle),
++      .spawn_bundle(SpriteBundle {
++          texture: image_handle,
            ..default()
        })
        .insert(second_pass_layer)
        .insert(GameScreen);

[rumbogs]

Thanks for the reply. Almost the same, the command buffer is a bit different, but I think that's expected since it's a different arhitecture. I'm rendering to a Mesh 2D though so this doesn't apply to my issue.

[hakolao]

I don't think using a SpriteBundle really is the solution here. It's a workaround. However, you should be able to use ImageBundle by disabling ui rendering from the secondary camera as explained here in #6181.

Add UiCameraConfig { show_ui: false }, to the camera with second_pass_layer.