WebGPURenderer: support depth buffer copies in WebGLBackend.copyFramebufferToTexture

[aardgoose]

As title.

remove faulty viewport flipping, the test was inverted and the flip is not required for the WebGPUBackend now.
enable screenshots for backdrop node examples.

[sunag]

remove faulty viewport flipping, the test was inverted and the flip is not required for the WebGPUBackend now.

Great update in .copyFramebufferToTexture().

Just about the viewport flipping, this code is for WebGLBackend follow the WebGPU specifications, if you run the webgpu_shadertoy example on WebGLBackend it will open the viewport flipped.

[aardgoose]

Hi, The problem I saw is the isFlipY() code isn't working as intended in all cases. isFlipY() returns true for the GLSLNodeBuilder, which inserts code which fails to compile when using the webgpu_backdrop example as a test.

vec2( gl_FragCoord.x, .y - gl_FragCoord.y )

because

const resolution = viewportResolution.build( builder );

just returned an empty string.

Removing the code resulted in the webgpu_backdrop example rendering correctly for both backends, when initially it had rendered with the viewport texture inverted with WebGL (before the recent changes to ViewportNode).

[sunag]

I understand that this resolves to the webgpu_backdrop example. I am checking the bug that occurred in ViewportNode.
I think we will need to make this inversion in the TextureNode, otherwise we will have an inconsistency problem.

The current code works correctly in webgpu_shadertoy and gives the expected result in both backends,
Let's use this visual reference as test:

material.colorNode = Nodes.viewportTopLeft;

Expected/Current	PR

[aardgoose]

rebased on fixed viewport code

[sunag]

Thanks!