Updating Shader to version 4.0

[perminder-17]

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[perminder-17]

This is still a work in progress PR

[github-actions]

Here are the build results
Avogadro2.AppImage
Win64.exe
Artifacts will only be retained for 90 days.

[github-actions]

Here are the build results
Avogadro2.AppImage
Win64.exe
Artifacts will only be retained for 90 days.

[github-actions]

Here are the build results
Avogadro2.AppImage
Win64.exe
Artifacts will only be retained for 90 days.

[ghutchis]

Please check the following patch. I get a bunch of errors from the shaders on my Mac, because texture2D is renamed to texture:
texture.patch

Nothing renders yet, but it also doesn't crash, which is a good start. 😄

[perminder-17]

Please check the following patch. I get a bunch of errors from the shaders on my Mac, because texture2D is renamed to texture: texture.patch

Nothing renders yet, but it also doesn't crash, which is a good start. 😄

Hmmm....good catch. I will fix it now.

I thought texture2D() is fully removed in WEBGL and texture2D() is only depricated in OPENGL new versions. Anyways, fixing it now. Thanks

[github-actions]

Here are the build results
Avogadro2.AppImage
Win64.exe
Artifacts will only be retained for 90 days.

[ghutchis]

Any "deprecated" OpenGL code is not allowed in OpenGL Core Profile.

So the trick is looking around for deprecated code.

[perminder-17]

Any "deprecated" OpenGL code is not allowed in OpenGL Core Profile.

So the trick is looking around for deprecated code.

Everything else in the code looks fine to me. Is there anything else that appears deprecated maybe?

[ghutchis]

@cryos - any ideas? In combination with OpenChemistry/avogadroapp#497 the shaders compile and link completely.

But we don't see anything rendered in the widget.

[cryos]

@cryos - any ideas? In combination with OpenChemistry/avogadroapp#497 the shaders compile and link completely.

But we don't see anything rendered in the widget.

Shaders are finicky, it would be looking at runtime issues, quirks or errors in updating. I had something pretty close to this but yeah I wasn't getting things to render correctly over a year back. I think the outColor versus gl_FragColor needs to be handled properly, I don't really see where outColor gets hooked up to anything, but it has been a while since I looked at this.

I don't see any discussion of the handling of the fragment color in this PR or the commits.

[ghutchis]

Thanks - @perminder-17 also got some feedback in the OpenGL community forum .. core profile requires VAO - vertex array objects: https://www.khronos.org/opengl/wiki/Tutorial2:_VAOs,_VBOs,_Vertex_and_Fragment_Shaders_(C_/_SDL)

There seems to be some other bits that need modernization (e.g., arrow*) but I think the VAO is the main missing piece.

[perminder-17]

Thankyou so much @cryos for your thoughts.

I think the outColor versus gl_FragColor needs to be handled properly, I don't really see where outColor gets hooked up to anything,

I'm really sorry if I'm not referring to the same thing, but what I feel is:

We can associate fragment shader outputs with colour attachments using a layout directive,
For e.g.

layout(location=0) out vec4 outColor;

Also, the same thing can happen in the CPU too by glBindFragDataLocation which should be called prior to linking.

If a shader statically assigns a location to a varying out variable in the shader text, that location is used and any location assigned with glBindFragDataLocation is ignored.
Reference: https://registry.khronos.org/OpenGL-Refpages/gl4/html/glBindFragDataLocationIndexed.xhtml

But since we're using a single colour attachment (i.e. replacing gl_FragColor rather than gl_FragData), is it necessary to explicitly specify the attachment? as any output variable defaults to attachment zero?