Pixel perfect text with multisampling about imgui HOT 9 CLOSED

Have you tried offsetting your orthogonal projection matrix by half a pixel instead?

I'm looking at the 0.375 trick and will add it as a suggestion in the comments.

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Ok. Without any changes to the library code, offsetting my projection matrix by half a pixel (0.375)
does work too. Offsetting by 0.5 doesn't work on my hardware though.

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I have added the following comment (or variants) in four places:

• In the header of imgui.cpp in the 'getting started' section.
• In the OpenGL and DirectX sample, above the render function.
• In the README file that is shown on the web page in the 'FAQ' section.

"
if text or lines are blurry when integrating ImGui in your engine:
- try adjusting ImGui::GetIO().PixelCenterOffset to 0.0f or 0.5f
- in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
"

I believe it should solve the problem for other users. What do you think?

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I actually noticed some blurry line in one of the engine I am testing on. It looks like the code could be:

// Align to be pixel perfect
pos.x = (float)(int)pos.x;
pos.y = (float)(int)pos.y;

And single pixel horizontal/vertical lines are sometimes misplaced. I am working on this now but it is a bit tricky testing on 5 codebase/renderers.

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Yeah I got some blurry lines on graph lines and column lines, to mention a few.

But I fixed it somehow, see screenshot below.
What I do is:

• Fix blurry lines with vtx_write->pos.xy = (float)(int)(vtx_write->pos.xy + 0.375f); in ImDrawList::AddVtx
• Use orthographic projection without offset
• Set PixelCenterOffset to 0.0
• Do gl_Position = projection * vec4(round(position), 0.0, 1.0); in GLSL shader.

The last line could be done without shaders by rounding all vertices before submitting them. I'm sure this will break on some other machine though.

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lightbits: could you disable "no border" in Window Options and post a screenshot of the output using your renderer? thanks. it's pretty messy here.

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Sure, with same setup as I described above:

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I'm having a hard time getting those rectangle outline to be perfect on all sort of renderers, with super sampling etc enabled. (they are rendered using 2 triangles per line, not using line primitives so I can merge draw calls)
I've got a sort of working formula on my 5 test suites here but I don't quite understand the reasonning behind it, which is a sign that it's probably not correct.

I think I will obsolete the "bordered" mode anyway because it is just ugly, but it is a convenient way to test the correctness of pixel accurate drawing so I am keeping it while I'm fixing those things.

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I have committed the code that you tested following our twitter exchange. I think the library should support renderer using multisampling better now. Unfortunately I broke some of the settings for previous users so they may have to change PixelCenterOffset or their projection matrix after updating.

To make sure it is working for you could you confirm that you can continue user ImGui with a vanilla copy of the code? (with only changes applied to user-side code)

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