end segment of circle arc scissoring

[rollraw]

version: 1.82
branch: master

at first, i noticed that with dx9 renderer strokes are always anti-aliased even if imgui anti-aliasing is disabled
using following code in a fresh imgui example:

ImGui::GetStyle().AntiAliasedLines = false;
ImGui::GetStyle().AntiAliasedFill = false;
ImGui::GetStyle().AntiAliasedLinesUseTex = false;
ImGui::GetForegroundDrawList()->AddCircle({ 300, 600 }, 50.f, IM_COL32(243, 104, 224, 255), 12, 1.0f);

we will see this next with dx9:

and next with dx11:

i guess it could be related to bugs of dx9, because i tried to set dx9 renderstates to disable anti-aliasing but nothing changes

at second, circles (no sense filled/stroked) last segment looking scissored with magic '12' number as segments count (that will look for precached points), due to reduced segments count by 1 due to closed primitive drawing

[ocornut]

Thank you for the report.
There are two distinct issues there.

With dx9 renderer strokes are always anti-aliased even if imgui anti-aliasing is disabled

First question: even if it was fully the case, would you have an issue with it?
I did that

ImGui::GetStyle().AntiAliasedLines = ImGui::GetIO().KeyShift;
ImGui::GetStyle().AntiAliasedFill = ImGui::GetIO().KeyShift;
ImGui::GetStyle().AntiAliasedLinesUseTex = ImGui::GetIO().KeyShift;

It doesn't look particularly "more" anti-aliased but I think the perception might vary depending on colors.

However it is possible there is something else in your app, e.g. multi-sample AA done by the app or by the GPU driver could alter that perception.

About the circle missing one segment:
Confirmed. I'm quite confused as 89685b3 (for 1.75) was explicitly intended to fix something and it appears it did the opposite. I think possibly the fix made sense before we switched to the new adaptive algorithm in 1.78 or a further change? Tagging @thedmd (or I'll check next time when I get back from holidays).

[thedmd]

@ocornut I will take a closer look at the missing circle segment.

[thedmd]

@ocornut It is fixed on PR. I think this is how it should be from the begging, not patching AddCircle was my oversight.

Commit and PR have an extra comment, which I hope make the change clear.

[rollraw]

However it is possible there is something else in your app, e.g. multi-sample AA done by the app or by the GPU driver could alter that perception.

it's not a my own app, just imgui example from latest commit, i also tried to explicitely disable multisample AA with

presentParams.MultiSampleType = D3DMULTISAMPLE_NONE;
presentParams.MultiSampleQuality = 0UL;

in the d3d device creation, but seems it doesnt helped, so yes could be related to gpu/drivers, but weird it happens only with dx9

[thedmd]

Is AA forced in driver settings?

[rollraw]

Is AA forced in driver settings?

you're right, found in nvidia docs about this, overriding of application antialising working only till dx10, it's so weird but ok i'm calm now

[ocornut]

Should be fixed by cb00972
Thanks @thedmd !