Method PathArcTo

src/imgui/imgui_draw.cpp:1258–1306

}

void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments)
{
    if (radius < 0.5f)
    {
        _Path.push_back(center);
        return;
    }

    if (num_segments > 0)
    {
        _PathArcToN(center, radius, a_min, a_max, num_segments);
        return;
    }

    // Automatic segment count
    if (radius <= _Data->ArcFastRadiusCutoff)
    {
        const bool a_is_reverse = a_max < a_min;

        // We are going to use precomputed values for mid samples.
        // Determine first and last sample in lookup table that belong to the arc.
        const float a_min_sample_f = IM_DRAWLIST_ARCFAST_SAMPLE_MAX * a_min / (IM_PI * 2.0f);
        const float a_max_sample_f = IM_DRAWLIST_ARCFAST_SAMPLE_MAX * a_max / (IM_PI * 2.0f);

        const int a_min_sample = a_is_reverse ? (int)ImFloor(a_min_sample_f) : (int)ImCeil(a_min_sample_f);
        const int a_max_sample = a_is_reverse ? (int)ImCeil(a_max_sample_f) : (int)ImFloor(a_max_sample_f);
        const int a_mid_samples = a_is_reverse ? ImMax(a_min_sample - a_max_sample, 0) : ImMax(a_max_sample - a_min_sample, 0);

        const float a_min_segment_angle = a_min_sample * IM_PI * 2.0f / IM_DRAWLIST_ARCFAST_SAMPLE_MAX;
        const float a_max_segment_angle = a_max_sample * IM_PI * 2.0f / IM_DRAWLIST_ARCFAST_SAMPLE_MAX;
        const bool a_emit_start = ImAbs(a_min_segment_angle - a_min) >= 1e-5f;
        const bool a_emit_end = ImAbs(a_max - a_max_segment_angle) >= 1e-5f;

        _Path.reserve(_Path.Size + (a_mid_samples + 1 + (a_emit_start ? 1 : 0) + (a_emit_end ? 1 : 0)));
        if (a_emit_start)
            _Path.push_back(ImVec2(center.x + ImCos(a_min) * radius, center.y + ImSin(a_min) * radius));
        if (a_mid_samples > 0)
            _PathArcToFastEx(center, radius, a_min_sample, a_max_sample, 0);
        if (a_emit_end)
            _Path.push_back(ImVec2(center.x + ImCos(a_max) * radius, center.y + ImSin(a_max) * radius));
    }
    else
    {
        const float arc_length = ImAbs(a_max - a_min);
        const int circle_segment_count = _CalcCircleAutoSegmentCount(radius);
        const int arc_segment_count = ImMax((int)ImCeil(circle_segment_count * arc_length / (IM_PI * 2.0f)), (int)(2.0f * IM_PI / arc_length));
        _PathArcToN(center, radius, a_min, a_max, arc_segment_count);
    }
}

void ImDrawList::PathEllipticalArcTo(const ImVec2& center, const ImVec2& radius, float rot, float a_min, float a_max, int num_segments)
{