Function ShowExampleAppCustomRendering

core/src/imgui/imgui_demo.cpp:7204–7438

Demonstrate using the low-level ImDrawList to draw custom shapes.

// Demonstrate using the low-level ImDrawList to draw custom shapes.
static void ShowExampleAppCustomRendering(bool* p_open)
{
    if (!ImGui::Begin("Example: Custom rendering", p_open))
    {
        ImGui::End();
        return;
    }

    // Tip: If you do a lot of custom rendering, you probably want to use your own geometrical types and benefit of
    // overloaded operators, etc. Define IM_VEC2_CLASS_EXTRA in imconfig.h to create implicit conversions between your
    // types and ImVec2/ImVec4. Dear ImGui defines overloaded operators but they are internal to imgui.cpp and not
    // exposed outside (to avoid messing with your types) In this example we are not using the maths operators!

    if (ImGui::BeginTabBar("##TabBar"))
    {
        if (ImGui::BeginTabItem("Primitives"))
        {
            ImGui::PushItemWidth(-ImGui::GetFontSize() * 15);
            ImDrawList* draw_list = ImGui::GetWindowDrawList();

            // Draw gradients
            // (note that those are currently exacerbating our sRGB/Linear issues)
            // Calling ImGui::GetColorU32() multiplies the given colors by the current Style Alpha, but you may pass the IM_COL32() directly as well..
            ImGui::Text("Gradients");
            ImVec2 gradient_size = ImVec2(ImGui::CalcItemWidth(), ImGui::GetFrameHeight());
            {
                ImVec2 p0 = ImGui::GetCursorScreenPos();
                ImVec2 p1 = ImVec2(p0.x + gradient_size.x, p0.y + gradient_size.y);
                ImU32 col_a = ImGui::GetColorU32(IM_COL32(0, 0, 0, 255));
                ImU32 col_b = ImGui::GetColorU32(IM_COL32(255, 255, 255, 255));
                draw_list->AddRectFilledMultiColor(p0, p1, col_a, col_b, col_b, col_a);
                ImGui::InvisibleButton("##gradient1", gradient_size);
            }
            {
                ImVec2 p0 = ImGui::GetCursorScreenPos();
                ImVec2 p1 = ImVec2(p0.x + gradient_size.x, p0.y + gradient_size.y);
                ImU32 col_a = ImGui::GetColorU32(IM_COL32(0, 255, 0, 255));
                ImU32 col_b = ImGui::GetColorU32(IM_COL32(255, 0, 0, 255));
                draw_list->AddRectFilledMultiColor(p0, p1, col_a, col_b, col_b, col_a);
                ImGui::InvisibleButton("##gradient2", gradient_size);
            }

            // Draw a bunch of primitives
            ImGui::Text("All primitives");
            static float sz = 36.0f;
            static float thickness = 3.0f;
            static int ngon_sides = 6;
            static bool circle_segments_override = false;
            static int circle_segments_override_v = 12;
            static bool curve_segments_override = false;
            static int curve_segments_override_v = 8;
            static ImVec4 colf = ImVec4(1.0f, 1.0f, 0.4f, 1.0f);
            ImGui::DragFloat("Size", &sz, 0.2f, 2.0f, 100.0f, "%.0f");
            ImGui::DragFloat("Thickness", &thickness, 0.05f, 1.0f, 8.0f, "%.02f");
            ImGui::SliderInt("N-gon sides", &ngon_sides, 3, 12);
            ImGui::Checkbox("##circlesegmentoverride", &circle_segments_override);
            ImGui::SameLine(0.0f, ImGui::GetStyle().ItemInnerSpacing.x);
            circle_segments_override |= ImGui::SliderInt("Circle segments override", &circle_segments_override_v, 3, 40);