Function ShowExampleAppCustomRendering

lib/imgui/imgui_demo.cpp:4441–4611

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.
    // 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!
    ImDrawList* draw_list = ImGui::GetWindowDrawList();

    if (ImGui::BeginTabBar("##TabBar"))
    {
        // Primitives
        if (ImGui::BeginTabItem("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 ImVec4 colf = ImVec4(1.0f, 1.0f, 0.4f, 1.0f);
            ImGui::PushItemWidth(-ImGui::GetFontSize() * 10);
            ImGui::DragFloat("Size", &sz, 0.2f, 2.0f, 72.0f, "%.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);
            if (ImGui::SliderInt("Circle segments", &circle_segments_override_v, 3, 40))
                circle_segments_override = true;
            ImGui::ColorEdit4("Color", &colf.x);
            const ImVec2 p = ImGui::GetCursorScreenPos();
            const ImU32 col = ImColor(colf);
            const float spacing = 10.0f;
            const ImDrawCornerFlags corners_none = 0;
            const ImDrawCornerFlags corners_all = ImDrawCornerFlags_All;
            const ImDrawCornerFlags corners_tl_br = ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_BotRight;
            const int circle_segments = circle_segments_override ? circle_segments_override_v : 0;
            float x = p.x + 4.0f, y = p.y + 4.0f;
            for (int n = 0; n < 2; n++)
            {
                // First line uses a thickness of 1.0f, second line uses the configurable thickness
                float th = (n == 0) ? 1.0f : thickness;
                draw_list->AddNgon(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, ngon_sides, th);         x += sz + spacing;  // N-gon
                draw_list->AddCircle(ImVec2(x + sz*0.5f, y + sz*0.5f), sz*0.5f, col, circle_segments, th);  x += sz + spacing;  // Circle
                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 0.0f,  corners_none, th);     x += sz + spacing;  // Square
                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f, corners_all, th);      x += sz + spacing;  // Square with all rounded corners
                draw_list->AddRect(ImVec2(x, y), ImVec2(x + sz, y + sz), col, 10.0f, corners_tl_br, th);    x += sz + spacing;  // Square with two rounded corners
                draw_list->AddTriangle(ImVec2(x+sz*0.5f,y), ImVec2(x+sz, y+sz-0.5f), ImVec2(x, y+sz-0.5f), col, th);      x += sz + spacing;      // Triangle
                draw_list->AddTriangle(ImVec2(x+sz*0.2f,y), ImVec2(x, y+sz-0.5f), ImVec2(x+sz*0.4f, y+sz-0.5f), col, th); x += sz*0.4f + spacing; // Thin triangle
                draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y), col, th);                               x += sz + spacing;  // Horizontal line (note: drawing a filled rectangle will be faster!)
                draw_list->AddLine(ImVec2(x, y), ImVec2(x, y + sz), col, th);                               x += spacing;       // Vertical line (note: drawing a filled rectangle will be faster!)
                draw_list->AddLine(ImVec2(x, y), ImVec2(x + sz, y + sz), col, th);                          x += sz + spacing;  // Diagonal line
                draw_list->AddBezierCurve(ImVec2(x, y), ImVec2(x + sz*1.3f, y + sz*0.3f), ImVec2(x + sz - sz*1.3f, y + sz - sz*0.3f), ImVec2(x + sz, y + sz), col, th);
                x = p.x + 4;