Gradients with ImGUI

gistfile1.txt

void gradient_rect( ImDrawList* list, const ImVec2& p_min, const ImVec2& p_max,
                    ImU32 col_top, ImU32 col_bottom, float rounding,
                    ImDrawFlags flags )
{
    /*
     * "It’s also that AddRectFilledMultiColor() doesn’t even support rounding.
     * In the event your shape could fill the window without requiring clipping
     * (which is always rectangular) you could use AddRectFilled() with rounding
     * and white color + the ShadeVertsLinearColorGradientKeepAlpha() function."
     * - ocornut
     * (https://github.com/ocornut/imgui/issues/6652#issuecomment-1653173953)
     */
    const ImRect bb( p_min, p_max );
    int vert_start_idx = list->VtxBuffer.Size;
    list->AddRectFilled( bb.Min, bb.Max, col_top, rounding, flags );
    int vert_end_idx = list->VtxBuffer.Size;
    ShadeVertsLinearColorGradientKeepAlpha( list, vert_start_idx, vert_end_idx,
                                            bb.Min, bb.GetBL( ), col_top,
                                            col_bottom );
}