Immediate-Mode—The Heidi® immediate-mode drawing interface (as opposed to a display-list system such as HOOPS®) is preferred by applications and graphics board developers who have their own graphics or geometry database.
Geometry—A primitive-based API incurs less function-call overhead than vertex-based APIs, such as OpenGL. Heidi supports dots, markers, polylines, polytriangles, polygons, ellipses, text, and images. Parametric surfaces, NURBS, and other geometric types are supported through application-specific toolkits.
Renderer Architecture—The ability to invoke and interconnect multiple renderers at run time is a key Heidi feature. Renderers are dynamically loaded. This allows an application to load only those renderers it needs and to load new renderers while the application is running (at the user's request, for example). New renderers can be added to an application without recompiling. Users can purchase renderers with additional capabilities from third-party vendors and use them in any Heidi-based application. Renderers are connected to each other so the advantages of each can be combined into one rendering system. The "stackable renderer architecture" is a patented feature of Heidi.
Hardware Acceleration—Heidi takes advantage of hardware acceleration either through standard interfaces, such as OpenGL and Direct 3D, or by direct hardware access to specialized 3D chips.
Hardcopy Programming Interface—The Heidi Device Interface, HDI, provides manufacturers and developers a complete environment for creating immediate-mode drivers for Hardcopy output from graphics software. It is the same interface used in the AutoCAD® plotting. Heidi software also supports Microsoft's Windows System Printer Driver plus an optimized version, clipboard and metafile, and specific drivers for GDI, HPGL, HPGL2, Postscript and Raster.
Visualization, Lighting, and Shading—Heidi supports flat and Gouraud color contouring. It also supports transparency, complex texture mapping, and diffuse, gloss, and specular materials. Point, directional, spot, and ambient light sources are fully supported. Heidi allows developers to implement shadows, extended material properties, ray tracing, radiosity, and other special effects.
Viewing and Modeling—Heidi supports multiple views, orthographic, perspective and skewed projections, object scaling, rotation and translation, camera pan, zoom, dolly, orbit, roll, and the new DWF Viewer architecture.
Color Models—Heidi supports RGB and indexed color modes. It provides color palette management and allows colormap sharing.
Shape Engines—The plug-in renderer mechanism in Heidi allows applications to implement specific kinds of draw commands called engines. A noteworthy example is the GDI font engine that can be used to manage TrueType fonts throughout the graphics pipeline.
Selection—Heidi implements 2D and 3D geometric primitive selection (picking) through dynamically loadable proximity, area, and polygonal selection renderers.