Drawn Object Appearance

These functions control how a graphically drawn object is rendered, i.e., how it appears in the graphics window.

public  void  G_set_shaded_state(
    Gwindow      window,
    BOOLEAN      state )

If the shaded state is TRUE, then polygons and quadmeshes are drawn as solid, shaded surfaces. Otherwise, only a wireframe outline is drawn for these objects. The default value is FALSE.

public  void  G_set_shading_type(
    Gwindow        window,
    Shading_types  type )

This function sets the method of interpolation of colours across a polygon or quadmesh. If a value of FLAT_SHADING is specified, then the interpolation is flat and discontinuous across polygon boundaries. If a value of GOURAUD_SHADING is specified, then the interpolation is smooth and continuous across polygon boundaries. GOURAUD_SHADING generally produces more pleasing results and is the default.

public  void  G_set_lighting_state(
    Gwindow      window,
    BOOLEAN      state )

This function enables or disables the use of lighting in the colour computation. If lighting is enabled, then the colours of objects are computed based on the object position and the states and colours of the defined lights. Otherwise, the object is shown in the colour specified when it is drawn. The default value is TRUE.

public  void  G_backface_culling_state(
    Gwindow     window,
    BOOLEAN     state )

This function enables or disables backface culling. When enabled, parts of objects which are not facing the viewer are not drawn. This is useful for systems which do not have a depth buffer with which to correctly perform occlusion. However, backface culling only works well for closed, convex surfaces, such as spheres or cubes. The default value is FALSE.

public  void  G_set_transparency_state(
    Gwindow        window,
    BOOLEAN        state )

Enables or disables the display of transparent surfaces. If enabled, objects that are drawn on top of other objects will be displayed as a composite based on the opacity of both objects. If disabled, the opacity of objects will be ignored, and the colour at any position in the window is based solely on the colour of the object that is on top. The default value is FALSE.