3.1.1 Transparency

There are several functions and variables for setup transparency. The general function is Alpha() which switch on/off the transparency for overall plot. It influence only for graphics which created after Alpha() call (with one exception, mglGraphGL). Function SetAlphaDef specify the default value of alpha-channel. You may switch off transparency of selected plot by function SetTransparent. Finally, function SetTranspType set the kind of transparency. See section Transparent surface sample, for sample code and picture.

Method on mglGraph (C++, Python): bool Alpha (bool enable)

C function: void mgl_set_alpha (HMGL gr, int enable)

Sets the transparency on/off and returns previous value of transparency. It is recommended to call this function before any plotting command. In any case it must be called before Finish() function if the last is used. Default value is transparency off. Unfortunately it switches the transparency on/off for all subplots. Use SetTransparent(false) in particular plot to disable its transparency.

Method on mglGraph (C++, Python): void SetAlphaDef (float val)

C function: void mgl_set_alpha_default (HMGL gr, float alpha)

Sets default value of alpha channel (transparency) for all plotting functions. Note, that OpenGL (mglGraphGL) has incorrect drawing for large values of alpha in case of several overlapping surfaces.

Method on mglGraph (C++, Python): void SetTransparent (bool val)

C function: void mgl_set_transp (HMGL gr, int enable)

Flag which temporary switches transparency on/off for the plot. This is the same as Alpha(val) but more correctly work in mglGraphGL class.

Method on mglGraph (C++, Python): void SetTranspType (int type)

C function: void mgl_set_transp_type (HMGL gr, int enable)

Set the transparency type. Normal transparency (‘0’) – below things is less visible than upper ones. It does not look well in OpenGL mode (mglGraphGL) for several surfaces. Glass-like transparency (‘1’) – below and upper things are commutable and just decrease intensity of light by RGB channel. Lamp-like transparency (‘2’) – below and upper things are commutable and are the source of some additional light. I recommend to set SetAlphaDef(0.3) or less for lamp-like transparency. See section Normal transparency, Glass-like transparency, Lamp-like transparency.

Obsolete option of mglGraph: float AlphaDef

Default value of alpha channel. See SetAlphaDef().

Obsolete option of mglGraph: bool Transparent

Flag which temporary switches transparency on/off for the plot. See SetTransparent().

Obsolete option of mglGraph: int TranspType

This variable set the transparency type. See SetTranspType().