4.2.1 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, OpenGL). Function alphadef specify the default value of alpha-channel. Finally, function transptype set the kind of transparency. See section Transparency and lighting, for sample code and picture.

MGL command: alpha [val=on]

Method on mglGraph: void 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. Default value is transparency off.

MGL command: alphadef val

Method on mglGraph: void SetAlphaDef (mreal val)

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

Sets default value of alpha channel (transparency) for all plotting functions. Initial value is 0.5.

MGL command: transptype val

Method on mglGraph: void SetTranspType (int type)

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

Set the type of transparency. Possible values are:

• 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 Types of transparency, for sample code and picture..

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