The ``Surface'' Menu

 

  
Figure 4.16: Surface Menu

The global surface properties represent the material structure and colouring used for all objects that are shown in patch style and do not have their own surface properties.

The rendering of the graphics is done using the Phong light model (but normally with flat-shading or Gouraud-shading). You may edit all the material-dependent parameters here while the light-sources are edited in the light-menu. This menu allows to change the global values; each scene can have local surface-properties which are edited in the manag-menu.

Note that some machines do not have the ability to reproduce the colours in sufficient resolution; you will see the gradation of colours on an object, which has a bad effect on the degree of reality.

The colors are edited with the GRAPE standard color-editor which supports both RGB and HSV model, HSV is some sort of polar coordinates for the RGB color cube, switch the color model by pressing the -Button. The current color is displayed in a rectangle. Note that ambient, diffuse and specular reflection are scaled with the lightsource's color: if their values are blue and the lights are green the result is black. If the diffuse reflection is 50one lightsource with 50is 50

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these buttons open file selectors which give you the uniue opportunity to load and save SUrface PROPerties.

resets the surface property to the default values but not background and linecolor, the button will be inactive if there is nothing to reset. Background and line color will not be reseted.

These rulers control the object's emission colour. Increasing the component values makes the surface more and more look like glowing.

The ambient colour controls the appearance of the surface in shadowy regions. Remeber again, that no real shadows or reflections are used so shadowy means in a bad angle to the light sources.

The diffuse colour influences those parts of the surface that are front-faced to any light source.

The specular colour effects the highlights on the surface, namely the small spots where the light sources shine very directly on it. The highlights' size is also controlled by the shinyness parameter:

An object's opacity value determines how much can be seen through it. The default value is 1.0, which means that the object is fully opaque, whereas a value of 0.0 indicates complete transparency. In simple situations you can achieve reasonable results using transparency, but be careful using this ruler, because current graphics hardware is not fully capable of rendering complex scenes containing transparent objects.

Values for this parameter range from 0 to 59. It describes the inverse size of the highlights.

, ,

these buttons open additional color editors for the global background, linecolor and textcolor settings respectively. Press to close them.

invert the global background, linecolor and textcolor settings: use this feature to get a good preview and appropriate settings for PostScript output, where the background will be white paper.